WO1999054453A1 - Novel genetically modified lactic acid bacteria having modified diacetyl reductase activities - Google Patents
Novel genetically modified lactic acid bacteria having modified diacetyl reductase activities Download PDFInfo
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- WO1999054453A1 WO1999054453A1 PCT/DK1999/000218 DK9900218W WO9954453A1 WO 1999054453 A1 WO1999054453 A1 WO 1999054453A1 DK 9900218 W DK9900218 W DK 9900218W WO 9954453 A1 WO9954453 A1 WO 9954453A1
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- C—CHEMISTRY; METALLURGY
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- C12N15/09—Recombinant DNA-technology
- C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
- C12N15/74—Vectors or expression systems specially adapted for prokaryotic hosts other than E. coli, e.g. Lactobacillus, Micromonospora
- C12N15/746—Vectors or expression systems specially adapted for prokaryotic hosts other than E. coli, e.g. Lactobacillus, Micromonospora for lactic acid bacteria (Streptococcus; Lactococcus; Lactobacillus; Pediococcus; Enterococcus; Leuconostoc; Propionibacterium; Bifidobacterium; Sporolactobacillus)
Definitions
- the present invention relates to the field of manufacturing food products by means of lactic acid bacterial cultures.
- the invention provides novel genetically modified strains of lactic acid bacteria that are modified to have enhanced or reduced diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity.
- modified bacteria are particularly useful in the manufacturing of food products having either a reduced or an increased content of the flavour compound diacetyl.
- Lactic acid bacteria are used extensively as starter cultures in the food industry in the manufacturing of fermented products including milk products such as e.g. yoghurt and cheese, meat products, bakery products, wine and vegetable products. Lactococcus species including Lactococcus lactis are among the most commonly used lactic acid bacteria in dairy starter cultures. Several other lactic acid bacteria such as Leuconostoc species, Pediococcus species, Lactobacillus species, Oenococcus species and Streptococcus species are also commonly used in food starter cultures.
- lactic acid bacterial starter culture When a lactic acid bacterial starter culture is added to milk or any other food product starting material under appropriate conditions, the bacteria grow rapidly with concomitant conversion of citrate, lactose or other sugar compounds into lactic acid/lactate and possibly other acids including acetate, resulting in a pH decrease.
- metabolites include ethanol, formate, acetaldehyde, ⁇ -acetolactate, acetoin, diacetyl, carbon dioxide and 2,3 butylene glycol (butanediol) . 2
- diacetyl (2,3-butanedione) is an essential flavour compound in dairy products such as butter, yoghurt, starter distillate, margarine, buttermilk and cheese.
- dairy products such as butter, yoghurt, starter distillate, margarine, buttermilk and cheese.
- other products such as fruit juices, beers and wines
- the compound is formed during fermentation of lactic acid bacterial species of e.g. Lactococcus, Leuconostoc and Lactobacillus by an oxidative decarboxylation of ⁇ -acetolactate which is formed from two molecules of pyruvate by the action of ⁇ -acetolactate synthase (ALS) .
- lactic acid bacterial species e.g. Lactococcus, Leuconostoc and Lactobacillus
- Diacetyl reducing enzymes commonly termed diacetyl reductases (DR) (acetoin:NAD oxidoreductases E.C. 1 .1 .1 .5), have been observed from many different sources, notably animal tissues (Provecho et al., 1 984), bacteria including Lactococcus (formerly Streptococcus) lactis (Crow, 1 990; Arora et al., 1 978), Bacillus species and Enterobacter species (Giovannini et al. 1 996), and yeast (Gibson et al., 1 991 ) . Boumerdassi et al.
- DR diacetyl reductases
- DR diacetyl reductase
- DR encompasses several enzymatic activities such as diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity which carry out the following enzymatic reactions; diacetyl + NAD(P)H — > acetoin + NAD(P) + , acetoin + NAD(P)H ⁇ --- > butanediol + NAD(P) + , respectively.
- L. lactis has been reported to possess two diacetyl reductases with activity for both diacetyl and acetoin. Both of these enzymes use NADH as cofactor (Crow, 1 990).
- Leuconostoc species including Leu. pseudomesenteroides are typically used in mixed starter cultures together with Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. lactis biovar. diacetylactis in the production of dairy products.
- a significant role of Leuconostoc species in such mixed cultures is to remove the acetaldehyde produced by the accompanying strains e.g. in the production of buttermilk and fresh cheeses.
- Leuconostoc strains will also remove diacetyl by reducing it into 3
- acetoin and/or butanediol a characteristic that is generally undesirable in the production of dairy products.
- the enzyme responsible for the reduction of diacetyl, diacetyl reductase is highly expressed in Leuconostoc species such as Leu. pseudomesente- roides which species is known to have about 100 times higher diacetyl reductase activity than L. lactis.
- one primary objective of the present invention is to provide lactic acid bacterial cultures of species, including Leuconostoc species, that inherently have one or more DR activities which, relative to the naturally occurring strains, has reduced or substantially eliminated DR activities under specific cofactor conditions.
