Molecular Characterization of Aniline Biodegradation by Some Bacterial Isolates having Unexpressed Catechol 2,3-Dioxygenase Gene

Abstract

Aromatic amines are potential mutagens and carcinogens, so biodegradation of them may protect our environment by safely getting rid of these compounds. In the present study, 5 aniline degrading isolates were recovered from 30 samples of sewage and agricultural wastewater, The five isolates were identified biochemically and by 16S rRNA gene sequence analysis as Achromobacter sp. (2 isolates), Pseudomonas sp. (2 isolates) and Enterobacter sp. (1 isolate). Biodegradation of aniline was measured by HPLC, and within 10 days, aniline degradation percentage was variable ranging from 27% to 61% of the initial aniline concentration with the formation of catechol as the byproduct which was further biodegraded to cis, cis muconic acid confirming that the isolate was following the ortho-cleavage pathway. Additionally, the ability of these isolates to degrade aniline was confirmed by measuring the optical density (OD) of the growth of the five isolates in the presence of aniline as sole carbon source using the microtiter plate method at 620 nm. The genomic DNA and plasmid of the isolates were then extracted. Screening for selected genes, known to encode aniline depredating enzymes; cat1,2, cat2,3, tadR, and tdnQ using PCR was done. It revealed the presence of cat1,2, tadR, and tdnQ in the plasmid preparation. Significance, and Impact of study: It was concluded that aniline is degraded by the five isolates through a pathway involving enzymes performing ortho-cleavage of the benzene ring and these isolates could have a potential role for use in bioremediation of aniline contaminated environments.

Comprehensive toxicological, metabolomic, and transcriptomic analysis of the biodegradation and adaptation mechanism by Achromobacter xylosoxidans SL-6 to diuron

“…According to previous reports, the biodegradation of 3,4-DCA mainly included two diverse reactions (dehalogenation and hydroxylation), followed by the formation of 4-chloroaniline (4-CA) and 1,2-dichlorobenzene (1,2-DCB) ( Silambarasan et al, 2020 ). 4-CA was dechlorinated and hydroxylated to generate aniline and 4-chlorocatechol respectively, and then, aniline was deaminated to generate catechol ( Mohlam et al, 2018 ; Li et al, 2022 ). Ultimately, ring-opening cleavage of catechol produced cis, cis -muconic acid ( Shahryari et al, 2018 ; Yu et al, 2020 ).…”