Alkalibacillus halophilus sp. nov., a new halophilic species isolated from hypersaline soil in Xin-Jiang province, China

Identification of bacterial communities in extreme sites of Pakistan using high throughput barcoded amplicon sequencing

Microorganisms thrive nearly everywhere including extreme environments where few other forms of life can exist. Geochemistry of extreme sites plays a major role in shaping these microbial communities and microbes thriving in such harsh conditions are untapped sources of novel biomolecules. To understand the structure and composition of such microbial communities, culture-independent bacterial diversity was characterised for two extreme sites in Pakistan, Khewra salt range and Murtazaabad hot spring. Barcoded amplicon sequencing technique was used to study the microbial communities. Physicochemical analysis of these sites was also conducted to study the dynamics of microbial communities under stressed conditions. Metagenomic sequencing of salt range soil samples yielded of 40,433 16S rRNA sequences, while hot spring sediments produced 76,449 16S rRNA sequence reads. Proteobacteria were predominant in saline soil while Firmicutes were most abundant in hot spring sediment. The taxonomic analysis of saline samples revealed 914 operational taxonomic units (OTUs) while that of hot spring sequences were clustered into 726 distinct OTUs. OTUs from genus Alkalibacillus were most abundant in hot spring sediments, whereas Haloarcula were more prevalent in saline soil. Some unidentified sequences were also present at each taxonomic level. Multivariate analysis indicated that electrical conductivity and pH are the major environmental factors involved in modelling microbial communities. This study revealed a poly-extremophilic microbial community in the Murtazaabad hot spring and characterised the unexplored halophilic microbial diversity of saline soil of Pakistan.

Alkalibacillus aidingensis sp. nov., an Bacterium Isolated from Aiding Lake in Xinjiang Province, North-West China

A bacterial strain, Gram staining negative, aerobic, long rod, motile bacterium with flagellum, designated strain YIM 98829^T, was isolated from the Aiding Lake in Xinjiang province, North-West China. The isolate produced oval subterminal endospores in swollen sporangia. The predominant menaquinone was MK-7. The cell wall peptidoglycan contained ornithine, serine, aspartic acid, glutamic acid, and alanine, while diaminopimelic acid could not be detected. The major whole-cell sugars contained xylose, glucose, galactose, and mannose. Diphosphatidylglycerol, phosphatidylglycerol, one unknown phospholipid, and two unidentified aminophospholipids were part of the polar lipid profile. Iso-C_15:0 and anteiso-C_15:0 were the major fatty acids. The DNA G + C content of the type strain was 38.0 mol%. Phylogenetic analysis indicated that the isolate belongs to the genus Alkalibacillus. However, it differed from its closest relatives, A. haloalkaliphilus DSM 5271^T (97.04%), A. filiformis 4AG^T (96.99%), and A. silvisoli BM2^T (96.95%) in some physiological characteristics. DNA-DNA hybridization result indicated low levels of relatedness between strain YIM 98829^T and A. haloalkaliphilus JCM 12303^T (16.9%). On the basis of physiological, phenotypic, and chemotaxonomic data, strain YIM 98829^T represents a novel species of genus Alkalibacillus, for which the name Alkalibacillus aidingensis sp. nov. is proposed. The type strain is YIM 98829^T (= NBRC 114103^T = CGMCC 1.17260^T = DSM 112470^T).

From ecophysiology to cultivation methodology: filling the knowledge gap between uncultured and cultured microbes

Earth is dominated by a myriad of microbial communities, but the majority fails to grow under in situ laboratory conditions. The basic cause of unculturability is that bacteria dominantly occur as biofilms in natural environments. Earlier improvements in the culture techniques are mostly done by optimizing media components. However, with technological advancement particularly in the field of genome sequencing and cell imagining techniques, new tools have become available to understand the ecophysiology of microbial communities. Hence, it becomes easier to mimic environmental conditions in the culture plate. Other methods include co-culturing, emendation of growth factors, and cultivation after physical cell sorting. Most recently, techniques have been proposed for bacterial cultivation by employing genomic data to understand either microbial interactions (network-directed targeted bacterial isolation) or ecosystem engineering (reverse genomics). Hopefully, these techniques may be applied to almost all environmental samples, and help fill the gaps between the cultured and uncultured microbial communities.

Evolution in the Bacillaceae

The family Bacillaceae constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to shape, this family has relied on several widely ranging approaches from classical taxonomy, ecological field studies, and evolution in soil microcosms to genomic-scale phylogenetics, laboratory, and directed evolution experiments. One unifying characteristic of the Bacillaceae , the endospore, poses unique challenges to answering questions regarding both the calculation of evolutionary rates and claims of extreme longevity in ancient environmental samples.

Alkalibacillus almallahensis sp. nov., a halophilic bacterium isolated from an inland solar saltern

A halophilic, Gram-staining-positive, non-motile, endospore forming rod-shaped bacterial strain, S1LM8T, was isolated from a sediment sample collected from an inland solar saltern located in La Malahá, Granada (Spain). Growth was observed in media containing 7.5–30 % total salts (optimum 15 % total salts), at pH 7–10 (optimum pH 8) and at 15–50 °C (optimum 35–38 °C). The predominant isoprenoid quinone was MK-7. It contained A1γ-type peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The G+C content of its genomic DNA was 38.2 mol%. The affiliation of strain S1LM8T with the species of the genus Alkalibacillus was determined by 16S rRNA gene sequence comparison. The most closely related species were Alkalibacillus halophilus YIM 012T with 99.8 % similarity, Alkalibacillus salilacus BH163T with 99.8 % similarity and Alkalibacillus flavidus ISL-17T with 98.1 % similarity between their 16S rRNA gene sequences. However, DNA–DNA relatedness between the novel isolate and the related species of the genus Alkalibacillus was less than 34 %. Based on the phylogenetic, phenotypic and chemotaxonomic features, a novel species, Alkalibacillus almallahensis sp. nov. is proposed. The type strain is S1LM8T ( = CECT 8373T = DSM 27545T).

Production of surfactant and detergent-stable, halophilic, and alkalitolerant alpha-amylase by a moderately halophilic Bacillus sp. Strain TSCVKK

A moderately halophilic alkalitolerant Bacillus sp. Strain TSCVKK, with an ability to produce extracellular halophilic, alkalitolerant, surfactant, and detergent-stable alpha-amylase was isolated from soil samples obtained from a salt-manufacturing industry in Chennai. The culture conditions for higher amylase production were optimized with respect to NaCl, substrate, pH, and temperature. Maximum amylase production of 592 mU/ml was achieved in the medium at 48 h with 10% NaCl, 1% dextrin, 0.4% yeast extract, 0.2% tryptone, and 0.2% CaCl(2) at pH 8.0 at 30 degrees C. The enzyme activity in the culture supernatant was highest with 10% NaCl at pH 7.5 and 55 degrees C. The amylase that was partially purified by acetone precipitation was highly stable in various surfactants and detergents. Glucose, maltose, and maltooligosaccharides were the main end products of starch hydrolysis indicating that it is an alpha-amylase.