Bacillus alkalilacus sp. nov., isolated from a sediment sample from a lake in India.

Abstract

An aerobic, endospore-forming, haloalkali-tolerant, Gram-stain-positive, motile, rod-shaped bacterium, designated strain AK73T, was isolated from a sediment sample collected from Sambhar lake, Jaipur, Rajasthan, India. Colonies were circular, 1-2 mm in diameter, glossy, smooth, yellowish and convex with an entire margin after 48 h growth on marine agar at pH 9 and 37 °C. Growth occurred at 15-42 °C, 0-10 % (w/v) NaCl and at a pH range of 7-12. Strain AK73T was positive for catalase and arginine dihydrolase 2 activities, hydrolysis of Tweens 20, 40 and 80, and negative for esculinase, caseinase, gelatinase, β-galactosidase, lipase (Tween 60) and urease activities. The fatty acids were dominated by branched iso-, anteiso-, saturated fatty acids with a high abundance of iso-C15 : 0, anteiso-C15 : 0, C16 : 0 and anteiso-C17 : 0; MK-7 was the major menaquinone. The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, four unidentified phospholipids and three unidentified lipids. The DNA G+C content of strain AK73T was 54 mol%. Analysis based on comparative 16S rRNA gene sequence analysis indicated that Bacillus alcalophilus was the nearest phylogenetic neighbour, with a pair-wise sequence similarity of 96.0 %. Phylogenetic analysis showed that strain AK73T formed a separate lineage but was loosely associated with a peripheral cluster of organisms that contained Bacillus gibsonii, Bacillus murimartini and Bacillus plakortidis with similarity values of 93.6, 93.5 and 93.4 %, respectively. Based on its phenotypic characteristics and on phylogenetic inference, strain AK73T represents a novel species of the genus Bacillus, for which the name Bacillus alkalilacus sp. nov. is proposed. The type strain is AK73T (=JCM 32184T=MTCC 12637T=KCTC 33880T).