Valorization of waste streams and C1 gases for sustainable food nutrients and value-added compounds production: Acetate as a promising intermediate

Abstract

Resource recovery from waste streams and C1 gaseous substrates (CO₂, CO and CH₄) are of extensive interest due to the insufficient utilization and threats to the environment. From a perspective of sustainability, valorization of waste streams and C1 gases into target energy-rich value-added products in a sustainable way offers tempting approaches for simultaneously alleviating the environmental problems and achieving a circular carbon economy, while it still suffers from the complicated compositions of feedstocks or the low solubility of gaseous feeds. Recently, a C2 feedstock-based biomanufacturing serving acetate as potential next-generation platform has received much attention, where different gaseous or cellulosic wastes are recycling into acetate and then be further processed into a wide range of valuable long-chain compounds. The different alternative waste-processing technologies that are being developed to generate acetate from various wastes or gaseous substrates are summarized, in which gas fermentation and electrochemical reduction from CO₂ represent the most promising routes for achieving high acetate yield. The recent advances and innovations in metabolic engineering for acetate bioconversion into various bioproducts ranging from food nutrients to value-added compounds were then highlighted. The challenges and promising strategies to reinforce microbial acetate conversion were also proposed, which conferred a new horizon for future food and chemical manufacturing with reduced carbon footprint.

Keywords: Acetate bioconversion; Carbon fixation; High-value biochemicals; Microbial cell factories; Waste recycling.