Nitratireductor pacificus sp. nov., isolated from a pyrene-degrading consortium

Abstract

Strain pht-3BT was isolated from a pyrene-degrading consortium of an enriched sediment from the Pacific Ocean, collected during the screening of polycyclic aromatic hydrocarbon-degrading bacteria. Cells were Gram-negative, short rods that were motile by means of flagella. Growth was observed at 0–7 % NaCl and 10–41 °C. The isolate was able to reduce nitrate to nitrite, but not to nitrogen. 16S rRNA gene sequence comparisons showed that strain pht-3BT was most closely related to Nitratireductor aquibiodomus NL21T (97.3 % 16S rRNA gene sequence similarity), N. indicus C115T (97.1 %), N. basaltis J3T (96.8 %) and N. kimnyeongensis KY 101T (96.7 %). DNA–DNA hybridization between strain pht-3BT and these reference strains revealed 55, 54, 28 and 42 % DNA–DNA relatedness, respectively. The dominant fatty acids were C19 : 0ω8c cyclo (22.6 %) and summed feature 8 (consisting of C18 : 1ω7c and/or C18 : 1ω6c; 60.4 %). The G+C content of the chromosomal DNA was 63 mol%. These characteristics were in good agreement with those of members of the genus Nitratireductor. According to cell morphology, physiology, fatty acid composition, 16S rRNA gene sequence analysis and DNA–DNA relatedness, the isolate belonged to the genus Nitratireductor but could be readily distinguished from recognized species of the genus. Therefore a novel species is proposed to accommodate strain pht-3BT, for which the name Nitratireductor pacificus sp. nov. is proposed. The type strain is pht-3BT ( = CCTCC AB 209302T = LMG 25541T = MCCC 1A01024T).