ANTARCTIC PENINSULA ENVIRONS AS A SOURCE FOR NEW ANTIMICROBIALS

DANILOVICH, MARIANA; SANCHEZ, LEANDRO; ACOSTA, FEDERICO; ARNAU,GONZALO; DELGADO, OSVALDO

Congreso; XI CONGRESO ARGENTINO DE MICROBIOLOGIA GENERAL; 2015

Antarctica is the biggest pristine area on Earth and represents one of the most valuable environmentsdue to its microbial diversity. It is indispensable to emphasize the study of pristine naturalextreme-ecosystems since numerous biologically active compounds including antibiotics, pesticides,hormones, growth factors, antioxidants, biosurfactants and enzymes have been isolated frommicroorganisms belonging to them. In the medicinal area, research and development of novelcompounds with antimicrobial activities has become in a priority due to the increased drug resistancein common bacterial pathogens along with the emergence of new pathogenicity. To deal with thissituation, a value-increasing strategy is on the spotlight: Bioprospecting. This process tends to directsearch for metabolites with biotechnological importance from microbial isolates in naturalenvironments with specific characteristics.Based on this premise, thirteen cold-adapted isolates from soil and water samples surroundingAntarctic Peninsula were studied for enzyme and antimicrobial production. The ability to producebiosurfactants was also tested.The enzymatic activities most frequently found among the isolates were as follow: lipase (46%),cellulase (23%), amylase (7%) and gelatinase (13%). Biosurfactant production was detected in 46% ofthe isolates. Three isolates were able to inhibit the growth of common food-borne pathogen bacteriaand also some phytopatogens. The isolates 2D, 5D and 6D were closely related to Halomonastitanicae (99.8, 98.9, 96.7% respectively) by 16S rRNA gene sequencing. The profile of sugar wasstudied by the API 50 CHB system and other physiological characteristics by API 20NE systems andAPI 50CH. Growth rate at different temperatures, pHs and NaCl tolerance were determined. Thesignificant influence of culture media and incubation temperature on antimicrobial production wereevaluated, being LB-SW medium and 25°C the optimal conditions for antimicrobial production.Besides to marked tolerance to enzymatic treatment and negative net charge at pH 8.0 duringelectrophoresis, the antimicrobial compounds showed wide inhibition spectrum against both,G-positive and G-negative pathogenic and phyto-pathogenic bacteria. The antagonist compoundswere produced during stationary phase of growth and concentrated from cell-free supernatant by usingSPE-C18 cartridges. The significance of this work lies in valuing pristine environments because oftheir importance as new sources of bioactive compounds and their possible role in agricultural orpharmaceutical biotechnological industries