• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.1
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• pp.60-63
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• 1992

Individual starter culture were inoculated into liquid medium and incubated at $40^{\circ}C$ for 16 hours. Whole cell were obtained and evaluated for ${\beta}-galactosidase$ activity using orthonitrophenyl-${\beta}-D-galactopyranoside$ (ONPG) as substrate. S. thermophilus had more ${\beta}-galactosidase$ activity than other Lactobacilli did. To study the effect of storage temprature on enzyme activity of yoghurt, some samples of cultured yoghurt were stored under refrigeration $(4^{\circ}C)$, and the others under room temperature $(23^{\circ}C)$. At $4^{\circ}C$, yoghurt had ${\beta}-galactosidase$ activity and many viable bacteria in 1 month. After 20 days, yoghurt had maximum ${\beta}-galactosidase$ activity. At $23^{\circ}C$, yoghurt had ${\beta}-galactosidase$ activity by 5 days. As this experiment shown ${\beta}-galactosidase$ activity was ascribed to viable bacteria, especially S. thermophillus. Commercial yoghurt had lower ${\beta}-galactosidase$ activity. There were considerable variations with regard to the lactose hydrolyzing capabilities of commercial yoghurt samples.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.358-367
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• 1983

Antibiotic-resistant strains of Salmonella typhimurium and Klebsiella pneumoniae died readily after their addition to raw sewage, but they grew in sterilized sewage. The decline was not a result of antibiotic stresses, and because the bacteria were able to survive in large numbers for at least 15 days in solutions containing no organic nutrients, it was not a result of competition. Toxin production, bacteriophages, and Bdellovibrio did not cause the disappearance of the two bacterial species. A decline was also evident if the sewage was first passed through a $3-{\mu}m$ filter or treated with cycloheximide or cycloheximide plus nystatin, but protozoa developed under these conditions. Little or no decline occurred if the sewage was filtered and treated with the eucaryotic inhibitors before adding S. typhimurium or K. pneumoniae, and protozoa were not detected. S. typhimurium increased in abundance if cycloheximide, streptomycin, and erythromycin or large amounts of glucose were added to sewage. Tetrahymena thermophilus did not significantly reduce the population of S. typhimurium in buffer when the density of the bacterium was about $10^4/ml$. However, when more than $10^8$ Enterobacter agglomerans cells per ml were added to the buffer, T. thermophilus reduced the abundance of E. agglomerans and S. typhimurium to $10^6$ and 10/ml, respectively. The density of S. typhimurium was further decreased by a second increment of E. agglomerans cells. The disappearance of S. typhimurium and K. pneumoniae from sewage thus is the result of predation by protozoa. It is proposed that predators will eliminate a prey species from a natural environment when an alternate prey is present at concentrations above the threshold number for active feeing by the predator and when the rate of growth of the prey is less than the rate of predation.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.677-686
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• 2004

The objective of this experiment was to select the best strain of lactic acid bacteria for the manufacture of new type of yogurt with rice powders. Changes in pH, titratable acidity, viable cell counts, viscosity, organic acid contents, carbohydrates during fennentation were monitored and sensory evaluation were examined. The yogurt added with 4% rice or skim milk powders and L. salivarius ssp. salivarius culture did not reach pH 4.5, because the production of acids in this media for the culture was weak. The yogurt added with 4% rice or skim milk powder with L. casei, the pH was low and the titratable acidity was high, and therefore the quality of yogurt after 8 hours from fermentation was not high. The yogurt added with 4% rice or skim milk powders with a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was considered best for achieving pH 4.5 and titratable acidity of 1.0 % from 8 to 14 hours. The yogurt with a mixed culture had more acetic acid. Galactose was accumulated when L. salivarius ssp. salivarius or the mixed culture were used for fermenting yogurt. In sensory evaluation, the yogurt with the mixed culture received high overall sensory score. From these results, a mixed culture of B. longum, L. acidophilus, Streptococcus salivarius ssp. thermophilus was identified as the best for the manufacture of yogurt added with rice powder.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.1
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• pp.66-72
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• 2014

