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Complete Sequencing and Pan-Genomic Analysis of Lactobacillus delbrueckii subsp. bulgaricus Reveal Its Genetic Basis for Industrial Yogurt Production  [PDF]
Pei Hao,Huajun Zheng,Yao Yu,Guohui Ding,Wenyi Gu,Shuting Chen,Zhonghao Yu,Shuangxi Ren,Munehiro Oda,Tomonobu Konno,Shengyue Wang,Xuan Li,Zai-Si Ji,Guoping Zhao
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015964
Abstract: Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus) is an important species of Lactic Acid Bacteria (LAB) used for cheese and yogurt fermentation. The genome of Lb. bulgaricus 2038, an industrial strain mainly used for yogurt production, was completely sequenced and compared against the other two ATCC collection strains of the same subspecies. Specific physiological properties of strain 2038, such as lysine biosynthesis, formate production, aspartate-related carbon-skeleton intermediate metabolism, unique EPS synthesis and efficient DNA restriction/modification systems, are all different from those of the collection strains that might benefit the industrial production of yogurt. Other common features shared by Lb. bulgaricus strains, such as efficient protocooperation with Streptococcus thermophilus and lactate production as well as well-equipped stress tolerance mechanisms may account for it being selected originally for yogurt fermentation industry. Multiple lines of evidence suggested that Lb. bulgaricus 2038 was genetically closer to the common ancestor of the subspecies than the other two sequenced collection strains, probably due to a strict industrial maintenance process for strain 2038 that might have halted its genome decay and sustained a gene network suitable for large scale yogurt production.
Influence of different carbon sources on exopolysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus (B3, G12) and Streptococcus thermophilus (W22)
Yuksekdag, Zehra Nur;Aslim, Belma;
Brazilian Archives of Biology and Technology , 2008, DOI: 10.1590/S1516-89132008000300019
Abstract: exopolysaccharides (epss) production was studied by lactobacillus delbrueckii subsp. bulgaricus (b3, g12) and streptococcus thermophilus (w22) in the medium containing various carbon sources (glucose, fructose, sucrose or lactose). for all the strains, glucose was the most efficient carbon source and b3, g12 and w22 strains produced 211, 175 and 120 eps mg/l respectively. also, the influence of different concentrations of glucose (5,10,15,20,25,30 g/l) on eps production and growth was studied. the results indicated that eps production and growth were stimulated by the high glucose concentration (30 g/l).
Influence of Different Sterilization Conditions on the Growth and Exopolysaccharide of Streptococcus thermophilus and Co-Cultivation with Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1  [PDF]
Junko Nishimura, Seiya Makino, Katsunori Kimura, Emiko Isogai, Tadao Saito
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.511080
Abstract: The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains; growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L.
Optimum Growth Patterns of Wild Strains of S. thermophilus and L. bulgaricus for Suitable Selection for Yoghurt
Tariq Masud,Khalida Sultana
Journal of Biological Sciences , 2002,
Abstract: Fifteen strains each of L. delbrueckii ssp. bulgaricus and S. thermophilus were screened and out of these, 9 strains of L. delbrueckii ssp. bulgaricus and 7 strains of S. thermophilus produced a desired amount of T.A.% at given period of time and temperature. It was further observed that strains of L. delbrueckii ssp. bulgaricus produced more developed acidity as compared to strains of S. thermophilus in all tested temperatures. Moreover, there was a variation among these strains for their developed acidity. There was an inverse relationship between generation time and acidity. S. thermophilus strain showed greater generation time that varied from 90.32 to 110.00 minutes and produced 1.32 to 1.10% T.A. Generation time for L. delbrueckii ssp. bulgaricus varied from 70.21 to 80.12 minutes and produced 1.35 to 1.23% T.A. at their respective optimum temperature.
