Aerobic cometabolism of 1,1,2,2-TeCA by a propane-growing microbial consortium (C2): Diversity of alkane monooxygenase genes and design of an on-site bioremediation process

•The microbial consortium C2 has the unique feature to co-metabolize TeCA under aerobic conditions.•Genes encoding alkane MOs belonging to AlkB, SDIMO and cytochrome P450 were characterized in C2.•Different bioreactor configurations were tested for the treatment of TeCA contaminated groundwater with C2.•A continuous stirred-tank reactor (CSTR) followed by a plug-flow reactor (PFR) gave the best performance.

Microbial degradation of 1,1,2,2-tetrachloroethane has been rarely analysed under aerobic conditions. In this work, the catabolic potential of a TeCA-degrading aerobic propanotroph consortium (C2) and the optimal bioreactor configuration for an on-site TeCA-bioremediation strategy with C2 were defined. More specifically, the diversity of alkane-oxidizing bacteria in C2 was assessed by means of clone libraries of genes coding for alkane monooxygenases (MOs) of different families (AlkB-like alkane hydroxylase, soluble di-iron MO and cytochromes P450). A large number of alkane MO sequences retrieved in this study showed the highest similarity with reference sequences belonging to Rhodococcus genus, suggesting a key role of this genus in TeCA/propane co-metabolism, while the remaining alkane MO sequences were mainly attributed to other Actinobacteria, to Bradhyrizobiaceae, and Cupriavidus genus. Further, the feasibility of an on-site TeCA bioremediation strategy with C2 was evaluated by simulating a continuous-flow aerobic co-metabolic process with different bioreactor configurations. Our results show that the configuration with a suspended-cell continuous stirred-tank reactor (CSTR) followed by a suspended-cell plug-flow reactor (PFR) was the one giving the best performance with consortium C2.