• Journal of Life Science
• /
• v.26 no.5
• /
• pp.571-583
• /
• 2016

Biogenic amines are produced primarily by microorganisms found in fermented foods and are often implicated in poisoning incidents in humans. In this study, 620 strains of microorganisms were isolated from traditional Korean fermented food in Sunchang in order to screen for non-biogenicamine-producing microorganisms present in these foods. One strain was identified and named Bacillus subtilis SCJ1, by using 16S rRNA sequencing and biochemical characterization. We investigated the cell growth of this organism in order to understand its potential for industrial application. To this end, we optimized the culture medium constituents by using the response surface methodology. The Plackett-Burman experimental design was used for screening of the medium constituents, such as molasses, yeast extract and peptone, for improving cell growth. In order to determine the optimal concentration of each constituent, we used a central composite design. Consequently, the optimized concentrations of molasses, yeast extract and peptone were predicted to be 27.5 g/l, 7.5 g/l and 17.5 g/l, respectively. By model verification, we confirmed that a 1.49-fold increase in dry cell weight compared to the basal medium-from 1.32 g/l, to 1.9722 g/l-was achieved.

• Food Science and Preservation
• /
• v.15 no.2
• /
• pp.169-173
• /
• 2008

Bacillus subtilis subsp. subtilis constitutes 90% of the total viable bacteria present on Capsosiphon fulvescens. We found that hydrogen peroxide (50 ppm) and NaOCl (50 ppm) were more effective than electrolyzed water (EW, 50ppm) against B. subtilis subsp. subtilis that was isolated from this seaweed. Relative to a control, 50 ppm hydrogen peroxide reduced the total viable population by $1.8{\pm}0.4$ log CFU/g, whereas 50 ppm EW increased the total viable population by $1.7{\pm}0.5$ log CFU/g. CFUs were evaluated following 30 days of storage at $4^{\circ}C$ using air- and vacuum-packaging. Samples treated with 50 ppm hydrogen peroxide and NaOCl showed a $1.6{\pm}0.1$-fold decrease in initial hardness ($7.9{\times}10^6dyne/cm^2$), while the samples treated with 50 ppm EW had a $2.1{\pm}0.1$-fold decrease in initial hardness ($7.9{\times}10^6dyne/cm^2$). Again, measurements were performed after storage at $4^{\circ}C$ for 20 days. This study indicates that B. subtilis subsp. subtilis is the most common contaminant in aerobically or anaerobically packaged seaweed and should therefore be the main target for quality control during long-term storage. Hydrogen peroxide and NaOCl are more effective than EW in inhibiting B. subtilis subsp. subtilis and in reducing total bacterial loads in air- and vacuum-packaged seaweed.

• KSBB Journal
• /
• v.26 no.3
• /
• pp.199-205
• /
• 2011

Using tetrameric ${\beta}$-galactosidase as a model protein, anchoring motives were screened in Bacillus subtilis spore display system. Eleven spore coat proteins were selected considering their expression levels and the location in the spore coat layer. After chromosomal single-copy homologous integration in the amyE site of Bacillus subtilis chromosome, cotE and cotG were chosen as possible spore surface anchoring motives with their higher whole cell ${\beta}$-galactosidase activity. PAGE and Wester blot of extracted fraction of outer layer of purified spore, which express CotE-LacZ or CotG-LacZ fusion verified the existence of exact size of fusion protein and its location in outer coat layer of purified spore. ${\beta}$-galactosidase activity of spore with CotE-LacZ or CotG-LacZ fusion reached its highest value around 16~20 h of culture time in terms of whole cell and purified spore. After intensive spore purification with lysozyme treatment and renografin treatment, spore of BJH135, which expresses CotE-LacZ, retained only 1~2% of its whole cell ${\beta}$-galactosidase activity. Whereas spore of BJH136, which has cotG-lacZ cassette in the chromosome, retained 10~15% of its whole cell ${\beta}$-galactosidase activity, proving minor perturbation of CotG-LacZ, when incorporated in the spore coat layer of Bacillus subtilis compared to CotE-LacZ. Usage of Bacillus subtilis WB700, of which 7 proteases are knocked-out and thereby resulting in 99.7% decrease in protease activity of the host, did not prevent the proteolytic degradation of spore surface expressed CotG-LacZ fusion protein.