Effect of Stress on Cells of Lactobacillus delbrueckii sp. Bulgaricus
Joana Silva,Ana Sofia Carvalho,Paula Teixeira,Paul A. Gibbs
Journal of Food Technology , 2013,
Abstract: Cultures of Lactobacillus delbrueckii sp. bulgaricus play an important role in the production of fermented foods and are frequently used as starter cultures for dairy fermentations combined with other species. It These cultures is are particularly used in the industrial production of yoghurt and cheeses. Large scale Pproduction methods of dried L. bulgaricus powders, for inoculating the production vat directly, involve treatments that stress cells in such a way that they lose some of their original activity. containing viable and active organisms which are long-term preserved during storage in the dried state, areis presented. This review covers the environmental stress responses in cells of L. bulgaricus which have been investigated. The responses of L. bulgaricus cells to heat, cold, acid, osmotic, oxygen, starvation, drying and during storage in the dried state are described. Attempts to improve the survival of L. bulgaricus during drying and subsequent storage in the dried state are also discussed in this review.
In vitro cholesterol uptake by Lactobacillus delbrueckii subsp. bulgaricus isolates
Ma?gorzata Ziarno
Acta Scientiarum Polonorum : Technologia Alimentaria , 2009,
Abstract: Background. Some researchers have indicated that Lactobacillus delbrueckii subsp. bulgaricus may provide additional health benefits, reduce serum cholesterol level, for example. The aim of this study was to determine cholesterol uptake by Lb. delbrueckii subsp. bulgaricus commercial yoghurt starter isolates in artificial GIT fluids. Material and methods. Lb. delbrueckii subsp. bulgaricus isolates were cultured in MRS broth and in artificial GIT fluids contained cholesterol at initial concentration ca. 560 μg/mL, as well as in MRS broth with cholesterol addition. Results. All Lb. delbrueckii subsp. bulgaricus showed ability to uptake of cholesterol from MRS broth and artificial GIT fluids. The isolates incubated in artificial gastric fluid removed the minimal amounts of cholesterol in comparison to the same isolates incubated in MRS broth. Only two isolates removed significantly more cholesterol from MRS broth that from duodenal fluid. The amount of removed cholesterol from artificial duodenal fluid ranged from 20 μg/mL to 78 μg/mL. All Lb. delbrueckii subsp. bulgaricus isolates survived worse in artificial GIT fluids than in MRS broth. The viability of Lb. delbrueckii subsp. bulgaricus in GIT fluids depended on isolate. Conclusions. These results proved that Lb. delbrueckii subsp. bulgaricus shows ability to uptake cholesterol from MRS broth and artificial GIT fluids, and the degree of cholesterol uptake depends on isolate and incubation environment. The ability of Lb. delbrueckii subsp. bulgaricus to survive in GIT varies according to the isolates and incubation environment.
Effects of Different Contents of Yogurt Starter/Probiotic Bacteria, Storage Time and Different Concentration of Cysteine on the Microflora Characteristics of Bio-Yogurt
Mahmoud Rezazad Bari,Roghieh Ashrafi,Mohammad Alizade,Leyla Rofehgarineghad
Research Journal of Biological Sciences , 2012,
Abstract: The objectives of this study, were to investigate the effects of different content of yogurt starter/probiotic bacteria, storage time and different concentration of cysteine on the microflora characteristics of bio-yogurt. The number of S. thermophilus and L. delbrueckii subsp. Bulgaricus were found to be higher in the samples with higher levels of starter. The numbers of L. acidophilus and B. bifidum were found to be higher in the samples with higher levels of added probiotic bacteria. The counts of S. thermophilus increased slowly during storage up to day 7 and decreased later L. delbrueckii subsp. Bulgaricus, B. bifidum and L. acidophilus counts, decreased during the storage period. Increasing of cysteine improved the viability of B. bifidum and L. delbrueckii subsp. Bulgaricus and it had no important effect on the viability of L. acidophilus and made the environment unfavourable for the growth of S. thermophilus.
