In vitro testing of antimicrobial activity of lactic acid bacteria and other organisms against onion spoilage organisms

Maximum post harvest loss in onions is attributed to microbial spoilage. So, LAB and antagonistic organisms were screened for their antimicrobial activities against isolated spoilage organisms. Aspergillus sp., Penicillium sp., Botrytis sp., Erwinia sp., Bacillus sp., and Staphylococcus sp., were isolated from Bangalore rose and Bellary red onion varieties. The antimicrobial activity of Lactic acid bacteria and antagonistic organisms were tested by agar cup method. Out of six Lactic acid bacterial strains NR-1 was found to be effective. Maximum areas of zone of inhibition were recorded in Erwinia sp.,(147.8sq.mm) fallowed by Staphylococcus sp.(94.2sq.mm) and also inhibit Aspergillus sp., (40sq.mm). Among Pseudomonas cultures, Pseudomonas putida was found to be more inhibitory than P.fluorescens. Pseudomonas putida inhibited Staphylococcus sp.,(188.5sq.mm) Aspergillus sp.,(56.5sq. mm). Among yeast cultures, Saccharomyces cervisiae inhibits Staphylococcus sp.,(308 sq.mm). Erwinia sp. (188.5 sq.mm) Aspergillus sp., (94.2sq. mm). None of lactic acid bacteria and other antagonistic organisms are not much active against fungal isolates. Sacharomyces boulardi could not inhibit any of the bacterial and fungal cultures. The present investigation showed that LAB and other organisms showed potent antimicrobial activity to reduce the post harvest bacterial spoilages of vegetables. These results suggest that this potent isolates could be used as a natural bio preservatives in perishable vegetables.