Studio dei sistemi di captazione del ferro in germi del genere Vibrio.

Vibrio genus includes bacterial species pathological both for different acquatic organisms and for man, and considering their wide diffusion in acquatic environment, the study of such germs concerns the interactions between them and environment, considered as abiotic elements, i.e. water, and as biotic resources like natural or breeding species, as well as man. The results of interactions germs-environment can be identified in the result of competition for micro- and macro-nourishments, in wich iron element becomes very important. The present research deals with the characterization of isolated Vibrio genus starting from Adriatic sea fish samples, and successive evidence of their iron trasmission systems. 64 bacterial strains have been isolated from seventy fish products samples including cods, mullets, soles, prawns, crabs and clams. The isolated ones have been characterized in a biochemistry way; then 22 have been considered bacteriums belonging to Vibrio genus (n°3 V. cholerae, n°9 V. alginolyticus and n°10 V. parahaemolyticus). These have been tested according to the resistence to an antibiotics range and to the haemolytic power by Kanagawa test made on Wagatsuma agar. Moreover on the examinated bacteriums have been valued the ability to produce siderophores, compounds with low molecular weight, able to bind iron and to represent growth, germination or virulence factors. The production of siderophores has been noticed by bacteriums growth on CAS agar, continuing then in their qualitative valuation by spectrophotometry assay. Moreover, the study of induction of Iron-Regulated Outer Membrane Proteins has been carried out; three different bacterial strains, belonging Vibrio genus, have been cultivated in iron-deficient and iron-enrichment conditions, through M9 Minimal Medium (MM9) with addition of EDDA and ferric chloride, respectively. The outer membrane proteins extracted have been separated in SDS-PAGE and strains grown in iron-deficient media have showed the induction of proteins of 78 kDa for V. alginolyticus and V. parahaemolyticus,77 kDa for V. cholerae. This research represents, relatively to Vibrio genus, a possible starting point in the approach of themes concerning the behaviour of microbic population and the pathogenesis of infections that could negatively affect fish productions and man’s health for fish consumption and for acquarium fish possible zoonosis risks. [...]