• Journal of Life Science
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• v.20 no.9
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• pp.1306-1313
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• 2010

The gene encoding esterase enzyme was cloned from a metagenomic library of cow rumen bacteria. The esterase gene (est1R) was 2,465 bp in length, encoding a protein of 366 amino acid residues, and the molecular weight of the enzyme was 61,166 Da. Est1R of rumen cosmid library shared 5.9% amino acid identity with Est1R (P37967) of PNB carboxylesterase, 6.1% with Est1R (1EEAA) of acetylcholinesterase and 6.1% with Est1R (1H23A) of chain A. BlastP in NCBI database analysis of Est1R revealed that it was not homologous to previous known lipases and esterases. Est1R showed optimum activity at pH 7.0 and $40^{\circ}C$. On the other hand, the enzyme was found to be most active without organic solvent, followed by 95% activity with methanol, and the enzyme activity was highly affected by hexane (lost 51% activity). Therefore, the novel esterase gene est1R is likely obtainable from cow rumen metagenome and may be utilized for industrial purposes.

• Journal of Mushroom
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• v.13 no.4
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• pp.305-309
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• 2015

In order to isolate compost-promoting bacteria with high activity of cellulase and xylanase, spent mushroom substrates with sawdust were collected from mushroom cultivation farm, Jinju, Gyeongnam in Korea. Among of the isolates, one strain, designated CA105 was selected by agar diffusion method. The strain CA105 was identified as members of the Bacillus subtilis by biochemical characteristics using VITEK 2 system. Comparative 16S rRNA gene sequence analysis showed that isolate CA105 formed a distinct phylogenetic tree within the genus Bacillus and was most closely related to Bacillus subtilis with 16S rRNA gene sequence similarity of 98.9%. On the basis of its physiological properties, biochemical characteristics and phylogenetic distinctiveness, isolate CA105 was classified within the genus Bacillus subtilis, for which the name Bacillus subtilis CA105 is proposed. The cellulase and xylanase activity of B. subtilis CA105 was slightly increased according to bacterial population from exponential phase to stationary phase in growth curve for Bacillus sp. CA105.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.194-202
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• 2003

To isolate alga-lytic bacteria, a number of samples were collected from Lake of Sukchon and Pal'tang reservoir where cyanobacteria blooming occurred. HY0210-AK1, which exhibited high alga-lytic activity, was isolated using Anabaena cylindrica lawn. The morphological and biochemical characteristics of the isolate HY0210-AK1 were very similar to that of the genus Rhizobium. Taxonomic identification including 16S rDNA base sequencing and phylogenetic analysis indicated that the isolate Hy0210-AK1 had a 99.1% homology in its 16S rDNA babe sequence with Sphingobium herbicidovorans. A. cylindrica NIES-19 was susceptible to the alga-lytic bacterial attack. The growth-inhibiting offset of the bacterium was not different on A. cylindrica NIES-19 when Sphingobium herbicidovorans HY0210-AK1 was in the lag, exponential, and stationary growth phase, although the alga-Iytic effect of S. herbici-dovorans HY0210-AK1 that in stationary growth phase was somewhat pronounced at the first time of inoculation. When S. herbicidovorans HY0210-AK1 was inoculated was inoculated with $1\times 10^{8}$ CFU $ml^{-1}$ together with A cylindrica NIES-19, the bacterium proliferated and caused algal lysis. A. cylindrica NIES-19 died when S. herbicidovorans HY0210 AKl was added to the algal culture but not when duly the filtrates from the bacterial culture was added. This suggests that extracellular substances are not responsible for inhibition of A. cylindrica NIES-19 and that algal Iysis largely attributed to direct interaction between S. herbicidovorans HY0210-AK1 and A. cylindrica NIES-19. The alga-lytic bacterium HY0210-AK1 caused cell lysis and death of three strain of Micro-cystis aeruginosa, but revealed no alga-Iytic effects on the Stephanodiscus hantzschii.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.363-369
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• 1989

