ITRAQ-based proteome profiling revealed the carbon metabolism regulation for mariculture wastewater treatment with Bacterial-Algal Coupling Technology

Abstract

Acidogenic fermentation coupled with microalgae cultivation is efficient for mariculture wastewater (MW) treatment and energy recovery, but there is limited information regarding carbon metabolic networks as a response to varied broth composition at the proteome level. In this study, ethanol-type, propionate-type, and butyrate-type fermentation effluent of MW were applied to microalgae cultivation. The carbon source composition of different types of acidogenic fermentation was optimized to enhance microalgal biomass production and nutrients removal. Compared with ethanol-type fermentation effluent, higher efficiency in biomass accumulation and ammonia assimilation of Chlorella pyrenoidosa was observed in propionate-type and butyrate-type. Lipid accumulation in microalgae was enhanced with ethanol-type fermentation effluent, and the maximum lipid content reached 513.3 and 546.7 mg/L at an inorganic carbon/organic carbon (IC/OC) ratio of 3:1 and 2:1, respectively. The increasing ratio of IC/OC improved the expression of key enzymes related to the photosynthetic system, which had a positive effect on carbohydrate production and microalgal growth. The upregulation of magnesium chelatase with bicarbonate supply was revealed by iTRAQ analysis, thereby promoting chlorophyll production in microalgal cells. In response to an increasing proportion of IC, more energy and precursor substances for lipid production were generated with the enhancing expression of glycolysis and pyruvate metabolism.