Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Expression, Purification, and Biochemical Properties of Arginase from Bacillus subtilis 168: Jin-Ju Yu , Ki-Bum Park , Su-Gon Kim , Suk-Heung Oh; J. Microbiol. 2013;51(2):222-228. Published online April 27, 2013; DOI: https://doi.org/10.1007/s12275-013-2669-9

Abstract: The arginine-degrading and ornithine-producing enzymes arginase has been used to treat arginine-dependent cancers. This study was carried out to obtain the microbial arginase from Bacillus subtilis, one of major microorganisms found in fermented foods such as Cheonggukjang. The gene encoding arginase was isolated from B. subtilis 168 and cloned into E. coli expression plasmid pET32a. The enzyme activity was detected in the supernatant of the transformed and IPTG induced cell-extract. Arginase was purified for homogeneity from the supernatant by affinity chromatography. The specific activity of the purified arginase was 150 U/mg protein. SDS-PAGE analysis revealed the molecular size to be 49 kDa (Trix·Tag, 6×His·Tag added size). The optimum pH and temperature of the purified enzyme with arginine as the substrate were pH 8.4 and 45°C, respectively. The Km and Vmax values of arginine for the enzyme were 4.6 mM and 133.0 mM/min/mg protein respectively. These findings can contribute in the development of functional fermented foods such as Cheonggukjang with an enhanced level of ornithine and pharmaceutical products by providing the key enzyme in arginine-degradation and ornithine-production.

Isolation and Characterization of Lactic Acid Bacteria Strains with Ornithine Producing Capacity from Natural Sea Salt: Jin-Ju Yu , Suk-Heung Oh; J. Microbiol. 2010;48(4):467-472. Published online August 20, 2010; DOI: https://doi.org/10.1007/s12275-010-0204-9

Abstract: Two lactic acid bacteria (LAB) having ornithine-producing capacity were isolated from Korean natural sea salt. They were Gram-positive, short rod-type bacteria, and able to grow anaerobically with CO2 production. The isolates grew well on MRS broth at 30-37°C and a pH of 6.5-8.0. The optimum temperature and pH for growth are 37°C and pH 7.0. The isolates fermented D-ribose, D-galactose, D-lactose, D-maltose, Dcellobiose, D-tagatose, D-trehalose, sucrose, D-melezitose, gentiobiose, D-glucose but not D-melibiose, inositol, and L-sorbose. The 16S rDNA sequences of the two isolates showed 99.5% and 99.6% homology with the Weissella koreensis S5623 16S rDNA (Access no. AY035891). They were accordingly identified and named as Weissella koreensis MS1-3 and Weissella koreensis MS1-14, and produced intracellular ornithine at levels of 72 mg/100 g cell F.W. and 105 mg/100 g cell F.W. and extracellular ornithine at levels of 4.5 mg/100 ml and 4.6 mg/100 ml medium, respectively, by culturing in MRS broth supplemented with 1% arginine. High cell growth was maintained in MRS broth with a NaCl concentration of 0-6%. These results show for the first time that Korean natural sea salts contain lactic acid bacteria Weissella koreensis strains having ornithine producing capacity.

Expression of c-Myc Is Related to Host Cell Death Following Salmonella typhimurium Infection in Macrophage: Jihyoun Seong , Hong Hua Piao , Phil Yeoul Ryu , Youn Uck Kim , Hyon E Choy , Yeongjin Hong; J. Microbiol. 2009;47(2):214-219. Published online May 2, 2009; DOI: https://doi.org/10.1007/s12275-008-0308-7

Abstract: It has been known that ornithine decarboxylase (ODC) induced by the binding of c-Myc to odc gene is closely linked to cell death. Here, we investigated the relationship between their expressions and cell death in macrophage cells following treatment with Salmonella typhimurium or lipopolysaccharide (LPS). ODC expression was increased by bacteria or LPS and repressed by inhibitors against mitogen-activated protein kinases (MAPKs) in Toll-like receptor 4 (TLR4) signaling pathway. In contrast, c-Myc protein level was increased after treatment with bacteria, but not by treatment with LPS or heat-killed bacteria although both bacteria and LPS increased the levels of c-myc mRNA to a similar extent. c-Myc protein level is dependent upon bacterial invasion because treatment with cytochalasin D (CCD), inhibitors of endocytosis, decreased c-Myc protein level. The cell death induced by bacteria was significantly decreased after treatment of CCD or c-Myc inhibitor, indicating that cell death by S. typhimurium infection is related to c-Myc, but not ODC. Consistent with this conclusion, treatment with bacteria mutated to host invasion did not increase c-Myc protein level and cell death rate. Taken together, it is suggested that induction of c-Myc by live bacterial infection is directly related to host cell death.

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