Turning food waste to microbial lipid towards a superb economic and environmental sustainability: An innovative integrated biological route

With the drastic growth of the economic and population, the global energy requirement is on the rise, and massive human and material resources have been put into the development of alternative and renewable energy sources. Biodiesel has been recognized as a green and sustainable alternative energy, but the raw materials-associated source and cost makes it difficult to achieve large-scale commercial production. Microbial lipids (ML) produced by oleaginous microbes have attracted more and more topics as feedstocks for biodiesel production because of their unique advantages (fast growth cycle, small footprint and so on). However, there are still many problems and challenges ahead towards commercialization of ML-based biodiesel, especially the cost of feedstock for ML production. Food waste (FW) rich in organic matters and nutrients is an excellent and almost zero-cost feedstock for ML production. However, current biological routes of FW-based ML production have some defects, which make it impossible to achieve full industrialization at present. Therefore, this review intends to provide a critical and comprehensive analysis of current biological routes of FW-based ML production with the focus on the challenges and solutions forward. The biological routes towards future FW-based ML production must be able to concurrently achieve economic feasibility and environmental sustainability. On this condition, an innovative integrated biological route for FW-based ML production has thus been put forward, which is also elucidated on its economic and environmental sustainability. Moreover, the prospective advantages, limitations and challenges for future scale-up of FW-based ML production have also been outlined, together with the perspectives and directions forward.