Microalgae with a truncated light-harvesting antenna to maximize photosynthetic efficiency and biomass productivity: Recent advances and current challenges

•A direct correlation exists between photosynthesis and microalgae biomass.•Wavelength and duration of light significantly influence algal growth.•Algae with small antenna size have high photosynthetic efficiency.•Productivity in a closed reactor, as well as an open pond system, is not uniform. Microalgae and the associated biomass have been advocated for various eco-friendly applications. Although, microalgae are a good source of biofuels, metabolites, and value-added products, their commercial cultivation suffers from limited biomass yield due to inefficient photosynthetic efficiency. Minimizing the light-harvesting antenna size of the photosystems has been recognized as an effective mechanism to enhance photosynthetic efficiency and overall biomass productivity in microalgal cultures. Several strategies including mutagenesis, through UV radiations and chemical mutagenesis, genetic engineering, and DNA insertional mutagenesis have been employed to obtain mutant strains possessing a regulated antenna with a regulated limited number of light-harvesting molecules. However, there are still a number of challenges associated with antenna mutants that need to be addressed. This review highlights the recent developments in truncated antenna mutants of microalgae, aiming to increase the photosynthetic efficiency and biomass productivity of the respective cultures.