Characterisation of Household Food Waste Microbial Communities During its Storage and Processing

Food waste (FW) is ubiquitous across the globe and is predicted to grow substantially due to increasing population pressures and unsustainable consumption patterns. While its environmental impacts such as greenhouse gas emissions and nutrient loss are well documented, yet the influence of FW on microbial dynamics within waste management environments remains largely unexplored. In particular, the microbial communities associated with household food waste has not been previously studied for their role in generation of bioaerosols and potential dissemination of antimicrobial resistance (AMR). To address this research gap, laboratory simulations and field investigations were undertaken to study the microbial communities inhabiting both, individual and mixed household FW, and a composting facility. The characterisation of both individual and mixed household FW microbial communities revealed that prolonged storage leads to significant shifts in microbial community composition and abundance. These microbial shifts, driven by various factors including FW composition and its physicochemical properties, facilitated the proliferation of potential pathogens and the released bioaerosols, posing health risks to individuals in contact with or proximity to FW. The findings also challenged the efficacy of conventional sanitation methods, such as bin liners and disinfectants, in controlling microbial hazards, emphasizing the need for innovative strategies to mitigate potential risks. Furthermore, the field investigations, examining the microbial communities present in an in-vessel composting facility, showed significant microbial transformations that occur during the composting process. The results demonstrated the effectiveness of composting in reducing pathogen loads, however, the isolation of bacteria from both solid and air samples which displayed high prevalence of AMR, particularly against broad spectrum antibiotics, raised concerns about the long-term fate of AMR and potential pathogens in compost. Overall, the results from this thesis demonstrated that the food waste harbours complex communities of microorganisms which can be aerosolised and thus can potentially present a risk to public health, particularly via spread of resistant strains. The detection of antimicrobial-resistant microorganisms in both household FW and compost underlines the potential for these environments to act as reservoirs that could be explored further in future to gain additional insights into underlying transmission pathways for AMR.