Abstract

North of Tunisia consists of numerous ecosystems including extreme hypersaline environments in which the microbial diversity has been poorly studied. The Sehline Sebkha is an important source of salt for food. Due to its economical importance with regards to its salt value, a microbial survey has been conducted. The purpose of this research was to examine the phenotypic features as well as the physiological and biochemical characteristics of the microbial diversity of this extreme ecosystem, with the aim of screening for metabolites of industrial interest. Four samples were obtained from 4 saline sites for physico-chemical and microbiological analyses. All samples studied were hypersaline (NaCl concentration ranging from 150 to 260 g/L). A specific halophilic microbial community was recovered from each site and initial characterization of isolated microorganisms was performed by using both phenotypic and phylogenetic approaches. The 16S rRNA genes from 77 bacterial strains and two archaeal strains were isolated and phylogenetically analyzed and belonged to two phyla Firmicutes and gamma-proteobacteria of the domain Bacteria. The results show that the Sehline Lake harbored novel prokaryotic diversity, never reported before for solar salterns. In addition, diversity measurement indicated an increase of bacterial diversity with rising salinity gradient, which is probably due to competition between bacteria and others species.

Key words: Sebkha, bacteria, extremophiles, biodiversity, screening.