Plasmid-encoded genes specifying aniline oxidation from Acinetobacter sp. strain YAA

Area of Science:

• Microbial degradation of aromatic compounds
• Plasmid-mediated catabolism
• Biochemistry of aniline oxidation

Background:

• Acinetobacter sp. strain YAA utilizes aniline and o-toluidine as sole carbon and energy sources.
• Aniline degradation pathways are crucial for bioremediation of contaminated environments.
• Previous studies suggested plasmid involvement in the catabolism of aromatic compounds.

Purpose of the Study:

• To elucidate the genetic basis of aniline utilization in Acinetobacter sp. strain YAA.
• To identify and characterize the genes responsible for aniline oxidation.
• To determine the role of plasmids in aniline degradation.

Main Methods:

• Acridine orange curing to assess plasmid involvement.
• Cloning of the gene cluster involved in aniline oxidation into Escherichia coli.
• Functional analysis of recombinant E. coli strains, including colorimetric assays.
• Subcloning and Southern hybridization to identify specific genes and their location.

Main Results:

• Aniline utilization in strain YAA was confirmed to be plasmid-encoded.
• A recombinant E. coli strain with an 18.5 kb insert showed yellow coloration, indicating 2-hydroxymuconic semialdehyde formation from aniline.
• Subcloning identified a 9.0 kb fragment responsible for catechol accumulation.
• The aniline oxygenase gene (atdA) was located on plasmid pYA1.

Conclusions:

• Aniline degradation in Acinetobacter sp. strain YAA proceeds via catechol.
• The pathway involves meta-cleavage of the benzene ring, mediated by plasmid-encoded genes including atdA.
• This study provides insights into the molecular mechanisms of plasmid-mediated aniline biodegradation.