• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.107-112
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• 1993

The optimal conditions for protoplast fusion between the cells of kanamycin resistant Lactobacillus bulgaricus IFO 13593 and those of lincomycin resistant Lactobacillus helveticus IAM 12090 were investigated in this study. The highest fusion frequency of 9.1*10-4 was obtained when protoplast fusion was carried out for 0.5 min using 40% PEG 4000 solution as a cell fusion stimulant and subsequent post-PEG-incubation was undergone at 30 for 30 min in the PPI medium.

• Journal of the Korean Society of Food Culture
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• v.25 no.1
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• pp.76-81
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• 2010

This study was conducted to evaluate the influence of Lactobacillus bulgaricus and/or Sterptococcus thermophilus on the fermentation of yoghurt containing 5% (w/v) buckwheat sprouts. The results revealed that after 12 hours of fermentation the appropriate pH, titratable acidity and number of viable cells were attained. At that time, the rutin content of the buckwheat sprout-added yoghurt prepared by the mixed culture method was not changed, but the quercetin content increased greatly. Conversely, the rutin content of yoghurt that only contained Streptococcus thermophilus was decreased while the quercetin content was increased. The total phenol contents as well as the DPPH radical scavenging activities of both the mixed culture and Streptococcus thermophilus yoghurt did not differ significantly. Taken together, the results revealed that the use of a mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus during the preparation of buchwheat sprout-added yoghurt was desirable due to the decrease in pH and increase in titratable acidity and viable cells that occurred after 12 hr of fermentation. Moreover, phytochemicals in buckwheat sprouts such as rutin, quercetin and phenol compounds were comparatively increased during fermentation and influenced the antioxidant activity in buckwheat sprout-added yoghurt.

• Korean Journal of Food Science and Technology
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• v.11 no.3
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• pp.200-205
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• 1979

Effects of monosodium phosphate, disodium phosphate, trisodium phosphate, ${\alpha}-polygel$, sodium ultrametaphosphate and sodium tripolyphosphate on the growth of bacteria, pH and acidity in single culture of Lactobacillus bulgaricus and mixed-culture of Lactobacillus bulgaricus and Streptococcus thermophilus were investigated. Phosphates exerted definite effect in enhancing the growth of the bacteria and acidity of the fermented milk. For the single-culture of Lactobacillus bulgaricus monosodium phosphate and sodium tripolyphosphate were most effective in terms of bacterial growth and acidity, whereas for the mixed-culture of Lactobacillus bulgaricus and Streptococcus thermophilus monosodium phosphate and disodium phosphate showed the best results. In the presence of the phosphates, particularly of trisodium phosphate, the decrease of viable count of bacteria in fermented milk during storage was reduced significantly. The stability of the fermented milk prepared with the mixed-culture of Lactobacillus bulgaricus and Streptococcus thermophilus was improved by the addition of phosphates, particularly of monosodium phosphate.

• The Korean Journal of Community Living Science
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• v.18 no.3
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• pp.399-406
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• 2007

Soybean seeds were fermented by Bacillus subtilis and/or Lactobacillus bulgaricus to improve solubility, viscosity, water holding capacity and oil holding capacity of soybean proteins in Chongkukjang. The maximum colony forming unit and protease activity of B. subtilis or L bulgaricus were observed after 60 hours of fermentation, and those of the mixed fermentation by two microorganisms were steadily increased during the fermentation periods. Solubilities of soybean proteins by B. subtilis or L bulgaricus were steadily increased before the values were considerably increased to 60 hours of fermentation, whereas water holding capacities of the proteins were decreased by B. subtilis or L. bulgaricus and those of the mixed fermentation were decreased progressively. Viscosities of soybean proteins by B. subtilis and/or L. bulgaricus were decreased progressively during the fermentation. Viscosities of soybean proteins by B. subtilis and/or L. bulgaricus were decreased progressively during the fermentation. Oil holding capacities of soybeans by B. subtilis or L. bulgaricus were maximum at 20 or 80 hours of fermentation and those of the mixed fermentation were decreased after 10 hours of the fermentation.

• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.600-605
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• 1998

Present study was investigate to evaluate the aluminum absorption effect on lactic acid bacteria(Lactobacillus acidophilus ATTC 4356, Lactogacillus bulgaricus ATTC 11842, Lactobacillus casei IFO 3533, and Streptococcus thermophilus KCTC 2185 ; LAB) and Clostridium perfringens ATCC 3627 (CP) in artificial intestinal tract. Their growth rate, aluminum accumulation and cellular distribution was studied under anaerobic broth system. All of above microbes were inhibited by adding 10 to 100ppm of aluminum. The degree of aluminum in LAB (Lactobacillus acidophilus ATCC 4356, Lactobacillus bulgaricus ATCC 11842, Lactobacillus casei IFO 3533, and Streptococcus thermophilus KCTC 2185) was higher than of CP. The largest amount of aluminum was accumulated in Lactobacillus bulgaricus ATCC 11842. Aluminum accumulation in LAB was distributed in 49.1% at cell wall, 27.3% at plasma membrane, and 23.6% at cytoplasm, respectively. This study suggests that LAB might help to eliminate the ingested aluminum in intestinal tract.

• Journal of environmental and Sanitary engineering
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• v.12 no.1
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• pp.85-95
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• 1997

Behavior of Listeria monocytogenes in Skim milk during fermentation by Lactobacillus bulgaricus YI-2 and Streptococcus lactis FYI-1 were determined. Autoclaved skim milk was inoculated with ca. 10$^{3}$ L. monocytogenes (Strain LM91-1 or LM 96-2) cells/ml, and with 5.0, 1.0, 0.5 or 0.1% of a milk culture of either L. bulgaricus TI-2 or S. lactis FYI-1. Skim milk containing ca. 10$^{3}$ L. monocytogenes was incubated at 37 or 42$\circ $C for 15 h with L. bulgaricus YI-2, and at 21 or 30$\circ $C for 15 h with S. lactis FYI-1. Cultured skim milks were stored at 4$\circ $C in the refrigerater. Samples were plated on Oxford Agar with oxford antimicrobic supplement to enumerate L. monocytogenes and on either modified MRS agar to enumerate lactic acid bacteria. L. monocytogenes survived the 15-h fermentation with S. lactis FYI-1 in all combinations of level of inoculum and temperature of incubation, but inhibition of growth ranged from 94 to 100%. When incubated with over the 1.0% of L. bulgaricus, L. monocytogenes inhibited or disappeared in fermented skim milk from 9 h after incubation. Especially, incubation at 42$\circ $C with 5.0% L. bulgaricus YI-2 as inoculum appeared to be the most effective inhibitory combination for strain LM 91-1, causing 100% inhibition in growth based on maximum papulation attained. In most instances of incubated with L. bulgaricus YI-2, growth of the pathogene appeared to be completely inhibited when the pH dropped below 4.38.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.1
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• pp.143-149
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• 1996

균주개량 방법의 일환으로 electrofusion 법을 이용하여 protease 화성, lipase 활성, 내열성, 내산성 등이 우수한 L. bulgaricus와 bacteriocin을 생산하는 L. acidophilus 간의 융합조건을 검토하였다. Electrofusion에 의해 생성된 융합주는 식별하기 위해 streptomycin(2mg/ml)과 lincomycin(5$\mu\textrm{g}$/ml)에 내성을 나타내는 L. bulgaricus 변이주이와 kanamucin (600$\mu\textrm{g}$/ml)에 내성을 나타내는 L. acidophilus 88 변이주를 분리하였다. Electrofusion을 500V/cm, 100mses(49phms, 2300 capacotance)에서 수행했을 때 가장 융합이 잘 일어났으며 전기장의 세시와 시간이 증가할수록 융합요율이 현저히 감소하였다. 2가 양이온은 대체적으로 융합효율을 감속시키는 경향을 나타내었으나 1mM MgCl$_2$에서 융합 효율이 약간 증가하였다. PEG 400을 elec-trogusion buffer에 30%되도록 첨가했을 때, 가장 양호한 융합효율을 나타내었으며 그 이상에서는 오히려 융합 효율이 감소하였다. Electrofusion법과 PEG 매개에 의한 융합법의 융합 효율을 비교한 결과, 거의 비슷한 융합 효율을 나타내었으나 electrofusion 법과 PEG매개에 의한 융합법을 혼합하였을 때 가장 양호한 융합 효율을 나타내었다.