Stress Response of Lactobacillus Delbrueckii ssp. Bulgaricus: The Importance of The Growth pH
Joana Silva,Ana Sofia Carvalho,Rita Ferreira,Paula Teixeira,Paul Gibbs
Journal of Food Technology , 2013,
Abstract: The degree of thermotolerance conferred on Lactobacillus delbrueckii ssp. bulgaricus, by an acid shock or a heat shock, when cells were grown in controlled and non-controlled pH conditions, during exponential and stationary growth phases, was evaluated. For exponential phase cells, thermotolerance was enhanced by submitting the cells to prior heat or acid shocks independently of the pH of growth conditions. Stationary phase cells were significantly more resistant to heating than cells in the exponential phase but only when growth occurred under non-controlled pH. Induced thermotolerance in stationary phase cells, was only observed for cells grown under controlled pH. Except for cells in the stationary growth phase grown under non-controlled pH, the heat or acid shock treatments resulted in an intracellular increase in the well - known heat shock proteins, GroES and GroEL. The presence of chloramphenicol negated the heat shock response and production of GroES and GroEL, confirming that de novo protein synthesis was involved in cell protection. These proteins were also identified in stationary phase cells grown under non-controlled pH, suggesting their involvement in induced thermotolerance during growth at low pH. Very few studies have investigated the response of stationary phase cells. The evaluation development of the response to sub-lethal stresses as a function of the pH conditions during growth is a new insight;. In fact, it was demonstrated that the pH of growth is a crucial factor.
Growth and viability of yogurt starter organisms in honey-sweetened skimmed milk
A Riazi, H Ziar
African Journal of Biotechnology , 2008,
Abstract: Lactic acid bacteria (LAB): Streptococcus thermophilus TA 040 and Lactobacillus delbrueckii spp. bulgaricus Lb 340, were cultured in reconstituted (10%, w/v) skimmed milk with 5 or 10% (w/v) polyfloral or unifloral honey. Inoculated samples were incubated aerobically at 42°C until milk coagulation. Samples were collected at 2 h intervals and examined for biomass and pH changes. Cell viability and post-acidifying activity of both strains during 28 days of storage at 4°C were also measured. A higher increase (P<0.05) in growth and acidifying activity of S. thermophilus monocultures was observed when 10% honey was added. However, L. bulgaricus did not show such a marked increase in its growth capacity. In associated cultures, LAB growth was slightly inhibited, whereas curdling time was prolonged by an hour when 10% honey was added and yogurt acidity was moderate. Cell viability improved by 5 to 6.6% for S. thermophilus and 10% for L. bulgaricus in pure honey-sweetened cultures over 28 days of refrigerated storage. This protective effect of honey on LAB cell viability was also observed in associated cultures (10 to 12% comparatively to the control).
Influence of gastrointestinal system conditions on adhesion of exopolysaccharide-producing Lactobacillus delbrueckii subsp. bulgaricus strains to caco-2 cells
Darilmaz, Derya Onal;Asl?m, Belma;Suludere, Zekiye;Akca, Gülcin;
Brazilian Archives of Biology and Technology , 2011, DOI: 10.1590/S1516-89132011000500009
Abstract: this study aimed to assess the transit tolerance of potential probiotic dairy lactobacillus strains in human uppergastrointestinal tract in vitro, and to evaluate the effect of eps production on the viability and adhesion of these strains. survival and adhesion of two exopolysaccharide (eps)-producing l. delbrueckii subsp. bulgaricus strains (b3 and b2) and e. coli atcc11229 were assessed after the exposure of different ph (gastric juice) and gastric plus pancreatic juice challenges. in the artificial gastric juice (ph 2), both the viability of the strain b3 and b2 was decreased. artificial juice treatments significantly reduced the adhesion to caco-2 cells (p< 0.05). high eps-producing b3 survived better in the adverse gastrointestinal conditions and showed better ability of adhesion to caco-2 cells when assessed for competition with e. coli atcc 11229 compared to low eps-producing b2. this investigation showed that eps production could be affected or be involved in the viability, adherence and competition of l. delbrueckii subsp. bulgaricus strains and support the potential of b3 strain for development of new probiotic products.
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