- Another objective of the invention is to provide lactic acid bacterial strain that, relative to the presently available strains, has a strongly enhanced DR activities. Using such strains which utilise diacetyl as a substrate it is possible to reduce or remove diacetyl in food products where the presence of this flavour compound is undesirable.
- the invention provides in a first aspect a genetically modified lactic acid bacterium, including the Leuconostoc pseudomesenteroides strains DSM 1 2099 and DSM 1 2465 and lactic acid bacteria essentially having the diacetyl reductase characteristics of these strains, that, relative to the lactic acid bacterium from which it is derived, is modified to have a reduction of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, said modified bacterium,
- the bacterium prior to being modified is capable of having at least one of said enzymatic activities under said cofactor conditions.
- the invention relates to a genetically modified lactic acid bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have a reduction of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, including the Leuconostoc pseudomesentero- ides strains DSM 1 2099 and DSM 1 2465 and lactic acid bacteria essentially having the diacetyl reductase characteristics of these strains, subject to the limitation, that the lactic acid bacterium is not Lactococcus lactis.
- the invention relates to a genetically modified lactic acid bacterium that has no detectable diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity, subject to the limitation, that the lactic acid bacterium is not Lactococcus lactis.
- the invention relates to a genetically modified lactic acid bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have an enhancement of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity which is at least 1 0 5
- Lactococcus lactis subsp. lactis strain DSM 1 2096 and lactic acid bacteria essentially having the diacetyl reductase characteristics of that strain.
- the invention pertains to a starter culture composition comprising such a genetically modified bacterium.
- a method of preparing a fermented food product comprising adding an effective amount of a bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have a reduction of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, or a composition comprising such a bacterium to a food product starting material wherein the bacterium or the composition is incapable of having at least one enzymatic activity selected from the group consisting of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity and keeping the starting material under conditions where the bacterium or the starter culture composition is capable of fermenting said starting material to obtain the fermented food, and a fermented food product obtainable by such a method which product has a content of diacetyl which is at least 1 0% higher than that of a
- the invention relates to a method of producing a food product, comprising adding an effective amount of a bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have an enhancement of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, or a composition comprising such a bacterium to a food product starting material that contains at least one of diacetyl, acetoin and butanediol, and keeping the starting material under conditions where the genetically modified lactic acid bacterium has at least one enzymatic activity selected from the group consisting of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity to obtain a product having a reduced content of diacetyl.
- the genetically modified lactic acid bacterium is a bacterium that, relative to the lactic acid bacterium from which it is derived, is modified so as to have a reduction of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, said bacterium, when grown under at least one of the above cofactor conditions, where the bacterium prior to being mutated is capable of having at least one of said enzymatic activities, is substantially incapable of at least one of said activities.
- the term "substantially incapable" indicates that the respective enzymatic activities can not be detected by the assay procedures described herein.
- lactic acid bacterium refers to a group of gram- positive, microaerophilic or anaerobic bacteria having in common the ability to ferment sugars and citrate with the production of acids including lactic acid as the predominantly produced acid, acetic acid, formic acid and propionic acid.
- the industrially most useful lactic acid bacteria are found among Lactococcus species, Streptococcus species, Lactobacillus species, Leuconostoc species, Oenococcus species and Pediococcus species.
- the strict anaerobes belonging to the genus Bifidobacterium is generally included in the group of lactic acid bacteria as these organisms also produce lactic acid and are used as starter cultures in the production of dairy products.
- genetic modification can be based on construction or selection of mutants of lactic acid bacteria or it can be based on recombinant DNA-technology.
- diacetyl reductase or “DR” is used herein it refers to any of the three mentioned specific activities, i.e. diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity.
- mutant is used in the conventional meaning of that term i.e. it refers to strains obtained by subjecting a lactic acid bacterial strain to any conventionally used mutagenization treatment including treatment with a chemical mutagen such as ethanemethane sulphonate (EMS) or N-methyl-N'-nitro-N-nitroguanidine (NTG), UV light or to spontaneously occurring mutants which are selected on the basis of a modified DR activity.
- EMS ethanemethane sulphonate
- NGT N-methyl-N'-nitro-N-nitroguanidine
- UV light or to spontaneously occurring mutants which are selected on the basis of a modified DR activity.
- mutants of lactic acid bacteria can be provided by such technology including site-directed mutagenesis and PCR techniques and other in vitro or in vivo modifications of DNA sequences coding for DR activities or sequences regulating the expression of genes coding for the DR activities, once such sequences have been identified and isolated.
- genetically modified bacteria according to the invention by conventional recombinant DNA-technology including insertion of sequences coding for DR activities, e.g. by replacing a native promoter for such coding sequences by a foreign promoter which either enhances or reduces the expression of the coding sequences. It is also possible to derive lactic acid bacterial strains according to the invention from species that do not have an inherent capability to produce DR activities by inserting genes coding for such activities isolated from a different organism comprising such genes. The source of such genes may be bacterial species, yeast species or mammal species. Additionally, it is envisaged that genetically modified bacteria according to the invention can be constructed by modifying metabolic pathways in a lactic acid bacterium that are not directly involved in DR pathways.