Quality characteristics of yogurt with added colored barely flour was investigated during fermentation by lactic acid bacteria. Chemical properties such as moisture, crude protein, starch, ash and ${\beta}$-glucan contents was measured. pH, acidity, brix, Hunter color value and growth of lactic acid bacteria in yogurt was investigated during fermentation by L. acidophilus, L. bulgaricus, and S. thermophilus mixed culture. Crude protein contents of Daeanchal and Boseokchal was 16.16 and 12.17%, respectively. Starch contents of daeanchal were shown lower score. The pH of yogurt by addition of barley flour (Daeanchal) addition 0 and 20% were 6.66 and 6.40, respectively. The pH of yogurt supplemented with barley flour tended to be lower than before control which was not added barely flours and oligosaccharide in yogurt. Titratable acidity of yogurt added barley flour was higher compared with that of control. Brix of yogurt was decreased during fermentation by lactic acid bacteria. Lightness of yogurt added barley flour (Daeanchal) addition 0 and 20% were 83.25 and 69.83, respectively. The original microbial population of the yogurt during 0, 5, 8, and 15 hr fermentation were 7.48, 7.79, 8.15, and 8.71 Log CFU/g, respectively. Moreover, the addition of colored barley flour was to promote the proliferation of lactic acid bacteria in yogurt. In our research, addition of colored barley flours added into the yogurt may also have contributed to growth of lactic acid bacteria.

• Food Science of Animal Resources
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• v.35 no.4
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• pp.541-550
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• 2015

The purpose of this study was to investigate the effect of lactic acid bacteria (LAB) cell wall extract on the proliferation and cytokine production of immune cells to select suitable probiotics for space food. Ten strains of LAB (Lactobacillus bulgaricus, L. paracasei, L. casei, L. acidophilus, L. plantarum, L. delbruekii, Lactococcus lactis, Streptococcus thermophilus, Bifidobacterium breve, and Pedicoccus pentosaceus) were sub-cultured and further cultured for 3 d to reach 7-10 Log colony-forming units (CFU)/mL prior to cell wall extractions. All LAB cell wall extracts failed to inhibit the proliferation of BALB/c mouse splenocytes or mesenteric lymphocytes. Most LAB cell wall extracts except those of L. plantarum and L. delbrueckii induced the proliferation of both immune cells at tested concentrations. In addition, the production of T_H1 cytokine (IFN-γ) rather than that of T_H2 cytokine (IL-4) was enhanced by LAB cell wall extracts. Of ten LAB extracts, four (from L. acidophilus, L. bulgaricus, L. casei, and S. thermophiles) promoted both cell proliferating and T_H1 cytokine production. These results suggested that these LAB could be used as probiotics to maintain immunity and homeostasis for astronauts in extreme space environment and for general people in normal life.

• KSBB Journal
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• v.32 no.3
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• pp.199-205
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• 2017

The aim of this study was to investigate probiotic characteristics and fermentation profile of selected lactic acid bacteria (LAB) isolated from traditional fermented foods. Antibacterial activity against various pathogens, acid and bile salt tolerance, cell hydrophobicity, and antibiotic resistance were examined. 16S rRNA sequencing was carried out to identify eight presumptive LAB isolates. In general, all identified LAB (Enterococcus faecium MG89-2, Lactobacillus plantarum MG207, L. paracasei MG310, L. casei MG311, Streptococcus thermophilus MG510, L. bulgaricus MG515, L. helveticus MG585, and L. fermentum MG590) showed strong antimicrobial activity. Also, the selected strains were resistant to bile acid up to 3% and their autoaggregation rates were as high as 60%. All selected strains tested were sensitive to chloramphenicol, tetracycline, and ampicillin, whereas resistant to nalidixic acid and kanamycin.

