Halotalea alkalilenta gen. nov., sp. nov., a novel osmotolerant and alkalitolerant bacterium from alkaline olive mill wastes, and emended description of the family Halomonadaceae Franzmann et al. 1989, emend. Dobson and Franzmann 1996

Abstract

A novel Gram-negative, motile, nonsporulating, rod-shaped bacterium isolated from alkaline sludge-like wastes (‘alpeorujo’ or ‘alperujo’) of two-phase olive oil extraction is described. The strain, designated AW-7T, is an obligate aerobe that is halotolerant (tolerating up to 15 % w/v NaCl), sugar-tolerant (tolerating up to 45 % and 60 % w/v (+)-d-glucose and maltose respectively; these are the highest concentrations tolerated by any known members of the Bacteria domain) and alkalitolerant (growing at a broad pH range of 5–11). Strain AW-7T is chemo-organotrophic. Ubiquinone-9 was detected in the respiratory chain of strain AW-7T. The major fatty acids present are C18 : 1 ω7c, C16 : 0, C19 : 0 cyclo ω8c, C12 : 0 3-OH and C16 : 1 ω7c/iso-C15 : 0 2-OH. Based on 16S rRNA gene sequence analysis, strain AW-7T showed almost equal phylogenetic distances from Zymobacter palmae (95.6 % similarity) and Carnimonas nigrificans (95.4 % similarity). In addition, low DNA–DNA relatedness values were found for strain AW-7T against Carnimonas nigrificans CECT 4437T (22.5–25.4 %) and Z. palmae DSM 10491T (11.9–14.4 %). The DNA G+C content of strain AW-7T is 64.4 mol%. Physiological and chemotaxonomic data further confirmed the differentiation of strain AW-7T from the genera Zymobacter and Carnimonas. Thus, strain AW-7T represents a novel bacterial genus within the family Halomonadaceae, for which the name Halotalea gen. nov. is proposed. Halotalea alkalilenta sp. nov. (type strain AW-7T=DSM 17697T=CECT 7134T) is proposed as the type species of the genus Halotalea gen. nov. A reassignment of the descriptive 16S rRNA signature characteristics of the family Halomonadaceae permitted the placement of the novel genus Halotalea into the family; in contrast, the genus Halovibrio possessed only 12 out of the 18 signature characteristics proposed, and hence it was excluded from the family Halomonadaceae.