- under cofactor conditions indicates the absence/presence in an appropriate medium of any non-protein substance required for biological activity of any of the enzyme activities according to the invention, such as NAD + , NADH, NADP + and NADPH.
- a genetically modified bacterium having a reduced diacetyl activity can be selected from any kind of lactic acid bacterial species which has an inherent DR activity, including Lactococcus spp., Streptococcus spp., Lactobacillus spp., Leuconostoc spp 8
- the invention relates in another aspect to a genetically modified lactic acid bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have a reduction of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, including the Leuconostoc pseudomesenteroides strains DSM 1 2099 and DSM 1 2465 and lactic acid bacteria essentially having the diacetyl reductase characteristics of these strains, subject to the limitation that the modified bacterium is not Lactococcus lactis.
- the above genetically modified bacterium is one that under cofactor conditions, where the bacterium prior to being genetically modified is capable of having at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity, is substantially incapable of at least one of said enzymatic activities.
- Such a bacterium includes a bacterium that is substantially incapable of at least one of diacetyl reductase activity and acetoin reductase activity in a medium containing NADH and not containing NADPH, a bacterium that is substantially incapable of at least one of diacetyl reductase activity and acetoin reductase activity in a medium containing NADPH and not containing NADH, a bacterium that is substantially incapable of at least one of diacetyl reductase activity and acetoin reductase activity in a medium containing both NADH and NADPH, a bacterium that is substantially incapable of butanediol dehydrogenase activity in a medium containing NAD + and not containing NADP + , a bacterium that is substantially incapable of butanediol dehydrogenase activity in a medium containing NADP + and not containing NAD + and a bacterium that is substantially incapable of
- the invention provides a genetically modified lactic acid bacterium that has no detectable diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity.
- a genetically modified lactic acid bacterium that has no detectable diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity.
- Such a bacterium is selected from any of the 9
- lactic acid bacterial species subject to the limitation, that the bacterium is not Lactococcus lactis.
- a genetically modified bacterium having reduced or no detectable DR activities can be derived from any lactic acid bacterial species which has an inherent DR activity, including Lactococcus spp. such as Lactococcus lactis subsp. lactis biovar. diace- ty/actis and Lactococcus lactis subsp. lactis, Streptococcus spp. including Streptococcus thermophilus, Lactobacillus spp., Leuconostoc spp. including Leuconostoc pseudomesenteroides., Pediococcus spp.. Oenococcus spp. and Bifi- dobacterium spp.
- Lactococcus spp. such as Lactococcus lactis subsp. lactis biovar. diace- ty/actis and Lactococcus lactis subsp. lactis
- the modified bacterium has substantially no detectable DR activities
- a bacterium that is modified to have a reduction of one or more of the above activities is also encompassed by the invention.
- a useful bacterium according to the invention is one that has a reduction in any of the DR activities which, relative to the bacterium from which it is derived, is at least 25 % such as at least 50% including at least 75 % e.g. at least 90% .
- the genetically modified bacterium according to the invention preferably has a DR activity reduction which is reduced by at least 25 times for anyone of the enzymatic activities such as at least 50 times, including at least 100 times or even at least 500 times, relative to the strain from which it is derived.
- the resulting food product preferably has an increased content of diacetyl which is at least 1 .1 times higher, such as at least 2 times higher, including at least 5 times higher or even at least 1 0 times higher, relative to a similar food product which is fermented using the strain from which the modified strain is derived.
- the modified bacterium according to the invention is derived by subjecting a parent lactic acid bacterial strain that under appropriate cofactor 10
- conditions is capable of having diacetyl reductase activity, acetoin reductase activity and/or butanediol dehydrogenase activity to a mutagenization treatment and selecting a strain that is substantially incapable of at least one of said enzymatic activities under identical cofactor conditions.
- the present invention relates in a further aspect to a genetically modified lactic acid bacterium that, relative to the lactic acid bacterium from which it is derived, is modified to have an enhancement of at least one of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity which is at least 1 0 times, including the Lactococcus lactis subsp. lactis strain DSM 1 2096 and lactic acid bacteria essentially having the diacetyl reductase characteristics of that strain.
- the genetically modified bacterium according to the invention preferably has an activity enhancement which is at least 1 0 times for anyone of the enzymatic activities such as at least 50 times or even at least 1 00 times, relative to the strain from which it is derived.
- a genetically modified bacterium having enhanced DR activities can be derived from any lactic acid bacterial species which has an inherent DR activity, including Lactococcus spp. such as Lactococcus lactis subsp. lactis biovar. diacety/actis and Lactococcus lactis subsp. lactis, Streptococcus spp. including Streptococcus thermophilus, Lactobacillus spp., Leuconostoc spp. including Leuconostoc pseudomesenteroides. , Pediococcus spp. and Bifidobacterium spp.
- modified bacteria can be a spontaneous mutant or be provided by subjecting a lactic acid bacterium that has inherent DR activities to a mutagenization treatment as described above or by inactivating or deleting one or more genes involved in the expression of the DR activities using conventional recombinant DNA-technology.
