Lactobacillus plantarum Isolates from Different Vegetables That Have Antifungal Activity against the Common Cheese Spoilage Mold Penicillium commune are Genetically Related

Introduction: Molds are the most common cheese spoilage organisms which can lead to economic loss as well as raising public health concerns due to the production of mycotoxins. In a previous study, 897 lactic acid bacteria (LAB) isolated from different herbs, fruits and vegetables were screened for their antifungal activity and 12 were confirmed as having strong activity against the common cheese spoilage mold Penicillium commune.  These 12 LAB were all identified by 16S rDNA sequencing as being Lactobacillus plantarum; however, it was not known if they are closely related L. plantarum isolates.

Purpose: This study aimed at determining if the 12 antifungal L. plantarum isolates were genetically related to each other and to 2 other L. plantarum strains (strain ATCC14917 from pickled cabbage and the commercial probiotic strain 299v).

Methods: Three different randomly amplified polymorphic DNA (RAPD) PCR primers (M13, P4 and P7) were tested for their ability to generate useful banding patterns using RAPD-PCR for the L. plantarum strains.

Results: It was found that one RAPD-PCR primer (M13) generated useful banding profiles with up to 9 bands visible between 750 bp and 3.5k bp.  The other primers generated only 2 or 3 bands.  All the 12 antifungal LAB isolates produced identical profiles as each other with the 3 primers and also to strain 299v, but were clearly different to strain ATCC14917.

Significance: These results demonstrate that the M13 primer is useful for genotyping antifungal L. plantarum isolates and that these antifungal L. plantarum isolates from different vegetables are likely to be closely related and therefore possibly share the same antifungal mechanism of action.