In silico prediction and in vitro analysis of bacteriocin and probiotic properties of Weissella cibaria NM1 isolated from Asian sea bass

Aims@#This study aims to predict the presence of bacteriocin- and probiotic-associated genes in the genome of Weissella cibaria NM1 isolated from Asian sea bass using a machine learning-based NeuBI prediction approach, followed by the investigation of the crude bacteriocin antimicrobial and probiotic properties via in vitro analysis.@*Methodology and results@#This study utilized the machine learning-based NeuBI prediction approach with a homology search of highly conserved bacteriocin-associated genes present in the genome of W. cibaria NM1. This approach discovered a putative bacteriocin gene (WC_2064) and bacteriocin operon with complete immunity, transporter, regulator and modifier genes. Furthermore, the genome of W. cibaria NM1 was found to harboured specific probiotic*associated genes that would contribute to acid and bile tolerance, adhesion on thehost cell and exhibited cholesterolreducing ability. On top of that, the genome also shows the absence of virulence and antibiotic resistance genes, which signifies the safety of W. cibaria NM1 as a potential probiotic candidate. In vitro study has confirmed the antipseudomonal activity of crude bacteriocin NM1 with MIC of 62.5 mg/mL. Weissella cibaria NM1 can tolerate 0.3% (v/v) of bile salt condition and the transit through the simulated gastric (pH 3 and 4) and small intestinal (pH 8) tract.@*Conclusion, significance and impact of study@#Current findings suggested in silico approach can speed up the search for putative bacteriocin and probiotic-associated genes from the genome of W. cibaria NM1. Nevertheless, further verification through experimental works will be deemed essential.

Enhanced killing of multidrug-resistant Pseudomonas aeruginosa ATCC10145 through a combined action of antibiotics and bacteriocin from Pediococcus pentosaceus TU2

Aims@#Due to its rapid development of resistance against most conventional antibiotics, there is an urgent need to develop new antimicrobial agents and strategies to overcome the challenges in combating multidrug-resistant Pseudomonas aeruginosa infections. This study aimed to determine the antipseudomonal potency of bacteriocin produced by Pediococcus pentosaceus TU2 when combined with conventional antibiotics.@*Methodology and results@#The checkerboard method and time-kill assay were conducted to investigate the antagonism interaction and kinetics of the bacteriocin TU2 and selected antibiotics against Pseudomonas aeruginosa ATCC10145. The scanning electron microscope (SEM) was used to observe the cell surface morphological changes of the treated P. aeruginosa ATCC10145. The combination of bacteriocin TU2 with ciprofloxacin and tetracycline resulted in a 4-fold reduction in minimum inhibitory concentration (MIC) and a fractional inhibitory concentration index (ΣFICI) of 0.5, indicating a synergistic interaction against P. aeruginosa ATCC10145. Similarly, the time-kill assay showed that the combination of bacteriocins TU2 respectively with chloramphenicol and tetracycline exerted enhanced bactericidal effect at 8 h and 10 h of treatments compared to treatment with antimicrobial agents alone. Results from SEM suggested that bacteriocin TU2 might cause pore formation on cells and thus enhanced the membrane permeability of antibiotics and intensified the membrane leakage that led to cell death of P. aeruginosa ATCC10145.@*Conclusion, significance and impact of study@#The combined antagonistic effect of bacteriocin TU2 and antibiotics could be a promising strategy in combating P. aeruginosa infections and may be applied in therapeutic industries.