Energy and carbon-efficient one-pot bioprocessing for upcycling non-sterile food waste into high-yield 2,3-butanediol production.

Food waste is a significant global issue whose unsatisfactory management leads to greenhouse gas emissions and loss of resources. Repurposing food waste from landfills to sustainable bioprocessing supports the circular bioeconomy. This study explores converting non-sterile food waste into 2,3-butanediol (2,3-BDO), a versatile chemical, using a one-pot bioprocessing (OPB) method which integrates enzymatic saccharification and fermentation to improve efficiency and reduce costs. Optimizing solid-to-liquid ratios (20 % w/v), inoculum sizes (10 % vol.) of Klebsiella pneumoniae strain PM2, and fermentation strategies (batch and fed-batch) maximizes yields. Fed-batch cultivation with constant feeding at 1.5 mL/h for 42 h reached a maximum titer of 78.4 g/L (85.5 % of the theoretical yield), a 33.5 % improvement over the benchmark separate hydrolysis and fermentation (SHF) process. Compositional variability of food waste (glucose r = 0.99) also greatly impacted 2,3-BDO production. Energy and carbon footprint analyses reveal that food waste biorefineries offer a significant reduction in energy consumption with a -0.86 kWh/kg-FW and carbon benefits of 1.41 kgCO2-eq./kg-FW over traditional disposal methods, reducing greenhouse gas emissions by 97.3 % compared to sugar biorefineries and promoting a circular economy. The findings underscore the potential of food waste as a sustainable feedstock for bioproducts, advocating for policy support to advance bioconversion technologies.