Production of cellulosic ethanol and value-added products from corn fiber

Abstract

Corn fiber, a by-product from the corn processing industry, mainly composed of residual starch, cellulose, and hemicelluloses, is a promising raw material for producing cellulosic ethanol and value-added products due to its abundant reserves and low costs of collection and transportation. Now, several technologies for the production of cellulosic ethanol from corn fiber have been reported, such as the D3MAX process, Cellerate™ process, etc., and part of the technologies have also been used in industrial production in the United States. The ethanol yields range from 64 to 91% of the theoretical maximum, depending on different production processes. Because of the multicomponent of corn fiber and the complex structures highly substituted by a variety of side chains in hemicelluloses of corn fiber, however, there are many challenges in cellulosic ethanol production from corn fiber, such as the low conversion of hemicelluloses to fermentable sugars in enzymatic hydrolysis, high production of inhibitors during pretreatment, etc. Some technologies, including an effective pretreatment process for minimizing inhibitors production and maximizing fermentable sugars recovery, production of enzyme preparations with suitable protein compositions, and the engineering of microorganisms capable of fermenting hexose and pentose in hydrolysates and inhibitors tolerance, etc., need to be further developed. The process integration of cellulosic ethanol and value-added products also needs to be developed to improve the economic benefits of the whole process. This review summarizes the status and progresses of cellulosic ethanol production and potential value-added products from corn fiber and presents some challenges in this field at present.

Mid–Long Chain Dicarboxylic Acid Production via Systems Metabolic Engineering: Progress and Prospects

“…The first step of this process requires the degradation of lignocellulose into monosaccharides or aromatic compounds via enzymatic or chemical methods. This is followed by the use of different microbial metabolic pathways to produce lactic acid, 3-hydroxypropionic acid, succinic acid, fatty acids, DDA, and other products. − However, the formation of certain toxic intermediates during the pretreatment of lignocellulose affects the growth of microorganisms, reducing the conversion rate and increasing production costs. , Therefore, the development of efficient pretreatment processes to reduce the generation of toxic and harmful substances could alleviate the problem of resource depletion caused by the use of fossil fuel-derived materials such as alkanes for the production of long-chain DCAs. Further, it could also reduce the use of sugar-based carbon sources.…”

“…112−114 However, the formation of certain toxic intermediates during the pretreatment of lignocellulose affects the growth of microorganisms, reducing the conversion rate and increasing production costs. 115,116 Therefore, the development of efficient pretreatment processes to reduce the generation of toxic and harmful substances could alleviate the problem of resource depletion caused by the use of fossil fuelderived materials such as alkanes for the production of longchain DCAs. Further, it could also reduce the use of sugarbased carbon sources.…”

Integrating 1G with 2G Bioethanol Production by Using Distillers’ Dried Grains with Solubles (DDGS) as the Feedstock for Lignocellulolytic Enzyme Production

“…Approximately 5% of the glucose is converted into yeast cells which are extracted into thin stillage and approximately 15-30% of the thin stillage is recycled back into the bioethanol production process while the rest is mixed into DDGS after drying [14,17]. However, there are other parts of corn crops that are wasted or turned into low agriculture products such as corn stover [18]. The main issue with 1G ethanol production is sustainability in terms of making more ethanol from all of the parts of the crops and not just from the grains.…”

Advancing Thermophilic Anaerobic Digestion of Corn Whole Stillage: Lignocellulose Decomposition and Microbial Community Characterization

“…Most studies on pretreatment have focused on improving the properties of DDGS (e.g., nutritive value) as an animal feed [9,10]. Since corn fiber contains approximately 35-40% hemicellulose, 15-20% cellulose, and 5-10% lignin [22,23], a tailored pretreatment could potentially make the cellulose and hemicellulose more amenable to subsequent bioprocessing by AD. This could potentially make more valuable renewable energy to supplement the operations of the bioethanol plant and lower costs while decarbonizing the whole operation.…”