BACTERIA FROM MARINE SALTERNS AS A MODEL OF MICROORGANISMS ADAPTED TO HIGH ENVIRONMENTAL VARIATIONS

摘要

Salterns represent peculiar environments showing wide gradient of salinity and high variation of other chemicophysical parameters. Being submitted to sudden and repeated fluctuations of temperature and water availability, they could be taken as a prototypical example of global changes. Here, organisms must cope with huge environmental stress. Prokaryotic communities are predominant at highest salinity representing a valid model to study these environments and possible adaptation strategies. To get a complete picture of total microbial diversity, cultural and culture-independent methods must be integrated. In this study, the microbial communities of various ponds within the 'Saline di Tarquinia' saltern, Italy has been studied by cultural and cultural-independent methods (PCR-DGGE). Average bacterial counts ranged from 0.2 to 2.5×10~5 cells/ml. Twelve bacterial strains were isolated in pure culture. The majority (67%) belonged to the y-proteobacteria class. Species affiliated to Bacilli and Actinobacteria were found also. PCR-DGGE fingerprinting showed a more complex situation. In fact, at least 32 bands, theoretically corresponding to single species, were detected. Re-amplification of predominant bands led to define a composite community mostly constituted by marine and halophilic species. This study represents the first detailed investigation on the bacterial community of Saline di Tarquinia.