The immobilization of organonitrile-degrading bacteria via the addition of biofilm-forming bacteria represents a promising technology for organonitrile-containing wastewater treatment,but simple mixing may reduce treatment efficiency,and the adherence of biofilm-forming bacteria is affected by electrostatic forces.The nitrile hydratase and amidase genes,which play critical roles in organonitriles degradation,were cloned and transformed into the biofilm-forming bacterium Bacillus subtilis N4 to construct the recombinant bacterium B.subtilis N4/pHTnha-ami,which possessed organonitrile-degrading and biofilm-forming capability.The nitrile hydratase and amidase genes were expressed upon lactose induction.The successfully modified carriers with a positive charge,identified by Fourier Transform Infrared (FI-RT) and X-ray photoelectron spectroscopy (XPS),promoted the adherence of B.subtilis N4/pHTnha-ami and biofilms formation (P < 0.05).Biofilms formed by the combination of B.subtilis N4/pHTnha-ami and this positively charged carriers demonstrated substantial resistance to organonitriles loading shock,and degraded the initial CN concentration (392.6mg/L) within 24 h in a moving bed biofilm reactor (MBBR) after operation for 32 d.The imputed quorum-sensing signal composition of biofilm samples from modified carriers indicated that B.subtilis N4/pHTnha-ami was successfully immobilized in the reactor.Further detection via high-throughput sequencing confirmed that B.subtilis N4/pHTnha-ami became the dominant genus.The knowledge obtained from this study provides important guidance to enhance the biological oxidation of toxic pollutants in wastewater.