Bioprospecting Studies of Halopholic Bacteria – Streptomyces sp. MA05 and Halobacterium sp. MA06

Halophile organisms such as Halobacterium salinarum and halophilic Actinomycetes flourish under the hostile hypersaline condition and are well known for their ability to produce novel bioactive compounds for bioprospecting analysis such as antibacterial, antifungal, anticancer, and enzyme analysis. In this present study, the objective is to isolate two types of halophiles, namely Halobacterium sp. MA06 and Streptomyces sp. MA05 based on their 16SrRNA gene sequencing. The two potential halophiles were isolated from the salt pan of Chennai, India. In order to evaluate enzyme analysis and pigment production of both the organism, optimization of the growth state of both species was performed on complex medium with various additives and different concentrations of sodium chloride and magnesium sulfate. The result showed that Halobacterium sp. MA06 produced orange colored pigment after characterization using GC-MS analysis. For Streptomyces sp. MA06, it was found to produce the enzyme amylase, hence Streptomyces sp. MA06 was subjected to producing the enzyme amylase, and the produced amylase will be characterized. The antimicrobial and anticancer activity was then carried out on the extract of Streptomyces sp. MA05 and the pigment of Halobacterium sp. MA06. In conclusion, the pigment from Halobacterium sp. MA06 and the enzyme amylase from Streptomyces sp. MA05 could be a novel bio-sourced for bioprospecting of bioactive natural products.

Characterization and partial purification of an antibacterial agent from halophilic actinomycetes Kocuria sp. strain rsk4

Introduction: The inevitable rise of antibiotic-resistant bacteria is a global health problem. These pathogens erode the utility of available antibiotics. Staphylococcus aureus is one of the major causes of community-acquired infections. The aim of work was to evaluate the marine actinomycetes for production of the antibacterial agent against pathogens. Methods: Halophilic actinomycetes were isolated, characterized and screened for production of antibacterial agent against pathogenic bacteria. The antibacterial compounds were extracted by solvent extraction and separated by TLC based bioautography. Antibacterial compound was further purified by flash chromatography followed by high-performance liquid chromatography (HPLC) techniques. The active fraction was characterized by spectroscopy techniques. The minimum inhibitory concentration of antibiotic was determined against pathogens. Results: A new halophilic actinomycetes strain rsk4 was isolated from marine water. It was designated as Kocuria sp. based on the physiological, biochemical and 16S rDNA sequence-based characters. It was able to produce broad-spectrum antibacterial compound and exhibited significant inhibitory activities against antibiotic-resistant S. aureus. The antibacterial compound was secreted optimally at 5% NaCl and neutral pH in the starch casein medium during stationary phase. The crude ethyl acetate extract was separated by chloroform-methanol, 24:1, v/v having Rf value 0.45. Bioassay of HPLC fractions confirms the presence of antibiotics picks at retention time: 3.24 minutes. The UV-Visible and mass spectra of the compound revealed that the active compound was different from other known antibiotics. The lowest minimum inhibitory concentration was recorded against S. aureus (30 µg/mL). Conclusion: The result suggests that a broad-spectrum antibacterial compound obtained from halophilic actinomycetes is effective against pathogenic bacteria. This compound may be a good alternative treatment against antibiotic-resistant pathogen S. aureus.

Antagonistic Properties of Some Halophilic Thermoactinomycetes Isolated from Superficial Sediment of a Solar Saltern and Production of Cyclic Antimicrobial Peptides by the Novel Isolate Paludifilum halophilum

This study has focused on the isolation of twenty-three halophilic actinomycetes from two ponds of different salinity and the evaluation of their ability to exert an antimicrobial activity against both their competitors and several other pathogens. From the 23 isolates, 18 strains showed antagonistic activity, while 19 showed activities against one or more of the seven pathogen strains tested. Six strains exhibited consistent antibacterial activity against Gram-negative and Gram-positive pathogens characterized at the physiological and molecular levels. These strains shared only 94-95% 16S rRNA sequence identity with the closely related species of the Thermoactinomycetaceae family. Among them, the potent strain SMBg3 was further characterized and assigned to a new genus in the family for which the name Paludifilum halophilum (DSM 102817T) is proposed. Sequential extraction of the antimicrobial compounds with ethyl acetate revealed that the crude extract from SMBg3 strain had inhibitory effect on the growth of the plant pathogen Agrobacterium tumefaciens and the human pathogens Staphylococcus aureus, Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa. Based on the HRESI-MS spectral data, the cyclic lipopeptide Gramicidin S and four cyclic dipeptides (CDPs) named cyclo(L-4-OH-Pro-L-Leu), cyclo(L-Tyr-L-Pro), cyclo(L-Phe-L-Pro), and cyclo(L-Leu-L-Pro) were detected in the fermentation broth of Paludifilum halophilum. To our knowledge, this is the first report on the isolation of these compounds from members of the Thermoactinomycetaceae family.

Isolation, Taxonomy, and Antagonistic Properties of Halophilic Actinomycetes in Saharan Soils of Algeria

ABSTRACTThe diversity of a population of 52 halophilic actinomycetes was evaluated by a polyphasic approach, which showed the presence of members of theActinopolyspora,Nocardiopsis,Saccharomonospora,Streptomonospora, andSaccharopolysporagenera. One strain was considered to be a new member of the last genus, and several other strains seemed to be new species. Furthermore, 50% of strains were active against a broad range of indicators and contained genes encoding polyketide synthetases and nonribosomal peptide synthetases.