Paenibacillus darwinianus sp. nov., isolated from gamma-irradiated Antarctic soil

Abstract

A novel bacterium, strain Br T , was isolated from gamma-irradiated soils of the Britannia drift, Lake Wellman Region, Antarctica. This isolate was rod-shaped, endospore forming, Gram-stainvariable, catalase-positive, oxidase-negative and strictly aerobic. Cells possessed a monotrichous flagellum. Optimal growth was observed at 18 6C, pH 7.0 in PYGV or R2A broth. The major cellular fatty acid was anteiso-C 15 : 0 (63.4 %). Primary identified lipids included phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. Total phospholipid was 60 % (w/w) of the total lipid extract. MK-7 was the dominant isoprenoid quinone. The genomic DNA G+C content was 55.6 mol%. Based on 16S rRNA gene sequence similarity, strain Br T clusters within the genus Paenibacillus with similarity values ranging from 93.9 to 95.1 %. Phylogenetic analyses by maximum-likelihood, maximum-parsimony and neighbourjoining methods revealed that strain Br T clusters with Paenibacillus daejeonensis (AF290916), Paenibacillus tarimensis (EF125184) and Paenibacillus pinihumi (GQ423057), albeit with weak bootstrap support. On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics, we propose that strain Br T represents a novel species, Paenibacillus darwinianus sp. nov. The type strain is Br T (5DSM 27245 T 5ICMP 19912 T ).The genus Paenibacillus belonging to family Paenibacillaceae was first resolved from members of rRNA group 3 bacilli by Ash et al. (1993) based on comparative 16S rRNA gene sequence analysis. Members of the genus Paenibacillus are characterized as rod-shaped, Gram-positive or variable (depending on growth phase), endospore-forming, aerobic or facultatively anaerobic bacteria, possessing anteiso-C 15 : 0 as the major cellular fatty acid and unsaturated menaquinone with seven units (MK-7) as the predominant isoprenoid quinone, and having a genomic DNA G+C content ranging between 40 and 54 mol% (Ash et al., 1993;Shida et al., 1997). The genus Paenibacillus contains several species that have been isolated from a wide range of cold environments including sediment (Montes et al., 2004) and soil (Marshall & Ohye, 1966; Rodríguez-Díaz et al., 2005) from the Antarctic Peninsula, a cold spring in China (Tang et al., 2011), soil on the Kafni glacier, Himalayas (Kishore et al., 2010), Alaskan soil (Nelson et al., 2009) and a peat bog in Northern China (Ming et al., 2012). In this study we investigated the taxonomic status of strain Br T isolated from Antarctic soils which were exposed to gamma irradiation, using a combination of physiological, biochemical, chemotaxonomic and phylogenetic techniques. Based on these analyses we propose strain Br T as a representative of a novel species, Paenibacillus darwinianus sp. nov.Soil samples on the Britannia drift, Lake Wellman Region (79 u 559 16.20 S 156 u 559 30.70 E) in the south-eastern Darwin Mountains, Antarctica, were collected for the isolation of bacteria (Aislabie et al., 2012 Colony morphology was observed on PYGV gellan gum plates after culturing for 4 days at...

Appraising Endophyte–Plant Symbiosis for Improved Growth, Nodulation, Nitrogen Fixation and Abiotic Stress Tolerance: An Experimental Investigation with Chickpea (Cicer arietinum L.)

“…Other research also reported large variation in colony morphology of endophytic strains from nodules of Glycine max and Lespedeza sp. [74,75]. In our study, endophytic Paenibacillus strains were found Gram-negative which confirmed the findings of Dsouza et al [75], Kittiwongwattana and Thawai [76], Valverde et al [77] and Wang et al [78] who reported several Paenibacillus strains including P. prosopidis PW21 T , P. uliginis DSM 21861 T , P. purispatti ES-MS17 T , P. lactis PSM15596 T and P. lamnae L7-75 T as Gram-negative or Gram-variable.…”

“…[74,75]. In our study, endophytic Paenibacillus strains were found Gram-negative which confirmed the findings of Dsouza et al [75], Kittiwongwattana and Thawai [76], Valverde et al [77] and Wang et al [78] who reported several Paenibacillus strains including P. prosopidis PW21 T , P. uliginis DSM 21861 T , P. purispatti ES-MS17 T , P. lactis PSM15596 T and P. lamnae L7-75 T as Gram-negative or Gram-variable. Generally, Paenibacillus species showed a Gram-positive reaction however due to a progressive increase in the numbers, cells became sensitive to the decolorizing step of the Gram-stain and electron microscopy showed these cells to be Gram-negative.…”

Genome-Based Comparative Analyses of Antarctic and Temperate Species of Paenibacillus

“…Here, we report genome analyses of three P. darwinianus strains, isolated from gamma-irradiated soils of the Ross Sea Region (RSR), Antarctica [26] . Soils of the RSR represent a unique environment characterised by physical extremes of low temperature, elevated ultraviolet radiation and geochemical extremes of high salinity, low water and low nutrient availability [27] .…”

Paenibacillus cisolokensis sp. nov., isolated from litter of a geyser

“…Growth occurs at 37-55 C (optimal at 45-50 C), at pH 6.0-9.0 (optimal at 6.0-7.0) and in TSB with 0-2.0 % (w/v) NaCl. Positive for oxidase and catalase activities, hydrolysis of starch, cellulose, xylan, aesculin, gelatin and chitin, nitrate reduction, acid (Wang et al, 2008); 3, P. daejeonensis DSM 15491 T (Lee et al, 2002); 4, P. darwinianus Br T (Dsouza et al, 2014); 5, P. wooponensis WPCB018 T (Baik et al, 2011); 6, 'P. marinum' THE22 (Bouraou et al, 2013); 7, P. pasadenensis SAFN-007 T (Osman et al, 2006 The type strain is LC2-13A T (=UICC B-42 T =NRRL B-65368 T =DSM 101873 T ), isolated from fallen leaf of Cisolok geyser, West Java, Indonesia.…”