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복합기능미생물 Bacillus velezensis GH1-13을 이용한 미생물제형 개발 및 생물학적 특성
박준경(Jun-Kyung Park),서선일(Sun-Il Seo),한귀환(Gui Hwan Han),김공민(Kong-Min Kim),김대혁(Dae-Hyuk Kim),송재경(JaeKyeong Song),김평일(Pyoung Il Kim) 한국생물공학회 2018 KSBB Journal Vol.33 No.4
Biological control of plant diseases including bacterial and fungal pathogens has been deliberated as a viable alternative method to harmful and expensive chemical control. Bacillus velezensis GH1-13 strain was reported as a multifunctional biological agent which inhibits the plant pathogens and utilized in sustainable agriculture for improving growth of the crops. The objective of this study is to evaluate the biological potential of Bacillus velezensis GH1-13 for effective use in agriculture and industrialization. The microbial formulations of GH1-13 strain were performed into liquid, powder, granule and pellet types. Total viable cells of four microbial formulations were verified more than 107 cfu/mL(g) during 8 weeks at 40℃, and the storage stability was considered under severe condition. Plant growth promoting of four formulation types were examined to pepper and tomato plants. The powder type showed the best effect such as stem length 25.6±0.72 cm, 10 petiole and stem length 35.3±0.46 cm, 11 petiole of pepper and tomato plant, respectively. Biocontrol effect of liquid and powder types was also tested against Colletotrichum gloeosporioides causing pepper anthracnose. The resulting, 100 fold diluted liquid type exhibited control effect of 65%, and side effect on pepper and tomato plants were not detected. From the results, we suggest that microbial formulations have significant effects as biological agents such as plant growth promoting and controlling the phytopathogenic fungi. In addition, we expect that microbial agent may be useful in agriculture, although further study is needed.
광합성세균 Rhodobater capsulatus PS-2의 대량배양 최적화 및 대사산물 분석
봉기문(Ki Moon Bong),김종민(Jong Min Kim),유재홍(Jae-Hong Yoo),박인철(In Chul Park),이철원(Chul Won Lee),김평일(Pyoung Il Kim) 한국생물공학회 2016 KSBB Journal Vol.31 No.3
Plant growth promoting (PGP) hormones, which are produced in a small quantity by bacteria, affect in plant growth and development. PGPs play an important role on the crop productivity in agricultural field. In this study, a photosynthetic bacterial strain producing the PGP was isolated from paddy soil. Bacterial isolate was gram negative, rod-shaped and motility positive. From the 16s rRNA gene sequence analysis, the isolate was identified as Rhodobacter capsulatus PS-2. The mass cultivation of R. capsulatus PS-2 was optimized by considering of the carbon, nitrogen and inorganic salt sources. Optimal medium composition was determined as Na-succinate 4.5 g, yeast extract 5 g, K2HPO4 1 g, MgSO4 5 g , per liter. From the result of 500 L fermentation for 2 days using the optimal medium, the viable cells were 8.7×109 cfu/mL. R. capsulatus PS-2 strain produced the carotenoid and indole-3-acetic acid (IAA). The carotenoid extraction and quantitative analysis were performed by HCl-assisting method. Total carotenoid contents from R. capsulatus PS-2 culture broth were measured as 7.02±0.04 and 6.93±0.05 mg/L under photoheterotrophic and chemoheterotrophic conditions, respectively. To measure the productivity of IAA, colorimetric method was employed using Salkowski reagent at optical density 535 nm. The results showed that the highest content of IAA was 197.44±5.92 mg/L in the optimal medium supplemented with 0.3% tryptophan.
황토로부터 분리한 Bacillus licheniformis의 항진균 chitinase 생산과 효소 특성
한귀환(Gui Hwan Han),봉기문(Ki Moon Bong),김종민(Jong Min Kim),김평일(Pyoung Il Kim),김시욱(Si Wouk Kim) 한국생물공학회 2014 KSBB Journal Vol.29 No.3
In this study, we isolated two novel chitinase producing bacterial strains from yellow loess samples collected from Jullanamdo province. The chitinase producing bacteria were isolated based on the zone size of clearance in the chitin agar plates. Both of them were gram positive, rod (2~3×0.3~0.4 μm), spore-forming, and motility positive. They were facultative anaerobic, catalase positive and hydrolyzed starch, gelatin, and casein. From the 16s rRNA gene sequence analysis, the isolates were labeled as Bacillus licheniformis KYLSCU01 and B. licheniformis KYLS-CU02. The isolates showed higher extracellular chitinase activities than B. licheniformis ATCC 14580 as a control. The optimum temperature and pH for chitinase production were 40oC and pH 7.0, respectively. Response Surface Methodology (RSM) was used to optimize the culture medium for efficient production of the chitinase. Under this optimal condition, 1.5 times higher chitinase activity of B. licheniformis KYLS-CU02 was obtained. Extracellular chitinases of the two isolates were purified through ammonium sulfate precipitation and anion-exchange DEAE-cellulose column chromatography. The specific activities of purified chitinase from B. licheniformis KYLS-CU01 and B. licheniformis KYLS-CU02 were 7.65 and 5.21 U/mg protein, respectively. The molecular weights of the two purified chitinases were 59 kDa. Further, the purified chitinase of B. licheniformis KYLS-CU01 showed high antifungal activity against Fusarium sp.. In conclusion, these two bacterial isolates can be used as a biopesticide to control pathogenic fungi.