In this study, the biochemical characterization of strong proteolytic bacteria and their extracellular pretense isolated from fermented fish paste were experimented for the purpose of industrial large scale-production by accelerated fermentation. The results obtained were as follows: Among 4 strains isolated from fermented fish paste, B. subtilis p-4 and B. licheniformis p-5, which grow well at $40^{\circ}C$, pH 7.0 and $1\%$ of salt contents, were the best proteolytic bacteria and were shown $0.48hr^{-1}$, $0.49hr^{-1}$ of specific growth rate in TPY medium, respectively. Maximum enzyme activity of B. subtilis p-4 was 335n mole-Tyr/min.ml after 30 hrs and that of B. licheniformis p-5 was 300n mole-Tyr/min.ml after 28 hrs of shaking culture. Purified pretense produced by B. subtilis p-4 and B. licheniformis p-5 showed maximum activity at $50^{\circ}C$, pH 7.0 and molecular weight were estimated to be 18,000, 30,000 by sephadex G-100 gel filtration, respectively. These were supposed to be a kind of metal chelator sensitive neutral pretense from the result of high sensitivity against EDTA, o-phe-nanthroline and metal ions such as $Cu^{2+},\;Ni^{2+},\;Zn{2+}$.

• The Korean Journal of Mycology
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• v.40 no.2
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• pp.118-123
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• 2012

In order to develop environment friendly fungicide for the control of citrus green mold (Penicillium digitatum) using endophytic bacteria, the 21 bacterial isolates were isolated from citrus leaves in seven different orchards in Jeju Province. Among the 21 bacterial isolates, 5 bacterial isolates presented antifungal activity against green mold pathogen P. digitatum. The CB3 isolate, which showed the most strong antagonistic effect, was selected through opposite culture against the pathogen. The rod-shaped, gram-positive bacterium CB3 was identified as Bacillus velezensis based on morphological, physiological characteristics, 16S rDNA, and gyr A gene sequence analysis. The isolate CB3 showed strong antifungal activity against two citrus postharvest pathogen P. digitatum. Citrus fruits were treated by wound inoculation with P. digitatum pathogen, and the control efficacy of CB3 culture broth was 66.7% ($1{\times}10^8$ cfu/ml). In conclusion, The stability of CB3 and its strong antifungal activity also lead us to believe that it has potential for application as an environment friendly biological control agent.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.298-304
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• 2012

Among 63 Bacillus strains grown at $60^{\circ}C$ from sixteen samples of homemade Korean soybean paste, one strain was selected for producing the thermostable protease. The isolate has been identified as Bacillus licheniformis on the basis of its 16S rDNA sequence, morphology and biochemical properties. Culture filtrate of the isolate showed maximal protease activity at the reaction condition of $60-65^{\circ}C$ and pH 11. The culture filtrate retained more than 87% of initial protease activity after incubation for 30 min at $60^{\circ}C$ without substrate. In order to develop the medium composition, effects of ingredients including nitrogen sources, carbon sources, metal ions and phosphate were examined for protease production of the isolate. Lactose and soytone peptone were the most effective carbon and nitrogen source for the enzyme production. After the late logarithmic growth phase the isolate began to produce the protease, and the maximum protease productivity was reached to 550 unit/ml in the optimized medium consisting of lactose (3%), soytone peptone (1.5%), $MgSO_4$ (0.1%), $K_2HPO_4$ (0.03%), and $KH_2PO_4$ (0.03%) at 28 h of incubation.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.33-39
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• 2014

One hundred forty four bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejeon area. Among them, one bacterial strain was selected for this study based on its emulsification activity, growth rate and surface tension activity, and this selected bacterial strain was identified as Pseudomonas sp. HN37 through physiological- biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. HN37 utilize the several aliphatic hydrocarbons, 3,5-dinitrosalicylic acid and 2,4-dichlorophooxyacetic acid as a sole carbon source. And this bacterial strain showed a high resistance to antibiotics such as ampicillin and chloramphenicol, as well as heavy metals such as Ba, Cr, Li and Mn. Also, it was found that the optimal pH and temperature for the cell growth, surface tension, and emulsification activity of Pseudomonas sp. HN37 were pH 6.0-9.0 and $30^{\circ}C$, respectively. The emulsification and surface tension activity was reached the maximum to 1% (V/V) crude oil and 1% (W/V) NaCl concentration. The surface tension of the culture broth was decreased from 62 to 27 dyne/cm after fifteen hours of inoculation in LB media.

