Mucilaginibacter oryzae sp. nov., isolated from soil of a rice paddy

A Gram-negative-staining, non-spore-forming bacterium devoid of flagella, designated strain B9 T , was isolated from rice paddy soil associated with the roots of Oryza sativa collected from Jinju, South Korea. Cells were straight rods, were catalase-and oxidase-positive and were able to hydrolyse pectin, xylan and laminarin. Growth of strain B9 T was observed between 15 and 35 6C (optimum 25-30 6C) and between pH 5.0 and 8.0 (optimum pH 6.5-7.5). Strain B9 T contained menaquinone-7 (MK-7) as a major isoprenoid quinone and summed feature 3 (C 16 : 1 v7c and/or iso-C 15 : 0 2-OH), iso-C 15 : 0 and C 16 : 0 as major fatty acids. The G+C content of the genomic DNA was 44.4 mol%. Comparative 16S rRNA gene sequence analysis showed that strain B9 T belonged to the genus Mucilaginibacter, a member of the family Sphingobacteriaceae, and was most closely related to Mucilaginibacter kameinonensis SCK T (95.9 % sequence similarity). O

Influence of Soil Components on the Biodegradation of Benzene, Toluene, Ethylbenzene, and o-, m-, and p-Xylenes by the Newly Isolated Bacterium Pseudoxanthomonas spadix BD-a59 ▿

A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, without enrichment, on minimal salts basal (MSB) agar containing 0.01% yeast extract, with BTEX as the sole carbon and energy source. Taxonomic analyses showed that the isolate belonged to Pseudoxanthomonas spadix, and until now, the genus Pseudoxanthomonas has not included any known BTEX degraders. The BTEX biodegradation rate was very low in MSB broth, but adding a small amount of yeast extract greatly enhanced the biodegradation. Interestingly, degradation occurred very quickly in slurry systems amended with sterile soil solids but not with aqueous soil extract. Moreover, if soil was combusted first to remove organic matter, the enhancement effect on BTEX biodegradation was lost, indicating that some components of insoluble organic compounds are nutritionally beneficial for BTEX degradation. Reverse transcriptase PCR-based analysis of field-fixed mRNA revealed expression of the tmoA gene, whose sequence was closely related to that carried by strain BD-a59. This study suggests that strain BD-a59 has the potential to assist in BTEX biodegradation at contaminated sites