Isolation and Molecular Characterization of Cold Adapted Microorganisms Producing Cold Active Biomolecules

SANCHEZ L. A,; DELGADO O.D.

Orlando, Florida

Congreso; 106th General Meeting of the American Society for Microbiology (ASM); 2006

American Society for Microbiology ASM

Background: Antimicrobial peptides are molecules widespread in life forms to mediate competition, and their industrial production could be important for the potential use as preservatives in food, cosmetical and pharmaceutical industries. Cold environments could be a suitable source of microorganisms with ability to produce cold-active antimicrobials with potential use in chilled-food preservation as the bacteriocins.Methods: Soil samples were collected from Staten Island Reservation, South Atlantic Ocean. Samples were inoculated into LB and incubated at 4 and 20°C and then streaked out on the same medium and incubated at 4°C Master plates were made considering different morphotype colonies. Production of an inhibitor was determined by the agar overlaid method. The size of antimicrobial compounds was estimated from growth onto cellophane film laid on agar plate surfaces. Bacterial characterization included Gram staining, morphology, sugar fermentation, catalase, oxidase, 16S rDNA and gyrB gene sequencing. Plasmid extraction was also performed. Thermostability, resistance to some proteases, catalase, peroxidase, lipase and α-amylase were used to determine antimicrobial nature.Results: Almost 8000 CFU were recovered. The percentage of viable bacteria isolated after incubation at 4 °C was lower (20%) than at 18°C (80%). Almost 30 were antimicrobial producers. One microorganism of each group was selected based on their size of inhibition zone, all displaying a psychrotolerant behavior. The proteinaceous nature of the antimicrobials was determined by enzymatic treatment. The antimicrobials are active against E. coli, P. aeruginosa, S. typhimurium, S. newport and S. enteritidis, L. monocytogenes, B. subtilis, S. sonnei, S. flexneri, S. aureus, S. epidermidis or M. luteus. Conclusions: The isolates were predominantly psychrotolerant. Antimicrobials isolated from subAntartic waters are active against Gram (+) and Gram (-) bacteria.