• Journal of Food Hygiene and Safety
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• v.23 no.4
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• pp.343-347
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• 2008

Recently, Sunshik has been issued because of easy-cook and well-being food. Sunshik basically was made of the heated cereals. Amount of spore-forming Bacillus cereus was detected and it has been caused some problem of food safety. B. cereus was isolate from 57 out of 161 Sunshik samples resulting in the isolation rate of 35.4%. Quantitative analysis of 57 samples showed that 21 samples were less than 100 CFU/g, 33 samples were between 100 and 1,000 CFU/g and distinctively even 3 (1.9%) samples had over 1,000 CFU/g. Typical morphology of B. cereus isolated from Sunshik was observed on MYP agar and then further characteristics was identified by using VITEK 2 (Biomeriux, France). 53 strains out of 57 strains isolated from Sunshik (about 93.0%) produced diarrheal enterotoxin in brain heart infusion broth which was detected by the Bacillus cereus enterotoxin reversed passive latex agglutination test kit (Oxoid England). The D-values of the B. cereus spores were $75^{\circ}C$ (37.1mim), $80^{\circ}C$ (22.5mim), $85^{\circ}C$ (4.9mim), and $90^{\circ}C$ (3.1mim) respectively. The Z-value was calculated $12.8^{\circ}C$ in Sunshik sample inoculated with B. cereus. Therefore, the management of B. cereus in Sunshik is required for the food-safety.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.51-57
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• 1970

On the basis of the specific interrelationship between the species or variety of leguminous crops and the species or strain of nodule bacteria, Rhizobia, the rhizobial species and strain must be effectively chosen for the successful inoculation. The present paper describes on some results of the isolation and taxonomic study on the native rhizobial strains isolated from the nodules of five species of leguminous crops such as numerous varieties of soy bean, lespedeza, birdfoot trefoil, ladino and red clovers. The isolated strains of soy bean nodule bacterium, Rhizobium japonicum were grouped through the inoculation test on variety Changdanbaikmock into the effective, noneffective and toxic strain for the nodule formation. In the study of the effect of some inorganic and organic nitrogenous compounds on the growth of Rhizobium japonicum strain Ac 20, a promotive response was showed by asparagine, and glutamine, but hydroxylamine, nitrite, hydrazine and azide was inhibitory at the concentration of $10^{-2}M/l$ in mannitol-yeast extract basal medium. In the physiological characteristics each strain showed somewhat different activities of the indole-3-actic acid formation and hydrogenase and discussed with these characters in relation to nodule forming ability.

• Korean Journal of Microbiology
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• v.51 no.2
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• pp.169-176
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• 2015

The malolactic fermentation (MLF), which is widely used in winemaking, is the conversion of malic acid to lactic acid conducted by the malolactic enzyme (Mle) of lactic acid bacteria. In order to select the strains with MLF among 54 lactic acid bacteria isolated from the traditionally fermented foods, we designed a primer set that specifically targets the conserved regions of the mle gene and then selected four strains that harbor the mle gene of Lactobacillus plantarum. All strains were identified as L. plantarum by analyzing the 16S rRNA sequences, biochemical properties, and the PCR products of the recA gene. From comparison of the mle gene sequences consisting of 1,644 bp, the nucleotide and amino acid sequence of strain JBE60 correspond to 96.7% and 99.5% with those of other three strains, respectively. The strain JBE60 showed the highest resistant against 10% (v/v) ethanol among the strains. The strains lowered the concentration of malic acid to average 43%. Considering the ethanol resistance and conversion of malic acid, the strain JBE60 is considered as a potential starter for the malolactic fermentation.