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Research Support, Non-U.S. Gov't
- Molecular Characterization of TEM-type [beta]-Lactamases Identified in Cold-Seep Sediments of Edison Seamount (South of Lihir Island, Papua New Guinea)
- Jae Seok Song , Jeong Ho Jeon , Jung Hun Lee , Seok Hoon Jeong , Byeong Chul Jeong , Sang-Jin Kim , Jung-Hyun Lee , Sang Hee Lee
- J. Microbiol. 2005;43(2):172-178.
- DOI: https://doi.org/2165 [pii]
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Abstract
- To determine the prevalence and genotypes of [beta]-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced [beta]-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five (16.7%) of thirty clones produced an extended-spectrum [beta]-lactamase. 837- and 259-bp fragments specific to bla_TEM genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM-1 was the most prevalent [beta]-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type [beta]-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type [beta]-lactamases of the pre-antibiotic era indicates that TEM-type [beta]-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.
- Effects of Lactic Acid Bacteria on Intestinal Microbial Enzyme Activity and Composition in Rats Treated with Azoxymethane
- Sang-Myeong Lee , Wan-Kyu Lee
- J. Microbiol. 2001;39(3):154-161.
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Abstract
- In recent years, colon cancer has been reported to be one of the most important causes of cancer morbidity and mortality in Korea. Epidemiological and experimental studies suggest that lactic acid bacteria (LAB) used to ferment dairy products inhibits colon carcinogenesis. The present study was designed to determine whether the colon cancer inhibitory effect of LAB (Bifidobacterium longum HY8001; Bif and Lactobacillus acidophilus HY2104; Lac) of Korean origin, is associated with intestinal microflora composition and certain enzyme activity in rats treated with azoxymethane (AOM). At five weeks of age, SD rats were divided at random into four (AOM alone, Bif, Lac, and Bif+Lac) groups. Oral administration of lactic acid bacteria cultures were performed daily until the termination of the study. Two weeks later, all animals were given a subcutaneous injection of AOM dissolved in normal saline at a dose of 15 mg/kg of body weight once weekly for 2 weeks. Every two weeks for 10 weeks, five of the rats in each group were randomly chosen for fecal specimen collection. The fecal specimens were used for assay of [beta]-glucuronidase and nitroreductase, and analysis of intestinal microflora composition. The activity of [beta]-glucuronidase which plays an important role in the production of the carcinogenic metabolite of azoxymethane was remarkably increased in the AOM alone group after AOM injection and maintained the high level during the experiment. However, LAB inhibited the AOM-induced increase in [beta]-glucuronidase activity. Nitroreductase activity decreased by 30-40% in LAB treated groups in comparison with that of the AOM alone group. The results of the present study suggest that LAB inhibits colon carcinogenesis by modulating the metabolic activity of intestinal microflora and improving the composition of intestinal microflora.
- Stable Secretion Vector Derived from the RCR (rolling-circle replication) Plasmid of Bacillus mesentericus
- Seung-Soo Lee , Jeong-Sun Han , In Hyung Lee , Young- Yel l Yang , Soon-Kwang Hong , Joo-Won Suh
- J. Microbiol. 2002;40(2):140-145.
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Abstract
- The 5.8 kb pMMH1, rolling-circle replication (RCR) plasmid of the wild type soil Bacillus mesentericus was developed into a novel secretion vector system in Bacillus subtilis. The pMMH1 turned out to have a replication origin and two open reading frames (ORFs) of the putative [gamma]-GTP and type I signal peptidase (sipP). To characterize the regions necessary for plasmid stability and high copy number, five vectors (pPS, pPP, pEN, pMN, pME) were constructed by disruption or deletion of each region in pMMH1. Like pMMH1, all constructed vectors were stable over 100 generations in a non-selective medium. Since pPS was the smallest (2.3 kb)of all, it was selected for the construction of a novel secretion vector. Using the [alpha]-amylase promoter/signal sequence of B. subtilils, the novel plasmid pJSN was constructed. When [beta]-glucosidase was expressed using pJSN, we found [beta]-glucosidase activity in the medium. This result strongly suggested that plasmid pJSN can be used for the production of bioactive peptides in B. subtilis.
- Glutathione Content and the Activities of GlutathioneSynthesizing Enzymes in Fission Yeast are Modulated by Oxidative Stress
- Yuk-Young Lee , Su-Jung Kim , Eun-Hee Park , Chang-Jin Lim
- J. Microbiol. 2003;41(3):248-251.
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Abstract
- Glutathione (GSH) is an important factor in determining tolerance against oxidative stress in living organisms. It is synthesized in two sequential reactions catalyzed by [gamma]-glutamylcysteine synthetase (GCS) and glutathione synthetase (GS) in the presence of ATP. In this work, the effects of three different oxidative stresses were examined on GSH content and GSH-related enzyme activities in the fission yeast Schizosaccharomyces pombe. GSH content in S. pombe was significantly enhanced by treatment with hydrogen peroxide, [beta]-naphthoflavone (BNF) and tert-butylhydroquinone (BHQ). Simultaneously, they greatly induced GCS and GS activity. However, they did not have any effects on glutathione reductase activity. These results suggest that GCS and GS activities in S. pombe are upregulated by oxidative stress.
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