Jian Shi

University of Kentucky | UKY · Department of Biosystems & Agricultural Engineering

Background Biomass pretreatment using certain ionic liquids (ILs) is very efficient, generally producing a substrate that is amenable to saccharification with fermentable sugar yields approaching theoretical limits. Although promising, several challenges must be addressed before an IL pretreatment technology can become commercially viable. One of t...

The enzymatic hydrolysis of cellulose is a thermodynamically challenging catalytic process that is influenced by both substrate‐related and enzyme‐related factors. In this study, a proteolysis approach was applied to recover and clean the partially converted cellulose at the different stages of enzymatic hydrolysis to monitor the hydrolysis rate as...

Lignin plays important biological functions in plant cell walls, but also contributes to the recalcitrance of the walls to deconstruction. In recent years, genetic modification of lignin biosynthesis pathways has become one of the primary targets of plant cell wall engineering. In this study, we used a combination of approaches to characterize the...

This chapter focuses on the recent development of biomass pre-treatment using ionic liquids (ILs). Lignocellulosic biomass, such as wood, grass, and agricultural residues, are a promising alternative source for the production of renewable fuels and chemicals. Because of the inherent recalcitrance, pre-treatment of lignocellulosic biomass is essenti...

The objective of this study was to understand how the non-microbial factors of L-AD effluent affected the microbiome composition and successions in the SS-AD digesters using both Illumina sequencing and qPCR quantification of major genera of methanogens. The SS-AD digesters started with a feedstock/total effluent (F/Et) ratio 2.2 (half of the efflu...

The use of certain ionic liquids (ILs) as pretreatment solvents for lignocellulosic biomass has gained great interest in recent years due to the IL's capacity for efficient cellulose dissolution in aqueous solution as compared to other common pretreatment techniques. A fundamental understanding on how these ILs in aqueous environments act on cellul...

Alcohols of increasing alkyl chain length were investigated as precipitants in an ionic liquid (IL) pretreatment system. Switchgrass samples pretreated by 1-ethyl-3-methylimidazolium acetate were characterized after the use of different alkyl chain lengths of alcohols as antisolvents. The resulting IL-pretreated switchgrass (PSG) samples were chara...

In order to enable the large-scale production of biofuels or chemicals from lignocellulosic biomass, a consistent and affordable year-round supply of lignocellulosic feedstocks is essential. Feedstock blending and/or densification offers one promising solution to overcome current challenges on biomass supply, i.e., low energy and bulk densities and...

Producing concentrated sugars and minimizing water usage are key elements in the economics and environmental sustainability of advanced biofuels. Conventional pretreatment processes that require a water-wash step can result in losses of fermentable sugars and generate large volumes of wastewater or solid waste. To address these problems, we have de...

Significance Ionic liquids (ILs) have unique properties applicable to a variety of industrial processes. Nearly universal solvating capabilities, low vapor pressures, and high thermal stabilities make these compounds ideal substitutes for a wide range of organic solvents. To date, the best performing ILs are derived from nonrenewable sources such a...

Biomass pretreatment with certain ionic liquids (IL) can be highly effective at generating a substrate that can be easily saccharified into fermentable sugars with high yields. In order to improve overall process economics, using mixtures of these ILs with water are more favored over the use of anhydrous IL; however, the solvent property of IL–wate...

Background Ionic liquid (IL) pretreatment could enable an economically viable route to produce biofuels by providing efficient means to extract sugars and lignin from lignocellulosic biomass. However, to realize this, novel IL-based processes need to be developed in order to minimize the overall production costs and accelerate commercial viability....

Glycoside hydrolases (GHs) are critical to cycling of plant biomass in the environment, digestion of complex polysaccharides by the human gut microbiome, and industrial activities such as deployment of cellulosic biofuels. High-throughput sequencing methods show tremendous sequence diversity among GHs, yet relatively few examples from the over 150,...

Certain ionic liquids (ILs) offer a potentially more sustainable and environmentally responsible alternative to organic solvents for many industrial applications, including biorefineries, where they are used to pretreat lignocellulose. To gain a more robust understanding of the roles of cations and anions in the process, we monitored the impact of...

Cost is one of the main impediments to ionic liquid (IL) utilization in a biorefinery context. Cost effective ionic liquids were designed to demonstrate that ILs can be competitive solvents in a bio-refinery, and tested for their efficiency as biomass pretreatment media. In addition the ionic liquids were designed to be effective in hydrous conditi...

Biomass pretreatment using certain ionic liquids (ILs), such as 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), can be highly effective at reducing the recalcitrance of lignocellulosic biomass to enzymatic degradation. However, current commercial enzyme cocktails, derived from filamentous fungi and developed for dilute acid pretreatment, are in...

Background: Lignocellulosic biorefineries must be able to efficiently process the regional feedstocks that are available at cost-competitive prices year round. These feedstocks typically have low energy densities and vary significantly in composition. One potential solution to these issues is blending and/or densifying the feedstocks in order to cr...

