Effet du Benzo [a] pyrene sur la croissance et la production du bacterioplancton provenant du canal et la lagune de Bizerte

Abstract

This study aims to determine the effect of Benzo[a]pyrene, an organic contaminant from the family of HAP on bacterioplankton in the lagoon (area slightly polluted by the B[a]py) and the channel (area heavily polluted by the B[a]py) of Bizerta in summer (July) and autumn (November) 2009. Planktonic bacterial communities collected from both stations were maintained in culture for 6 days under three different treatments, control (uncontaminated) and two contaminations with 0.5 mg l super(-1) (B[a]py1) and 1 mg l super(-1) (B[a]py2) of B(a)py. During incubations, the abundance of bacteria and their production and growth rates were determined. In July, the bacterioplankton exhibited higher density in the channel (5 10 super(8) cells l super(-1)) than in the lagoon (3 10 super(9) cells l super(-1)), whereas bacterial abundances were similar between both stations during November (10 10 super(-1)cells super(-1)), but exceeded those of summer. During the incubations bacteria seemed to degrade the B[a]py and used this contaminant as growth substrate during both seasons and in both stations. The contaminations, performed in both stations during the two months, were followed by significant increases in abundance, growth and production of bacteria. These results suggest that B[a]py has a stimulatory effect on heterotrophic bacteria in the canal and the lagoon of Bizerte