• Journal of Life Science
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• v.17 no.7 s.87
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• pp.970-975
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• 2007

For the screening of ${\gamma}-aminobutyric$ acid (CABA)-producing bacteria, 86 bacterial strains which produce GABA were isolated from Kimchi and Salted fisk .Among these, three strains designated AML15, AML45-1, AML72 with relatively high GABA productivity were selecled by thin layer chromatography (TLC). To elucidate the relationship between isolated strains and the genus Lactobacillus, their 16S rDNA sequence were examined. The result of their DNA sequences showed 99% similarity with Lactobacillus brevis ATCC 367. On the basis of the these results, isolated strains were identified as Lactobacillus brevis and designated L. brevis AML15. In order to determine the optimum conditions for GABA production, the isolated strains were cultivated in pyridoxal phosphate (PLP) and monosodium glutami. acid (MSG). Results showed that L. brevis AML15 had the highest CABA productivity with 10,424 $nM/{\mu}l$ concentration in MRS broth containing 5% (w/v) MSG and 10 ${\mu}M$ PLP at pH 5.0. The results imply that L. brevis AML15 has the potential to be developed as a strain for GABA hyper-production.

• Journal of fish pathology
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• v.28 no.2
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• pp.63-69
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• 2015

The biological characteristics of Bacillus sp.CPB-St as a probiotic strain to control fish streptococcosis was determined. Based on 16S rRNA sequencing, Bacillus sp.CPB-St was identified as Bacillus pumilus and named B. pumilus CPB-St (Abbreviated as CPB-St). Growth inhibitory activity of CPB-St against Streptococcus spp. was examined at three different incubation temperatures ($20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$) and three culture media (NA, TSA, and BHIA) based on the diameter of inhibition zone. Its activity (inhibition zone of 11~29 mm) at $20^{\circ}C$ was higher than that (12~21 mm) at $30^{\circ}C$. Its activity (29 mm) in NA media was the same as that (29 mm) in TSA media. However, it was higher than that (22 mm) in BHIA media. The inhibitory activity of CPB-St against Streptococcus spp. was high at pH7. However, its activity was the same at salinity of 0.5% to 3%. CPB-St showed maximum growth after incubation at $25^{\circ}C$ for 48 h. To use CPB-St as probiotics, settlement studies in fish intestine and its efficacy through feeding are needed. CPB-St was highly resistant to gastric juice at pH4 and flounder's bile salt as well as deoxycholic acid at $300{\mu}g/ml$. CPB-St showed optimal viability in 1% NaCl. It showed similar growth in 0% to 7% NaCl. CPB-St could tolerate $-20^{\circ}C$ and $-70^{\circ}C$ for 45 min. There was no difference in the growth of the strain between room temperature and $4^{\circ}C$. Fish diet supplemented with CPB-St could be stored at low temperature without cell loss. Therefore, CPB-St might be used as probiotics to control streptococcosis of fish.

• Journal of Life Science
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• v.17 no.11
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• pp.1562-1570
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• 2007

