Strains of pink-pigmented facultative methylotrophs which were isolated previously from various environments and assigned tentatively to the genus Methylobacterium were characterized in comparison with authentic strains of previously known species of this genus. Most of the isolates derived from chlorinated water supplies exhibited resistance to chlorine, whereas 29 to 40% of the isolates from air, natural aquatic environments, and clinical materials were chlorine resistant. None of the tested authentic strains of Methylobacterium species obtained from culture collections exhibited chlorine resistance. Numerical analysis of phenotypic profiles showed that the test organisms could be divided into 19 clusters at a similarity level of 80%, at which all established Methylobacterium species tested were separated from each other except M. organophilum and M. rhodesianum. The chlorine-resistant isolates were randomly distributed among all clusters. The 16S ribosomal DNA (rDNA) sequence-based phylogenetic analyses showed that representatives of the isolates together with known Methylobacterium species formed a line of descent distinct from that of members of related genera in the alpha-2 subclass of the Proteobacteria and were divided into three subclusters within the Methylobacterium group. These results demonstrate that there is phenotypic and genetic diversity among chlorine-resistant Methylobacterium strains within the genus.

Two kinds of 2-methylisoborneol-producing blue-green algae, Oscillatoriageminata and O.limnetica, and three kinds of geosmin-producing algae, O.amoena, O.splendida, and Aphanizomenonflos-aquae, were isolated from a park pond, a fish-cultivation pond, a river, and a reservoir. An oscillatorian species isolated from an air conditioning cooling tower was shown to yield both 2-methylisoborneol and geosmin simultaneously. Care was taken to ensure that the blue-green algae identified were those responsible for the musty odor compounds.

We detected some heterotrophic bacteria from drinking tank-water by using standard agar medium cultured for 7 days at 25C. Bacteria produced pink water-insoluble pigment were isolated most frequently. These isolates were polar monotrichous gram-negative rod and vacuolated. They produced weakly urease, oxidase and catalase. They utilized D-arabinose, galactose, methanol, ethanol and glycerol as carbon sources. They contained a large amount of unsaturated straight-chain fatty acid C 18:1. The G+C ratio of DNA base composition ranged from 65.8 to 66.3. The isolates were identified as Protomonas extorquens. Good growth of these bacteria were observed at 30C, and between pH5.0 and 9.0 by incubation of sterilized drinking water in tank. Growth was not observed in the presence of 1.5% sodium chloride. The generation-times of P. extorquens were determined by duplicate experiments about 5.4h. They have been survived for a long period (250 days) in tankwater. The resistance of P. extorquens to free residual chlorine was very high. The exposure time to kill completely 105 cfuml-1 in 1.0mg•1-1 of free residual chlorine was 10 minutes. P. extorquens is worthy of notice as unknown pathogens for men and source of nosocomial infection.

Some of the volatile metabolites of eight species of blue-green algae of the genera Oscillatoria, Phormidium, Aphanizomenon, and Anabaena were identified by gas chromatography mass spectrometry (GC-MS). As a result, five sesquiterpene alcohols (C15H26O) and two sesquiterpene hydrocarbons (germacrene-D and γ-cadi-nene) were detected in the cultures of Oscillatoriasplendida. O. amoena, and Anabaenamacrospora. Three aliphatic hydrocarbons (n-heptadecane,1-heptadecene and 7-methylheptadecane) were also identified in the cultures of most of these algae. None of these compounds appeared to impart an unpleasant taste or odor to water supplies.

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