Overexpression of hlyB and mdh genes confers halotolerance in Fremyella diplosiphon, a freshwater cyanobacterium

Publication date: Available online 24 April 2017 Source:Enzyme and Microbial Technology Author(s): Behnam Tabatabai, AnithaChristy S. Arumanayagam, Oluwatomisin Enitan, Arunmani Mani, Savithiry S. Natarajan, Viji Sitther Fremyella diplosiphon is a freshwater cyanobacterium that has great potential as a biofuel agent due to its ability to grow in low light intensity and acclimation to different wavelengths. To enhance its halotolerance for growth in 35gL−1 sodium chloride (NaCl), plasmids harboring hemolysin B (hlyB) and malate dehydrogenase (mdh) genes were transformed into wild type F. diplosiphon (WT-Fd33). Electroporation-mediated overexpression of the genes resulted in two transformants, HSF33-1 and HSF33-2, with 9- and 20-fold increases in hlyB and mdh transcript levels. In addition, up-regulation of proteins at the expected size ranges of 50–60kDa for HlyB and 40–50kDa for MDH was observed. Two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry revealed a protein spot corresponding to HlyB in HSF33-1 with a significant MOWSE score of 164 and 3% sequence coverage, and a spot corresponding to MDH in HSF33-2 gave a significant MOWSE score of 124 with 10% sequence coverage. Physiological evaluation in BG11/HEPES medium and seawater adjusted to 35gL−1 NaCl confirmed that the transformants could thrive in high salinity with no loss of photosynthetic pigments. Results of...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research