Lactobacillus plantarum can control undesirable organisms in soil to create a balanced environment that can protect plant life from diseases by producing plantaricin A. L. plantarum from two conditions was isolated. Six isolates from healthy soil and four isolates from soil that have black rot disease in brassica plants. Existence of plnA in each L. plantarum isolate was demonstrated by PCR using gene-specific primers. Three out of six L. plantarum isolates from healthy soil and one out of four L. plantarum isolates from soil have black rot disease in brassica plant showing the presence of plnA. L. plantarum IYP1718 from soil that has black rot disease in brassica plants, was chosen for sequence analysis. The amplified PCR fragment was confirmed to have 100% similarity with the plnA sequence in GenBank. A phylogenetic tree based on sequence analysis confirmed that plnA has closeness with plantaricin G and similarity with enterococcin from Enterococcus faecalis BFE 1071 based on the pairwise distance. Sequence analysis showed that there are 4 ORFs, but only 2 ORFs could be identified. The results of this study imply that L. plantarum plays a role in controlling undesirable organisms in soil by producing plnA.