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Masaru Nomura - One of the best experts on this subject based on the ideXlab platform.
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Rapid PCR-Based Method Which Can Determine Both Phenotype and Genotype of Lactococcus lactis Subspecies
Applied and environmental microbiology, 2002Co-Authors: Masaru Nomura, Miho Kobayashi, Takashi OkamotoAbstract:A highly efficient, rapid, and reliable PCR-based method for distinguishing Lactococcus lactis subspecies (L. lactis subsp. lactis and L. lactis subsp. cremoris) is described. Primers complementary to positions in the glutamate decarboxylase gene have been constructed. PCR analysis with extracted DNA or with cells of different L. lactis strains resulted in specific fragments. The length polymorphism of the PCR fragments allowed a clear distinction of the L. lactis subspecies. The amplified fragment length polymorphism with the primers and the restriction fragment length polymorphism of the amplified products agreed perfectly with the identification based on genotypic and phenotypic analyses, respectively. Isolates from Cheese Starters were investigated by this method, and amplified fragments of genetic variants were found to be approximately 40 bp shorter than the typical L. lactis subsp. cremoris fragments.
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Growth energetics of Lactococcus lactis subsp. lactis biovar diacetylactis in cometabolism of citrate and glucose
International Dairy Journal, 1999Co-Authors: Hiromi Kimoto, Masaru Nomura, Ichirou SuzukiAbstract:Abstract Certain strains of lactic acid bacteria present in commercial Cheese Starters, characterized by faint transparent colonies on an agar plate containing 1 mg kg −1 crystal violet (CVT), were identified as Lactococcus lactis subsp. (ssp) lactis biovar diacetylactis. The effect of citrate on the growth of these strains (CVT strains) in the presence of glucose was studied, in comparison with L. lactis strains. Molar growth yield from glucose ( Y G , g dry weight/mole of glucose consumed) for CVT strains grown on glucose plus citrate was significantly higher than the control (i.e. without citrate), but not for other L. lactis strains tested. Enhanced Y G was also observed at a pH-controlled experiment, indicating that enhanced Y G did not result from a buffering effect of citrate. CVT strains, in contrast to other strains of the same species, were shown to obtain enough energy to enhance Y G on glucose–citrate mixtures.
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Production of γ-Aminobutyric Acid By Cheese Starters During Cheese Ripening
Journal of dairy science, 1998Co-Authors: Masaru Nomura, H. Kimoto, Y. Someya, S. Furukawa, I. SuzukiAbstract:Nine mixed-strain Starters were examined for their abilities to produce γ-aminobutyric acid. Six commercial Starters were found to produce γ-aminobutyric acid in a skim milk culture. The bacterium that produced γ-aminobutyric acid was isolated from the mixed-strain Starters, identified as citrate-utilizing Lactococcus lactis ssp. lactis (formerly L. lactis ssp. lactis biovar diacetylactis) and designated as strain 01-7. A cell extract showed glutamate decarboxylase activity, for which the optimum pH was 4.7. In pH-controlled cultivation, γ-aminobutyric acid was generated at pH 5.0 but not above pH 5.5. Cheeses were prepared experimentally using strain 01-7 to determine the relationship between the pH values and the production of γ-aminobutyric acid during Cheese ripening. γ-Aminobutyric acid increased linearly in the experimental Cheeses as the pH of the Cheese decreased. Based on these results, γ-aminobutyric acid was concluded to be produced by the Cheese Starters during ripening.
Sang-dong Lim - One of the best experts on this subject based on the ideXlab platform.
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Production of benzoic acid as a natural compound in fermented skim milk using commercial Cheese starter
Journal of dairy science, 2017Co-Authors: Sun-young Park, Miyoung Yoo, Hyun-dong Paik, Sang-dong LimAbstract:In this study, we investigated the production of natural benzoic acid (BA) in skim milk fermentation by 5 kinds of commercial Cheese Starters. Five kinds of starter were inoculated into 10% reconstituted skim milk, and then the culture was incubated at 2-h intervals for 10 h at 30, 35, and 40°C. In fermentation by MW 046 N+LH 13, the starter for making raclette, BA was highly detected after 8 h at 30 and 35°C. In fermentation by LH 13, the starter for making berg, BA steadily increased and was highly detected at 40°C. In fermentation by TCC-3+TCC-4, the starter for making Caciocavallo and mozzarella, BA was detected after 2 h at 40°C. Also, BA was detected after 4 and 8 h at 35 and 30°C, respectively. In fermentation by Flora-Danica, the starter for making Gouda, BA was increased until 6 h and decreased after 6 h at all temperatures. Among the 5 kinds of fermentation, the level of BA was the highest in fermentation by Flora-Danica at 6 h at 35°C, at 14.55 mg/kg.