• Korean Journal of Organic Agriculture
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• v.24 no.3
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• pp.497-510
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• 2016

This study was carried out to get basic resources for the industrial use of Lactobacillus bulgaricus SP5. The antibacterial activity of the supernatant obtained from Lactobacillus bulgaricus SP5 was tested against the pathogenic bacteria such as Escherichia coli KCCM 11234, Salmonella enteritidis KCCM 3313, Salmonella enteritidis KCCM 12021, and Salmonella typhimurium KCCM 40253. The supernatant of L. bulgaricus SP5 showed antibacterial activity against tested pathogenic bacteria. The antibacterial activity was examined after adjusting pH and heat treatment of supernatant. Heat treatment of supernatant had antibacterial activity against pathogenic bacteria at all temperature. However, pH changes showed no antibacterial activity. Antibacterial activity of the supernatant was confirmed to be due to organic acids (lactic, acetic, phosphoric, succinic, pyroglutamic, citric, malic, and formic acid).

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.246-250
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• 1991

Conditions for the production and regeneration in Lactobacillus bulgaricus protoplasts were investigated. Protoplasts of L bulgaricus strains were obtained by treatment with mutanolysin and lysozyme together in a protoplast forming buffer containing 0.02 M N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) (pH 7.0) and 0.5 M sucrose. High protoplast yield was obtained from cells cultured in the de Man, Rogosa and Sharpe(MRS) medium at the middle to late logarithmic growth phase. Regeneration was efficiently accomplished with a complex medium containing 1% sucrose, 20 mM $MgCl_2$, 5% gelatin, and 0.5% bovine serum albumin. The frequency of regeneration of protoplasts was 10~20% after 5 days of incubation at $30^{\circ}C$.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.8-14
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• 2014

The objective of this work is to investigate and compare several functional properties of lactic acid bacteria (LAB), Lactobacillus casei SK-7 isolated from home-made yogurt and Lactobacillus bulgaricus YK-11 from commercial yogurt. Initially, physiological and biochemical properties of SK-7 and YK-11 were characterized. Phylogenetic analysis using 16S rRNA sequencing were performed to identify the strains, and the strain could be assigned to Lactobacillus casei and Lactobacillus bulgaricus, designated as L. casei SK-7 and L. bulgaricus YK-11. Phylogenetic tree of SK-7 and YK-11 was plotted based on 16S rRNA sequence comparisons. Production of lactic acid and organic acid, and pH changes in the cultures of SK-7 and YK-11 were monitored during 72 h. During the incubation period, several functional properties of L. casei SK-7 and L. bulgaricus YK-11 were examined. L. casei SK-7 and L. bulgaricus YK-11 cultures eliminated 93.9% and 88.2% of nitrite, respectively. Antioxidant activity of cultural supernatants of SK-7 and YK-11 were 62.6%, 54.9%, and activity of ${\beta}$-galactosidase were 14.9 units/mg and 13.1 units/mg, respectively. The antimicrobial activities were examined with 20-fold concentrated culture supernatants from the cultures of SK-7 and YK-11. The activities of SK-7 supernatants were clearly observed against all microorganisms in this work, whereas no activities were observed in YK-11 supernatants. Although it might be conducted additional functional research, functional properties of LAB isolated from home-made yogurt have been shown to be better than those of commercial yogurt in this work.