Fifty strains of moderately halophilic bacteria were isolated from various salty environments in Iran. A strain designated as SA-2 was shown to be the best producer of extracellular lipase and was selected for further studies. Biochemical and physiological characterization along with 16S rDNA sequence analysis placed SA-2 in the genus Salinivibrio. The optimum salt, pH, temperature and aeration for enzyme production were 0.1 M KCl, pH 8, 35 degrees C and 150 rpm, respectively. The enzyme production was synchronized bacterial growth and reached a maximum level during the early-stationary phase in the basal medium containing 1 M NaCl. Triacylglycerols enhanced lipase production, while carbohydrates had inhibitory effects on it. The maximum lipase activity was obtained at pH 7.5, 50 degrees C and CaCl(2) concentration of 0.01 M. The enzyme was stable at pH range of 7.5-8 and retained 90% of its activity at 80 degrees C for 30 min. Different concentrations of NaNO(3), Na(2)SO(4), KCl and NaCl had no affect on lipase stability for 3 h. These results suggest that the lipase secreted by Salinivibrio sp. strain SA-2 is industrially important from the perspective of its tolerance to a broad temperature range, its moderate thermoactivity and its high tolerance to a wide range of salt concentrations (0-3 M NaCl).

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Saline environments are largely unexplored sources for actinomycetes with the potential to produce biologically active secondary metabolites. A total of 34 actinomycete strains from water, sediments and mostly rhizosphere (82%) were collected from different sites of Howz Soltan Lake in Iran. Based on phylogenetic analysis, the isolated strains belonged to the genera Streptomyces, Nocardia and Saccharomonospora. Among the isolated actinomycetes, several strains had valuable biotechnological applications such as growth inhibition of human tumor cells. The results of cytotoxic assay revealed strain act9 having the most potent extract (19.716 ± 5.72 µg/ml) against the MDA-MB-231 human breast cancer cell. Also 38% of the strains had an antimicrobial activity against some pathogenic and nonpathogenic microorganisms. The ethyl-acetate extract of act18 showed the most antibacterial effect against Staphylococcus aureus, MRSA, and was further analyzed by GC/MS. Ar-tumerone (26.41%) and Butyl isodecyl phthalate (21.77%) were the main constituents detected in the extract.. This is the first time this compound is being detected in a prokaryote. Act18 showed the most 16s rRNA sequence similarity to Streptomyces youssoufiensis. In addition, a number of the isolates produced different enzymes including lipase, amylase, protease, gelatinase, urease and lecetinase. Also, the plant growth promoting activity of some actinomycete strains were shown. Some of the strains belonging to the genera Streptomyces and Nocardia increased the seed germination, stem length and the number of Echium leaves during the 20 days. Consequently, it was concluded that actinomycetes isolated from these saline lake habitats are potentially valuable for biotechnological applications.

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