Biodegradation of Para Amino Acetanilide by Halomonas sp. TBZ3

Antibacterial activity of Lake Urmia derived-Halomonas

Isolation of new microbial species from extreme environments is one of the most efficient approaches for the development of novel bioactive metabolites. The aim of the present study was to explore the pharmaceutical bacterial resources from the water and sediments of hypersaline Lake Urmia. Using different culture conditions and media led to the isolation of 20 bacterial strains. Halophilic bacteria were screened for the production of antibacterial agent against multi-drug resistant strains of Escherichia coli through agar well diffusion assay. Halophilic bacteria DNA extraction was done by boiling method. The results showed that two Halomonas strains, LUH16 and LUH20 identified by analysis of 16S rRNA gene sequences were the potent producers of antimicrobial metabolites against various strains of E. coli. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of eight secondary metabolites with the relevant antimicrobial properties. Our findings led us to focus on Halomonas strains as potent producers of antimicrobial compound that might be an alternative against antibiotic-resistant pathogens such as pathogenic Escherichia coli.

Biotechnological impacts of Halomonas: a promising cell factory for industrially relevant biomolecules

Extremophiles are the most fascinating life forms for their special adaptations and ability to offer unique extremozymes or bioactive molecules. Halophiles, the natural inhabitants of hypersaline environments, are one among them. Halomonas are the common genus of halophilic bacteria. To support growth in unusual environments, Halomonas produces various hydrolytic enzymes, compatible solutes, biopolymers like extracellular polysaccharides (EPS) and polyhydroxy alkaloates (PHA), antibiotics, biosurfactants, pigments, etc. Many of such molecules are being produced in large-scale bioreactors for commercial use. However, the prospect of the remaining bioactive molecules with industrial relevance is far from their application. Furthermore, the genetic engineering of the respective gene clusters could open up a new path to bio-prospect these molecules by overproducing their products through heterologous expression. The present survey on Halomonas highlights their ecological diversity, application potential of the their various industrially relevant biomolecules and impact of these biomolecules on respective fields.

Halomonas diversa sp. nov., isolated from deep-sea sediment of the Pacific Ocean

A novel Gram-stain-negative, facultatively anaerobic, rod-shaped bacterium, designated as D167-6-1^T, was isolated from deep-sea sediment collected from the Pacific Ocean. The cells were catalase- and oxidase-positive, and motile by means of peritrichous flagella. Growth occurred at NaCl concentrations ranging from 0 to 19 % (optimum, 2-8 %, w/v), from pH 6 to 11 (optimum, 7-8) and at temperatures between 4 and 45 °C (optimum, 33 °C). Phylogenetic analysis based on 16S rRNA, gyrB and rpoD gene sequences and its genome sequence revealed that strain D167-6-1^T formed a monophyletic branch within the genus Halomonas and was most closely related to Halomonas saliphila, Halomonas pellis, Halomonas kenyensis, Halomonas daqingensis, Halomonas desiderata and Halomonas lactosivorans (with 98.5, 98.5, 98.4, 98.1, 97.5 and 97.8 % 16S rRNA sequence similarity, respectively). The complete genome size of strain D167-6-1^T was 4.49 Mb, with a DNA G+C content of 62.8 mol%. The estimated averagenucleotide identity and DNA-DNA hybridization values between strain D167-6-1^T and other closely related species were 77.59-85.35 % and 22.0-30.6 %, respectively. The principal cellular fatty acids (>5 %) were C_18 : 1  ω7c, C_16 : 0, C_19 : 0 cyclo ω8c, summed feature 3 (C_16 : 1  ω7c/C_16 : 1  ω6c) and C_17 : 0 cyclo. The polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, aminophospholipid and two unidentified phospholipids. The predominant respiratory quinones were Q-9 and Q-8. The combined genotypic and phenotypic data show that strain D167-6-1^T represents a novel species of the genus Halomonas, for which the name Halomonas diversa sp. nov. is proposed, with the type strain D167-6-1^T (=MCCC 1A13316^T=KCTC 72441^T).

Halomonas urmiana sp. nov., a moderately halophilic bacterium isolated from Urmia Lake in Iran

In the course of screening halophilic bacteria in Urmia Lake in Iran, which is being threatened by dryness, a novel Gram-negative, moderately halophilic, heterotrophic and short rod-shaped bacteria was isolated and characterized. The bacterium was isolated from a water specimen and designated as TBZ3^T. Colonies were found to be creamy yellow, with catalase- and oxidase-positive activities. The growth of strain TBZ3^T was observed to be at 10-45 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 7.0) and in the presence of 0.5-20 % (w/v) NaCl (optimum, 7.5 %). Strain TBZ3^T contained C_16 : 0, cyclo-C_19 : 0  ω8c, summed feature 3 (comprising C_16 : 1  ω7c and/or C_16 : 1  ω6c) and summed feature 8 (comprising C_18 : 1  ω7c and/or C_18 : 1  ω6c) as major fatty acids and ubiquinone-9 as the only respiratory isoprenoid quinone. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, glycolipid, unidentified phospholipid and unidentified polar lipids were detected as the major polar lipids. Strain TBZ3^T was found to be most closely related to Halomonas saccharevitans AJ275^T , Halomonas denitrificans M29^T and Halomonas sediminicola CPS11^T with the 16S rRNA gene sequence similarities of 98.93, 98.15 and 97.60 % respectively and in phylogenetic analysis strain TBZ3^T grouped with Halomonas saccharevitans AJ275^T contained within a large cluster within the genus Halomonas. Based on phenotypic, chemotaxonomic and molecular properties, strain TBZ3^T represents a novel species of the Halomonas genus, for which the name Halomonas urmiana sp. nov. is proposed. The type strain is TBZ3^T (=DSM 22871^T=LMG 25416^T).