Cold-adapted microorganisms as producers of cold-active bacteriocins.

DELGADO O D; GOMEZ F; SIÑERIZ F

EEUU

Congreso; IUMS 2005; 2005

International Union of Microbiologyical Societies

Background: The production of bacteriocins is widely recognized and is important for their potential use as preservatives in food, cosmetics and pharmaceuticals industries. Cold environments could be a suitable source of microorganisms with ability to produce cold-active antimicrobials with potential use in chilled-food preservation. Methods: Soil samples were aseptically collected from the Staten Island Reservation in the South Atlantic Ocean and were kindly provided to us by Dr. JL Esteves. Samples were inoculated into LB and incubated at 4 and 20°C. Samples were then streaked out on M9 and incubated at the same temperature. Master plates were made by picking up different morphotype colonies. Inhibitor production was determined using the deferred antagonism procedure of Kekessy & Piguet. ITS and ARDRA analysis were performed for grouping the similar isolates. Bacterial characterization included Gram staining, morphology, catalase and oxidase, 16S rDNA partial sequencing was also performed. Trypsin, proteinase K, pronase E, catalase, peroxidase, lipase and α-amylase were used to determine antimicrobial nature. Results: Almost 8000 CFU were recovered and picked out. The number of viable bacteria isolated after incubation at 4 °C were lower (20%) than at 18°C (80%). Almost 30 were antimicrobial producers. ITS and ARDRA patterns led to group the isolates into 8 OTUs. 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 and being active against E. coli, P. aeruginosa,S. typhimurium, S. newport and S. entiritidis. Some of them inhibited S. flexnerii, S. aureus, S. epidermidis or M. luteus. Conclusions: Cold-active isolates from Staten Island soils were predominantly psychrotolerant, a common finding in permanently cold environments. The detection rate for antimicrobial production was 0.3%, comparable to reported rates. In nature, antibiotics and other secondary metabolites serve multiple survival-related functions and may play a primary role in population dynamics. Inhibitor producers are therefore qualified to avoid competition by close related species with similar environmental requirements.