||Microbial Community Analysis of Restaurant Cutting Boards in Seri Kembangan，Malaysia and the Identification of Factors Associated with Foodborne Bacteria Growth
Noor, Azira Binti Abdul Mutalib
Foodborne diseases have been associated with microorganisms like bacteria,fungi, viruses and parasites. Most commonly, the outbreaks take place due to theingestion of pathogenic bacteria like Salmonella typhi, Escherichia coli,Staphylococcus aureus, Vibrio cholerae, Campylobacter jejuni, and Listeriamonocytogens. The disease usually happens as a result of toxin secretion of themicroorganisms in the intestinal tract of the infected person. Usually, the level ofhygiene in the food premises reflect the quality of the food item, hence restaurantor stall with poor sanitary condition is said to be the contributor to food poisoningoutbreak. In Malaysia, food poisoning cases are not rare because the hot andhumid climate of this country is very suitable for the growth of the foodbornebacteria, thus the government implements strict rules to ensure workers andowners of food premises prioritize the cleanliness of their working area. Studies offood safety are important, and the results can give information about the types ofmicroorganisms, and factors that affect their growth. The result is crucial todetermine how the spread of foodborne bacteria can be controlled safely and theoutbreak can be reduced.This study adopts the pyrosequencing technique to identify bacteria present on 26kitchen cutting boards collected from different grades of food premises aroundSeri Kembangan, Malaysia. The analysis generated 452,401 of total reads ofOTUs with an average of 1.4 × 107 bacterial cells/cm2. Proteobacteria, Firmicutesand Bacteroidetes were identified as the most abundant phyla in the samples.Taxonomic richness was generally high with >1000 operational taxonomic units(OTUs) observed across all samples. The highest appearance frequencies (100%)were OTUs closely related to Enterobacter sp., E. aerogenes, Pseudomonas sp.and P. putida. Several OTUs were identified most closely related to knownfoodborne pathogens including Bacillus cereus, Cronobacter sakazaki, C.turisensis, Escherichia coli, E. coli O157: H7, Salmonella bongori, S. enterica, S.paratyphi, S. typhi, S. typhimurium and Yersinia enterocolitica ranging from 0.005-0.68% relative abundance. The condition and grade of the food premises on athree-point cleanliness scale did not correlate with the bacterial abundance andtype. To add, the community composition of FBB based on premise grades alsoshowed no similarity. Regardless of the status and grades, all food premises havethe same likelihood to introduce foodborne bacteria from cutting boards to theirfoods and must always prioritize the correct food handling procedure, in order toavoid an unwanted outbreak of foodborne illnesses.This study further analyzes the effect that might be created by othermicroorganisms in order to support or suppress the number of pathogenic bacteria.The analysis found that high bacteria group contains a low percentage of FBBcompared to low bacteria group. The results also showed that although premisegrade C contains significantly higher numbers of overall bacteria, it did notinfluence the number of FBB. The combinations of Clostridiales, Flavobacteriales,and Lactobacillales in the high bacteria group were found to have significantnegative associations with FBB. Despite the finding that Citrobacter, Enterobacter,Erwinia, Klebsiella and Pantoea had significant positive correlation with FBB, thepopulation of these bacteria was small. This study suggested that highbackground biota and a combination of different bacteria have an advantage inpreventing FBB from reaching the infectious dose level thus, considered harmless.
九州工業大学博士学位論文 学位記番号:生工博甲第258号 学位授与年月日:平成28年3月25日
1: INTRODUCTION|2: LITERATURE REVIEW|3: MATERIALS AND METHODS|4: ANALYSIS OF MICROBIAL COMMUNITY AND FOODBORNE PATHOGENIC BACTERIA AND THEIR CORRELATION WITH GRADES OF FOOD PREMISES|5: ECOLOGICAL RELATIONSHIP OF MICROBIAL COMMUNITY AND FACTORS ASSOCIATED WITH THE PRESENCE OF FOODBORNE BACTERIA|6: CONCLUDING REMARKS, AND RECOMMENDATIONS FOR FUTURE RESEARCH