Microbial community structure and function in response to the shift of sulfide/nitrate loading ratio during the denitrifying sulfide removal process

Influence of acetate-C/NO3(-)-N/S(2-) ratio to the functional microbial community during the denitrifying sulfide removal process is poorly understood. In this study, the authors investigated the phylogenetic and functional bacterial community for elemental sulfur (S(0)) recovery and nitrate (NO3(-)) removal, with the switched S(2-)/NO3(-) molar ratio ranged from 5/2 to 5/9. Optimised S(2-)/NO3(-) ratio was evaluated as 5/6, with the bacterial genera predominated with Thauera, Enterobacter, Thiobacillus and Stappia, and the sqr gene highly expressed. However, insufficient or high loading of acetate and NO3(-) resulted in the low S(0) recovery, and also significantly modified the bacterial community and genetic activity. With S(2-)/NO3(-) ratio of 5/2, autotrophic S(2-) oxidisation genera were dominated and NO3(-) reduction activity was low, confirmed by the low expressed nirK gene. In contrast, S(2-)/NO3(-) ratio switched to 5/8 and 5/9 introduced diverse heterotrophic nitrate reduction and S(0) over oxidisation genera in accompanied with the highly expressed nirK and sox genes.

Authors: Huang C, Li ZL, Chen F, Liu Q, Zhao YK, Zhou JZ, Wang AJ. ;Full Source: Bioresource Technology. 2015 Aug 12;197:227-234. doi: 10.1016/j.biortech.2015.08.019. [Epub ahead of print] ;