This experiment was conducted to develop fertilizer which promotes plant growth as well as suppressing pathogenic fungi. The fertilizer was made from the mixture of Ju-Back (Korean rice wine cake) and indigenous rhizosphere-bacterium. The main ingredients of Ju-Back were investigated as 6.04% total nitrogen, 42.59% total carbohydrate, 1.01% available phosphate, 73.42% organic matter, 7.72% potassium oxide, 1.35% calcium oxide, 0.53% magnesium oxide. The enzyme activities of Ju-Back were estimated to be 980 units/g for ${\alpha}-amylase$, 300 units/g for glucoamylase, and 1800 units/g for acid pretense. Indigenous rhizosphere bacteria which produced antifungal agent were isolated from soil, and was selected KMU-13 strain which can antagonize against various plant pathogenic fungi (Botrytis cinerea KACC 40573, Sclerotinia sclerotiorum KACC 41065, Fusairum oxysporum KACC 40052, Pythium aphanidermatum KACC 40156, Phytophthora capsici KACC 40476 and Glomerella cingulata KACC 40299). KMU-13 strain was identified as Bacillus subtilis KMU-13 by biochemical and 16s rDNA analysis. The organic fertilizer was made as prototype which was composed 20% Ju-Back, 70% carrier, 9.7% microorganism cultivated solution, 0.3% trace-element. We also investigated an application of fertilizer using Ju-Back for cultivating lettuce (Lactuca sativar) which were grown in three soil conditions that had chemical fertilizer, barnyard manure, lime power, urea, potassium chloride and superphosphate as a control, the whole quantity (80 kg/10a) of posted fertilizer with the control and the half quantity (40 kg/10a) with the control. The growth characteristics were examined and analysed with several weeks interval from 3 weeks to 8 weeks on head length (cm), head width (cm/head), number of leaf and fresh weight (g/plant). The results are summarized as follows. The head width and fresh weight of lettuce were the highest at posted fertilizer 1 (whole quantity) was applied chemical, organic matter (Ju-Back) and carrier. The head length was the highest at posted fertilizer 2 (whole quantity) was applied Ju-Back only.

• Journal of fish pathology
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• v.33 no.2
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• pp.111-118
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• 2020

The genus Edwardsiella belonging to the family Enterobacteriaceae is a member of Gram-negative rod-shaped bacteria that cause disease in diverse aquatic organisms such as fish, amphibians and reptiles as well as avians and mammals including human throughout the world. This genus had been composed of three species, E. hoshinae, E. ictaluri and E. tarda, but recent researches erected two novel species, E. anguillarum and E. piscicida that were conventionally identified as E. tarda. In this study, we isolated seven strains belonging to the genus Edwardsiella from freshwater fishes that had been reared at inland fish farms in South Korea and investigated their biochemical characteristics and molecular phylogenetic relationships. The seven strains showed typical characteristics of four Edwardsiella species, E. anguillarum, E. ictaluri, E. piscicida and E. tarda, by biochemical analyses of Gram staining, indole and hydrogen sulfide (H2S) production, and API (Analytic Profile Index) 20E test. Molecular phylogenetic analyses inferred from DNA sequence data of both 16S ribosomal RNA (rRNA) and DNA gyrase subunit B (gyrB) genes were congruent with the biochemical characteristics. As a result, both biochemical and molecular phylogenetic analyses identified four strains isolated from three Anguilla species as E. anguillarum, E. piscicida and E. tarda, two strains from Pelteobagrus fulvidraco and Silurus asotus as E. ictaluri, and one strain from Moroco oxycephalus as E. piscicida. In this study, we isolated and successfully identified recently newly erected species, E. anguillarum and E. piscicida in addition to historically notorious pathogenic species, E. ictaluri and E. tarda. In the future study, systematic and comprehensive monitoring of the four Edwardsiella species are required for studying differences in pathogenicity among freshwater fishes.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.16-23
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• 2005

In order to develop a new microbial fungicide using endophytic bacteria for the control of anthracnoses occurring on various crops, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth medium, their antifungal activities were tested for in vivo antifungal activity against cucumber anthracnose caused by Colletotrichum orbiculare. As the results, liquid cultures of 28 strains showed potent antifungal activities more than $90\%$ against cucumber anthracnose. At 3-fold dilutions of liquid cultures, 18 strains inhibited the development of cucumber anthracnose of more than $70\%$. They were further tested for in vivo antifungal activity against red pepper anthracnose caused by C. coccodes and in vitro antifungal activity against C. acutatum, a fungal agent causing red pepper anthracnose. Among 18 strains, a bacterial strain EB215 isolated from cucumber roots displayed the most potent antifungal activity against Colletotrichum species. It was identified as Burkholderia cepacia based on its physiological and biochemical characteristics, Biolog test and 16S rDNA gene sequence. It also controlled effectively the development of rice blast (Magnaporthe grisea), rice sheath blight (Corticium sasaki), tomato gray mold (Botrytis cinerea), and tomato late blight (Phytophthora infestans). Studies on the characterization of antifungal substances produced by B. cepacia EB215 are in progress.