Use of conserved randomly amplified polymorphic DNA (RAPD) fragments and RAPD pattern for characterization of Lactobacillus fermentum in Ghanaian fermented maize dough

The present work describes the use of randomly amplified polymorphic DNA (R APD) for the characterization of 172 dominant Lactobacillus isolates from p resent and previous studies of Ghanaian maize fermentation. Heterofermentat ive lactobacilli dominate the fermentation flora, since approximately 85% o f the isolates belong to this group, Cluster analysis of the RAPD profiles obtained showed the presence of two main clusters. Cluster 1 included Lacto bacillus fermentum, whereas cluster 2 comprised the remaining Lactobacillus spp, The two distinct clusters emerged at the similarity level of <50%. Al l isolates in cluster 1 showed similarity in their RAPD profile to the refe rence strains of L. fermentum included in the study. These isolates, yieldi ng two distinct bands of approximately 695 and 773 bp with the primers used , were divided into four subclusters, indicating that several strains are i nvolved in the fermentation and remain dominant throughout the process. The two distinct RAPD fragments were cloned, sequenced, and used as probes in Southern hybridization experiments. With one exception, Lactobacillus reute ri LMG 13045, the probes hybridized only to fragments of different sizes in EcoRI-digested chromosomal DNA of L. fermentum strains, thus indicating th e specificity of the probes and variation within the L. fermentum isolates.