- the genetically modified bacteria according to the invention are useful as starter cultures in the production of food products. Accordingly, in a further important aspect, the invention relates to a starter culture composition comprising a bacterium according to the invention either having enhanced or a reduced or eliminated DR activities.
- such a composition comprises the bacteria in a concentrated form including frozen, dried or freeze-dried concentrates typically having a concentration of viable cells which is in the range of 1 0 4 to 1 0 2 cfu per g including at least 10 4 cfu per gram of the composition, such as at least 1 0 5 cfu/g, e.g. at least 1 0 6 cfu/g, such as at least 10 7 cfu/g, e.g. at least 10 8 cfu/g, such as at least 1 0 9 cfu/g, e.g. at least 1 0 10 cfu/g, such as at least 1 0 1 1 cfu/g of the composition.
- the composition may as further components contain cryoprotectants and/or conventional additives including nutrients such as yeast extract, sugars and vitamins.
- the composition will in certain embodiments comprise a multiplicity of strains either belonging to the same species or belonging to different species.
- a typical example of such a useful combination of lactic acid bacteria in a starter culture composition is a mixture of a Leuconostoc spp. and one or more Lactococcus spp. such as Lactococcus lactis subsp. lactis or Lactococcus lactis subsp. lactis biovar. diacetylactis.
- Such a mixed culture can be used in the manufacturing of fermented milk products such as buttermilk and cheese.
- one or more of the strain components may be a modified bacterium according to the invention.
- a method comprises that an effective amount of such bacteria or a composition comprising the bacteria are added to a food product starting material wherein the bacterium or the composition is incapable of having at least one of the above DR enzymatic activities and keeping the starting material under conditions where the bacterium or the starter 1 2
- culture composition is capable of fermenting said starting material to obtain a fermented food product.
- Useful food product starting materials include any material which is conventionally subjected to a lactic acid bacterial fermentation step such as milk, vegetable materials, meat products, fruit juices, must, doughs and batters.
- the fermented products which are obtained by the method include as typical examples dairy products such as cheese including fresh cheese products, and buttermilk.
- the use in food starter cultures of bacteria according to the invention that have a reduced or lacking DR activity will result in final products having a content of the desired flavour compound diacetyl which is higher than would otherwise be obtained if a non-modified lactic acid bacterium was used. Accordingly, it is an important aspect of the invention to provide a fermented food product obtainable by the above method which product has a content of diacetyl which is at least 1 0% higher such as at least 20% higher or at least 30% higher than that of a product fermented under identical conditions with a parent strain for the genetically modified bacterium.
- Examples of such food products include milk-based products such as cheese and buttermilk, vegetable products, meat products, fruit juices, wines and bakery products.
- the mutant when used as a component of a mixed flavour-forming starter culture for the fermentation of one of the above starting materials, the mutant has a significant effect on the diacetyl stability during storage of the resulting fermented product.
- an advantageous feature of the fermented food product according to the invention is that the food product can be stored for several weeks with less reduction in the diacetyl content than is the case with a food product fermented under identical conditions with the parent strain of the genetically modified bacterium.
- the fermented product is one which at least 1 0% of its initial diacetyl content is retained after storage for 20 days or more at about 4°C. when stored under appropriate storage conditions, such as at least about 20% of its initial diacetyl content e.g. at least about 30% and preferably at least about 40% e.g. 1 3
- This method comprises adding an effective amount of a lactic acid bacterium that has been modified to have at least one increased DR activity or a composition containing such a bacterium to a food product starting material that contains at least one of diacetyl, acetoin and butanediol, and keeping the starting material under conditions where the genetically modified lactic acid bacterium has at least one enzymatic activity selected from the group consisting of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity to obtain a product having a reduced content of diacetyl.
- the products resulting from such a method have no detectable content of diacetyl.
- Fig. 1 shows native-PAGE gels containing cell free extracts of wild-type strain of Leu. pseudomesenteroides DB1 334.
- the gels were incubated with diacetyl + NADH (A); butanediol + NAD + (B); and acetoin + NADH (C), and stained with Meldola's blue and MTT. 2, 4, and 8 ⁇ g of protein, respectively were loaded onto each gel;
- Fig. 2 shows native-PAGE gels containing cell free extracts of wild-type strain of Leu. pseudomesenteroides DB1 334 and mutant strain MM084 stained with the zymogram technique. The gels were incubated with diacetyl + NADPH (A) or butanediol + 14
- Fig. 3 illustrates the diacetyl content in reconstituted skimmed milk fermented by the mixed cultures A and B during fermentation and storage.
- the reconstituted skimmed milk was fermented at 22 °C in non-shaken bottles and subsequently stored at 4°C, and
- Fig. 4 illustrates the diacetyl content in sour cream fermented with the mixed cultures C and D during fermentation and storage.
- the cream was fermented at 22 °C and subsequently stored at 4°C.
- Partially purified NADH-dependent diacetyl reductase from Leuconostoc pseudomesenteroides showed that the enzyme is responsible for at least three enzymatic reactions: (i) diacetyl + NADH — > acetoin + NAD + ; (ii) acetoin + NADH — > butanediol + NAD + ; and (iii) butanediol + NAD + — > acetoin + NADH.
