It is well known that pesticides act as C & N sources for the microorganism or we can say that microorganisms utilize pesticides (insecticide/fungicide) as C & N sources for their growth and shows resistance towards pesticides. What is the basic mechanism in that? Does a microbe directly utilize a pesticide or are there steps involved in it (meaning first breakdown of the substrate and then utilization of it)? Or are some sort of enzymes or enzymatic secretions involved in it? Which thing or mechanism provides resistance towards pesticides?
I will be very thankful if anyone can provide some diagrammatic representation of the mechanism involved or some links for proper understanding.
Dear Kunal obviously they use pesticides as C/N source; It may be environmental acquired character for many microorganisms. Nevertheless, it may be through genetically operated process too. For instance, gene opd(organo phosphate degrading) causes degradation of organo phosphates by cascade of reactions to some end products; these end products will be utilized by respective microbe for its metabolism, Ex for organophosphate degraders, Flavobacterium sp., Go thru the following links u get some stuff from below linked articles
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC154515/pdf/1694.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2832351/pdf/0029-09.pdf
Hi Kunal
In case of the metabolism for aromatic degradation it is the described chain of hydroxyaltion and ring fission .
http://www.genome.jp/kegg-bin/show_pathway?map00623+1.1.1.35
Microbes can draw energy out of this process, otherwise it would not happen, but you will not find a big number of MO that can use this pathways as a sole source of C or N, it is a secondary metabolism and carried out in a functionalized biotop. A screening on pesticides as f.E sole carbonsource will offer you for sure highly regulated degraders, but not every organism that you find is able to do this.
Hello Kunal
you are correct in tihnking that pesticides are C & N sources which can support microbial growth. The compounds are broken down step-by-step, and there are typically a large number of steps before complete mineralisation of the compounds. My experince is with herbicedes such as 2,4-D and glyphosate. For 2,4-D, the initial steps in breakdown are either removal of the carboxylic acid side chain by TfdA, a ketoglutarate and iron dependant dioxygenase, or by dechlorination. There are then a number of subsequent steps which usually lead into the general benzoate degradation pathway. Details can be found at KEGG here;
http://www.genome.jp/kegg-bin/show_pathway?ko00361+K06912
For glyphosate, degradation typically depends upon the action of a speacialised group of phosphonatase-expressing (C-P lyase) microorganisms which break the C-P bond. Degradation then proceeds, again by a number of steps, to complete mineralisation.
So in neither case is the pesticide utilised directly, but degradation proceeds by a number of specific steps.
I hope thid helps
Andy Neal
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