Antibacterial activity of Lake Urmia derived-Halomonas.

Isolation of new microbial species from extreme environments is one of the most efficient approaches for the development of novel bioactive metabolites. The aim of the present study was to explore the pharmaceutical bacterial resources from the water and sediments of hypersaline Lake Urmia. Using different culture conditions and media led to the isolation of 20 bacterial strains. Halophilic bacteria were screened for the production of antibacterial agent against multi-drug resistant strains of Escherichia coli through agar well diffusion assay. Halophilic bacteria DNA extraction was done by boiling method. The results showed that two Halomonas strains, LUH16 and LUH20 identified by analysis of 16S rRNA gene sequences were the potent producers of antimicrobial metabolites against various strains of E. coli. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of eight secondary metabolites with the relevant antimicrobial properties. Our findings led us to focus on Halomonas strains as potent producers of antimicrobial compound that might be an alternative against antibiotic-resistant pathogens such as pathogenic Escherichia coli.

Isolation and screening of lipolytic fungi from coastal waters of the southern caspian sea (north of iran).

BACKGROUND: Lipases (acylglycerol acylhydrolase, E. C. 3. 1. 1. 3) are widely distributed among microorganisms, animals and plants, catalyzing the hydrolysis of triglycerides to free fatty acids and glycerol. Their commercial application includes pharmaceutical, chemical, and paper industries. OBJECTIVES: This study aimed to isolate and screen lipolytic fungi from coastal waters of the southern Caspian Sea by Internal Transcribed Spacer-Polymerase Chain Reaction (ITS-PCR), and to optimize their lipolytic activity, pH and temperature. The ITS regions possess a high variation among taxonomically distinct fungal species and even within species. MATERIALS AND METHODS: All fungal were tested to determine their lipolytic activity by the Tributyrin agar plate assay. After DNA extraction, lipase-producing fungi were identified via ITS-PCR of rDNA region with ITS1 and ITS4 primers. RESULTS: Four fungal species were isolated from water samples of the Caspian Sea (north of Iran) between February and June 2011. The nucleotide sequences reported for three of these isolates have been assigned accession numbers from NCBI Gene Bank database. Among these species, Cladosporium langeronii showed maximum lipolytic activity (34 U/mL) and maximum clear zone formation (6 mm) on the Tributyrin agar plates. The optimum pH and temperature for activity were 8.0 and 35°C, respectively. CONCLUSIONS: The findings of this study indicated that these isolates were plant pathogenic fungi, which entered seawater from the environment, and were likely to have a suitable lipase activity on plant oils.