A methanotroph-based biorefinery: Potential scenarios for generating multiple products from a single fermentation

Abstract

Methane, a carbon source for methanotrophic bacteria, is the principal component of natural gas and is produced during anaerobic digestion of organic matter (biogas). Methanotrophs are a viable source of single cell protein (feed supplement) and can produce various products, since they accumulate osmolytes (e.g. ectoine, sucrose), phospholipids (potential biofuels) and biopolymers (polyhydroxybutyrate, glycogen), among others. Other cell components, such as surface layers, metal chelating proteins (methanobactin), enzymes (methane monooxygenase) or heterologous proteins hold promise as future products. Here, scenarios are presented where ectoine, polyhydroxybutyrate or protein G are synthesised as the primary product, in conjunction with a variety of ancillary products that could enhance process viability. Single or dual-stage processes and volumetric requirements for bioreactors are discussed, in terms of an annual biomass output of 1000 tonnesyear(-1). Product yields are discussed in relation to methane and oxygen consumption and organic waste generation.

On the Edge of Research and Technological Application: A Critical Review of Electromethanogenesis

“…In addition, the methanotroph community is rather interesting from the commercial point of view since recent studies have suggested the new methanotroph-based biorefinery concept [186]. Methanotrophs are able to generate multiple products from methane fermentation such as feed supplement, ectoine, sucrose, biofuels, biopolymers, surface layers, metal chelating protein, enzymes and/or heterologous proteins [187]. Nowadays, companies such as Mango Materials are commercializing biomethane to bioplastics [128] since a life cycle analysis has recently shown that biomethane conversion to bioplastics is carbon neutral and energetically and economically feasible [188].…”

Bacterial cytosolic proteins with a high capacity for Cu(I) that protect against copper toxicity

“…Some methanotrophs, including Methylosinus trichosporium OB3b, can use a soluble iron sMMO when copper levels are low, with switchover regulated by copper18. MMOs and methanotrophs have great potential for biotransformations giving a range of products, in bioremediation and for mitigating the release of methane, a potent greenhouse gas, to the atmosphere192021. Understanding copper handling and the expression of either pMMO or sMMO is essential for all these biotechnological applications.…”

Ectoine bio-milking in methanotrophs: A step further towards methane-based bio-refineries into high added-value products

“…It retails in the pharmaceutical industry at approximately US$1000 kg -1 and its production at a global scale accounts for approx. 15000 tones year -1 [9]. In this regard, biotechnologies for the production of ectoine have received increasing attention in the last two decades due to their simpler and highly specific product synthesis in comparison with chemical processes [8].…”