Delving into the lifestyle of Sundarban Wetland resident, biofilm producing, halotolerant Salinicoccus roseus: a comparative genomics-based intervention.

BACKGROUND: Microbial community played an essential role in ecosystem processes, be it mangrove wetland or other intertidal ecologies. Several enzymatic activities like hydrolases are effective ecological indicators of soil microbial function. So far, little is known on halophilic bacterial contribution and function on a genomic viewpoint of Indian Sundarban Wetland. Considering the above mentioned issues, the aims of this study was to understand the life style, metabolic functionalities and genomic features of the isolated bacterium, Salinicoccus roseus strain RF1H. A comparative genome-based study of S. roseus has not been reported yet. Henceforth, we have considered the inclusion of the intra-species genome comparison of S. roseus to gain insight into the high degree of variation in the genome of strain RF1H among others. RESULTS: Salinicoccus roseus strain RF1H is a pink-red pigmented, Gram-positive and non-motile cocci. The bacterium exhibited high salt tolerance (up to 15% NaCl), antibiotic resistance, biofilm formation and secretion of extracellular hydrolytic enzymes. The circular genome was approximately 2.62978 Mb in size, encoding 574 predicted genes with GC content 49.5%. Presence of genomic elements (prophages, transposable elements, CRISPR-Cas system) represented bacterial virulence and multidrug-resistance. Furthermore, genes associated with salt tolerance, temperature adaptation and DNA repair system were distributed in 17 genomic islands. Genes related to hydrocarbon degradation manifested metabolic capability of the bacterium for potential biotechnological applications. A comparative pangenome analysis revealed two-component response regulator, modified C4-dicarboxylate transport system and osmotic stress regulated ATP-binding proteins. Presence of genes encoding arginine decarboxylase (ADC) enzyme being involved in biofilm formation was reported from the genome. In silico study revealed the protein is thermostable and made up with ~ 415 amino acids, and hydrophilic in nature. Three motifs appeared to be evolutionary conserved in all Salinicoccus sequences. CONCLUSION: The first report of whole genome analysis of Salinicoccus roseus strain RF1H provided information of metabolic functionalities, biofilm formation, resistance mechanism and adaptation strategies to thrive in climate-change induced vulnerable spot like Sundarban. Comparative genome analysis highlighted the unique genome content that contributed the strain's adaptability. The biomolecules produced during metabolism are important sources of compounds with potential beneficial applications in pharmaceuticals.

Salinicoccus cyprini sp. nov., isolated from the gut of mirror carp, Cyprinus carpio var. specularis.

A novel orange to pink coloured bacterial strain designated as CT19T was isolated from the gastrointestinal tract of mirror carp, Cyprinus carpio var. specularis (Lacepède, 1803) collected from the Gobind Sagar reservoir at village Lathiani, Una, Himachal Pradesh, India. Cells of the strain were found to be aerobic, Gram-stain-positive, non-motile and non-spore-forming coccoids. Based on the 16S rRNA gene sequence, the strain was closely related to Salinicoccus hispanicus J-82T (=DSM 5352T; 97.4 %), followed by S. sesuvii CC-SPL15-2T (=DSM 23267T; 96.4 %), S. amylolyticus JC304T (=KCTC 33661T; 95.6 %) and S. roseus DSM 5351T (95.4 %). Identity with all other members of the genus were <94.5 %. The draft genome of strain CT19T was assembled to 2.4 Mbp with a G+C content of 47.9 mol%. Average nucleotide identity and digital DNA-DNA hybridization values between strain CT19T and S. hispanicus J-82T were found to be 85.9 and 31.3% respectively which is far below the threshold for species delineation. Iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 0, C16 : 0 and anteiso-C17 : 0 were the major cellular fatty acids of strain CT19T. Major polar lipids were diphosphatidylglycerol, phosphatidylgylcerol and an unidentified glycolipid. Respiratory quinone system was composed of menaquinone-6 and major cell wall amino acid was l-lysine. Based on phylogenomic, physiological and biochemical characteristics, strain CT19T represents a novel species of the genus Salinicoccus for which the name Salinicoccus cyprini sp. nov. is proposed. The type strain is CT19T (=KCTC 43022T =CCM 8886T=MCC 3834T).

Production, characterization and antimicrobial activities of bio-pigments by Aquisalibacillus elongatus MB592, Salinicoccus sesuvii MB597, and Halomonas aquamarina MB598 isolated from Khewra Salt Range, Pakistan.

