• Journal of Life Science
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• v.33 no.6
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• pp.506-511
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• 2023

The purposes of this study were to isolate and characterize lactic acid bacteria with antibacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA) from fermented food and to confirm the antibacterial activities of fermented rice products using the isolated lactic acid bacterium. Three bacteria, namely, Weissella sp. ISF-1, ISF-2, and ISF-3, were selected from fermented squid based on the 16S rRNA gene sequence. All three strains grew well in an MRS medium containing 5% (w/v) NaCl and showed antibacterial activity against Bacillus cereus, Staphylococcus aureus, and MRSA. Their growth was excellent at 0% ~ 5% (w/v) NaCl and relatively good up to 7% (w/v) NaCl. The initial pH of 8 was optimal for their growth, and good growth was also observed at pH 6, 7, and 9. The lyophilisates of the fermented rice using Weissella sp. ISF-1 showed antibacterial activities against B. cereus, S. aureus, and MRSA. We inferred that isolated lactic acid bacteria could be useful in the development of probiotics and biopreservatives for foods and in the treatment of MRSA and may increase the value of rice products.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.489-498
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• 2013

A new Bacillus strain degrading starch, named Bacillus sp. UEB-S, was isolated from a southern Tunisian area. Amylase production using solid-state fermentation on millet, an inexpensive and available agro-resource, was investigated. Response surface methodology was applied to establish the relationship between enzyme production and four variables: inoculum size, moisture-to-millet ratio, temperature, and fermentation duration. The maximum enzyme activity recovered was 680 U/g of dry substrate when using $1.38{\times}10^9$ CFU/g as inoculation level, 5.6:1 (ml/g) as moisture ratio (86%), for 4 days of cultivation at $37^{\circ}C$, which was in perfect agreement with the predicted model value. Amylase was purified by Q-Sepharose anion-exchange and Sephacryl S-200 gel filtration chromatography with a 14-fold increase in specific activity. Its molecular mass was estimated at 130 kDa. The enzyme showed maximal activity at pH 5 and $70^{\circ}C$, and efficiently hydrolyzed starch to yield glucose and maltose as end products. The enzyme proved its efficiency for digesting raw cereal below gelatinization temperature and, hence, its potentiality to be used in industrial processes.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.131-137
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• 2021

This study aimed at isolating lactic acid bacteria with anti-MRSA (methicillin-resistant Staphylococcus aureus) bacteriocin activity from fermented shrimp. We selected three strains, named Weissella sp. S1, S2, and S3, using analysis based on 16S rRNA gene sequences. All strains showed appropriate growth in an MRS medium containing 5% (w/v) NaCl and showed antibacterial activities against Bacillus cereus, Escherichia coli, Staphylococcus aureus, and MRSA. The strains exhibited similar growth rates at 0-5% NaCl, with approximate reduction in growth rate observed at 9% NaCl. Weissella sp. S1, S2, and S3 exhibited maximum growth rates at pH 7, 9, and 8, respectively. The crude bacteriocin was prepared from Weissella sp. S3 and subjected to characterization. The remaining activities after 30 min of exposure at each temperature were 100%, beyond 75%, and 49% at 4℃ and 37℃, 50℃ and 70℃, and 100℃, respectively. The remaining activities after 24 h of exposure at each pH were 100%, 75%, and 49% at pH 3 and 5, 7 and 9, and 10, respectively. Use of 50% (v/v) ethanol or isopropanol treatment did not diminish the antibacterial activity of the bacteriocin, while the 50% (v/v) hexane treatment reduced the activity by 51%. The molecular weight of the bacteriocin was nearly 6 kDa that was quantified using tricine-SDS-PAGE. Our findings suggest that Weissella sp. S3 may be considered a probiotic and useful source of antimicrobial substances in the development of bio-preservatives for food or in MRSA treatment.

• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.930-938
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• 2012

High levels of xylanase activity (143.98 IU/ml) produced by the newly isolated Paenibacillus campinasensis G1-1 were detected when it was cultivated in a synthetic medium. A thermostable xylanase, designated XynG1-1, from P. campinasensis G1-1 was purified to homogeneity by Octyl-Sepharose hydrophobic-interaction chromatography, Sephadex G75 gel-filter chromatography, and Q-Sepharose ion-exchange chromatography, consecutively. By multistep purification, the specific activity of XynG1-1 was up to 1,865.5 IU/mg with a 9.1-fold purification. The molecular mass of purified XynG1-1 was about 41.3 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Sequence analysis revealed that XynG1-1 containing 377 amino acids encoded by 1,134 bp genomic sequences of P. campinasensis G1-1 shared 96% homology with XylX from Paenibacillus campinasensis BL11 and 77%~78% homology with xylanases from Bacillus sp. YA-335 and Bacillus sp. 41M-1, respectively. The activity of XynG1-1 was stimulated by $Ca^{2+}$, $Ba^{2+}$, DTT, and ${\beta}$-mercaptoethanol, but was inhibited by $Ni^{2+}$, $Fe^{2+}$, $Fe^{3+}$, $Zn^{2+}$, SDS, and EDTA. The purified XynG1-1 displayed a greater affinity for birchwood xylan, with an optimal temperature of $60^{\circ}C$ and an optimal pH of 7.5. The fact that XynG1-1 is cellulose-free, thermostable (stability at high temperature of $70^{\circ}C{\sim}80^{\circ}C$), and active over a wide pH range (pH 5.0~9.0) suggests that the enzyme is potentially valuable for various industrial applications, especially for pulp bleaching pretreatment.

• Microbiology and Biotechnology Letters
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• v.23 no.5
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• pp.506-512
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• 1995

A cell aggregation factor produced by Aspergillus sp. LAM 94-142 was purified and partially characterized. The factor was purified about 15 folds from culture broth by IRA 420 and IRC 120 treatment, 1% NaCl added acetone precipitation, and Sepharose 4B column chromatography with overall yield of 48%. It was heteropolysaccharide consisted of mannose, arabinose, and glucose with a molar ratio, 31:17:2, and its molecular weight was estimated to be about 900,000 daltons by Sepharodse 4B gel filtration method. The optimum pH and temperature was 8 and 40$\circ$C, respectively. The factor was stable in pH range of 3-9 and at 100$\circ$C for 90 min. The cell aggregation activity of the factor was inhibited by the addition of Hg$^{2+}$, Fe$^{2+}$, Cu$^{2+}$, and some polypeptides such as milk casein or hemoglobin. The factor aggregated Bacillus subtilis, B. macerans, B. turingiensis, E. coli, Peudomonas aeruginosa, P. fluorescens, P. malophilia, and weakly aggregated Staphylococcus sp., Sarcina lutea, P. putida and Cryptococcus neoformnans, but it didn't aggregate various strains of Candida sp. and Saccharomyces sp.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.72-79
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• 2005

A new Bacillus peptidase, bacillopeptidase DJ-2 (bpDJ-2), with molecular mass of 42 kDa and isoelectric point (pI) of 3.5- 3.7, was purified to homogeneity from Bacillus sp. DJ-2 isolated from Doen-Jang, a traditional Korean soybean fermented food. The enzyme was identified as an extracellular serine fibrinolytic protease. The optimal conditions for the reaction were pH 9.0 and $60^{\circ}C$. The first 18 amino acid residues of the N-terminal amino acid sequence of bpDJ-2 were TDGVEWNVDQIDAPKAW, which is identical to that of bacillopeptidase F (bpf). However, based on their Nterminal amino acid sequence, molecular size, and pI, it is different from that of bpf and extracellular 90 kDa. The whole (2,541 bp, full-bpDJ-2) and mature (1,956 bp, mature-bpDJ-2) genes were cloned, and its nucleotide sequence and deduced amino acid sequence were determined. The expressed proteins, full-bpDJ-2 and mature-bpDJ-2, were detected on SDSPAGE at expected sizes of 92 and 68 kDa, respectively.

