Effect of bacteriocin from isolated Lactococcus lactis JC10 on Xaanthomonas campestris, causal agent of bacterial leaf blight in Piper betle L. (Paan)

Subhas Chandra Jana, Malay Mandal


Bacteriocin was produced in MRS broth media by incubating Lactococcus lactis JC10 for 5 h. Crude neutralized bacteriocin was purified by acetone precipitation. Neutralized crude bacteriocin and 0-40% acetone cut fraction was used later for all the tests. Preliminary studies of inhibition against Xanthomonas campestris (causal agent of bacterial leaf blight in Piper betle L.) by bacteriocin was performed by spot on lawn method. Viability of test organism was examined by streaking crude and 0-40% acetone cut bacteriocin fraction treated viable X. campestris cells. SEM analysis was performed to study the mode of action of bacteriocin. Test bacteriocin showed significant amount of inhibition of X. campestris. Whereas neutralized crude bacteriocin killed viable cells of X. campestris within 3:30 h of incubation, 0-40% acetone cut fraction of crude bacteriocin killed viable cells only after 1 h of incubation at 30°C. Scanning electron micrograph showed that crude bacteriocin can change the shape of cells after 1 h of treatment and 0-40% cut fraction can totally rapture the cells within 1 h of treatment. The changes observed in the X. campestris cells in SEM analysis is probably because of the complete disarrangement of the plasma membrane followed by degradation of the integrity of the cell wall.


Xanthomonas campestris; Piper betle L. (Paan); bacteriocin; biocontrol.

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