• Mycobiology
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• v.33 no.2
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• pp.90-96
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• 2005

Sixty two out of the sixty four species of fungal isolates tested could produce both $exo-{\beta}1,4-gluconase\;(C_1)$ and $endo-{\beta}1,4-gluconase\;(C_x)$ on pure cellulose and rice straw as carbon source in Czapek's medium. Fifty-eight and fifteen species were able to grow at $25^{\circ}C$ and at $45^{\circ}C$, respectively. Eleven species could grow at both $25^{\circ}C$ and $45^{\circ}C$ while, four species appeared only at $45^{\circ}C$. The most cellulolytic species at $25^{\circ}C$ was Trichoderma koningii producing 1.164 $C_1$ (mg glucose/1 ml culture filtrate/1 hr) and 2.690 $C_x$ on pure cellulose, and 0.889 $C_1$, and 1.810 $C_x$ on rice straw, respectively. At $45^{\circ}C$, the most active thermotolerant species were Aspergillus terreus, followed by A. fumigatus. Talaromyces thermophilus was the highest active thermophilic species followed by Malbranchea sulfurea. Most of these species were also active in fermentation of rice straw at 25 and $45^{\circ}C$ (P<0.05). The most active ones were T. koningii, A. ochraceus and A. terreus, which produced 201.5, 193.1 and 188.1 mg crude protein/g dry straw, respectively.

• Korean Journal of Human Ecology
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• v.12 no.2
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• pp.265-273
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• 2003

The aim of this study was to investigate the effect d concentrated fermented milk on the improvement of defecation in female students with constipation. This yogurt was fermented with Bifidobacterium, L. acidophilus, and S. thermophilus and supplemented with oligosaccharides, dietary fiber, and yeast and mushroom extracts. 44 female students with constipation were sampled as subjects and fed 150ml fermented milk per day for 2 weeks period. After each defecation, the subjects were examined for the status of stool evacuation by questionnaires. The frequency of stool evacuation, fecal amount, time spending for evacuation, fecal color and shape, and refreshing feeling after evacuation were remarkably improved after ingestion of fermented milk for 2 weeks. These effects were greater in the heavy constipation group than in the mild group. The fecal odor did rot decrease significantly after 2 weeks of intake of fermented milk, but the odor thended to decrease after the intake of fermented milk These results indicated that the ingestion of concentrated fermented milk is effective to improve the constipation.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.309-315
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• 1994

Selective agar media were constructed for the counting of bifidobacteria in dairy produ- cts containing bifidobacteria, lactobacilli and streptococci. This media containing antibiotics inhibited the growth of lactobacilli and streptococci at less than 10$^{5}$ cfu/ml, but had no influence on the recovery of bifidobacteria. In order to inhibit the growth of 10$^{5}$ cfu/ml of lactobacilli and streptoco- cci, the addition of 1.0~2.0 $\mu$g/ml of tetracycline in BL agar medium was needed. When 25 $\mu$g/ml of neomycin and paromomycin were mixed with 1.0 $\mu$g/ml of tetracycline in BL agar medium, it was able to inhibit the growth of 10$^{6}$ cfu/ml of lactobacilli and streptococci but had a little negative effect on the recovery of colonies of bifidobacteria. The results revealed that the BL agar medium containing 1.0 $\mu$g/ml of tetracycline was suitable to count the cell number of bifidobacteria selecti- vely in the presence of a 1 to 10$^{5}$-fold excess of L. casei, L. acidophilus and S. salivarius subsp.thermophilus.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.211-219
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• 2019

The effect of microencapsulation on previously isolated Lactobacillus delbrueckii 94/L4 as starter culture for yogurt, and Lactobacillus casei 97/L3 as a probiotic candidate was investigated. Preliminary results showed that L. delbrueckii 94/L4 exhibited tolerance to bile, unlike L. casei 97/L3. Freeze drying significantly (p < 0.05) reduced the viability of both isolates by log 0.71-2.70. Although microencapsulation preserved the viability of L. casei 97/L3 cells exposed to simulated gastrointestinal tract conditions for 120 min, it did not impart significant (p < 0.05) protection against loss of viability during the first 30 min of exposure. Conversely, microencapsulated L. delbrueckii 94/L4 with the addition of Streptococcus thermophilus 24/S1 as starter culture was successfully incorporated into milk to form yogurt, yielding a significantly (p < 0.05) improved product quality.