Food waste (FW) management by biological process is more attractive and eco-friendly approach than thermo-chemical conversion or landfilling. However, FW composition and physico-chemical and biological characteristics affect the overall biological process in terms of product yield and degradation rate. To overcome this major bottle-neck, the pretreatment of FW is proposed. Therefore this review aims to provide a comprehensive summary of the importance of pretreatment of FW with respect to FW management by anaerobic digestion (AD) and dark fermentation (DF). It also reviews the existing knowledge gaps and future research perspectives for better integration of FW pretreatments for AD and DF, which should include (i) the preservation of carbon mass through freeze and thaw, or drying; and (ii) improve the carbon accessibility through particle size reduction and thermal pretreatments for high-rate bioenergy recovery.

Fibers come from natural and fossil resources and are an essential commodity widely used by textile industries. Considering current supply and future demands, the repurposing of agricultural residues into fibers is an eco-friendly, attractive option that might mitigate environmental pollution. In this review, we have summarized multiple alternate secondary sources for fiber production, with a case study using banana plant residual biomass, a common agricultural waste in many developing countries. Specifically, in this review we have compared the different processing methods, e.g., chemical, mechanical, or biological methods, for repurposing agricultural residual biomass (including banana waste) into fibers. The development and analysis of an integrated biorefinery approach is needed to promote the fiber production from various agro-residual biomasses within the framework of circular bioeconomic concepts.

Aerobic methane-oxidizing bacteria of the Alphaproteobacteria have been found to express a novel ribosomally synthesized post-translationally modified polypeptide (RiPP) termed methanobactin (MB). The primary function of MB in these microbes appears to be for copper uptake, but MB has been shown to have multiple capabilities, including oxidase, superoxide dismutase and hydrogen peroxide reductase activities, the ability to detoxify mercury species, as well as acting as an antimicrobial agent. Herein, we describe the diversity of known MBs as well as the genetics underlying MB biosynthesis. We further propose based on bioinformatics analyses that some methanotrophs may produce novel forms of MB that have yet to be characterized. We also discuss recent findings documenting that MBs play an important role in controlling copper availability to the broader microbial community, and as a result can strongly affect the activity of microbes that require copper for important enzymatic transformations, e.g. conversion of nitrous oxide to dinitrogen. Finally, we describe procedures for the detection/purification of MB, as well as potential medical and industrial applications of this intriguing RiPP.