The research presented in this memory was carried out at the Institut Pasteur in Côte d’Ivoire and carried out on E. coli and Salmonella spp. The objective of this study was to isolate E. coli and Salmonella spp. strains resistant to antibiotics from wastewater from the Port-Bouët slaughterhouse. From September 2017 to March 2018, 17 strains of E. coli and 7 Salmonella spp. were isolated in 63 samples of wastewater collected at the slaughterhouse of Port-Bouët. Their identification was performed according to conventional bacteriological tests. An antibiogram according to the disk diffusion method was carried out for 21 antibiotics commonly used in human and veterinary medicine. The prevalence observed was 26.98% for E coli strains. and 11.11% for Salmonella spp. All strains of E. coli showed complete (100%) resistance to 3rd generation cephalosporins, aztreonam, amocixillin + clavulanic acid, and ampicillin. However, family resistance rates of quinolones, aminoglycosides, sulfonamides and cyclins remain very high. The sensitivity of E. coli to imipenem and amikacin was 100%. Salmonella spp. strains, on the other hand, were resistant only to beta-lactam at lower levels compared to E. coli strains. coli. In-depth studies are needed to determine the resistance mechanisms of these bacteria.

Phytoplankton abundance in relation with physico-chemical parameters were investigated at 11 stations monthly from May 2014 to april 2015 in Aghien lagoon. Distribution of phytoplankton abundance had homogeny within the entire lagoon. However it notices differences between seasons. The high abundance was recorded in the low rainy season (2.3 107 cells/mL) and the low one in the high dry season (1.1 107 cells/mL).The seasonality is confirmed by Indicator value and RDA. Three groups were determined according seasons. The high rainy season assemblage was influence by conductivity and high temperature. Ammonium, BOD, dissolved oxygen and pH influence species of low dry season. Concerning the group 3 (high dry season and low rainy season), abundance of species is associated to high value of turbidity and nitrate. Indeed, the phytoplankton community of Aghien lagoon is still dominated by Cyanobacteria such as Microcystis wesenbergii (Komarek.) Komarek., M. aeruginosa (Kützing) Nägeli., Microcystis sp., Aphanocapsa incerta (Lemm.) Cronb. & Kom. and Anabaena circinalis Rabenh.ex Born. & Flash. These species are responsible for different blooms recorded in the Aghien lagoon. It also important to identified the kind of toxins these bloom-forming cyanobactorial produce in this lagoon.