Production of Bio-Derived Fuels and Chemicals

The great demand for, and impending depletion of petroleum reserves, the associated impact of fossil fuel consumption on the environment, and volatility in the energy market have elicited extensive research on alternative sources of traditional petroleum-derived products such as biofuels and bio-chemicals. Fossil oil is largely associated with gasoline, however, approximately 6000 petroleum-derived products currently exist in the market, with diverse applications. Ironically, while biofuels are more popular with the public, the other petroleum-derived products have not attracted similar attention despite the vast economic values for these products. Thus, given the finite nature of petroleum, it is timely to deploy substantial resources and research efforts to the development of renewable chemicals (similar to the efforts devoted to biofuels). Theoretically, bio-production of gasoline-like fuels and the 6000 petroleum-derived products is within the realm of possibility, because aquatic and terrestrial ecosystems harbor an abundance of diverse microorganisms, capable of catalyzing unlimited numbers of chemical reactions. Moreover, the fields of synthetic biology and metabolic engineering have evolved to the point that a wide range of microorganisms can be induced or manipulated to catalyze foreign or vastly improve indigenous biosynthetic reactions. Hence the need for this Special Issue to provide a platform for highlighting recent progress on fuel and chemical production from renewable resources such as lignocellulosic biomass. This Special Issue, titled Biofuels and Biochemicals Production, consists of 13 articles in which eleven and two are research and review articles, respectively. The Special Issue covers themes on the development of different methodologies for efficient conversion of lignocellulosic biomass, agricultural wastes, carbon dioxide, and carbon monoxide to fuels (ethanol, butanol, hydrogen), chemicals (2,3-butanediol, acetone, acetic acid), and enzymes (cellulase). Some of the articles in this Special Issue provide recent advancements on pretreatment and hydrolysis of lignocellulosic biomass (LB) to lignocellulosic biomass hydrolysates (LBH), challenges associated with LBH utilization, and recommended mitigation strategies. Consistent with the Biofuels and Biochemicals Production theme, the research groups of Moreno [1] and Rosentrater [2] evaluated different pre-treatment technologies for efficient disruption and separation of lignin from the hemicellulose component of the LB to facilitate enzymatic hydrolysis of the carbohydrate fraction to fermentable sugars. By combining acid-catalyzed steam explosion and alkali-based extrusion process, the protective lignin structure of barley straw was disrupted, which resulted in hydrolysates with significant amounts of glucan and hemicellulose sugars, minimal concentrations of lignocellulose derived microbial inhibitory compounds (LDMICs), and a solid residue with significant amounts of lignin [1]. In addition, the Low-Moisture Anhydrous Ammonia (LMAA) pre-treatment method enhanced enzymatic hydrolysis of the cellulose component of the LB to glucose, thus, the potential is great for LMAA for LB pre-treatment [2]. Consistent with enzymatic hydrolysis of the cellulose component of LB, Bajaj’s group contributes an article that highlights the capacity of Bacillus subtilis SV1 to use agroindustrial residues (LB) as carbon and nitrogen sources for