Enhanced accumulation of glycogen, lipids and polyhydroxybutyrate under optimal nutrients and light intensities in the cyanobacterium Synechocystis sp. PCC 6803.

摘要

Aims: Glycogen (GL) and lipids (LP) are efficient biofuel substrates, whereas polyhydroxybutyrate (PHB) is a potent biodegradable plastic. This study aimed to increase accumulation of these three compounds in Synechocystis sp. PCC 6803. Methods and Results: Under autophototrophic growth, co-accumulation of the three compounds reached maximum level in a mid-stationary phase at 39.2% of dry weight (22.7% GL, 14.1% LP and 2.4% PHB). Nitrogen deprivation increased this to 61.5% (36.8% GL, 11.2% LP and 13.5% PHB), higher than that achieved by phosphorus, sulfur, iron or calcium deprivation. Combining nitrogen deprivation with 0.4% (w/v) glucose addition for heterophototrophic growth and optimizing the light intensity (200 micro mol photons m-2 s-1) synergistically enhanced combined accumulation to 71.1% of biomass (41.3% GL, 16.7% LP and 13.1% PHB), a higher level than previously reported in Synechocystis. However, the maximum coproductivity of GL, LP and PHB (at 0.72 g l-1) was obtained in the 12-day heterophototrophic culture without nitrogen deprivation. Conclusion: Accumulation of GL, LP and PHB was enhanced under both autophototrophic and heterophototrophic conditions by optimizations of nutrient and light supplies. Significance and Impact of the Study: This study provides a means for increasing co-production of potent bioenergy substrates and useful biomaterials in Synechocystis which may also be applicable to other cyanobacteria.