Raoultella electrica sp. nov., isolated from anodic biofilms of a glucose-fed microbial fuel cell

Abstract

A Gram-stain-negative, non-spore-forming, rod-shaped bacterium, designated strain 1GBT, was isolated from anodic biofilms of a glucose-fed microbial fuel cell. Strain 1GBT was facultatively anaerobic and chemo-organotrophic, having both a respiratory and a fermentative type of metabolism, and utilized a wide variety of sugars as carbon and energy sources. Cells grown aerobically contained Q-8 as the major quinone, but excreted Q-9 and a small amount of Q-10 when cultured with an electrode serving as the sole electron acceptor. The G+C content of the genomic DNA of 1GBT was 54.5 mol%. Multilocus sequence typing (MLST) analysis showed that strain 1GBT represented a distinct lineage within the genus Raoultella (98.5–99.4 % 16S rRNA gene sequence similarity and 94.0–96.5 % sequence similarity based on the three concatenated housekeeping genes gyrA, rpoB and parC. Strain 1GBT exhibited DNA–DNA hybridization relatedness of 7–43 % with type strains of all established species of the genus Raoultella . On the basis of these phenotypic, phylogenetic and genotypic data, the name Raoultella electrica sp. nov. is proposed for strain 1GBT. The type strain is 1GBT ( = NBRC 109676T = KCTC 32430T).