BIO-PHYSICOCHEMICAL CHARACTERIZATION AND APPLIED STUDIES OF CAROTOVORICIN NA5 (CrNA5) ON BLB AFFECTED RICE PLANTS

Abstract

Erwinia carotovora is a common soil borne plant pathogen, which generally infects plants of family Solanacea. In the present study, bacteriocin (CrNA5), produced by an indigenously isolated E. carotovora NA5 has been characterized and its possible anti phytopathogenic potential was shown in the field studies. CrNA5 showed its antimicrobial activity against many gram-positive and gram-negative bacteria including those associated with the plant diseases. The bacteriocin showed substantial stability against wide range of temperatures and pH. Additionally, it was also found resistant to the treatment of metal ions, organic solvents and non-proteolytic enzymes. Conversely, its inactivation by proteinase K and protease suggested its protein nature. Mode of action studies revealed that CrNA5 is bactericidal, particularly against Xanthomonas oryzae oryzae. The electron micrograph of CrNA5 revealed spherical particle (empty head) like structures implicating the vestigial bacteriophage based origin of carotovoricin. In silico analyses were also conducted in order to deduce the plausible ratio of the amino acids present in the protein. The In vivo experiments showed the efficacy of CrNA5 against X. oryzae oryzae (Xoo), the causative agent of bacterial leaf blight (BLB) of rice, both in controlled conditions (green house) as well as in field trials. To the best of our knowledge, the present study is the first of its kind with the bacteriocin of Erwinia origin (tested against the BLB infected plants in the field). It is expected that the present study will help visit new insights of the bacteriocins produced by Erwinia carotovora and their potential (application) as anti phytopathogenic agent.