Journal of Microbiology

Volume 37(1); March 1999

Analysis of the Changes in Metabolic Diversity of Microbial Community in pH-gradient Microcosm: Ahn, YoungBeom , Cho, Hong Bum , Choi, Yong Keel; J. Microbiol. 1999;37(1):1-9.

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Abstract: The Biolog redox technology was carried out for evaluation of acidification effect on microbial communities at each stage of pH gradient microcosm. While the number of heterotrophic bacterial population and activities of extracellular enzyme decreased as the pH decreased, the number of total bacteria in the microcosm was not affected. The average color development of sample at each pH-gradient showed a sigmoidal curve, and at higher pH, more overall color development appeared in Biolog plates. Average color development value in Biolog plates was stabilized at 50 hours as an optimum incubation time. The color production in the Biolog plates was caused by cell density at above pH 5.0, but by cell activity below pH 4.0. Principal component analysis of color responses revealed distinctive patterns among the pH-gradient microcosm samples.

The Bacterial Community of Southern Lake Baikal in Winter: Ahn, Tae Seok , Hong, Sun Hee , Kim, Dong Joo , Suck, Jung Hyun , Drucker, Valentin V.; J. Microbiol. 1999;37(1):10-13.

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Abstract: The bacterial abundance, proportion of respiring bacteria, and bacterial community of southern Lake Baikal were analyzed at 1 m and 400m depths during winter. The total bacterial numbers were 5.1×10^5 cells m^l-1 at 1 m and 2.5×10^5 cells ml^-1 at 400 m depth, which are about half and quarter of the numbers of other lakes. The proportion of respiring bacteria was as low as 2.5% at 1 m and 1.4% at 400 m depth. Considering the amount of organic carbon which need to be degraded and low proportion of respiring bacteria, the bacteria could be assumed to have high activities. The EUB/DAPI ratios were 77 and 89% at 1 m and 400 m depths, respectively. Of the bacterial community, the other group was dominant at both depths, and gamma group of proteobacteria followed next. But the beta group of proteobacteria and Cytophaga-Flavobacterium groups occupied very small proportions.

Purification and Characterization of Two Extracellular Proteases from Oligotropha carboxydovorans DSM 1227: Kang, Beom Sik , Jeon, Sang Jun , Kim, Min Young; J. Microbiol. 1999;37(1):14-20.

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Abstract: Two extracellular proteases, EP I and EP II, from cells of Oligotropha carboxydovorans (formerly Pseudomonas carboxydovorans) DSM 1227 grown in nutrient broth were purified to greater than 95% homogeneity in five steps using azocasein as a substrate. The final specific activities of EPs I and II were 214.9 and 667.4 units per mg of protein. The molecular weights of native EPs I and II were determined to be 23,000. Sodium dodecyl sulfate-gel electrophoresis revealed the two enzymes to be monomers. The enzymes were found to be serine-type proteases. The activity of EP I was stimulated by Ca^2+, Mg^2+, and Ba^2+, but that of EP II was not. The enzymes were completely inhibited by Fe^2+, Hg^2+, Co^2+, Zn^2+, and Cd^2+. EDTA and EGTA exhibited a strong inhibitory effect on EP I. The optimal pH for the two enzymes was pH 9.0. The optimal temperatures for EP I and II were 60 and 50℃, respectively. The enzymes were stable under alkaline conditions. The thermal stability of EP I was higher than that of EP II. Cell-free extracts did not inhibit the purified enzymes. The enzymes were active on casein, azocasein, azocoll, and carbon monoxide dehydrogenase, but weakly active with bovine serum albumin.

Purification and Properties of Novel Calcium-binding Proteins from Streptomyces coelicolor: Chang, Ji Hun , Yoon, Soon Sang , Lhee, Sang Moon , Park, I Ha , Jung, Do Young , Park, Yong Sik , Yim, Jeong Bin; J. Microbiol. 1999;37(1):21-26.

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Abstract: Two novel calcium-binding proteins, named CAB-I and CAB-II, have been isolated from Streptomyces coelicolor. Purification of the calcium-binding proteins involved heat treatment, fractionation with ammonium sulfate, acid treatment, anion exchange and hydrophobic interaction column chromatography, FPLC gel filtration, and preparative isoelectric focusing. A chelex competitive assay and ^45Ca autoradiography verified the calcium-binding ability of the proteins. The major band CAB-II has an apparent molecular weight of 26,000 determined by SDS-polyacrylamide gel electrophoresis and 340,000 determined by gel filtration. The isoelectric point of this molecule showed the acidic nature of the molecule. N-terminal amino acid sequence analysis shows homology to rat Ca^2+/calmodulin-dependent protein kinase-II (CAB-II) and yeast phosphoprotein phosphatase (CAB-I).

