Cloning of Salinity Tolerant Gene from a Soil-Borne Bacterium and its Characterization

A salt tolerant gene was isolated and characterized from a highly salt tolerant soil - borne bacterium, Bacillus coagulans. The genomic library was prepared in ZAP expression vector. The amplified library had inserts ranging from 0.5 – 3.8 kb. The library was screened for isolation of salt tolerant recombinant clones by functional assay using LB agar containing 4% NaCl. Salt tolerant recombinant clone was able to grow much faster than the wild strain on LB agar plates containing 4% NaCl. Size of the gene responsible for salt tolerance was 3.8 kb and had restriction sites for a number of restriction enzymes like HindIII, SmaI, PstI, ClaI, SacI and SpeI. The restriction map of the gene was developed through single and double digestion with the restriction enzymes. The sequence of the insert revealed ORF of 393 amino acids and using BLASTP nr-na database, the insert was identified as ornithine amino transferase, which is known to play an important role in biosynthesis of proline – an important osmolyte involved in salt tolerance of many species of bacteria and plants.