Jae-heon Kim

Saccharothrix violacea sp. nov., isolated from a gold mine cave, and Saccharothrix albidocapillata comb. nov.

The generic position of two isolates from soils inside a gold mine cave in Kongju, Korea, was determined by 16S rDNA sequencing and chemotaxonomic characteristics. Phylogenetic analysis indicated that both of the isolates formed a clade with Lentzea albidocapillata and members of the genus Saccharothrix of the family Pseudonocardiaceae. The chemical composition of the isolates and of Lentzea albidocapillata was consistent with that of the genus Saccharothrix, which is characterized by a type III cell wall (the meso-isomer of diaminopimelic acid, and galactose and rhamnose as characteristic whole-cell sugars), MK-9(H4) as the major menaquinone, and a phospholipid type PII pattern (phosphatidylethanolamine as a diagnostic phospholipid). The combination of morphological features, chemotaxonomic characters and phylogenetic data supported the proposal that Lentzea albidocapillata, the only and type strain of the genus Lentzea, should be transferred to the genus Saccharothrix. On the basis of physiological properties, cellular fatty acid composition and DNA-DNA hybridization data, two new species within the genus Saccharothrix are proposed: Saccharothrix violacea sp. nov., type strain LM 036T (= IMSNU 50388T), and Saccharothrix albidocapillata comb. nov., type strain DSM 44073T (=IMSNU 21253T).

Neutral lipids and lipase activity for actinorhodin biosynthesis of Streptomyces coelicolor A3(2)

Neutral lipid accumulation during early growth phase of Streptomyces coelicolor A3(2) was essential for the actinorhodin production during later growth. The activities of lipase and isocitrate dehydrogenase were increasing and decreasing, respectively, suggesting that the degradation products of neutral lipids serve actinorhodin biosynthesis as precursors.

H2O2 resistance is linked to the degree of fatty acid unsaturation in Streptomyces coelicolor A3(2)

In Streptomyces coelicolor A3(2), as the content of palmitoleic acid increased with decreasing growth temperature, H2O2 resistance decreased. Production of thiobarbituric acid-reactive substances upon H2O2 treatment was increased by supplementing unsaturated fatty acids. Therefore, the content of palmitoleic acid is a determining factor for the survival of Streptomyces coelicolor A3(2) subjected to H2O2 stress.

Ahniella affigens gen. nov., sp. nov., a gammaproteobacterium isolated from sandy soil near a stream

A bacterial strain, designated D13T, was isolated from sandy soil near a stream in Sinan-gun, Republic of Korea. Cells were Gram-stain-negative, aerobic, non-motile and flexible rod-shaped. Growth occurred at 15-35 °C (optimum 30 °C) and pH 6.5-8.0 (pH 7.0). NaCl was not obligatory for growth but could be tolerated at up to 0.5 % (w/v) NaCl. The DNA G+C content of the genomic DNA of strain D13T was 57.7 mol% and a phylogenetic analysis of the 16S rRNA gene sequence revealed that strain D13T formed a distinct evolutionary lineage within the family Rhodanobacteraceae of the order Lysobacterales. Strain D13T showed highest 16S rRNA sequence similarity to Lysobacter hankyongensis KTCe-2T (92.7 %), followed by Luteimonas cucumeris Y4T (92.7 %), Dyella japonica XD53T (92.6 %) and Aquimonas voraii GPTSA 20T (92.5 %). The major cellular fatty acids (>10 % of the total) were iso-C16 : 0, iso-C15 : 0 and summed feature 9 (iso-C17 : 1ω9с and/or C16 : 0 10-methyl). The respiratory quinone was ubiquinone-8 and the major polar lipids of the isolate consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylmonomethylethanolamine. Based on polyphasic analysis, strain D13T could be differentiated from other genera in the family Rhodanobacteraceae, which suggests that strain D13T represents a novel species of a new genus in the family Rhodanobacteraceae, for which the name Ahniella affigens gen. nov., sp. nov. is proposed. The type strain is D13T (=KACC 19270T=JCM 31634T).