Degradation of Nitriles by Mixed Biofilms of Nitrile-Hydrolyzing Bacteria in Submerged Packed-Bed Reactor

• Published in: Indian journal of microbiology Vol. 62; no. 4; pp. 610 - 617
• Main Authors: Zorina, A. S., Maksimov, A. Yu, Maksimova, Yu. G.
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01.12.2022; Springer Nature B.V
• Subjects: Acetonitrile; Acrylonitrile; Alcaligenes; Bacteria; Basalt; Biodegradation; Biofilms; Biofilters; Biomedical and Life Sciences; Carbon; Carbon fibers; Carboxylic acids; Degradation; Fibers; Leaching; Life Sciences; Medical Microbiology; Metagenomics; Microbiology; Nitriles; Open systems; Original; Original Research Article; Reaction products; Reactors; Rhodococcus; Substrates; Utilization; Wastewater treatment; Water purification; Organocyanides; Acrylonitrile; Biofilter; Wastewater treatment; Acetonitrile
• ISSN: 0046-8991; 0973-7715
• DOI: 10.1007/s12088-022-01030-z

Degradation of nitriles by mixed biofilms of nitrile-hydrolyzing bacteria Alcaligenes faecalis 2 and Rhodococcus ruber gt 1 grown on basalt and carbon carriers, in a submerged packed-bed reactor was studied. It was shown the formation of a massive mixed biofilm of Al. faecalis 2 and R. ruber gt 1 and the effective removal of nitriles and products of their degradation from the reaction medium. After the accumulation of carboxylic acid and some of the unprocessed substrate, the system adapts to 600–1000 h of biofilter operation, which is expressed in a decrease in the content of substrate and reaction products in the medium. The rate of acetonitrile and acrylonitrile utilization was 0.072–0.086 and 0.039–0.215 g/h, respectively, and acrylonitrile utilization with maximum rate was realized by a mixed biofilm on carbon fibers. Biofilms grown on mixed fibers in a "sandwich"-type reactor had the best characteristics for the transformation of aceto- and acrylonitrile (removal capacity of 99.6–99.9%, nitrile utilization rate of 0.080–0.095 g/h). Biofilms grown on basalt fiber with a diameter of 4–12 μm are also well suited for the degradation of acetonitrile (removal capacity of 100%, nitrile utilization rate of 0.086 g/h). The results of metagenomic analysis showed the resistance of Al. faecalis 2 and R. ruber gt 1 mixed biofilms against leaching from a biofilter and to competitive growth in an open system, indicating the advantages of biofilms over homogeneous biomass for wastewater treatment from nitrile compounds. Biofilms of two species of nitrile hydrolyzing bacteria on basalt and carbon fibers effectively purify water from nitriles in a submerged packed-bed reactor.