Influent carbon to phosphorus ratio drives the selection of PHA-storing organisms in a single CSTR

Water Research X

article

Antoine Brison¹  Pierre Rossi¹  Nicolas Derlon¹ 

[1] ETH Zürich, Institute of Environmental Engineering

关键词: Polyhydroxyalkanoates (PHAs);    Dual carbon and phosphorus limitation;    Growth conditions;    Cellular phosphorus requirements;    Biomass PHA content;    Long-term selection;   

DOI  :  10.1016/j.wroa.2022.100150

学科分类：社会科学、人文和艺术（综合）

来源: Academic Press

【 摘 要 】

Enriching a biomass with a high fraction of polyhydroxyalkanoate-storing organisms (PHA-storers) represents an essential step in the production of PHAs (bioplastics) from municipal wastewater using mixed microbial cultures. A major challenge is however to create selective growth conditions that are favourable to PHA-storers. Our study thus investigates to what extent the influent COD to phosphorus (COD:P) ratio can be used as a tool for the robust selection of PHA-storers in a single continuous-flow stirred-tank reactor (CSTR). Therefore, we operated five CSTRs in parallel, fed with synthetic wastewater (50% acetate - 50% propionate) with different COD:P ratios (200−1000 gCOD gP −1 ), and performed a detailed analysis of the microbial communities over long-term (30−70 solid retention times). Our study demonstrates that efficient and robust selection of PHA-storers can be achieved in a single CSTR at high influent COD:P ratios. The selective advantage for PHA-storers increases with the influent COD:P ratio, but only if growth conditions remain limited by both C-substrate and P. In contrast, selection performance deteriorates when COD:P ratios are too high and growth conditions are limited by P only. At an optimal COD:P ratio of 800 gCOD gP −1 , a stable microbial community consisting of >90% PHA-storers and dominated by Pannonibacter sp. was selected in the long-term. Finally, our results suggest that high COD:P ratios provide a selective advantage to microorganisms with low cellular P requirements, explaining why different PHA-storers (i.e., Xanthobacter sp . vs. Pannonibacter sp. ) were selected depending on the influent COD:P ratio (i.e., 200 vs. 800 gCOD gP −1 ). Overall, our results provide relevant insights for the development of a new approach for selecting PHA-storers, based on the use of a single CSTR and control of the influent COD:P ratio.

【 授权许可】

CC BY|CC BY-NC-ND