• Korean Journal of Microbiology
• /
• v.17 no.2
• /
• pp.72-80
• /
• 1979

24 samples which were incoulated with Aspergillus flavus and Bcillus subtilis and cultured on the steamed soybean media under various conditions-pH, moisture and temperature were-investigated on the production of aflatoxin by the interaction of these two microorganisms. 1) The amount of aflatoxin produced by mixed cultures of Aspergillus flavus and Bacillus subtilis was decreased significantly rather than that of single cultures of Aspergillus flavus. 2) Maximum production of crude aflatoxin was 2,560 ppm $(B_1,\;0.908\;ppm;\;B_2,\;0.261\;ppm;\;G_1,\;1.162\;ppm;\;G_2,\;0.229\;ppm)$ at 30% moisture, pH 5.0 and $20^{\circ}C$, whereas minimum production was 1.107 ppm $(B_1,\;0.341\;ppm;\;B_2,\;0.104\;ppm;\;G_1,\;532\;ppm;\;G_2,\;0.130\;ppm)$ at 63% moisture, pH 9.0 and $40^{\circ}C$.

• Microbiology and Biotechnology Letters
• /
• v.16 no.2
• /
• pp.79-84
• /
• 1988

Dye materials and cross linking agents were used for the determination of $\beta$-glucanase activities. The objective of this study was to prepare the blue coloured substrates which are sensitive, specific and simple for the determination of $\beta$-glucanase in malt and Bacillus subtilis K-4-3 enzymes. This method is based on the principle of measuring colorimetrically the split product of coloured and cross linked substrate. The best coupling of dye stuff of $\beta$-glucan was cibacron blue 3G-A and the colour released can suitably be measured at 623nm. Optimal concentration of dye and cross linking agents was 1.5g and 1.25$m\ell$ under 0.1N NaOH. The sensitivity comparison proved that the stained $\beta$-glucan method is much more sensitive than the DNS method to determine reducing sugar released by the enzyme.

• Microbiology and Biotechnology Letters
• /
• v.44 no.2
• /
• pp.185-193
• /
• 2016

A novel proteolytic bacterium was isolated from soil at Yeungnam University, South Korea. The strain, named FBL-1, was rod-shaped with a smooth surface. Biolog and API 50CHB test results revealed that strain FBL-1 was a Bacillus species. Based on 16S rDNA sequencing and chemotaxonomic characterization, the strain was identified as Bacillus subtilis because it had the highest homology with Bacillus subtilis subsp. subtilis NCIB 3610 (99.5%). In liquid culture at 37℃ with shaking at 200 rpm, fructose and yeast extract were found to be the best carbon and nitrogen sources, respectively, for cell growth and protease production. The highest protease activity (451.640 U/ml) was obtained when the strain was cultured in medium containing 20 g/l of fructose and 5 g/l of yeast extract. Although further studies are needed to characterize the protease and enhance its activity, the newly isolated protein-degrading B. subtilis FBL-1 can be applicable for the production of peptides and for the degradation of proteins in various industries.

• Korean Journal of Poultry Science
• /
• v.43 no.3
• /
• pp.159-167
• /
• 2016

A total of 528 broilers ($47{\pm}0.1g$; 1 day of age) were used in a 35-day feeding trial to evaluate probiotics, prebiotics and their interactive effects on growth performance, blood characteristics, relative organ weight and meat quality. Broilers were randomly distributed into 1 of 6 treatments on the basis of body weight (BW) (4 replicate pens per treatment, 22 broilers per pen). The dietary treatments were CON, basal diet; B, CON + 0.1 g kg-1 Bacillus subtilis; K, CON + 1 g kg-1 Kefir; G, CON + 1 g kg-1 ${\beta}-glucan$; GB, G + 1 g kg-1 Bacillus subtilis; and GK, G + 1 g kg-1 Kefir. The overall effects indicated that broilers fed the K, G and GK diets had greater body weight gain (BWG) than those fed the CON diet (P<0.05). The number of white blood cells increased (P<0.05) in the GB group compared with the CON, B and G treatments; however, the lymphocyte percentage in the B group was higher than in the G group. The weight of bursa fabricii was lower in the B and G groups compared to the K group (P<0.05), whereas a higher spleen weight was observed in chickens that were fed the GB and GK diets compared to the B group (P<0.05). The treatments did not affect the meat quality parameters, except for meat redness, which improved with all of the supplementation groups (P<0.05). The population of Lactobacillus spp. in gizzard was significantly higher in the K treatment compared with CON, B, G and GB. In conclusion, supplementation with kefir and ${\beta}-glucans$ improved growth performance.

