Abstract: The invention involves mutant or recombinant Chlorophyte algal organisms that have a genetic modification in a gene encoding a chloroplastic signal recognition particle 43 (cpSRP43). In one embodiment the Chlorophyte organisms are Trebouxiophyte algae that are diploid or polyploid for a gene encoding a chloroplastic signal recognition particle 43 (cpSRP43). The mutant organisms can have a genetic modification in one allele of the gene but not in another allele of the gene. The mutant or algal organisms have higher biomass and lipid productivity. Additional mutant or algal organisms are disclosed that also have a genetic modification to one or more genes encoding a light harvesting chlorophyll a/b (binding) protein.