Abstract

A Gram-negative, anaerobic, non-motile, non-spore-forming bacterial strain, designated YN3PY1T, was isolated from a chloroethene-dechlorinating consortium originally enriched from river sediment. The strain enhanced the dechlorination of cis-dichloroethene to ethene by Dehalococcoides, especially at the early stages of cultivation. Strain YN3PY1T was the first isolate of the genus Bacteroides, obtained from animal- independent environments, and its 16S rRNA gene had the highest sequence similarity (97.1%) with Bacteroides luti JCM 19020T in the ‘Coprosuis’ clade of the genus Bacteroides. Strain YN3PY1T formed a phylogenetic cluster with other phylotypes detected from sediments and paddy soil, and the cluster was affiliated with a linage of so-called free-living Bacteroides detected from animal-independent environments, suggesting specific adaptations to sediment-like environments. The strain showed typical phenotypes of Bacteroides, i.e., polysaccharolytic anaerobe having anteiso-C15:0 as the most abundant fatty acid and MK-11 as one of the major respiratory quinones. Additionally, the strain uniquely transforms glucose to lactate and malate, has MK-12 as another major respiratory quinone, and grows at comparatively low temperatures, i.e. 10–40°C, with an optimum at 28°C. Based on the presented data, strain YN3PY1T (= KCTC 15656T = NBRC 113168T) can be proposed as a novel species of the genus Bacteroides and named as Bacteroides sedimenti sp. nov.

• Keywords: Bacteroides sedimenti; chloroethenes; dechlorination; free-living Bacteroides