Chemical Profiling of Antimicrobial Metabolites from Halophilic Actinomycete Nocardiopsis_sp. Al-H10-1 (KF384482) Isolated from Alang, Gulf of Khambhat, India

The overuse of antibiotics has resulted in the development of drug resistant, a major problem in disease curing processes i.e. development of drug resistance. The World Health Organization (WHO) released its first list of the most concerning pathogens for human health in 2017 which suggested that there are total 12 bacterial families which have developed multiple drug resistance and for which novel antibiotics are required immediately (WHO 2017). There is a requirement to explore some novel compounds to overcome this issue. Thus our study aimed at exploration of marine actinomycetes as a valuable resource for novel products with antimicrobial properties. The halophilic actinomycete Nocardiopsis_sp. Al-H10-1 (KF384482) was isolated from saline water (20 m away from shore) of Alang coast (Gulf of Khambhat), Bhavnagar, Gujarat, India. The isolate Al-H10-1 was identified as Nocardiopsis sp. through rigorous morphological and cultural characteristics; the species was confirmed through 16s rRNA phylogenetic analysis. The antimicrobial potential of Nocardiopsis sp. Al-H10-1 was assessed against a range of Gram-positive and Gram-negative bacteria as well as three fungi, there it demonstrated antimicrobial activity against four Gram negative bacteria and one Gram positive bacteria. Further active antimicrobial compounds present in ethyl acetate extract was identified using Gas Chromatography-Mass Spectroscopy (GC-MS). GC-MS analysis showed the presence of 17 compounds which included antimicrobial compounds like 2, 4-bis (1, 1-dimethylethyl)-Phenol, Dibutyl phthalate as well as various types of alkanes and their derivatives.

Paraglycomyces xinjiangensis gen. nov., sp. nov., a halophilic actinomycete

A novel halophilic actinobacterium, designated strain TRM 49201T, was isolated from a hypersaline soil in Xinjiang Province, north-west China. The strain was aerobic, Gram-stain-positive and halophilic. The aerial mycelium was chaotic with irregular branches, and spherical sporangia containing several spherical spores developed at mycelial aggregations. The strain had an optimum NaCl concentration for growth of 8–13 % (w/v). The whole-cell sugar pattern of strain TRM 49201T consisted of xylose and ribose. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-10(H2). The polar lipids were diphosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, phosphatidylglycerol, phosphatidylcholine and four unknown phospholipids. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 70 mol%. Phylogenetic analysis showed that strain TRM 49201T can be distinguished from representatives of Glycomyces, Stackebrandtia and Haloglycomyces, the three existing genera in the family Glycomycetaceae, based on low 16S rRNA gene sequence similarities ( < 94.42 %). Strain TRM 49201T is thus considered to represent a novel species of a new genus in the family Glycomycetaceae, for which the name Paraglycomyces xinjiangensis gen. nov., sp. nov. is proposed. The type strain of Paraglycomyces xinjiangensis is TRM 49201T ( = NRRL B-24926T = CCTCC AA 2013002T = KACC 17683T).

Prauserella isguenensis sp. nov., a halophilic actinomycete isolated from desert soil

Two actinomycete strains, designated H225T and H137, were isolated from two soil samples collected from the arid region of Ahbas at Béni-Isguen (Mzab), located in the Algerian Sahara. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the novel strains should be assigned to the genus Prauserella of the family Pseudonocardiaceae , and they were therefore subjected to a polyphasic taxonomic study. These two strains contained meso-diaminopimelic acid as the diagnostic diamino acid and arabinose and galactose as major whole-cell sugars. The diagnostic phospholipid was phosphatidylethanolamine. The predominant menaquinone was MK-9(H4), and the major fatty acid was iso-C16 : 0. DNA–DNA hybridization values between strain H225T and its closest phylogenetic neighbours, namely Prauserella flava DSM 45265T, Prauserella alba DSM 44590T, Prauserella aidingensis DSM 45266T, Prauserella salsuginis DSM 45264T and Prauserella sediminis DSM 45267T, were clearly below the 70 % threshold used for species delineation. The genomic DNA G+C content of strains H225T and H137 was 70.4 mol%. On the basis of phenotypic and genotypic data, strains H225T and H137T are considered to represent a novel species of the genus Prauserella , for which the name Prauserella isguenensis sp. nov. is proposed. The type strain is H225T ( = DSM 46664T = CECT 8577T).