Background: The aim of this study was to discover new natural products from novel actinomycetes isolated from unexplored Urmia Hypersaline Lake.Methods: Marine samples were collected from different points in the coastal of Urmia lake and totally 20 actinomycetes were isolated using different isolation media. All the isolates were characterized and identified by microscopical and macroscopical observations. Sequencing and analysis of 16S rDNA from chosen isolates was performed.Results: Identification of the isolates revealed that all isolates belong to the genus Streptomyces sp. The isolated marine actinomycetes were screened for their antimicrobial activity against the human bacterial pathogens Salmonella typhi, Escherichia coli, Bacillus cereus, Staphylococcus aureus and Klebsiella pneumonia. Among 20 isolates, 8 showed antibacterial activity. The marine isolate Streptomyces sp. CS1 was found to be more efficient in the production of secondary metabolites.Conclusion: In conclusion, escalating reports on discovery of diverse natural compounds from halophilic and halotolerant actinomycetes, which inhabit in Urmia Lake, suggested that this physiological group has enormous capacity to produce array of secondary metabolites with disparate activities.

Aims Microorganisms are present not only in common environment, but also in extreme environments. Salt lakes with near or at saturating salinity are spread all over the world. Urmia Salt Lake is one of these Hypersaline environments. The present study aimed at evaluating prokaryotic diversity in Hypersaline environment by culture-independent method. Materials & Methods In this experimental study, different regions of Urmia Lake were sampled and the genomic material extracted from the water sample was used as a pattern for the amplification of 16S rDNA and a fragment of the bop gene via polymerase chain reaction. By cloning, each of the amplified fragments belonging to a single strain was amplified by T/A cloning vector. To further investigate the biodiversity of Haloarchaea, the biodiversity of bop gene was studied in addition to studying 16S rDNA. Findings By cloning and sequencing, 6 bacteria genera, including Acaryochloris, Adhaeribacter, Brachybacterium, Gloeocapsopsis, Cesiribacter, and Bacillus were identified. Archaeal library belonged to 5 genera, including Halonotius, Halolamina, Haloquadratum, Halomicroarcula, and Halorhabdus. The clone libraries of bacterial belonged to 4 phyla, including Bacteroidetes, Cyanobacteria, Actinobacteria, and Firmicutes. . The clone libraries of bop gene (as a molecular marker) belonged to genera, including Halorubrum, Natrialba, Haloquadratum, and Natrinema. The bop phylogeny was closely related to the 16S rDNA phylogeny. Conclusion By cloning and sequencing, 6 bacteria genera, including Acaryochloris, Adhaeribacter, Brachybacterium, Gloeocapsopsis, Cesiribacter, and Bacillus were identified. The bop phylogeny is closely related to the 16S rDNA phylogeny.

Laccases, copper-containing polyphenol oxidases, have numerous biotechnological and industrial applications, especially in industries that require high salt concentrations such as pulp and paper industries, tanneries, and textile industries. In the current study, solid and liquid bacterial culture media containing CuSO4 (3 mM) and guaiacol (0.01% w/v) were used to isolate laccase-producing bacteria from the shore sediments of Hypersaline Lake Urmia. Bacteria producing reddish-brown colonies on the culture medium containing guaiacol were considered as laccase-producing strains. Intracellular and extracellular laccase activities were measured spectrophotometrically at 420 nm using ABTS (2,2-azino-di-[3-ethylbenzo-thiazolin-sulphonate]) as a substrate. In this study, four bacterial strains were isolated from the shore sediments of Lake Urmia using a culture medium containing guaiacol, of which only one strain was detected with significant extracellular laccase activity. Microscopic investigation and 16S rRNA gene sequence analysis showed that this strain is a rod-shaped Gram-positive bacterium belonging to the genus Brevibacterium and was named Brevibacterium sp. strain LUBr01. The 16S rRNA sequence of LUBr01 strain is available on the GenBank nucleotide database under the accession number MN588176.1. Due to the proper laccase activity, LUBr01 can be useful for industrial process related to laccase. Also, saline Lake Urmia can act as a source of microorganisms with the ability to produce special enzymes such as laccase that can be used in salinity conditions.