• Korean Journal of Microbiology
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• v.29 no.4
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• pp.250-257
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• 1991

An obligate methanol-oxidizing bacterium, Methylobacillus sp. strain SK1, which grows only on methanol was isolated from soil. The isolate was nonmotile Gram-negtive rod. It does not have internal membrane system. The colonies were small, whitish-yellow, and smooth. The guanine plus cytosine content of the DNA was 48 mol%. Cellular fatty acids consisted predominantly of large amounts of straight-chain saturated $C_{16:0}$ acid and unsaturated $C_{16:1}$ acid. The major ubiquinone was Q-8, and Q-10 was present as minor component. The cell was obligately aerobic and exhibited catalase, but no oxidase, activity. Poly-.betha.-hydroxybutyrate, endospores, or cysts were not observed. the isolate could grow only on methanol in mineral medium. Growth factors were not required. The isolate was unable to use methane, formaldehyde, formate, methylamine, and several other organic compounds tested as a sole source of carbon and energy. Growth was optimal at 35.deg.C and pH 7.5. It could not grow at 42.deg.C. The doubling time was 1.2h at 30.deg.C when grown with 1.0%(v/v) methanol. The growth was not affected by antibiotics inhibiting cell wall synthesis and carbon monoxide but was completely suppressed by those inhibiting protein synthesis. Methanol was found to be assimilated through the ribulose monophosphate pathway. Cytochromes of b-, c-, and o- types were found. Cell-free extracts contained a phenazine methosulfate-linked methanol dehydrogenase activity, which required ammonium ions as an activator. Cells harvested after the late exponential phase seemed to contain blue protein.ein.

• The Korean Journal of Mycology
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• v.19 no.1
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• pp.32-40
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• 1991

Mitochondria in Pleurotus ostreatus were isolated and purified by the stepped sucrose density gradient centrifugation, to investigate the effects of the light on the enzymatic activity of the mitochondrial ATP synthase. This enzyme, which was illuminated by the light ranging from 400 nm to 700 nm, showed that the specific activity was stimulated at 490 nm for 15 sec. Effects of organic compounds on the mitochondrial ATP synthase were also investigated at the optimum conditions; The activities of this enzyme were increased to 168 percent by the addition of 2,6-dichlo­rophenol indophenol(DCPIP), 224 percent by phenazine methosulfate(PMS), but inhibited 91 per­cent by oligomycin, 14 percent by 2-heptyl-4-hydroxyquinoline-N-oxide(HQNO) and 75 percent by 2,4-dinitrophenol (DNP), respectively. Effects of metal ions of the mitochondrial ATP synthase were investigated at the optimum conditions. The activities of the enzyme were inhibited 35 percent by $Ca^{2+}$, 14 percent by $Co^{2+}$ and 73 percent by $Mn^{2+}$. For effects of anions, the activities of this enzyme were inhibited 80 percent by $CN^{-}$, 52 percent by $SO_{4}\;^{2-}$, 28 percent by each of $CO_{3}\;^{2-}$­and $NO_{3}\;^{-}$, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.134-144
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• 2003

A rhizobacterium Pseudomonas cholororaphis O6 produced several secondary metabolites, such as phenazines, protease, and HCN that may be involved in inhibition of the growth of phytopathogenic fungi. In field study, P. chlororaphis O6 treatment on wheat seed suppressed root rot disease caused by Fusarium culmorum. The major organic acids of cucumber root exudates were fumaric acid, malic acid, benzoic acid, and succinic acid. Glucose and fructose were major monosaccharides in cucumber root exudates. The total amount of organic acids was ten times higher than that of the sugars. P. chlororaphis O6 grew well on cucumber root exudates. The dctA gene of P. chlororaphis O6 consisted of a 1,335 bp open reading frame with a deduced amino acid sequence of 444 residues, corresponding to a molecular size of about 47 kD and pI 8.2. The deduced dctA sequence has ten putative transmembrane domains, as expected of a membrane-embedded protein. Our results indicated that organic acids in cucumber root exudates may play an important role in providing nutrient source for root colonization of biological control bacteria, and the dctA gene of P. chlororaphis O6 may be an important bacterial trait that is involved in utilization of root exudates.