Applied Microbiology (Switzerland) · Published 2026-08-04 · DOI 10.3390/applmicrobiol6080088
Joaida W. Gonzales, Gwen L. Amurao, Elaiza G. Catangui, Caillie T. Maring, Alliyah Nua, Gabriel Martin Oleo, Megan Angeline Santos, Leonardo A. Guevarra, Nicanor Austriaco
Lactic acid bacteria (LAB) are promising oral drug delivery systems due to their probiotic properties, safety, and ability to stimulate mucosal immunity. In this study, we characterized five LAB strains, <i>Lacticaseibacillus casei</i> ATCC 393, <i>Lacticaseibacillus paracasei</i> UST1611, <i>Lactiplantibacillus plantarum</i> UST1611, <i>Limosilactobacillus reuteri</i> LR08, and <i>Lacticaseibacillus rhamnosus</i> GG, to assess their potential as a microbial chassis for oral drug delivery. We tested competence for transformation, plasmid stability, GFP expression under a constitutive promoter, survival under simulated gastrointestinal conditions, and survival in the gut of <i>Danio rerio</i> larvae. Successful transformation with the pTRKH3-ermGFP plasmid was achieved in <i>L. casei</i> ATCC 393, <i>L. paracasei</i> UST1611, and <i>L. reuteri</i> LR08. We also showed that the <i>L. casei</i> ATCC 393 strain had significantly higher protein expression than its <i>L. paracasei</i> UST1611 and <i>L. reuteri</i> LR08 counterparts. In the absence of selection, <i>L. casei</i> ATCC 393 and <i>L. paracasei</i> UST1611 retained their plasmid for 48 h. <i>L. reuteri</i> LR08 retained it for up to 72 h. The three transformed strains showed comparable tolerance to simulated gastrointestinal pH, though <i>L. casei</i> and <i>L. reuteri</i> were more resistant to 0.3% greater bile. In vivo testing showed the highest survival for <i>L. casei</i> ATCC 393 and <i>L. paracasei</i> UST1611 in the gut of zebrafish (<i>Danio rerio</i>) larvae. Overall, our results suggest that, among the five strains tested, <i>L. casei</i> ATCC 393 is the most promising candidate for an LAB-based microbial system for oral drug delivery.
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Gonzales, J., Amurao, G., Catangui, E., et al. (2026). Assessing the Potential of Five Strains of Different Lactic Acid Bacterial Species as a Microbial Chassis for Oral Drug Delivery. Applied Microbiology (Switzerland). https://doi.org/10.3390/applmicrobiol6080088