- the enzymatic properties of diacetyl reductase were demonstrated by staining native PAGE gels using the zymogram technique as described in the following.
- the immobilised enzyme is allowed to react with a substrate and cofactor with a subsequent dye staining.
- the same technique was also used to screen an ethanemethane sulphonate (EMS) mutagenized Leu. pseudomesenteroides population for the absence of diacetyl reductase (butanediol dehydrogenase activity) activity by direct staining of colonies immobilised onto nitrocellulose membranes.
- EMS ethanemethane sulphonate
- Leu. pseudomesenteroides was cultivated in M 1 7 medium (Terzaghi & Sandine, 1 975) supplemented with 0.5% glucose at 25°C under anaerobic conditions.
- Leu. pseudomesenteroides was cultivated in 10 ml M 1 7 (0.5% glucose) for 3 days followed by cultivation for 1 20 minutes in the presence of 1 50 ⁇ l of EMS. After EMS treatment, 0.2 ml of the culture was inoculated into ten tubes each containing 1 0 ml of M 1 7 and incubated for 3 days for phenotypic expression. The mutation frequency was monitored by plating 0.1 ml from each tube onto M 1 7 plates containing 500 ⁇ g/ml of streptomycin.
- Tris-HCI gradient gels with Tris-Glycine (pH 8.3) as running buffer
- native-PAGE was run at 1 50 V for 2.5 hours. Staining of native gels was performed both with 0.25 % Coomassie brilliant blue in 1 0% acetic acid and 40% methanol and with the zymogram technique (see below) . SDS-PAGE was run using a 1 2% separation gel, 4% stacking gel and with Tris-Glycine (pH 8.3) as running buffer at 200 V for 45 minutes.
- Zymogram staining of native-PAGE gels for identification of diacetyl reductase activity and butanediol dehydrogenase activity was performed as follows: for diacetyl reductase activity the gel was incubated for 1 5 minutes with 1 2 mM diacetyl, 1 .5 mM NADH, 0.5 M Na-phosphate buffer (pH 6.1 ) and for butanediol dehydrogenase activity the gel was incubated for 1 5 minutes with 72 mM butanediol, 1 mM NAD + , 0.5 M Na-phosphate buffer.
- the gel was subsequently incubated for 30 minutes under dry conditions before the addition of a solution consisting of 0.02 mM Meldola's blue (8- Dimethylamino-2,3-benzophenoxazine) 0.8 mM MTT (3-[4,5-Dimethylthiazol-2-yl] 2,5- diphenyltetrazolium bromide; Thiazolyl blue) in 1 00 mM phosphate buffer (pH 8.2) (Provecho et al, 1 984; Gibson et al, 1 991 ) . Visible bands appeared within 20 minutes.
- Leu. pseudomesenteroides was cultivated in M 1 7 (0.5% glucose). The cells were harvested in the exponential growth phase by centrifugation at 6000 rpm for 1 5 minutes and washed in cold 50 mM Na-phosphate buffer (pH 6) . The pellet was 1 7
- Diacetyl reductase activity was measured spectrophotometrically by monitoring the oxidation of NADH at 340 nm in a reaction mixture with the following composition:
- Lactate dehydrogenase was measured by monitoring the oxidation of NADH at 340 nm in a reaction mixture with the following composition: 50 mM Tris-acetate buffer 20 (pH 6), 0.5 mM fructose-1 ,6-diphosphate, 25 mM pyruvate and 0.5 mM NADH.
- the specific enzymatic activities were expressed as micromoles of converted substrate per milligram of protein per minute (equivalent to units per milligram protein).
- Protein content was measured by using the BCA Protein Assay Reagent (Pierce) with bovine serum albumin as the standard.
- the enzyme converts diacetyl + NADH into acetoin + NAD + or acetoin + NADH into butanediol + NAD + .
- these reagents react with the reduced cofactor (NADH) and the gel becomes purple except where diacetyl reductase is located.
- the band corresponding to diacetyl reductase becomes colourless.
- Incubation with butanediol and NAD + results in the reverse result.
- Fig. 1 shows a native-PAGE gel incubated with different substrates and cofactors followed by staining with MTT and Meldola's blue.
- an EMS mutagenized DB1 334 population was screened by incubating the cells in a reaction mixture of butanediol + NAD + . Lysed cells with an intact diacetyl reductase (butanediol dehydrogenase activity) were stained purple whereas a diacetyl reductase (DR) mutant should become colourless. Approximately 1 700 clones were screened and 1 clone appeared colourless. This putative DR mutant was restreaked three times and repeatedly stained 1 9
- the selected mutant was designated MW008.
- Cell-free extracts of the DR mutant (MW008) and DB1 334 were used for measuring the diacetyl reductase, butanediol dehydrogenase, acetoin reductase and lactate dehydrogenase activities. Lactate dehydrogenase activity measurements were used as a positive control for enzymatic activity of the strains. The results of the enzyme activities are summarised in Table 1 .1 .
