Natronomonas moolapensis sp. nov., non-alkaliphilic isolates recovered from a solar saltern crystallizer pond, and emended description of the genus Natronomonas

Abstract

Two isolates of non-alkaliphilic, extremely halophilic archaea, with very similar characteristics, were recovered from a marine solar saltern crystallizer. Cells were pleomorphic, motile and Gram-stain-negative and grew on a limited range of carbon sources, with pyruvate being the best substrate. Optimum growth occurred at 18-20 % (w/v) NaCl, pH 6.0-8.5 and 37-40 degrees C. Both isolates possessed typical archaeal lipids, and their 16S rRNA gene sequences were 99.8 % identical. Phylogenetic tree reconstructions indicated that they were most closely related to the haloalkaliphile Natronomonas pharaonis (97.5 % similarity to the type strain), but the different phenotypic properties and low DNA-DNA hybridization values between Nmn. pharaonis DSM 2160(T) and the two isolates suggested that they represent a novel species within the genus Natronomonas. The name Natronomonas moolapensis sp. nov. is proposed for these isolates, with the type strain being 8.8.11(T) (=JCM 14361(T) =CECT 7526(T) =DSM 18674(T)). An emended description of the genus Natronomonas is also provided.