Hypersaline ecosystems offer unique habitats to microbial populations capable of withstanding extreme stress conditions and producing novel metabolites of commercial importance. Herein, we have characterized for the first time the production of bioactive pigments from newly isolated halophilic bacterial species. Halophilic bacteria were isolated from Khewra Salt Range of Pakistan. Three distinctly colored isolates were selected for pigment production. Selected colonies were identified as Aquisalibacillus elongatus MB592, Salinicoccus sesuvii MB597, and Halomonas aquamarina MB598 based on morphological, biochemical, and physiological evidences as well as 16S rRNA analysis. The optimum pigment production observed at mesophilic condition, nearly neutral pH, and moderate salinity was validated using response surface methodology. Different analytical techniques (UV spectroscopy, infrared spectroscopy, and HPLC) characterized these purified pigments as derivatives of bacterioruberin carotenoids. Antioxidant activity of pigments revealed up to 85% free-radical scavenging activity at the concentration of 30 µg ml-1. Pigments also showed significant antimicrobial activity against Bacillus subtilis, Bacillus pumilus, Enterococcus faecalis, Bacillus cereus, Klebsiella pneumoniae, Alcaligenes faecalis, Pseudomonas geniculata, Enterococcus faecium, Aspergillus fumigatus, Aspergillus flavus, Fusarium solani, and Mucor spp., suggesting potential biomedical applications.

Development of the first gene expression system for Salinicoccus strains with potential application in bioremediation of hypersaline wastewaters.

Salinicoccus salsiraiae IM408 (=CGMCC13032) is a novel halophilic bacterium that we isolated from the saline soil of Da Gang Oilfield. It tolerates 60 g/l sodium chloride and up to 123 g/l (1.5 M) sodium acetate and has shown a potential application in bioremediation of wastewater with high salt and high chemical oxygen demand (COD). Two plasmids, pS408-1 and pS408-2, were identified in S. salsiraiae IM408, and the sequences and copy numbers of the plasmids were determined. Based on these plasmids, two shuttle vectors containing a replicon for Escherichia coli, ampicillin, and chloramphenicol resistance genes, as well as the replicon from pS408-1 or pS408-2, were constructed and named as pTCS101 and pTCS201, respectively. A suitable host strain, named S. salsiraiae PE01, was also developed from the wild-type by plasmid elimination. Using the plasmid pTCS101 as an expression vector, L-lactate dehydrogenase from Staphylococcus aureus was expressed successfully in S. salsiraiae PE01. This is the first gene expression system for the Salinicoccus genus. It has provided the potential for expression of desired proteins or for establishment of desired pathways in Salinicoccus strains, which would make these halophiles more advantageous in future biotechnological applications.

Complete genome sequence of Salinicoccus halodurans H3B36, isolated from the Qaidam Basin in China.

Salinicoccus halodurans H3B36 is a moderately halophilic bacterium isolated from a sediment sample of Qaidam Basin at 3.2 m vertical depth. Strain H3B36 accumulate N (α)-acetyl-α-lysine as compatible solute against salinity and heat stresses and may have potential applications in industrial biotechnology. In this study, we sequenced the genome of strain H3B36 using single molecule, real-time sequencing technology on a PacBio RS II instrument. The complete genome of strain H3B36 was 2,778,379 bp and contained 2,853 protein-coding genes, 12 rRNA genes, and 61 tRNA genes with 58 tandem repeats, six minisatellite DNA sequences, 11 genome islands, and no CRISPR repeat region. Further analysis of epigenetic modifications revealed the presence of 11,000 m4C-type modified bases, 7,545 m6A-type modified bases, and 89,064 other modified bases. The data on the genome of this strain may provide an insight into the metabolism of N (α)-acetyl-α-lysine.

Genome sequence of the moderately halophilic bacterium Salinicoccus carnicancri type strain Crm(T) (= DSM 23852(T)).

Salinicoccus carnicancri Jung et al. 2010 belongs to the genus Salinicoccus in the family Staphylococcaceae. Members of the Salinicoccus are moderately halophilic and originate from various salty environments. The halophilic features of the Salinicoccus suggest their possible uses in biotechnological applications, such as biodegradation and fermented food production. However, the genus Salinicoccus is poorly characterized at the genome level, despite its potential importance. This study presents the draft genome sequence of S. carnicancri strain Crm(T) and its annotation. The 2,673,309 base pair genome contained 2,700 protein-coding genes and 78 RNA genes with an average G+C content of 47.93 mol%. It was notable that the strain carried 72 predicted genes associated with osmoregulation, which suggests the presence of beneficial functions that facilitate growth in high-salt environments.