• Food Science and Preservation
• /
• v.22 no.4
• /
• pp.545-552
• /
• 2015

This study investigated the quality characteristics of popped rice Doenjang prepared with different Bacillus strains (Bacillus subtilis KACC 15935, and Bacillus subtilis HJ18-9). The changes in the enzyme activity (protease, cellulase, and ${\alpha}$-amylase), amino-type nitrogen and ammonia-type nitrogen contents, and the reducing sugar were investigated during the fermentation period. Enzymes such as protease, cellulase, and a-amylase plays an important role in the changes in composition of nutrients, and in flavor and taste of popped rice Doenjang. Protease activities of the popped rice deonjang fermented with different Bacillus strains (control, B. subtilis KACC 15935, and B. subtilis HJ18-9) was in the range of 171.77-185.97 unit/g at the beginning of fermentation, and there were no significant differences among the samples. On the other hand, the protease activity in popped rice Doenjang fermented with B. subtilis HJ18-9 increased significantly up to $248.77{\pm}4.53unit/g$ at the end of fermentation (p<0.05). Cellulase activity and a-amylase activity of popped rice Doenjang in HJ18-9 was higher than these of other samples. After 56 days of fermentation, amino-type nitrogen in popped rice deonjang fermented with control, B. subtilis KACC 15935, and B. subtilis HJ18-9 increased significantly up to $174.99{\pm}3.70$, $166.59{\pm}1.40$, $225.39{\pm}3.70mg%$, respectively (p<0.05). These results suggested that B. subtilis HJ18-9 was a suitable starter for the preparation of soybean paste.

• Korean Journal of Microbiology
• /
• v.51 no.1
• /
• pp.48-60
• /
• 2015

612 strains isolated from Korean traditional fermented food in Sunchang and their investigated biochemical characterization and ability of biogenic amines non-producing. We selected the SCJ4 having various activity by measurement of extracellular enzyme, antioxidant and antimicrobial activities. Selected strain SCJ4 by 16S rRNA sequencing and biochemical characterization was named Bacillus subtilis SCJ4. And then, we investigated cell growth of SCJ4, and optimized of culture medium constituents using response surface methodology as statistically method. Response surface methodology used Plackett-Burman experimental design for screening of medium constituent. Tryptone, peptone and $MgSO_4$ as medium constituent improving cell growth selected. In order to find out optimal concentration on each constituent, we carried out central composite design. Consequently, optimized concentrations of tryptone, peptone and $MgSO_4$ were predicted to be 15.35 g/L, 12.235 g/L, and 3.5 g/L respectively. Through the model verification, we confirmed about 1.28-fold improvement of the dried cell weight from 0.8767 g/L to 1.1222 g/L when compared to basal medium.

• Journal of Microbiology and Biotechnology
• /
• v.4 no.1
• /
• pp.68-74
• /
• 1994

A bacterial strain YB-70 which has powerful biocontrol activity against Fusarium solani causing plant root-rot resulting in considerable losses of many economical crops was isolated and selected from over 500 isolates from a ginseng rhizosphere in suppressive soil, and identified as a strain of Bacillus subtilis. In several biochemical and in vitro antibiosis tests on F. solani with culture filterates from B. subtilis YB-70, our data strongly indicated metabolites which mediated inhibition of the fungal growth were presumed to be heat-stable, micromolecular, and ethyl alcohol solutable antifungal substances. Suppression of root-rot by B. subtilis YB-70 was demonstrated in pot trials with eggplant (Solanum melongena L) seedlings. Treatment of the seedling with the bacterial suspension (1.7~1.9$\times$$10^5$ CFU/g) in F. solani-infested soil significantly reduced disease incidences by 68 to 76% after 25 to 30 days. The results supported that B. subtilis YB-70 have excellent potentials as a biocontrol agent.