• Food Science and Preservation
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• v.21 no.3
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• pp.442-450
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• 2014

In this study, we isolated a cellulase-producing bacterium isolated from traditional Korean fermented soybean paste and investigated the effect of culture conditions on the production of cellulase. This bacterium, which was identified as Bacillus subtilis 4-1 through 16S rRNA gene sequence analysis, showed the highest cellulase activity when the cells were grown at $45^{\circ}C$ for 24 hours in the CMC medium supplemented with 1.0% of soluble starch and 0.1% yeast extract. The initial optimum pH of the medium was observed in the range of 5.0~9.0. The optimal pH and temperature for the production of cellulase from B. subtilis 4-1 were pH 9.0 and $60^{\circ}C$ respectively. In addition, the enzyme showed significant activity in the temperature range of $20{\sim}90^{\circ}C$, which indicates that B. subtilis 4-1 cellulase is an alkaline-resistance and thermo-stable enzyme. This enzyme showed higher activity with CMC as the substrate for endo-type cellulase than avicel or pNPG as the exo-type substrates for exo-type cellulase and ${\beta}$-glucosidase. These results suggest that the cellulase produced from B. subtilis 4-1 is a complex enzyme rather than a mono-enzyme.

• Microbiology and Biotechnology Letters
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• v.17 no.6
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• pp.563-567
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• 1989

An alkalophilic bacterium isolated from compost was selected, identified and tested for the production of glutamic acid from ammonium fumarate. The bacterium was closely related to Bacillus brevis. The conditions for glutamic acid production were pH 8.0, 2% fumaric acid, and 0.8% nutrient broth. The mechanism of glutamic acid formation in this strain was postulated as following scheme. (1) Ammonium fumarate longrightarrow Aspartic acid (2) Aspartic acid ＋ $\alpha$-Ketoglutaric acid longrightarrow Glutamic acid + Oxaloacetic acid.

• Journal of Microbiology and Biotechnology
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• v.20 no.11
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• pp.1546-1554
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• 2010

A bacterial strain capable of producing extracellular ${\alpha}$-galactosidase was isolated from a sample of sugarcane industrial waste. Microbiological, physiological, and biochemical studies revealed that the isolate belonged to Bacillus sp. Furthermore, based on a 16S rDNA sequence analysis, the new isolate was identified as Bacillus megaterium VHM1. The production of ${\alpha}$-galactosidase was optimized based on various physical culture conditions. Guar gum and yeast extract acted as the best carbon and nitrogen sources, respectively. The optimum pH was 7.5 and the enzyme remained stable over a pH range of 5-9. The enzyme was optimally active at $55^{\circ}C$ and thermostable with a half-life of 120 min, yet lost 90% of its residual activity within 120 min at $60^{\circ}C$. One mM concentrations of $Ag^2$, $Cu^2$, and $Hg^{2+}$ strongly inhibited the ${\alpha}$-galactosidase, whereas the metal ions $Fe^2$, $Mn^{2+}$, and $Mg^{2+}$ had no effect on the ${\alpha}$-galactosidase activity, and $Zn^{2+}$, $Ni^{2+}$, and $Ca^{2+}$ reduced the enzyme activity slightly. When treated with the B. megaterium VHM1 enzyme, the flatulence-causing sugars in soymilk were completely hydrolyzed within 1.5 h.

• BMB Reports
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• v.32 no.5
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• pp.480-485
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• 1999

Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 mol of pyridoxal 5'-phosphate (PLP) per mol subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constsnt, $K'_D$, for PLP was determined with the apoenzyme to be about $1.2\;{\mu}M$. The isoelectric point was 4.9. The optimal temperature and pH for the $\alpha,\beta$-elimination of L-tyrosine were found to be $80^{\circ}C$ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, $\beta$-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7% and 31% relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in a, $\beta$-elimination, was the only D-amino acid racemized by the enzyme. The $K_m$ values for L-tyrosine, L-DOPA, S-(o-nitrophenyl)-L-cysteine, $\beta$-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.