Controlled Turgidity; a simple and efficient method for transformation of Halobacterium salinarum R1.

Halobacterium salinarum as a model organism has been used for archeal genomics studies in many investigations. This well-known microorganism loves hyper saline habitat and transformation of DNA for genetic manipulation of the halophile by conventional methods eg. electroporation is impossible and current specific procedure is time consuming, sensitive and difficult. Therefore the development of easy and efficient methods for genetic manipulation especially transformation of this species are important. In this study we introduced a simple method for H. salinarum transformation with high efficiency. This method is based on the controlled short time swelling- deswelling of this halobacterium. Exposure of the halophile to hypo-osmotic shock was done by adding deionized water containing the desired plasmid to the cell suspension that decreased NaCl concentration to around 2.5 M. After 60 seconds the shock removed by the re-increasing salt concentration of suspension to 3.3M. During the osmotic shock plasmids from low concentrated fluid gets sucked in through the cell membrane. Transformation confirmed by PCR and colony count. In comparison with conventional PEG mediated method the frequency of 105 transformants/µg of DNA revealed that osmotic shock is an efficient transformation method in H. salinarum. Consequently this easy and fast transformation method could be used instead of other laborious methods in this microorganism and probably to transform other halophiles