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Short communication: Change of naturally occurring benzoic acid during skim milk fermentation by commercial Cheese Starters.
Journal of dairy science, 2016Co-Authors: Noori Han, Sun-young Park, Sunyoung Kim, Miyoung Yoo, Hyun-dong Paik, Sang-dong LimAbstract:This study sought to investigate the change of naturally occurring benzoic acid (BA) during skim milk fermentation by 4 kinds of commercial Cheese Starters used in domestic Cheese. The culture was incubated at 3-h intervals for 24h at 30, 35, and 40°C. The BA content during fermentation by Streptococcus thermophilus STB-01 was detected after 12h at all temperatures, sharply increasing at 30°C. In Lactobacillus paracasei LC431, BA was detected after 9h at all temperatures, sharply increasing until 18h and decreasing after 18h at 30 and 35°C. In the case of R707 (consisting of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris), BA increased from 6h to 15h and decreased after 15h at 40°C. The BA during STB-01 and CHN-11 (1:1; mixture of S. thermophilus, Lc. lactis ssp. lactis, Lc. lactis ssp. cremoris, Lc. lactis ssp. diacetylactis, Leuconostoc mesenteroides ssp. cremoris) fermentation was detected after 3h at 35 and 40°C, sharply increasing up to 12h and decreasing after 15h at 35°C, and after 6h, increasing up to 9h at 30°C. After 3h, it steadily decreased at 40°C. The highest amount of BA was found during the fermentation by R707 at 30°C; 15h with 12.46mg/kg.
Jean-christophe Vuillemard - One of the best experts on this subject based on the ideXlab platform.
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Characterization of aromatic properties of old-style Cheese Starters
Journal of dairy science, 2010Co-Authors: N. Lacroix, Daniel St-gelais, Claude P. Champagne, Jacinthe Fortin, Jean-christophe VuillemardAbstract:Old-style Cheese Starters were evaluated to determine their ability to produce Cheese aroma compounds. Detailed analyses of the aroma-producing potential of 13 old-style starter cultures were undertaken. The proteolytic profile of the Starters was established by an accelerated ripening study using a model Cheese slurry and compared with those of a commercial aromatic starter and commercial Cheddar Cheeses. To evaluate the aromatic potential of the starter cultures, quantification of free amino acids liberated and volatile compounds after 15 d of ripening at 30°C as well as sensory analysis were carried out. Results showed that proteolysis patterns of all 13 starter cultures in the curd model were comparable to those of commercial Cheddar Cheeses. All tested cultures demonstrated the ability to produce high amounts of amino acids recognized as precursors of aroma compounds. Several differences were observed between the Starters and commercial Cheddar Cheeses regarding some amino acids such as glutamate, leucine, phenylalanine, proline, and ornithine, reflecting the various enzymatic systems present in the Starters. Starters Bt (control) and ULAAC-E exhibited various significant differences regarding their free amino acid profiles, as confirmed by sensory analysis. In addition, identification of volatile compounds confirmed the presence of several key molecules related to aroma, such as 3-methylbutanal and diacetyl. Besides the aroma-producing aspect, 2 Starters (ULAAC-A and ULAAC-H) seem to possess an important ability to generate large amounts of γ-aminobutyric acid, which contributed up to 15% of the total amino acids present in the model curd after 15 d ripening. γ-Aminobutyric acid is an amine well-known for its antihypertensive and calming effects.
Viviana Beatriz Suárez - One of the best experts on this subject based on the ideXlab platform.
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Yeasts from autochthonal Cheese Starters: technological and functional properties
Journal of applied microbiology, 2013Co-Authors: Ana Griselda Binetti, M. Carrasco, Jorge Reinheimer, Viviana Beatriz SuárezAbstract:Aims The aim of this work was to identify 20 yeasts isolated from autochthonal Cheese Starters and evaluate their technological and functional properties. Methods and Results The capacities of the yeasts to grow at different temperatures, pH, NaCl and lactic acid concentrations as well as the proteolytic and lipolytic activities were studied. Moreover, survival to simulated gastrointestinal digestion, hydrophobicity, antimicrobial activity against pathogens and auto- and co-aggregation abilities were evaluated. The sequentiation of a fragment from the 26S rDNA gene indicated that Kluyveromyces marxianus was the predominant species, followed by Saccharomyces cerevisiae, Clavispora lusitaniae, Kluyveromyces lactis and Galactomyces geotrichum. RAPD with primer M13 allowed a good differentiation among strains from the same species. All strains normally grew at pH 4·7–5·5 and temperatures between 15 and 35°C. Most of them tolerated 10% NaCl and 3% lactic acid. Some strains showed proteolytic (eight isolates) and/or lipolytic (four isolates) capacities. All strains evidenced high gastrointestinal resistance, moderate hydrophobicity, intermediate auto-aggregation and variable co-aggregation abilities. No strains inhibited the growth of the pathogens assayed. Conclusions Some strains from dairy sources showed interesting functional and technological properties. Significance and Impact of the Study This study has been the first contribution to the identification and characterization of yeasts isolated from autochthonal Cheese Starters in Argentina. Many strains could be proposed as potential candidates to be used as probiotics and/or as co-Starters in Cheese productions.
