Generation and characterization of reduced PSII antenna size mutants of Chlorella sorokiniana for improved Biomass

Abstract

Abstract Biofuel production from algal biomass is the fundamental component in developing a sustainable energy source that can replace fossil fuels. However, cost effectiveness need to duly taken into account as there is substantial difference between the higher cost of biofuel production and relatively low cost of fossil fuels. Studies on Chlorella species attract sufficient attention to improve algal biomass production capacity. One of the critical problems is inefficient use of light caused by its unequal distribution. The current study describes the development of photosynthetic Chlorella sorokiniana mutants by EMS mutagenesis. Mutagenesis and visual phenotypic selection procedures were applied and three C. sorokiniana chlorophyll mutants (CSCM) have been identified. The selected CSCM8, CSCM10 and CSCM21 mutant strains show diverse phenotypes with 33–47% reduced chlorophyll content. Further characterization reveal that these selected mutants had 23–44% reduced antenna size, improved effective quantum yield of PSII [Y(II)], reduced regulated (light-activated) energy dissipation Y(NPQ), and reduced non-photochemical quenching (NPQ). Moreover, the characterised mutants in artificial condition showed 19–34% increase biomass productivity. The study indicates that genetic modification of C. sorokiniana with smaller antenna size can improve the biomass content; further, these mutants can be used for strain improvement having higher lipid content.