Evaluation de la pollution bactériologique des eaux marines portuaires de Beja?a et étude de l'halotolérance bactérienne et de l'apport en osmoprotecteurs

Abstract

In spite of bactericidal effect of marine environment, the numerations, by MPN and/or membrane filtration, of total and faecal coliforms, fecal streptococci and Pseudomonas ( fluorescens group) show their abundance in coastal waters of Bejaïa city attesting their pollution. The halotolerance appreciation of marine bacterial populations, on mineral medium M 63 with increasing salt concentrations (NaCl ; 0 to 1,2 M) indicates a feeble haloadaptation. Exogenous glycine betaine, a powerful osmoprotectant, or culturing on rich medium (Trypticasc-Soy Broth) improve significantly the cells resistance to salt stress. The adding of natural extracts of algae or marine sediments permits also a remarkable osmoprotection. Furthermore. E. coli P2C50 remains at higher densities in supplementing seawater by either Ulva lacluca thalli or sediments than in control. That is probably the consequence of organic matter present in algae and sediments witch constitute not only a nutrient sources for E. coli but also an appreciable sources of osmoprotection.