R.p. Ross - One of the best experts on this subject based on the ideXlab platform.
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Use of lacticin 481 to facilitate delivery of the bacteriophage resistance plasmid, pCBG104 to Cheese Starters.
Journal of applied microbiology, 2002Co-Authors: Susan Mills, Aidan Coffey, Lisa O'sullivan, D. Stokes, Colin Hill, Gerald F. Fitzgerald, R.p. RossAbstract:Aims: Use of lacticin 481 to facilitate the conjugal transfer of the bacteriophage resistance plasmid pCBG104 to various starter cultures. Methods and Results: A raw milk isolate of Lactococcus was found to harbour determinants for lacticin 481 production and immunity and phage resistance on a plasmid designated pCBG104. The lacticin 481 was successfully used to mobilize the phage resistance determinant to a variety of Cheese Starters enabling the formation of highly phage resistant Starters. In addition, it facilitated the stacking of a number of phage resistance genes, namely a type I restriction modification system, a phage abortive infection system and a phage adsorption blocking system in a single Lactococcus strain without the use of recombinant techniques. The transconjugants were all shown to produce lacticin 481 and to contain the entire 481 operon. Subsequently one transconjugant was selected and successfully used for large-scale cheddar Cheese manufacture. Conclusions: Lacticin 481 could be used as a food-grade selectable marker to facilitate the introduction of advantageous traits to starter cultures for industrial food fermentations. Significance and Impact of the Study: Food-grade selectable markers greatly facilitate the introduction of various advantageous traits to starter cultures for industrial food fermentation. Indeed self-cloning which is becoming increasingly important for strain improvement has a requirement for the identification and demonstration of the utility of tools such as lacticin 481.
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Traditional and molecular approaches to improving bacteriophage resistance of Cheddar and Mozzarella Cheese Starters
Irish Journal of Agricultural and Food Research, 2001Co-Authors: Aidan Coffey, D. Stokes, Gerald F. Fitzgerald, R.p. RossAbstract:Infection by bacteriophage (bacterial viruses) during dairy fermentations remains a major cause of starter culture failure in Cheddar and Mozzarella manufacture, often resulting in substantial economic losses. A variety of practical measures to alleviate the problem of phage infection have been adopted over the years. The application of genetic techniques to improve the phage resistance of starter cultures for dairy fermentations is currently being explored and this approach has significant potential to alleviate the problem. This review highlights the significant developments that have been made in understanding the interaction between dairy starter cultures and bacteriophage in industry. It also describes the exploitation of molecular methodology to genetically defend these bacteria from the ever-present threat of bacteriophage and the scientific advances, which formed the basis for these achievements. Attention is also given to the development of food-grade approaches to improve genetic traits of industrial starter strains in the context of phage resistance.
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an application in cheddar Cheese manufacture for a strain of lactococcus lactis producing a novel broad spectrum bacteriocin lacticin 3147
Applied and Environmental Microbiology, 1996Co-Authors: M P Ryan, Colin Hill, R.p. RossAbstract:Lactococcus lactis DPC3147, a strain isolated from an Irish kefir grain, produces a bacteriocin with a broad spectrum of inhibition. The bacteriocin produced is heat stable, particularly at a low pH, and inhibits nisin-producing (Nip+) lactococci. On the basis of the observation that the nisin structural gene (nisA) does not hybridize to DPC3147 genomic DNA, the bacteriocin produced was considered novel and designated lacticin 3147. The genetic determinants which encode lacticin 3147 are contained on a 63-kb plasmid, which was conjugally mobilized to a commercial Cheese starter, L. lactis subsp. cremoris DPC4268. The resultant transconjugant, DPC4275, both produces and is immune to lacticin 3147. The ability of lacticin 3147-producing lactococci to perform as cheddar Cheese Starters was subsequently investigated in Cheesemaking trials. Bacteriocin-producing Starters (which included the transconjugant strain DPC4275) produced acid at rates similar to those of commercial strains. The level of lacticin 3147 produced in Cheese remained constant over 6 months of ripening and correlated with a significant reduction in the levels of nonstarter lactic acid bacteria. Such results suggest that these Starters provide a means of controlling developing microflora in ripened fermented products.