Development of the first gene expression system for Salinicoccus strains with potential application in bioremediation of hypersaline wastewaters.

Salinicoccussalsiraiae IM408 (=CGMCC13032) is a novel halophilicbacterium that we isolated from the saline soil of Da Gang Oilfield. It tolerates 60 g/l sodium chloride and up to 123 g/l (1.5 M) sodium acetateand has shown a potential application in bioremediation of wastewater with high salt and high chemical oxygen demand (COD). Two plasmids, pS408-1 and pS408-2, were identified in S. salsiraiae IM408, and the sequences and copy numbers of the plasmids were determined. Based on these plasmids, two shuttle vectorscontaining a repliconfor Escherichia coli, ampicillin, and chloramphenicol resistance genes, as well as the repliconfrom pS408-1 or pS408-2, were constructed and named as pTCS101 and pTCS201, respectively. A suitable host strain, named S. salsiraiae PE01, was also developed from the wild-type by plasmid elimination. Using the plasmid pTCS101 as an expression vector, l-lactate dehydrogenase from Staphylococcus aureus was expressed successfully in S. salsiraiae PE01. This is the first gene expression system for the Salinicoccusgenus. It has provided the potential for expression of desired proteins or for establishment of desired pathways in Salinicoccusstrains, which would make these halophilesmore advantageous in future biotechnological applications.