Microscopic Examination of the Suppressive Action of Antifungal Substances from Pseudomonas aeruginosa on Asexual Sporulation of Fungi: Yoon, Kwon S. , Min, Bu Y. , Choi, Hyoung T. , Lee, Jong K. , Kim, Kun W.; J. Microbiol. 1999;37(1):27-34.

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Abstract: Two fractions with unusual antifungal activity that suppress asexual sporulation of several fungi were obtained from culture filtrate of Pseudomonas aeruginosa and were partially purified through the repeated silicagel flash column chromatographies. The sporulation-suppressive actions of these fractions in Aspergillus nidulans, Rhizopus stolonifer, and Coprinus cinereus, were analyzed by light and electron microscopes. The germination ability of the spores produced in the presence of these fractions were also checked to determine the persistent effects of these antifungal substances on the next generation. Light microscopic observation of developing sporangia of R. stolonifer grown in the presence of both fractions revealed that the significant number of sporangia failed to reach maturity, and frequently, uncontrolled growths of hyphae and rhizoids from the sporangiophores were found. In A. nidulans addition of these fractions appeared to cause different classes of morphological abnormality in conidia development, which included aborted formation of conidiogenous cells from the apex of conidiophores and enhanced hyphal growths either at the tip or middle of the conidiophores. Germination abilities of spores obtained from the cultures grown in the presence of antifungal fractions were 40∼60% in Aspergillus, 50∼80% in Coprinus (thallic spores), and 30∼40% in Rhizopus compared to those of normal spores.

Molecular Cloning and Analysis of Sporulation-Specific Glucoamylase (SGA) Gene of Saccharomyces diastaticus: Kang, Dae Ook , Hwang, In Kyu , Oh, Won Keun , Lee, Hyun Sun , Ahn, Cheol Soon , Kim, Bo Yeon , Mheen, Tae Ick , Ahn, Hong Seog; J. Microbiol. 1999;37(1):35-40.

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Abstract: Sporulation-specific glucoamylase (SGA) gene was isolated from genomic library of Saccharomyces diastaticus 5114-9A by using glucoamylase non-producing mutant of S. diastaticus as a recipient. When the glucoamylase activities of culture supernatant, periplasmic, and intracellular fraction of cells transformed with hybrid plasmid containing SGA gene were measured, the highest activity was detected in culture supernatant. SGA produced by transformant and extracellular glucoamylase produced by S. diastaticus 5114-9A differed in enzyme characteristics such as optimum temperature, thermostability, and resistance to SDS and urea. But the characteristics of SGA produced by sporulating yeast cells and vegetatively growing transformants were identical.

Expression of Human Mitochondiral Aldehyde Dehydrogenase 2 in Mammalian Cells using Vaccinia Virus-T7 RNA Polymerase: Kang, Su Min , Yoo, Seung Ku , Lee, Ki Whan; J. Microbiol. 1999;37(1):41-44.

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Abstract: Human mitochondrial aldehyde dehydrogenase 2 (ALDH2) is mainly responsible for oxidation of acetaldehyde generated during alcohol oxidation in vivo. A full-length cDNA of human liver ALDH2 was successfully expressed using a vaccinia virus-T7 RNA polymerase system. The expressed ALDH2 had an enzymatic activity as high as the native human liver ALDH2 enzyme.

Isolation and Characterization of Pigment-deficient Mutants from Azomonas agilis PY101: You, Kyung Man , Lee, Sang Hyeon , Park, Yong Keun; J. Microbiol. 1999;37(1):45-49.

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Abstract: To investigate the mechanism of cadmium tolerance in a cadmium-resistant Azomonas agilis PY101 that produces a specific fluorescent pigment promoted by cadmium, we carried out Tn5 mutagenesis and isolated four pigment-deficient mutants. In these mutants, Ppg1, Ppg2, and Ppg3 remarkably reduced the pigment production to 15.3%, 11.2%, and 13.9%, respectively. Especially, Ppg4 mutant did not produce the pigment at all. None of the mutants grew in the presence of 1500 ppm of CdCl₂in growth medium, and they exhibited differential sensitivities to cadmium. Ppg1, Ppg2, Ppg3, and Ppg4 mutants were sensitive to 900 ppm, 1100 ppm, 1000 ppm, and 800 ppm of CdCl2, respectively. These mutants also showed noticeable increase, from 8.8-fold to 13.2-fold, in the size of growth inhibition zone compared with that of the will type after treatment with cadmium. Therefore, the pigment production of A. agilis PY101 was found to decrease the toxic effects of cadmium to the bacterium.

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