Enhanced mass transfer rate and solubility of methane via addition of alcohols for Methylosinus trichosporium OB3b fermentation

Biological conversion of methane to polyhydroxyalkanoates: Current advances, challenges, and perspectives

Methane emissions and plastic pollution are critical global challenges. The biological conversion of methane to poly-β-hydroxybutyrate (PHB) not only mitigates methane emissions but also provides biodegradable polymer substitutes for petroleum-based materials used in plastics production. This work provides an early overview of the methane-based PHB advances and discusses challenges and related strategies. Recent advances of PHB, including PHB biosynthetic pathways, methanotrophs, bioreactors, and the performances of PHB materials are introduced. Major challenges of methane-based PHB production are discussed in detail; these include low efficiency of methanotrophs, low gas-liquid mass transfer efficiency, and poor material properties. To overcome these limitations, various approaches are also explored, such as feast-famine regimes, engineered microorganisms, gas-permeable membrane bioreactors, two-phase partitioning bioreactors, poly-β-hydroxybutyrate-co-hydroxyvalerate synthesis, and molecular weight manipulation.

Methane to bioproducts: the future of the bioeconomy?

Methanotrophs have been studied since the 1970s, but interest has increased tremendously in recent years due to their potential to transform methane into valuable bioproducts. The vast quantity of available methane and the low price of methane as natural gas have helped to spur this interest. The most well-studied, biologically-derived products from methane include methanol, polyhydroxyalkanoates, and single cell protein. However, many other high-interest chemicals such as biofuels or high-value products such as ectoine could be made industrially relevant through metabolic engineering. Although challenges must be overcome to achieve commercialization of biologically manufactured methane-to-products, taking a holistic view of the production process or radically re-imagining pathways could lead to a future bioeconomy with methane as the primary feedstock.