IMPACT OF CONDITIONS OF CULTIVATION AND ADSORPTION ON ANTIMICROBIAL ACTIVITY OF MARINE-BACTERIA

The potency of free-living and animal-associated marine bacteria to pr oduce antimicrobial substances has been studied in 491 strains isolate d from northern and southern parts of the Pacific Ocean. A total of 26 % (126 out of 491) of the strains examined produced antimicrobial comp ounds against 11 test bacterial strains (TBS) including the fish patho gens Aeromonas hydrophila and Vibrio anquillarum. Antimicrobial substa nces (AS) produced by marine bacteria were especially active against S taphylococcus epidermidis, Proteus vulgaris, Enterococcus faecalis, an d Candida albicans. Twelve strains, isolated from different sources, w ere chosen as promising candidates, producing a number of AS. Producti on of AS varied within 24 to 72 h, increasing in a culture medium base d on natural sea water with Br-ions, and after attachment to polymeric surfaces. In order to study the influence of adsorption, selected str ains with a high potential for antimicrobial production were cultivate d on polymeric surfaces with different hydrophobicities and chemical f unctionalities. These parameters of the surface hydrophobicity (measur ed by means of water contact angles) and chemical functionality of the surfaces were manipulated using the photo-and thermochemistry of a po lymeric system (diazo-naphto-quinone/novolak) commonly used as a photo resistant material in semi-conducto-manufacturing. The highest antimic robial activities occurred on hydrophilic surfaces (standard exposed p hotoresistant films), whereas the number of attached cells was greater on hydrophobic surfaces, characterized as unexposed resistant films. These results suggest that the chemical nature of induced hydrophilici ty may also be a major factor in controlling antimicrobial activity of adsorbed bacteria.