Probiotic Potential of Lactic Acid Bacteria Isolated from Tomato Fruit

Abstract

Probiotics are beneficial microbes, primarily from the genera Lactobacillus and Bifidobacterium, that play a pivotal role in promoting host health through nutritional, immunological, and physiological functions. As a result, there has been a significant increase in global research and application of probiotics across the medical, food, and pharmaceutical industries. The present study aimed to isolate, identify, and characterise lactic acid bacteria strains from tomato with probiotic potential. Fresh tomato samples were procured from various markets within the Calabar metropolis. Presumptive LAB isolates were subjected to Gram staining, catalase testing, and assessments for capsule formation and ropiness.  Genomic DNA was extracted using the GenElute Bacterial Genomic DNA Kit. Antibiotic susceptibility was determined using the disc diffusion method with Neo-Sensitabs (Rosco Diagnostica, Denmark) on MRS agar. The result showed that all three isolates were able to grow at 2 % and 4 % NaCl concentrations; however, only isolate JGE-139 showed growth at 6.5% NaCl. All the isolates grew very well at 37°C and showed slight growth at 15°C and 45°C. All the isolates were sensitive to Ampicillin, Tetracycline, Chloramphenicol, and Erythromycin. The 16S rDNA of the isolates showed a percentage similarity to other species ranging from 99%-100%. Molecular identification via 16S rRNA sequencing confirmed the identity of the isolates as Lactobacillus plantarum, Lactobacillus paracasei and Lactococcus lactis subsp. cremoris. These results highlight the probiotic potential of these LAB strains, especially JGE-139, for future applications in food preservation, gut health enhancement, or as adjuncts in treating gastrointestinal disorders.