Abstract:
Chilli plant leaf spot is caused by bacteria belonging to several species in the genus
Xanthomonas especialy
Xanthomonas campestris. Infected chilli plant were collected from local area of Coimbatore and botanical name was confirmed as
Capsicum annum and were processed for isolation of
Xanthomonas. Among the processed samples colonies with typical characteristics namely smooth, round (1.5cm-2cm) with entire margins were picked and were subjected to morphological and biochemical characteristics. Isolates are reacted negatively to gram staining under a light microscope.
Xanthomonas campestris were able to utilize citrate, gelatin is liquefied, indole is produced, catalase is positive, nitrate is reduced, starch and casein is hydrolysed, oxidase is positive.
Xanthomonas campestris can able to grow on nutrient agar with 5% glucose.
Lactobacillus sp is a probiotics bacteria found mainly associated with milk products. Raw cow milk sample were collected from the local area of Coimbatore and processed for isolation of
Lactobacillus. Among the processed samples colonies with typical characteristics pure, white, small (2-3mm diameter) with entire margins were picked and were subjected to morphological and biochemical characteristics. The isolates were identified as
Lactobacillus acidophilus and
Lactobacillus sporogenes. The isolates reacted positively to gram staining under a light microscope.
Lactobacillus sp not able to reduce nitrates, gelatin is not liquefied, indole is not produced, acidic and non acidic end products are not produced and are catalase negative. The cultures supernatant obtained from the bacteriocin producer strain were tested for the antibacterial activity against isolates of
Xanthomonas campestris by agar well diffusion assay. Inhibitory zones shows that the strain
Lactobacillus acidophilus show strong antimicrobial activity. For the
in vitro efficacy of LAB as biocontrol and Plant Growth Promoting Bacteria, chilli seeds from two varieties (CO1, K2) were treated with LAB strain and treated seeds showed inhibitory activity against
Xanthomona campestris strain. They can resist the bacterial infection and showed good percentage of increase in shoot length and root length in the seeds treated with
Lactobacillus acidophilus. The use of chemicals and bacteriocides in agriculture as well as the environmental pollution would be avoided by LAB as a promising PGPB and Biocontrol agent.