تقی صالحی زهرایی

Antibiotic resistance is regrettably increasing. Recently, application of postbiotics against various microbial pathogens can safely be considered to formulate/substitute with antibiotics. As such, we aimed to investigate the inhibitory effect of Lactobacillus Paracasei against the most common Staphylococcal and coliform pathogens.

The standard strain of Lactobacillus (L.) paracasei was cultivated in MRS medium. Then, the inhibitory effects of different obtained postbiotics along with negative-and-positive controls on two pathogenic bacteria, Staphylococcus (S.) aureus and Escherichia (E.) coli, was evaluated by the MIC test using the microdilution method on 96-well plates. The results were determined at 630 nm.

The effect of all isolated postbiotics except group C (supernatant obtained with sonication-heat shock treatment) compared to the negative controls (without treatment) was statistically significant (p<0.05). Also, the postbiotic group D (supernatant obtained with sonication-thermal shock-freeze treatment) had as remarkably inhibitory effect as positive control (with meropenem treatment) on S. aureus (p=0.0006) and E. coli (P=0.0003). Also, different groups of postbiotics had almost similarly non-significant effect on S. aureus versus E. coli.

Results of this study emphasize the antibacterial potential of Lactobacillus paracasei postbiotics against common pathogens, and these postbiotics can be considered as one of the promising candidates for development and further biomedical and pharmaceutical applications.