Halomonas alkaliphila sp. nov., a novel halotolerant alkaliphilic bacterium isolated from a salt pool in Campania (Italy)

Abstract

A halotolerant and alkaliphilic Gram-negative bacterium, strain 18bAGT, that grows aerobically at the optimum temperature of 37°C, and at pH 7.5-10 (optimum 9.0), was isolated from a salt pool located in Montefredane in Campanial Region (South of Italy). The isolate tolerated high concentration of NaCl up to 20%. Strain 18bAGT accumulated osmolytes and polyhydroxybutyrate, produced exopolysaccharide and possessed α-glucosidose activity. The predominant respiratory quinones were ubiquinones, Q8 and Q6(6H); phosphoethanolamine, phosphatidylglycerol and disphosphatidylglycerol were the predominant polar lipids. Major fatty acids were C16: 1, C16: 0, and C18:0. On the basis of 16S rRNA gene sequence similarity, 18bAGT was shown to belong to Halomonas genus. Analysis of 16S rRNA gene revealed a high similarity of strain 18bAGT to Halomonas venusta (DSM 4743T) and Halomonas hydrothermalis (DSM 15725T). Level of DNA-DNA relatedness between strain 18bAGT and the most related species Halomonas venusta and Halomonas hydrothermalis was 56.0% and 41.2%, respectively. The G+C content (mol%) of DNA was 53.0. The RiboPrinting patterns of Halomonas venusta and 18AGT showed a pattern similarity of 0.50. On the basis of genomic information and phenotypic characteristics strain 18bAGT represents a new species, for which the name Halomonas alkaliphila sp. nov. is proposed. The type strain is 18bAGT (=DSM 16354T =ATCC BAA-953T).