- DR Diacetyl reductase
- AR acetoin reductase
- BUTDH butanediol dehydrogenase
- LDH lactate dehydrogenase
- this strain was used for fermentation of milk supplemented with diacetyl and acetaldehyde. Surprisingly, the mutant strain was able to reduce diacetyl despite the absence of NADH-dependent diacetyl reductase activity. Measurements of cell free extract of the mutant with diacetyl + NADPH, acetoin + NADPH and butanediol + NADP + showed similar activities as the wild type. Therefore, it was most likely that DB1 334 has two diacetyl reductases responsible for diacetyl degradation. In order to prevent diacetyl reduction during milk fermentation, also the NADPH-dependent diacetyl reductase of DB1 334 must be mutated.
- Example 1 the construction of a diacetyl reductase mutant with no essentially activity for diacetyl + NADH is described. However, the mutant possessed diacetyl reductase activities as the wild-type strain when using NADPH as cofactor. This strain was able to degrade diacetyl at the same rate as the wild-type strain. The NADH-dependent diacetyl reductase mutant was subjected to further mutagenization and screened for mutants incapable of reducing diacetyl both in the presence of NADH and NADPH as cofactors. 21
- Leuconostoc pseudomesenteroides DB1 334 CHCC21 14
- MW008 NADH-dependent diacetyl reductase mutant, see Example 1
- MM084 NADH-, NADPH-dependent diacetyl reductase mutant, this Example).
- DB1 334, MW008 and MM084 were cultivated on M 1 7 (0.5% glucose) plates, or in liquid medium, at 25°C under anaerobic conditions.
- MW008 was cultivated in 1 0 ml M 1 7 (0.5 % glucose) for three days followed by cultivation for 1 20 minutes in the presence of 1 50 ⁇ l of EMS. After EMS treatment, 0.2 ml of the culture was inoculated into ten tubes each containing 1 0 ml of M 1 7 and incubated for 3 days for phenotypic expression. The mutation frequency was monitored by plating 0.1 ml from each tube on M 1 7 plates containing 500 ⁇ g/ml of streptomycin.
- Mutated cells were plated on M 1 7 (0.5 % glucose) and incubated for 2 days at 25°C anaerobically and streaked onto duplicate M 1 7 plates. After another 2 days of incubation one of the duplicate plates was used for screening. The colonies were transferred onto a nitrocellulose membrane and soaked for 1 .5 minutes in chloroform for cell lysis. After cell lysis, the membrane was washed with distilled water and dried for 20 minutes.
- the membrane was subsequently incubated for 30 minutes in a solution containing; 0.5 M Na-phosphate buffer (pH 6.1 ), 72 mM butanediol, 1 mM NAD + or NADP + , 0.02 mM Meldola's blue (8-Dimethylamino-2,3-benzophenoxazine), 0.08 mM MTT (3-[4,5-Dimethylthiazol-2yl] 2,5-diphenyltetrazolium bromide; Thiazolyl blue) . 22
- Native-PAGE was run at 1 50 V for 2.5 hours using 4-20% Tris-HCI gradient gels with Tris-Glycine (pH 8.3) as running buffer. Staining of native gels was performed with the zymogram technique (see below) .
- Zymogram staining of native-PAGE gels for identification of diacetyl reductase activity, acetoin reductase activity and butanediol dehydrogenase activity was performed as follows: for diacetyl reductase activity the gel was incubated for 1 5 minutes with 1 2 mM diacetyl, 1 .5 mM NADH or NADPH, 0.5 M Na-phosphate buffer (pH 6.1 ), for acetoin reductase activity the gel was incubated for 1 5 minutes with 36 mM acetoin, 1 .5 mM NADH or NADPH, 0.5 M Na-phosphate buffer (pH 6.1 ) and for butanediol dehydrogenase activity the gel was incubated for 1 5 minutes with 72 mM butanediol, 1 mM NAD + or NADP + , 0.5 M Na-phosphate buffer.
- the gel was next incubated for 30 minutes under dry conditions before the addition of a solution consisting of 0.02 mM Meldola's blue (8-Dimethylamino-2,3-benzophenoxazine), 0.08 mM MTT (3-[4,5- Dimethylthiazol-2yl] 2,5-diphenyltetrazolium bromide; Thiazolyl blue) in 100 mM phosphate buffer (pH 8.2) (Provecho et al, 1 984; Gibson et al, 1 991 ) . Visible protein bands appeared within 20 minutes.
- DB1 334, MW008 and MM084 were cultivated in M 1 7 (0.5 % glucose) until mid exponential phase.
- the cells were harvested by centrifugation at 6000 rpm for 1 5 minutes and washed in cold 50 mM Na-phosphate buffer (pH 6).
- the pellet was resuspended in cold 50 mM Na-phosphate buffer (pH 6) and sonicated for 3 x 2 minutes.
- the sonicated cell mixture was centrifuged at 6000 rpm for 1 5 minutes and the supernatant was stored at -20°C until analysed for protein concentration and enzyme activities.
- Diacetyl reductase activity was measured spectrophotometrically by monitoring the oxidation of NADH or NADPH at 340 nm in a reaction mixture with the following composition: 50 mM Na-phosphate buffer (pH 6.1 ), 36 mM diacetyl and 0.5 mM NADH or NADPH.
