Editorial: Editors’ showcase: fuels and chemicals

Throughout its history, industrial microbiology has answered multiple challenges; food and beverage, antibiotics, pharmaceuticals, nutraceuticals, biomaterials, and fuels and chemicals, often with billions of dollars' worth of impact on markets and society. But these e>orts pale in comparison to the challenge of planetary-scale carbon management, which must balance circularizing a carbon economy with sequestering excess environmental carbon. Biorefineries integrating carbon capture with diverse bioproduct markets o>er our best route to stabilize an unbalanced global carbon cycle while powering a robust and equitable bioeconomy.Earth's responses to changing carbon flux take place over geological timescales. Human activities are more acute, impactful perturbations of this cycle and the planet's adaptation is clearly lagging. Fossil fuels have driven human advancement, but no matter how beneficial, that scale of influence has significant impacts. Greenhouse gases, climate change, ocean acidification, microplastics, soil depletion, aquatic eutrophication, air quality, water pollution, and acid rain are all linked to fossil fuel use. Wealth and power are concentrated alongside fossil fuel reserves at national, regional, corporate, and individual levels. Non-uniform distribution of these resources stresses energy justice and equity. Social, political, and economic divisions are created and reinforced by access and availability of fossil energy.Advances in microbiology o>er accelerated routes to adapt biology to new and rapidly changing carbon compounds. Molecular biology, genetic engineering, and all the -omics provide opportunities to fundamentally change how carbon cycles through our world.Coupling carbon management to a circular bioeconomy is driven by the combined economics. As carbon credits and carbon-valuation routes develop, economics will tilt towards a circular bioeconomy based on a balance of products vs. sequestration and away from fossil fuels. Biorefineries, powered by industrial microbiology, o>er an alternative to fossil-based industries while managing carbon at a global scale. A broad portfolio of conversion processes applicable to a diverse range of feedstocks and a suite of bioproducts will ensure that biorefinery options are available across all social, political, and geographical landscapes.In Frontiers in Industrial Microbiology -Fuels and Chemicals inaugural Editors Showcase, four articles highlight the importance and potential of industrial microbiology to enable advanced biorefineries.In Perspectives on biorefineries in microbial production of fuels and chemicals, Decker et al summarize biorefinery e>orts and indicate key learnings and crucial opportunities to expand from a narrowly focused, single product-centric process to a cascading biorefinery approach where carbon management and bioeconomy markets drive utilization of diverse feedstocks by multiple processes. A true biorefinery should balance managing carbon while providing biofuels and bioproducts to a robust bioeconomy. A larger portfolio of bioproducts provides more adaptable market economics. Having a range of conversion technologies available to be tuned to local feedstocks and advantaged markets will broaden bioconversion and expand the bioeconomy, leading to increased opportunities and more equitable energy, fuel, and bioproduct generation and distribution.Wei and Himmel o>er insight into more e>icient industrial microbiology through Continuous multimodal technologies in industrial microbiology: potential for achieving high process performance and agility. They detail how disconnecting biocatalysis steps normally carried out simultaneously in fermentation into discrete unit operations can improve e>iciency and yield while reducing costs. Enabled by advances in membrane separations and solvent extraction, discrete steps can be optimized by chemical, electrochemical, or biological catalysis. Temperature, pH, and redox can be adjusted separately for each step, increasing overall e>iciency while reactor size and flow rate adjusts for di>erences in unit operations flux. Immobilized enzymes, whole cell catalysis, and cell-free systems can be designed with state-of-the-art tools for processes ranging from single step transformations to entire metabolic pathways.Lignocellulosic biomass has been touted for decades as a renewable, low carbon alternative to fossil fuels. Pretreatments to get the polysaccharides often result in degradation and inhibitor formation, limiting fermentability of the hydrolysate. This often requires additional process steps to detoxify and clean up the resultant sugars, adding cost. In Metabolic engineering in lignocellulose biorefining for high-value chemicals: recent advances, challenges, and outlook for enabling a bioeconomy, Lama et al have showcased a comprehensive review of alternative biochemicals from lignocellulose that have been enabled by metabolic engineering. They point out key advances in genetic tools that have advanced microbial tolerance of hydrolysate, co-utilization of various sugars, and expanded microbial conversion of multiple hydrolysate components to diverse products. Having multiple options for products and conversion paths for varied monomers is essential for flexibility in adapting to changing markets and di>erent feedstocks.Biorefineries are not just for carbon. Hydrogen has long been considered an "ideal" fuel, however production is challenging. In Biohydrogen: prospects for industrial utilization and energy resiliency in rural communities, Mandalika et al discuss opportunities to decarbonize industrial processes and provide energy security and resiliency when traditional energy sources are too expensive or lost due to infrastructure failure. The authors clarify the decarbonization advantages of biohydrogen made through dark fermentation or steam reforming of biomethane in avoided carbon by displacing fossil fuel feedstocks and through biological generation routes. By proposing to couple bioH2 production from local waste feedstocks to production of fertilizer and sequestered carbon, the authors provide yet another option for biorefineries to impact markets by tackling energy justice and carbon management while stimulating a local bioeconomy and improving local ecosystems. Future biorefineries will look very di>erent from today's linear operations. Advances in industrial microbiology developed through new genetic tools, novel operational paradigms, step-wise process optimization, better models and artificial intelligence, broadening of feedstocks, integration of carbon management and sequestration, and market advantages through diverse product portfolios will transform the biorefinery landscape. New configurations hold the promise to break the fossil fuel-dependency of energy and economy availability and a>ordability and directly impact the lives of everyday people as well as the global ecology. As global society comes to grips with our influence on the carbon cycle, biorefineries o>er a clear route to economically co-manage carbon and a circular bioeconomy while promoting energy justice and equity. This vision is going to take commitment and e>ort to develop, with industrial microbiology being the critical technology for its success.This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy LLC, for the U.S. Department of Energy (DOE) under contract no. DE-AC36-08GO28308. Funding was provided by the U.S. DOE, OOice of Energy EOiciency and Renewable Energy Bioenergy Technologies OOice. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.