Virgibacillus kekensis sp. nov., a moderately halophilic bacterium isolated from a salt lake in China

Abstract

A Gram-positive, moderately halophilic, motile, strictly aerobic, endospore-forming, oxidase-and catalase-positive, rod-shaped bacterium, strain YIM kkny16 T , was isolated from a saline mud sample collected from the Keke salt lake in the Qaidam Basin, north-west China. This isolate grew in the presence of 0-25 % (w/v) NaCl and at pH 6.0-10.0 and 10-50 6C; optimum growth was observed with 10 % (w/v) NaCl and at pH 7.0 and 37 6C. Strain YIM kkny16 T had meso-diaminopimelic acid as the diagnostic diamino acid, MK-7 as the predominant respiratory quinone, with a significant amount of MK-6, and anteiso-C 15 : 0 , iso-C 14 : 0 and C 16 : 1 v7c alcohol as major fatty acids. Major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content was 41.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences confirmed that strain YIM kkny16 T was a member of the genus Virgibacillus, exhibiting sequence similarities of 94.9-97.3 % to the type strains of recognized Virgibacillus species. Strain YIM kkny16 T could be differentiated from recognized Virgibacillus species based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of evidence from this polyphasic study, strain YIM kkny16 T is considered to represent a novel species of the genus Virgibacillus, for which the name Virgibacillus kekensis sp. nov. is proposed. The type strain is YIM kkny16 T (5DSM 17056 T 5CGMCC 1.6298 T ).At the time of writing, the genus Virgibacillus comprises 11 recognized species, with Virgibacillus olivae (Quesada et al., 2007) and Virgibacillus halophilus (An et al., 2007) being the most recently described. Virgibacillus pantothenticus (Heyndrickx et al., 1998) is the type species. During a recent study of the microbial diversity of the Keke salt lake in the Qaidam Basin of Qinghai Province, north-west China, a moderately halophilic rod-shaped bacterium, designated strain YIM kkny16 T , was isolated from a saline mud sample. Phenotypic and chemotaxonomic characterization, together with phylogenetic analysis based on 16S rRNA gene sequences, showed that strain YIM kkny16 T was related to members of the genus Virgibacillus, but represented a novel species.Strain YIM kkny16 T was isolated from a saline mud sample by plating 1 : 10 serial dilutions of the sample on Difco marine agar 2216 (MA; pH 7.2) at 28 u C for 2 weeks. The strain was maintained both in Difco marine broth (MB) supplemented with 20 % (v/v) glycerol at 280 u C and as lyophilized cultures at 4 u C. Unless otherwise indicated, morphological and physiological studies were performed with cells grown on MA supplemented with 10 % (w/v) NaCl, and on ISP medium 2 agar (Shirling & Gottlieb, 1966), nutrient agar and trypticase soy agar (BBL) as controls. Cells for chemotaxonomic and molecular systematic studies were grown in MB supplemented with 10 % (w/v) NaCl in shake flasks (with shaking at aboutThe GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain YIM kkny1...

Virgibacillus salinus sp. nov., a moderately halophilic bacterium from sediment of a saline lake

“…Strain XH-22 T had diaminopimelic acid in the cell-wall peptidoglycan, MK-7 as the predominant menaquinone, and anteiso-C 15 : 0 , C 16 : 0 and iso-C 14 : 0 as major fatty acids. Chen et al, 2008). During the course of a study of halophilic bacteria from a saline lake in China, a moderately halophilic, Gram-positive bacterium, designated strain XH-22 T , was isolated.…”

Virgibacillus arcticus sp. nov., a moderately halophilic, endospore-forming bacterium from permafrost in the Canadian high Arctic

“…The fatty acid profile of strain Hal 1 T was similar to those of the type strains of all recognized species of the genus Virgibacillus (see Table 1), in that strain Hal 1 T shared the same dominant fatty acids and also possessed anteiso-C 15 : 0 as the major fatty acid. Specifically, the anteiso-C 15 : 0 content of the type strains of both V. carmonensis and V. necropolis (grown on MA) was also high, 65.54±1.4 and 71.5 % (Heyrman et al, 2003), respectively; the corresponding value for the type strains of all other Virgibacillus species is in the range 30.5-52.9 % (data from An et al, 2007;Chen et al, 2008).…”

“…V. carmonensis, V. necropolis and strain Hal 1 T did not grow in the presence of ampicillin, chloramphenicol, rifampicin, erythromycin and streptomycin. Antibiotic sensitivity data for other species of Virgibacillus have been documented only for Virgibacillus kekensis and Virgibacillus olivae (Quesada et al, 2007;Chen et al, 2008). Similarities to strain Hal 1 T exist in that both V. kekensis and V. olivae were sensitive to ampicillin and rifampicin, V. kekensis was sensitive to chloroamphenicol (V. olivae was resistant) and V. olivae was sensitive to erythromycin (not tested for V. kekensis) (Quesada et al, 2007;Chen et al, 2008).…”

“…Strain Hal 1 T was able to grow at NaCl concentrations of 0-20 % (w/v) and did not have an absolute NaCl requirement for growth; optimal growth was at 5 % (w/v) NaCl. At the time of writing, the genus Virgibacillus comprised 14 recognized species Chen et al, 2008;Heyndrickx et al, 1999;Heyrman et al, 2003; Hua et al, 2008;Lee et al, 2006a; Quesada et al, 2007;Yoon et al, 2004bYoon et al, , 2005Wang et al, 2008). et al, 2007) was added to 50 ml of J HM medium and incubated with shaking at 37, 23 and 5 u C. Growth was noted after 2 weeks incubation at 23 uC and after 1 month at 5 uC.…”

Virgibacillus zhanjiangensis sp. nov., a marine bacterium isolated from sea water

“…This fatty acid profile was similar to those of the recognized Virgibacillus species, although there were differences in the proportions of some fatty acids (Lee et al 2006;Chen et al 2008.…”