Sphingobium hydrophobicum sp. nov., a hydrophobic bacterium isolated from electronic-waste-contaminated sediment.

Abstract

Four hydrophobic bacteria were isolated from sediment at Guiyu, an electronic-waste recycling site in southeastern China. The isolates had high cell surface hydrophobicity with microbial-adhesion-to-hydrocarbon score of 71.4 %. 16S rRNA gene sequences of the strains all showed highest similarity to the hydrophilic Sphingobium xenophagum DSM 6383T (99.9 % 16S rRNA gene sequence similarity), followed by Sphingobiumczechense DSM 25410T (97.1 %). However, DNA-DNA hybridization revealed that the isolates and S. xenophagum DSM 6383T exhibited low DNA-DNA relatedness with a hybridization value of 54.5±0.5 %. The genomic DNA G+C content was 64.2 mol% and the predominant quinone was ubiquinone Q-10. Spermidine was the major polyamine component. The major fatty acids were C18 : 1ω7c, C16 : 1ω7c, C16 : 0, C14 : 0 2-OH and C14 : 0. In contrast to its closest relative S. xenophagum DSM 6383T, the isolates had a much higher proportion of C16 : 0 and C14 : 0 and a much lower proportion of C18 : 1ω9t. Sphingoglycolipid was present and diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylmonomethylethanolamine were detected in the polar lipid pattern. Phosphatidyldimethylethanolamine and phosphatidylcholine, which are present in S. xenophagum DSM 6383T, were not detected in the isolates. Results of DNA-DNA relatedness, cell surface hydrophobicity, fatty acids, polar lipids, and biochemical and physiological properties reveal that the isolates represent a novel species of the genus Sphingobium, for which the name Sphingobium hydrophobicum sp. nov. is proposed. The type strain is C1T (=CCTCC AB 2015198T=KCTC 42740T).