Role of Biotransformation on the Dynamics of Antimicrobial Resistance

Quaternary ammonium compounds (QACs) are cationic antimicrobial agents extensively used in domestic, industrial and medical settings. Development of antimicrobial resistance by bacteria upon exposure to QACs in these settings is evident. Given the fact that bacterial biotransformation plays a significant role in the removal of QACs, the proposed research aims to systematically evaluate the role of biotransformation on the control, development and dissemination of resistance to QACs in a microbial community having members with different tolerance to that agent. The outcomes of this research will have significant contribution for the protection of human and environmental health by answering the following questions:

1. Do QAC degrading and non-degrading microorganisms co-exist in the environments which possess a risk to human and environmental health?

2. Does biotransformation confer resistance to microorganisms having this capability?

3. Does QAC biotransformation favor the survival of the most sensitive member in a microbial community?

4. Can biotransformation play a role in the development and dissemination of antimicrobial resistance in a microbial community therefore possess a threat to human health?

Synopsis

Graphical Abstract

Progress & Outcomes

1. Laboratory Infrastructure: BIOMIG started its progress in Sept 2011. Currently it is well established for cutting-edge research with 15 m2 space, Agilent HPLC, Thermalcycler, nanophotometer, autoclave, microcentrifuge etc. and 2 brilliant students

2. BAC Degrading Community Development: Four BAC degrading communities have been developed from sewage, activated sludge, soil and sea sediment. Microbial community structure of these communities will be identified using 16S rDNA based cloning and metagenomics.

3. Isolation of BAC Degraders and Non-degraders: 20 BAC-degrading Pseudomonas spp. were isolated from each microbial community. In addition, 5 non-degraders (E.coli etc.) were isolated. Phylogenetic identity of each isolate will be determined based on 16S rDNA gene. Whole genome of selected 4 out of 20 BAC degraders will be sequenced to identify BAC degradation and resistance genes. 

4. BAC Degradation Kinetics and Biotransformation Pathway: BAC biodegradation kinetics of Pseudomonas spp. isolates and detailed biotransformation pathways were elucidated. Most of the isolates were able to mineralize BACs completely where as several isolates transformed BACs to BDMA. 

Fig. Time course of BAC degradation by a Pseudomonas spp. strain isolated from activated sludge

Fig. BAC biotransformation pathway observed in 90% of the isolates