Dethiosulfovibrio faecalis sp. nov., a novel proteolytic, non-sulphur-reducing bacterium isolated from a marine aquaculture solid waste bioreactor.

Abstract

A new Dethiosulfovibrio strain, designated F2BT, was isolated from an anaerobic digester for treating solid waste from a marine recirculating aquaculture system. The motile, Gram-negative, non-spore-forming curved rods were 2-7 µm long and 1 µm in diameter. Growth occurred at temperatures ranging from 20 to 40 °C with a maximum rate of growth at 30 °C. The pH range for growth was pH 6.0-8.0, with a maximum rate of growth at pH 7.5. This isolate was halotolerant growing in NaCl concentrations ranging from 0 to 1.6 M with a maximum rate of growth at 0.4 M. Similarly to the five described Dethiosulfovibrio species, this obligate anaerobe isolate was fermentative, capable of utilizing peptides, amino acids and some organic acids for growth, but unlike described strains in the genus did not reduce thiosulphate or elemental sulphur to hydrogen sulphide during fermentation of organic substrates. The G+C content of 55 mol% is similar to the described Dethiosulfovibrio species. The average nucleotide identity analysis between whole genome sequences showed less than 93.15% sequence similarity between strain F2BT and the five other described Dethiosulfovibrio species. Differences in the physiological and phylogenetic characteristics between the new strain and other Dethiosulfovibrio specied indicate that F2BT represents a novel species of this genus and the epithet Dethiosulfovibrio faecalis sp. nov. is proposed. The type strain is F2BT (=DSM 112078T=KCTC25378T).