- Butanediol dehydrogenase activity was measured spectrophotometrically by monitoring the reduction of NAD + or NADP + at 340 nm in a reaction mixture with the following composition: 50 mM Na-phosphate buffer (pH 6.1 ), 72 mM butanediol and 0.5 mM NAD + or NADP + .
- Acetoin reductase activity was measured spectrophotometrically by monitoring the oxidation of NADH or NADPH at 340 nm in a reaction mixture with the following composition: 50 mM Na-phosphate buffer (pH 6.1 ), 36 mM acetoin and 0.5 mM NADH or NADPH. Lactate dehydrogenase activity was measured by monitoring the oxidation of NADH at 340 nm in a reaction mixture with the following composition: 50 mM Tris-acetate buffer (pH 6), 0.5 mM fructose- 1 ,6-diphosphate, 25 mM pyruvate and 0.5 mM NADH. The specific activities of the enzymes were expressed as micromoles of converted substrate per milligram of protein per minute (equivalent to units per milligram protein) .
- Protein concentration was measured by using the BCA Protein Assay Reagent (Pierce) with bovine serum albumin as the standard.
- mutagenized MW008 was screened by incubating the cells in a solution consisting of butanediol and NADP + . Possible mutants were colourless whereas cells with an intact diacetyl reductase were stained purple. Approximately 3500 clones were screened with the zymogram method. Two possible mutants were further restreaked three times and repeatedly restained with 24
- Cell free extracts of DB1 334, MW008 and MM084 were used for measuring diacetyl reductase, acetoin reductase and butanediol dehydrogenase activities. As a positive control for the activity of the strains, lactate dehydrogenase activity was also measured.
- the enzyme activities of DB1 334, MW008 and MM084 are summarised in Table 2.1 . Values for lactate dehydrogenase activities of the mutants were comparable to the wild-type strain (data not shown).
- DR Diacetyl reductase
- AR acetoin reductase
- BUTDH butanediol dehydrogenase
- n.d not detectable, activities below the detection limit ⁇ 0.005 U/mg.
- wild-type Leu. pseudomesenteroides is capable of reducing diacetyl into acetoin and butanediol due to diacetyl reductase activities using either NADH or NADPH as cofactors.
- An NADH-dependent diacetyl reductase mutant was capable of reducing diacetyl at the same rate as that of the wild-type strain during milk fermentation. When using NADPH as cofactor, the mutant had enzyme activities comparable to the wild-type strain. Mutagenesis and screening of MW008 with the zymogram technique resulted in the isolation of an NAD(P)H-dependent diacetyl reductase mutant. Such a mutant would be incapable of reducing diacetyl into acetoin and butanediol by means of diacetyl reductase.
- the diacetyl reductase mutant MM084 is isolated as a double mutant of Leuconostoc pseudomesenteroides strain DB1 334 and lacks both NADH and NADPH dependent DR.
- mutant MM084 When cultivated in milk as a pure culture, MM084 does not reduce diacetyl and acetoin. Due to this characteristic, mutant MM084 is assumed to be a suitable strain for use as a component in mesophilic cultures which results in an improved diacetyl stability in the fermented products. In this Example, the effect of the mutant MM084 on flavour formation and stability in fermented milk was investigated with main focus on the concentration of diacetyl. 26
- strains used in this example originate from the Chr. Hansen Culture Collection:
- Lactococcus lactis subsp. lactis biovar. diacetylactis strain DB1 341 (D strain); Lactococcus lactis subsp. lactis biovar. diacetylactis -acetolactate decarboxylase deficient mutant MC01 0 (Curie et al . 1 999) (D strain); Leuconostoc pseudomesenteroides DB1 334 (L strain); Leuconostoc pseudomesenteroides DR " mutant MM084 (L strain).
- the milk or cream was inoculated with a total of 1 % of inoculum and incubated at 22°C until pH reached 4.60 ⁇ 0.05. Following incubation, the bottles were kept at 4°C.
- the sour cream fermented with the cultures C and D was sensorically evaluated after 1 , 7, 1 4, 21 , and 28 days, respectively.
- the sour cream had a mild, clean and fresh flavour.
- the fresh flavour was maintained during a prolonged storage.
- the strain MM084 is suitable for use as a component of a mixed aroma-forming culture.
- the mixed cultures composed with MM084 had a significantly improved diacetyl stability during storage and a significant higher content of diacetyl at the end of fermentation and after storage. Such a mixed culture is beneficial in the production of sour cream and cream cheeses.
- the L. lactis subsp. lactis mutant strain DN223 is both a lactate dehydrogenase (LDH) and pyruvate formate lyase (PFL)defective. DN223 is strictly aerobic and the lack of capability to grow anaerobically (even in the presence of acetate) is most likely due to a constraint on the intracellular redox balance, as the net consumption of NAD + in the glycolysis can no longer be regenerated due to the two enzymatic defects. Exogenous acetoin was expected to assist in the regeneration of NAD + under anaerobic conditions by conversion into 2,3-butanediol by the enzyme diacetyl reductase (DR).
