Caldimonas meghalayensis sp. nov., a novel thermophilic betaproteobacterium isolated from a hot spring of Meghalaya in northeast India

Abstract

While studying the microbial diversity of hot springs of North-east India we isolated a strain AK31T from the Jakrem hot spring of Meghalaya. The strain formed light yellow colonies on nutrient agar and was Gram negative, non spore-forming rods, motile with single polar flagellum. The strain was positive for oxidase and catalase and hydrolysed starch and weakly urea. The predominant cellular fatty acids were C16:0 (34.8 %), C17:0 cyclo (27.1 %), C16:1 ω7c and/or iso-C15:0 2OH (summed feature 3) (9.6 %), C10:0 3OH (8.0 %), C12:0 (5.8 %), C14:0 (5.3 %) and C18:1 ω7c (5.3 %). Strain AK31T contained ubiquinone-8 as the major respiratory quinone and diphosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids and one unidentified glycolipid as the polar lipids. The G + C content of the DNA of the strain AK31T was 66.7 mol%. The 16S rRNA gene sequence analysis indicated that strain AK31T was member of the genus Caldimonas and closely related to Caldimonas manganoxidans JCM 10698T and Caldimonas taiwanensis On1T with 96.9 % similarity and with Aquincola tertiaricarbonis L10T and Azohydromonas australica IAM 12664T with 96.5 and 96.4 % similarity respectively. Phylogenetic analyses indicated that the strain AK31T clustered with C. manganoxidans JCM 10698T and C. taiwanensis On1T with a phylogenetic distance of 3.25 %. Based on data from the current polyphasic study, strain AK31T is proposed as a novel species of the genus Caldimonas, for which the name Caldimonas meghalayensis sp. nov. is proposed. The type strain of C. meghalayensis is AK31T (= MTCC 11703T = JCM 18786T).