Evaluation of antimicrobial activity and disruption of biofilm formation by postbiotics against multidrug resistant pathogens | |
| Author | Rice, Daniel Lee |
| Call Number | AIT Thesis no.FB-24-06 |
| Subject(s) | Drug resistance in microorganisms Probiotics Biofilms |
| Note | A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Engineering and Bioprocess Technology |
| Publisher | Asian Institute of Technology |
| Abstract | The rise of multi-drug resistant (MDR) foodborne pathogens presents a significant challenge to public health, necessitating innovative approaches to combat these threats. This study aims to determine the antibiotic resistance profiles of various foodborne pathogens and evaluate the efficacy of postbiotics derived from lactic acid bacteria (LAB) in addressing these resistant strains. As such, this study determined the antibiotic resistance profiles of foodborne pathogens Bacillus cereus, Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium, and Vibrio parahaemolyticus using the Kirby-Bauer antimicrobial resistance assay. The bacteria were tested against antibiotics from 10 different antibiotic classes. Each pathogen exhibited resistance to at least four different classes of antibiotics, classifying the bacteria as multi-drug resistant (MDR), with resistance overlap from each species to penicillin and four out of the five showing resistance to tetracyclines, glycopeptides, and sulfonamides. Then the antibacterial activities of the cell free supernatant (CFS) for Bifidobacterium bifidum, Lactobacillus casei, and Lactobacillus plantarum tested against the five pathogens for antibiofilm and antibacterial activity. Both Lactobacillus sp. CFS exhibited the highest MIC at 0.083 (fraction of total volume) for Bacillus cereus and at 0.17 for the remaining bacteria, while the Bifidobacterium bifidum MIC was 0.33 for all bacteria. The antibiofilm activity of the CFS against Bacillus cereus and Staphylococcus aureus exhibited the same MBIC as the MIC showing a correlation between cell inhibition and biofilm inhibition. The L. casei CFS also disrupted mature biofilms at 2x MIC by 63.39 ± 4.5 and 45.90 ± 3.44 for Staphylococcus aureus and Bacillus cereus, respectively. At the MIC there was no biofilm disruption. Furthermore, pH neutralization of the CFS removed all inhibition of the samples, while heat treatment showed no significant difference in the MIC and MBIC. The main antibacterial components of the CFS are therefore likely organic acids and heat stable pH dependent bacteriocins. The CFS of Lactobacillus casei and Lactobacillus plantarum demonstrated potential as postbiotic alternatives for traditional antibiotics through the inhibition of MDR pathogens and the inhibition of biofilm formation. |
| Year | 2024 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Anal, Anil Kumar |
| Examination Committee(s) | Loc, Thai Nguyen;Cruz, Simon Guerrero;Shrestha, Pravin Malla |
| Scholarship Donor(s) | AIT Fellowship |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2024 |