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Lipase is one of the most important hydrolytic enzymes widely used in various commercial activities such as food, dairy, pharmaceutical and detergent inducteries. In this experiment, Taguchi method was attempted as a powerful method to optimize the factors affecting enzyme production and to investigate the interactions among these factors and their optimum combination in Salinivibrio sp. SA2. The optimum conditions for pH, temperature, shaker's rpm, olive oil concentration and salt type turned out to be 8, 35 °C, 100 rpm, 2% and sodium chloride 1 M, respectively. Significant factors influencing on the lipase production proved to be pH, agitation and Salt type. The maximum lipase activity in optimum condition and at the 5% significance level (p< 0.05) was 120.4 U/mg.

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Saline soils are widely spread in Iran. These intact soils are a great source for the isolation of new bacteria with highly functional metabolites in biotechnology. Actinomycete strains were isolated on starch casein agar and ISP2 with different concentrations of sodium chloride (0, 5 and 10%) from treated soil samples. Pure colonies were cultured on a casein glycerol medium. After complete growth, the plates were covered with a thin layer of Muller Hinton Agar (1%) containing methicillin-resistant Staphylococcus aureus (MRSA). Active metabolites of selected strains were extracted and their antibacterial activities analyzed by agar well diffusion method. 38% of isolates produced antibiotics against the pathogen. The metabolites produced by act-2 and act-5 isolates, which had a more effective inhibition zone against MRSA, were extracted and anti MRSA activity of act-5 extract was shown. The antimicrobial activity of act-5 against other bacteria was also investigated and the bacterium was identified. In this study halophilic actinomycetes producing bioactive compounds were isolated from the saline soils of Qom and the anti-MRSA potential of their metabolites was investigated for the first time. The results of this study show the potential of saline soil actinomycetes for the production of useful metabolites.


 

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Nowadays plant endophytic bacteria have found diverse and useful applications in biotechnology; therefore, much attention has been paid to the isolation, identification, and evaluation of these microorganisms. Since the sterilizing plant tissue surfaces from epiphytic bacteria is difficulty, the efficacy of three different screening methods for endophytic bacteria including 1- HClO sterilization, 2- Periodic sterilization (modified tyndallization) and 3- Triton X100 and HClO sterilization, was evaluated in this study. The modified Tyndallization is an innovative method used in this study to appropriately remove the internal spores of epiphytic bacteria, considered to be an obstacle to the isolation of endophytes. Most of the endophytic bacteria were isolated from dicotyledons and leaves. Endophytic bacteria were also studied for the production of different hydrolase enzymes, whereas the protease enzyme was produced in a wide range of endophytic bacteria in greater quantities than other enzymes. The EndoA strain was molecularly identified and found to be 100% similar to Bacillus halotolerans.

 

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Saline rhizospheric areas are untouched environments for isolating actinomycetes with the potential of valuable salt tolerant enzyme production. In this study, we isolated and evaluated a total number of of 26 actinomycete strains from plant rhizosphere of the periphery of Dasht-e-Kavir desert. Isolated actinomycetes produced different enzymes. Among them 50, 46, 39, 27, 10 and 7 % of the isolates produced amylase, lipase, protease, gelatinase, lecithinase and urease, respectively. The most frequently produced enzymes among the isolates were amylase, lipase and protease. Combined hydrolytic activity was also detected in some actinomycete strains. Among the isolates, strains Q1, Q4 and Q11 with the most diverse enzymes production, were identified and their 16s rRNA analysis showed that they are mostly similar to the Streptomyces scopiformis, Streptomyces argenteolus and Streptomyces manipurensis, respectively. Finally, due to the enzymatic diversity obtained and the valubility of the halophilic bacterial enzymes in industry, it seems that actinomycetes isolated from this saline habitat are potentially suitable for biotechnological applications.