Optimization of microalgae cuture media for transformed Chlorella vulgaris PKVL7422

Abstract

expression system is being used instead of bacterial system for the production of recombinant proteins. However, mass culturing techniques for transformed microalgae such as Chlorella vulgaris have rarely developed. Hence, in this study we aimed to increase the growth of transformed Chlorella vulgaris (PKVL7422) whose nitrate reductase gene was knocked out, by using NH4 instead of NO3 and other modifications of BG11 media. Growth of the transformed microalgae in the modified medium named as BGPK was examined by culturing in BG11 based medium containing one of the following chemicals: K2HPO4 (0.17mM, 1.7mM 5mM, 10mM, 15mM, 20mM, 25mM, 30mM), glucose (0%, 0.1%, 0.3%, 0.5%, 1.0%, 2.0%, 3.0%), (NH4)2HPO4, NH4Cl, (NH4)2SO4, and CH3CO2NH4 (17mM, 5mM, 10mM, 15mM, 20mM, 25mM, 30mM). Growth of C. vulgaris was measured using microplate reader at OD680nm. The results showed that in the presence of 20mM of (NH4)2HPO4 and 0.5% of glucose C. vulgaris growth rate increased up to 49.67% compare that of in BGNK growth rate, 13.67%. Our data indicates that BGPK is a better medium for Chlorella vulgaris PKVL7422 transformation system than BGNK and this study can be a model for developing an efficient medium for microalga recombinant expression system.