Hyun-Hyo Suh

Production and Properties of a Lipopeptide Biosurfactant from Bacillus subtilis C9

Abstract A lipopeptide biosurfactant, C9-BS produced by Bacillus (B.) subtilis C9, emulsified hydrocarbons, vegetable oil and crude oil. A high yield of C9-BS was obtained from a culture of B. subtilis C9 using a carbohydrate substrate, while a hydrocarbon substrate inhibited the production of the biosurfactant. The optimum medium for the production of C9-BS was as follows (g/l): glucose, 40; NH4HCO3, 13.5; K2HPO4, 10.5; NaH2PO4, 1.5; MgSO4·7H2O, 0.5; MnSO4·4H2O, 0.05; yeast extract, 0.5. The initial pH was 8.0 and the culture temperature was 30°C. The biosurfactant C9-BS was obtained by collection of the foam that overflowed in the fermentor culture. The production of the biosurfactant by B. subtilis C9 was growth-associated. Under O2-limited conditions, C9-BS was produced in a 3-fold higher yield compared to that under O2-sufficient conditions. C9-BS is soluble in ethanol, acetone, methanol, butanol, chloroform, dichloromethane and alkaline water. The biosurfactant C9-BS lowered the surface tension of water to 28.5 dyne/cm, and the CMC (critical micelle concentration) was 40 μM. C9-BS was stable from pH 5.0 to pH 9.5, in incubation at 100°C for 1 h, and at a salt concentration of 1,000 mM for NaCl and 10 mM for CaCl2.

Characterization of bioflocculant produced by Bacillus sp. DP-152

A strain (designated DP-152) which produces an excellent flocculating substance was isolated from soil samples and identified as Bacillus species. The major flocculating substance (bioflocculant DP-152) produced by Bacillus sp. DP-152 was purified by ethanol precipitation and cetylpyridinium chloride (CPC) precipitation and gel permeation chromatography. In kaolin suspension, the highest flocculating activity was obtained at the bioflocculant concentration of 1 mg/l. The bioflocculant DP-152, which has an estimated molecular weight of over 2 × 106 daltons, is a novel bioflocculant derived from sugar components consisting of glucose, mannose, galactose, and fucose in an approximate molar ratio of 8 : 4 : 2 : 1. Some of its physico-chemical properties were also determined.

Immunomodulating activity of a fucoidan isolated from Korean Undaria pinnatifida sporophyll

A fucoidan, isolated from Korean Undaria pinnatifida spoprophyll (UP-F), was investigated for its immunomodulating activity on murine macrophages and splenocytes, and its activity was compared with that of fucoidan from Fucus vesiculosus (FV-F). Treatment of UP-F resulted in inhibition of the growth of murine macrophage RAW 264.7 cells, but its cytotoxicity was not observed in normal murine splenocytes. FV-F was shown to be highly cytotoxic to both immune cells, and its cytotoxic activity was higher than that of UP-F. Treatment of UP-F induced TNF-α in a dose-dependent manner from two types of macrophages, RAW 264.7 cells and murine peritoneal macrophages. The TNF-α-inducing activity of UP-F was higher than that of FV-F. UP-F also actively induced chemokines (RANTES and MIP-1α) from RAW 264.7 cells. Furthermore, treatment of UP-F gave rise to activation of murine splenocytes to produce cytokine (IL-6) and chemokines (RANTES and MIP-1α), showing significantly higher activity than that of FV-F. These results indicate that UP-F is less cytotoxic to immune cells than FV-F, and possesses immunomodulating activity to produce cytokines and chemokines from macrophages and splenocytes.

Characterization and Purification of the Bacteriocin Produced by Bacillus licheniformis Isolated from Soybean Sauce

A bacteriocin-producing bacterium identified as Bacillus licheniformis was isolated from soybean sauce. Antibacterial activity was confirmed by paper disc diffusion method, using Micrococcus luteus as a test organism. The bacteriocin also showed antibacterial activities against Bacillus sphaericus, Lactobacillus bulgaricus, Lactobacillus plantarum, Paenibacillus polymyxa, and Pediococcus dextrinicus. Optimal culture conditions for the production of bacteriocin was attained by growing the cells in an MRS medium at a pH of 6.5～7.0 and a temperature of 37℃ for 36～48 hr. Solvents such as chloroform, ethanol, acetone, and acetonitrile had little effect on bacteriocin activity. However, about 50% of bacteriocin activity diminished with treatment of methanol and isopropanol at the final concentration of 50% at 25℃ for 1 hr. It was stable against a pH variation range from 3.0 and 7.0, but the activity reduced to 50% at a pH range from 9.0 to 11.0. Its activity was not affected by heat treatment at 100oC for 30 min and 50% of activity was retained after heat treatment at 100℃ for 60 min, showing high thermostability. The bacteriocin was purified to a homogeneity through ammonium sulfate precipitation, SP-Sepharose ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (HPLC). The entire purification protocol led to a 75-fold increase in specific activity and a 13.5% yield of bacteriocin activity. The molecular weight of purified bacteriocin was estimated to be about 2.5 kDa by tricine-SDS-PAGE.Characterization and Purification of the Bacteriocin Produced by Bacillus licheniformis Isolated from Soybean Sauce. Sung-Sub Jung 1 , Jung-I Choi 1 , Woo-Hong Joo 2 , Hyun-Hyo Suh 3 , Ae-Sil Na, Yong-Kweon Cho, Ja-Young Moon, Kwon-Chul Ha, Do-Hyeon Paik and Dae-Ook Kang*. Department of Biochemistry and Health Science, Changwon National University, Changwon 641-773, Korea, Interdisciplinary Program in Biotechnology, Graduate School, Changwon National University, Department of Biology, Changwon National University, Department of Environmental Engineering, Jinju National University, Jinju 660-758, Korea A bacteriocin-producing bacterium identified as Bacillus licheniformis was isolated from soybean sauce. Antibacterial activity was confirmed by paper disc diffusion method, using Micrococcus luteus as a test organism. The bacteriocin also showed antibacterial activities against Bacillus sphaericus, Lactobacillus bulgaricus, Lactobacillus plantarum, Paenibacillus polymyxa, and Pediococcus dextrinicus. Optimal culture conditions for the production of bacteriocin was attained by growing the cells in an MRS medium at a pH of 6.5~7.0 and a temperature of 37 o C for 36~48 hr. Solvents such as chloroform, ethanol, acetone, and acetonitrile had little effect on bacteriocin activity. However, about 50% of bacteriocin activity diminished with treatment of methanol and isopropanol at the final concentration of 50% at 25 o C for 1 hr. It was stable against a pH variation range from 3.0 and 7.0, but the activity reduced to 50% at a pH range from 9.0 to 11.0. Its activity was not affected by heat treatment at 100 o C for 30 min and 50% of activity was retained after heat treatment at 100 o C for 60 min, showing high thermostability. The bacteriocin was purified to a homogeneity through ammonium sulfate precipitation, SP-Sepharose ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (HPLC). The entire purification protocol led to a 75-fold increase in specific activity and a 13.5% yield of bacteriocin activity. The molecular weight of purified bacteriocin was estimated to be about 2.5 kDa by tricine-SDS-PAGE.