- DR diacetyl reductase
- a test tube containing 1 0 ml of DN medium (Dickely et al., 1 995) supplemented with acetate was inoculated with a single colony of DN223 picked from an agar plate and incubated aerobically overnight at 30°C. 1 00 ⁇ l of the overnight culture was spread onto two agar plates containing DN medium supplemented with 2.0 g/L sodium 30
- the diacetyl activities of strain CMH-1 53 were measured with diacetyl as substrate and NADH as cofactor and are expressed as the units of [ ⁇ moles NADH consumed per min. per mg of protein] according to the assay described in Example 1 .
- the diacetyl activities of strain CMH-1 53 were compared with other L. lactis subsp. lactis strains (Table 4.1 ).
- diacetyl activities of strain CHM-1 53 were measured using either diacetyl, acetoin or 2,3-butanediol as substrate and NADH, NAD + , NADPH or NADP + as cofactor and are expressed as units of [ ⁇ moles NADH or NADPH produced or consumed per min. per mg of protein] according to the assay described in Example 1 .
- strain CMH-1 53 The diacetyl activities of strain CMH-1 53 were compared with other L. lactis subsp. lactis strains (Table 4.2). 31
- n.d not detectable, activities below the detection limit ⁇ 0.005 U/mg.
- n.d not detectable, activities below the detection limit ⁇ 0.005 U/mg.
- n.d not detectable, activities below the detection limit ⁇ 0.005 U/mg.
- CMH-1 53 The specific diacetyl reductase activities of CMH-1 53 are significantly increased compared to other L. lactis strains with various phenotypes (Table 4.1 and 4.2) whereas CMH-1 53 has no detectable LDH activity (Table 4.3) .
- the mutant strain L. lactis subsp. lactis CMH-1 53 has the phenotype Ldh " /Pfl7Dr + + , as it is only capable of anaerobic growth if supplied with acetoin and acetate.
- Lactococcus lactis nonsense suppressors and construction of a food-grade cloning vector Mol. Microbiol.15:839-847.
- the applicants request that a sample of the deposited microorganisms only be made available to an expert nominated by the requester until the date on which the patent is granted or the date on which the application has been refused or withdrawn or is deemed to be withdrawn.
Abstract
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EP99913127A EP1071760A1 (en) | 1998-04-21 | 1999-04-20 | Genetically modified lactic acid bacteria having modified diacetyl reductase activities |
CA2326405A CA2326405C (en) | 1998-04-21 | 1999-04-20 | Novel genetically modified lactic acid bacteria having modified diacetyl reductase activities |
BR9910131-9A BR9910131A (en) | 1998-04-21 | 1999-04-20 | Genetically modified lactic acid bacteria having modified diacetyl reductase activities |
NZ508136A NZ508136A (en) | 1998-04-21 | 1999-04-20 | Genetically modified lactic acid bacteria having modified diacetyl reductase activities |
AU31385/99A AU754472B2 (en) | 1998-04-21 | 1999-04-20 | Novel genetically modified lactic acid bacteria having modified diacetyl reductase activities |
NO20005292A NO20005292L (en) | 1998-04-21 | 2000-10-20 | New genetically modified lactic acid bacteria having modified diacetyl reductase activities |
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Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0199105A1 (en) * | 1985-04-10 | 1986-10-29 | Döhler GmbH | Alcohol-free beverages on the base of cereals, process and microorganisms for their production |
-
1999
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Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0199105A1 (en) * | 1985-04-10 | 1986-10-29 | Döhler GmbH | Alcohol-free beverages on the base of cereals, process and microorganisms for their production |
Non-Patent Citations (5)
Title |
---|
ARORA B C ET AL: "Mutants of Streptococcus lactis subsp. diacetylactis lacking diacetyl reductase activity", ACTA MICROBIOLOGICA POLONICA, vol. 27, no. 4, 1978, pages 353 - 358, XP002086555 * |
BOUMERDASSI H ET AL: "Isolation and properties of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 mutants producing diacetyl and acetoin from glucose", APPLIED AND ENVIRONMENTAL MICROBIOLOGY, vol. 63, no. 6, June 1997 (1997-06-01), pages 2293 - 2299, XP002086557 * |
CROW V L: "Properties of 2,3-butanediol dehydrogenases from Lactococcus lactis subsp. lactis in relation to citrate fermentation", APPLIED AND ENVIRONMENTAL MICROBIOLOGY, vol. 56, no. 6, June 1990 (1990-06-01), pages 1656 - 1665, XP002086556 * |
JAKUBOWSKA J ET AL: "Evaluation of lactic acid streptococci for the preparation of frozen concentrated starter cultures", ACTA MICROBIOLOGICA POLONICA, vol. 29, no. 2, 1980, pages 135 - 144, XP002086558 * |
KUILA R K AND RANGANATHAN B: "Ultraviolet light-induced mutants of Streptococcus lactis subspecies diacetylacis with enhanced acid- or flavor-producing abilities", JOURNAL OF DAIRY SCIENCE, vol. 61, no. 4, 1978, pages 379 - 383, XP002086554 * |
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BR9910131A (en) | 2001-01-09 |
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