Marinobacter maroccanus sp. nov., a moderately halophilic bacterium isolated from a saline soil.

Abstract

During the taxonomic investigation of exopolymer producing halophilic bacteria, a rod shaped, motile, Gram-stain-negative, aerobic, halophilic bacterium, designated strain N4^T, was isolated from a natural saline soil located in the northern Morocco. The optimal growth of the isolate was at 30-37 ºC and at pH 6.0-9.0, in the presence of 5-7% (w/v) NaCl. Useful tests for the phenotypic differentiation of strain N4^T from other <i>Marinobacter</i> species included α-chymotrypsin and α-glucosidase activities and the carbohydrate assimilation profile. The major fatty acids detected in strain N4^T were C18:1 ω9c, C16:0, and C16:1 ω7c/C15:0 iso 2-OH. Sequence analysis of the 16S rRNA indicated that strain N4^T belonged to the genus <i>Marinobacter</i> and was closely related to <i>Marinobacter adhaerens</i> NC17506^T (99.04%), <i>Marinobacter salsuginis</i> SD-14B^T (98.97%), and <i>Marinobacter flavimaris</i> SW-145^T (98.36%). Phylogenetic analysis of the rpoD gene sequence also showed that the nearest neighbours of strain N4^T were <i>M. adhaerens</i> (90.63%) and <i>M. salsuginis</i> (91.13%). Strain N4^T showed 87.98% similarity in the average nucleotide identity (ANI) with <i>M. flavimaris</i> and <i>M. salsuginis</i>, and 87.47% with <i>M. adhaerens</i>. In the in-silico genome-to-genome distance (GGD), strain N4^T showed DNA-DNA hybridization (DDH) values of 33.30% with <i>M. adhaerens</i>, 34.60% with <i>M. flavimaris</i> and 34.70% with <i>M. salsuginis</i>. DNA G+C content of N4^T was 57.3 mol%. Based on the results of phenotypic characterization, phylogenetic analysis and genome comparison, strain N4^T represents a novel species of the genus <i>Marinobacter</i>, for which the name <i>Marinobacter maroccanus</i> sp. nov. is proposed. The type strain is N4^T (=CECT 9525^T=LMG 30466^T).