Proteomic analysis of hydrogen production in Chlorella pyrenoidosa under nitrogen deprivation

Previously, Chlorella pyrenoidosa strain IOAC707S was found to produce hydrogen under nitrogen deprivation in seawater medium, without dark incubation, N-2 flushing or addition of uncoupler, which made it a candidate for clean and renewable energy production. To understand the molecular mechanism underlying hydrogen production by C. pyrenoidosa under nitrogen deprivation, iTRAQ-based proteomic analysis was conducted to investigate the differences in protein abundance under nitrogen deprivation (L1-N) compared with the control (CK). In total, 119 KEGG pathways were mapped for 2383 proteins, among which, the expression levels of most proteins involved in chlorophyll synthesis were down-regulated, while those involved in chlorophyll degradation were up-regulated in the L1-N culture; the expression level of serine glyoxylate aminotransferase involved in photorespiration was up-regulated 1.25 fold in the L1-N culture at 44 h, and the expression levels of most proteins involved in mitochondrial respiration were up-regulated in the L1-N culture. These results indicated a decrease of chlorophyll and an increase of respiration, which favored the establishment of anaerobiosis and hydrogen production.

Automated summary

The study revealed that the molecular mechanism of hydrogen production by Chlorella pyrenoidosa under nitrogen deprivation involves changes in the expression levels of proteins related to chlorophyll synthesis and degradation, photorespiration, and mitochondrial respiration, promoting the establishment of anaerobiosis and hydrogen production.