Detection and Molecular Characterisation of Probiotic Bacteria from Musa paradisiaca and Citrus sinensis

Abstract

Background: Fruits may harbour lactic acid bacteria with probiotic potential, but the molecular identities and genetic relatedness of isolates associated with Musa paradisiaca and Citrus sinensis remain insufficiently documented. Aims: This study isolated presumptive probiotic bacteria from banana and orange samples and identified them using biochemical tests and 16S rRNA-based molecular analysis. Methods: Samples obtained from storage centres, street hawkers and retail shops were mashed, serially diluted and cultured on de Man, Rogosa and Sharpe agar. Colonies were screened by Gram staining and catalase, coagulase, oxidase and sugar fermentation tests. DNA was extracted from presumptive isolates, quantified and amplified by polymerase chain reaction. Amplicons were evaluated by agarose gel electrophoresis, digested with XbaI and EcoRI, and compared by restriction fragment length polymorphism analysis. Results: Eight presumptive probiotic isolates were obtained. Biochemical and molecular analyses identified the isolates as Lactobacillus plantarum, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus rhamnosus, Streptococcus thermophilus, Bifidobacterium lactis, Lactobacillus bulgaricus and Bifidobacterium bifidum. Electrophoretic and restriction profiles showed both shared and distinct banding patterns, indicating genetic relatedness alongside variation among the isolates. Conclusion: The findings indicate that the examined banana and orange samples contained bacteria identified as lactic acid bacteria and bifidobacteria with putative probiotic relevance. Molecular analysis supported the biochemical identification and demonstrated distinguishable genetic patterns among the isolates. Further evaluation is required to establish strain-level identity, safety and functional probiotic properties.