Chloramphenicol acetyl transferase producing bacteria

Chloramphenicol acetyl transferase (CAT) is an enzyme encoded by plasmids that detoxify the antibiotic chloramphenicol. It is responsible for chloramphenicol resistance in bacteria. Chloramphenicol acetyl transferase covalently attaches an acetyl group from acetyl-CoA to chloramphenicol which prevents chloramphenicol from binding to ribosomes. CAT is used as a reporter gene marker for the successful uptake of the gene of interest. It is used to measure chloramphenicol in body fluids and also to inactivate chloramphenicol where the antibiotic has been added as potential reversible inhibitor of protein synthesis. Production of CAT enzyme is a rarely frequented area and hence it will be of great use if an indigenous methodology is developed to produce CAT enzyme with cost effectiveness. Commercial synthesis of this enzyme is complicated and is expensive too. Hence the aim of the study is to isolate CAT producing microbes from soil by inoculating the soil in nutrient agar containing chloramphenicol as substrate, thereby only those organisms that can make use of chloramphenicol will survive and multiply. This screening resulted in 44 isolates and all of them were characterized by macroscopy followed by microscopy and biochemistry. Of these 44 isolates 4 were shortlisted and were gene sequenced. The short listed strains were coded as BDU2, BDU3, BDU4 & BDU5 and their sequence was deposited in gene bank.