Lacibacterium aquatile gen. nov., sp. nov., a new member of the family Rhodospirillaceae isolated from a freshwater lake

Abstract

A bacterial strain designated LTC-2(T) was isolated from a freshwater lake in Taiwan and characterized using a polyphasic taxonomic approach. Cells of strain LTC-2(T) were Gram-reaction-negative, facultatively anaerobic, poly-β-hydroxybutyrate-accumulating, motile by means of a monopolar flagellum, non-spore-forming, slightly curved rods surrounded by a thick capsule and formed creamy white colonies. Growth occurred at 10-37 °C (optimum, 20-30 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and with 0-1.0 % NaCl (optimum, 0 %). The predominant fatty acids were C18 : 1ω7c, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The major isoprenoid quinone was Q-10 and the DNA G+C content was 58.5 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidyldimethylethanolamine, two uncharacterized phospholipids and two uncharacterized aminophospholipids. The major polyamines were putrescine, homospermidine and spermidine. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain LTC-2(T) forms a distinct lineage with respect to closely related genera in the family Rhodospirillaceae, most closely related to the genera Elstera and Dongia, and the levels of 16S rRNA gene sequence similarity with respect to the type species of related genera were less than 94 %. On the basis of the genotypic and phenotypic data, strain LTC-2(T) represents a novel genus and species of the family Rhodospirillaceae, for which the name Lacibacterium aquatile gen. nov., sp. nov. is proposed. The type strain is LTC-2(T) ( = BCRC 80445(T) = LMG 26999(T) = KCTC 32017(T)).