Title : NADPH oxidase mutants show significant triacylglycerol accumulation without retardation of growth ability and cell damage under nitrogen starvation stress: new insights into a new target in lipid productivity improvement for biofuel industrialization
Chlamydomonas reinhardtii is a model microalga for the study of fatt aacid biosynthesis and carbon allocation towards lipid accumulation in the form of triacylglycerol as lipid body after nitrogen starvation. Several studies have reveal the metabolic manipulation in the partition of membrane lipid to TAG accumulation such as the involvement of autophagy and reactive oxygen species. However, the growth of C. reinhardtii are inhibited and in turn, a decline in lipid production although lipid content per cell appears a significant increase t around 65-10% dry weight. Recently, the research on the maintenance of growth ability under nitrogen starvation shows a progress. The present study demonstrates that the mutation in respiratory burst oxidase (RBO) gene expression keeps the Chlamydomonas cells a 2-fold biomass production and high TAG accumulation ability by nitrogen shortage challenge. We propose that NADPH oxidase-mediated signalling pathway is associated with the Chlamydomonas growth and the inhibition of TAG formation. Further studies on the negative factors downstream NADPH oxidase for the blockage of fatty acid biosynthesis and TAG formation are necessary.