Characterization of halophilic microbial community from a Sardinian hypersaline environment

RUGGERI, CLAUDIO;Durante L;Livretti F;La Colla P;TAMBURINI, ELENA

2011-01-01

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Abstract

The Molentargius Regional Nature Park is one of the largest wetlands in South Sardinia (Italy). It is important for the maintenance of the floral and faunal biodiversity and for the breeding of numerous endangered species of birds, such as flamingos. This Park, included in 1976 in the Ramsar list of wetlands of international importance, also comprises sites known as Saline, solar salterns whose salt exploitation activities ended in 1984. The nearness of the towns of Cagliari and Quartu leads to excessive anthropization of the Molentargius area that may affect the site's ecology. The Saline consists of a multi-pond system with different NaCl concentrations, ranging from seawater to saturation amounts. These hypersaline environments are inhabited by halophilic microorganisms, archaea and bacteria, which have evolved specialized mechanisms of osmoregulation in order to tolerate such extreme conditions. The study of the halophilic microbial communities in Saline is important to understand the ecology of such extreme environments and can give information useful for the management of these areas. Moreover, microbial communities are important factors known to influence the crystal salt quality during salt exploitation, although the mechanism of this process is not jet fully understood. To our knowledge, the present study constitutes the first analysis centred on halophilic microbial communities inhabiting the Molentargius solar salterns. Water samples were collected in the 2010 summer. Salinity, temperature, pH, oxygen concentration and oxygen percentage of saturation were measured in situ. A combination of culture-dependent and -independent approaches was employed to characterize the microbial community. Different isolation procedures, cultural media and carbon sources were used. The phylogenetic diversity of the isolates was evaluated by ARDRA and 16S rRNA gene sequence analysis, whereas the microbial community structure was analysed by Terminal Restriction Fragment Length Polymorphism technique