Prevalence and Bio-control of Foodborne Pathogens (Salmonella and Staphylococcus aureus) in Raw and Ready-to-eat Poultry Meat | |
| Author | Akbar, Ali |
| Call Number | AIT Diss. no.FB-14-01 |
| Subject(s) | Meat inspection Foodborne diseases Poultry |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. FB-14-01 |
| Abstract | The aim of this study was to investigate the prevalence of two prominent foodborne pathogens namely Salmonella and Staphylococcus aureus ( S. aureus ) in raw and ready - to - eat poultry meat and its products, and biopreservative approaches for those products targeting the flow of the two pathogens. Lactic acid bacteria (LAB) were isolated from fermented milk and were used in the study against the target bacteria ( Salmonella and S. aureus ) isolated from meat products for biopreservation of meat products. Lactococcus lactis subsp. lactis was isolated from local fermented milk. The antibacterial activity of the L . lactis subsp. lactis was determined against S. typhimurium , S. aureus and Escherichia coli ( E. coli ) using agar well, spot on lawn and mix culture study methods. The probiotics characteristics were analysed by exp osing them to a range of pH, bile salt, salt (NaCl) and temperature s . Bacteriocin from the isolate ( L . lactis subsp. lactis ) was partially purified and used for the biopreservation of poultry meat against the target bacteria ( Salmonella and S. aureus ). The L. lactis was found active against both of the target bacteria with higher e ffect on S. aureus as compare d to Salmonella . The partially purified bacteriocin was found active against the target bacteria in poultry meat . T he target bacterial count was reduc ed from 10 5 – 10 6 CFU/mL to 10 1 CFU/mL in case of S . aureus and 10 2 CFU/mL in case of S . typhimurium after three days of incubation at temperature ( 2±2 ° C). Protective culture study of L . lactis subsp. lactis was found e ffective to reduce the number of foodb orne pathogens in poultry meat.A total number of 209 raw poultry meat samples were collected and studied in this study. Out of which 5.26% samples were found contaminated with Salmonella and 18.18% with S. aureus . All the Salmonella and S. aureus isolates were found resistant to at least one antibiotic. The Salmonella isolates (73%) showed resistance to tetracycline, while S. aureus isolates were found highly resistant to tetracycline equal to 45%. Some of the Salmonella isolates showed multi - drug resistan ce to almost five antibiotics out of nine antibiotics used in the study. Multidrug resistant S. aureus isolates were also found in the study. Ready - to - eat chilled poultry meat samples (181) were collected from different supermarket s of greater Bangkok regi on. All the samples were examined for the presence of S. aureus and Salmonella species. The Salmonella isolates were confirmed with API 20E kit, polyvalent antisera “O” and “H” and 16s rDNA. Only one (0.55%) sample was found contaminated with Salmonella , s howed 99.8% phylogenetic similarity with Salmonella enterica . Risk assessment analysis in context of foo d safety at consumer levels was conducted. The temperature ≤ 4 °C was found effective for storage as the log number of microorganism s were decreasing. The microwave treatment revealed that the shape, structure and weight of the meat pieces had direct impac t on pathogens reduction. The treatment time 30 – 60 s in microwave oven was found effective for the elimination of target bacteria in meat pieces with weight below 90 g, whereas the pieces with higher weight need ed more time for total bacterial elimination. Salmonella enterica showed the potential to pass through the simulated gastric fluid . Out of all 181 samples , 11 (6%) was found contaminated with S. aureus . Out of total 11 isolates, 10 (91%) of the S. aureus isolates were found resistant to at least one antibiotic used in this study. Two isolates were found resistant to methicillin. Lactococcus lactis subsp. lactis was used as bio - control agent. All the isolates were found sensitive to its metabolites. The zones of inhibitions were found in the range of 5.0 ± 0 .70 and 19.8 ± 0 .83 against the majority of the isolates. Lactococcus lactis subsp. lactis as a competitive flora in mixed culture (LAPTg broth) and protective culture in poultry meat were found effective against S. aureus isolates. The growth of S. aureus isolates was negative after 32 h incubation in mixed culture. The number of S. aureus isolates was substantially reduced to log one CFU/g after 25 days of incubation in protective culture study. The pH of the test samples was also decreased abruptl y with the passage of time. Zinc oxide nanoparticles were prepared and tested against the target bacteria both in - vitro and in challenge study. The antibacterial activity of the nanoparticles was determined in solid and liquid media using nutrient agar and broth. Zinc oxide nanoparticles loaded active film of calcium alginate was prepared for active packaging against the Salmonella and S . aureus . The film was used as an active packaging (a challenge study) in ready - to - eat poultry meat against same pathogens , and reduced the number of inoculated target bacteria from log seven to zero within 10 days of its incubation at 8 ± 1 ° C. This study confirmed the presence of Salmonella and S. aureus in raw and ready - to - eat poultry meat and its products. Lactococcus la ctis subsp. lactis and zinc oxide nanoparticles showed antibacterial potential against the target bacteria and can be used as a source of biopreservation and bio - control in poultry meat products. |
| Year | 2014 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. FB-14-01 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| 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) | Athapol Noomhorm;Datta, Avishek; |
| Scholarship Donor(s) | University of Balochistan (UoB) , Quetta , Pakistan;Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2014 |