Four lignocellulosic biomass feedstocks including corn stover, wheat straw, yard waste and leaves were evaluated for methane production via solid-state anaerobic digestion (SS-AD). Results showed that the highest methane yield was attained for corn stover (81.2 L kg−1 volatile solids (VS)), followed by wheat straw (66.9 L kg−1 VS), leaves (55.4 L k...

Effluents from three liquid anaerobic digesters, fed with municipal sewage sludge, food waste, or dairy waste, were evaluated as inocula and nitrogen sources for solid-state batch anaerobic digestion of corn stover in mesophilic reactors. Three feedstock-to-effluent (F/E) ratios (i.e., 2, 4, and 6) were tested for each effluent. At an F/E ratio of...

Microbial pretreatment of lignocellulosic feedstocks is an environment friendly alternative to physio-chemical pretreatment methods. A better understanding of the interactive fungal mechanisms in biological systems is essential for enhancing performance and facilitating scale-up and commercialization of this pretreatment technique. In this study, m...

Corn stover fractions (leaves, cobs, and stalks) were studied for enzymatic digestibility after pretreatment with a white rot fungus, Ceriporiopsis subvermispora. Among the three fractions, leaves had the least recalcitrance to fungal pretreatment and the lignin degradation reached 45% after 30 days of pretreatment. The lignin degradation of stalks...

Burn, baby, burn! A new bifunctional catalyst (Ga/ZSM-5) displays increased selectivity for the production of aromatic compounds during the catalytic fast pyrolysis of biomass. With this Ga-promoted ZSM-5 catalyst, olefins such as ethylene and propylene, which are produced as intermediates, are more efficiently converted into aromatics, especially...

Six biomass pretreatment processes to convert switchgrass to fermentable sugars and ultimately to cellulosic ethanol are compared on a consistent basis in this technoeconomic analysis. The six pretreatment processes are ammonia fiber expansion (AFEX), dilute acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxi...

The spent wheat straw from horse stall bedding has lower cellulose and hemicellulose contents, but higher volatile fatty acid content than raw wheat straw. Biogas production from solid-state anaerobic digestion (SS-AD) of spent wheat straw and raw wheat straw was compared in this study. The SS-AD tests were conducted at 22% total solids (TS) conten...

Dacotah switchgrass was pretreated with sulfuric acid concentrations of 0.5, 1.0, and 2.0 wt.% at 140, 160, and 180 °C and with 1 and 3 wt.% sulfur dioxide at 180 °C over a range of times. Sulfur dioxide loadings of 0%, 1%, 3%, 5%, and 10%wt.% of dry biomass were also tested at 180 °C for 10 min. Sugar yields were tracked for pretreatment and subse...

Previous studies have shown that alkali pretreatment prior to anaerobic digestion (AD) can increase the digestibility of lignocellulosic biomass and methane yield. In order to simplify the process and reduce the capital cost, simultaneous alkali treatment and anaerobic digestion was evaluated for methane production from fallen leaves. The highest m...

Feedstock quality of switchgrass for biofuel production depends on many factors such as morphological types, geographic origins, maturity, environmental and cultivation parameters, and storage. We report variability in compositions and enzymatic digestion efficiencies for three cultivars of switchgrass (Alamo, Dacotah and Shawnee), grown and harves...

Dilute sulfuric acid (DA), sulfur dioxide (SO(2)), liquid hot water (LHW), soaking in aqueous ammonia (SAA), ammonia fiber expansion (AFEX), and lime pretreatments were applied to Alamo, Dacotah, and Shawnee switchgrass. Application of the same analytical methods and material balance approaches facilitated meaningful comparisons of glucose and xylo...

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Accellerase 1000 cellulase, Spezyme CP cellulase, β-glucosidase, Multifect xylanase, and beta-xylosidase were evaluated for hydrolysis of pure cellulose, pure xylan, and switchgrass solids from leading pretreatments of dilute sulfuric acid, sulfur dioxide, liquid hot water, lime, soaking in aqueous ammonia, and ammonia fiber expansion. Distinctive...

In this paper we demonstrate an integrated process for the production of high octane gasoline from maple wood by hydrolysis of maple wood into aqueous carbohydrate solutions followed by aqueous phase hydrodeoxygenation of the sugar solutions. The aqueous carbohydrate solutions were prepared by both hydrolysis in hot water and hydrolysis with dilute...

Wheat straw is one of the most commonly used bedding materials in horse stall. The finished straw bedding materials, or horse mulch, has lower cellulose and hemicellulose contents, whereas higher total volatile fatty acids (total VFA) concentration than wheat straw. Biogas production from solid-state anaerobic digestion (SS-AD) of horse mulch and w...

Although many economic studies assume continuous Simultaneous Saccharification and Fermentation (cSSF) will be the preferred configuration for commercial applications to achieve higher productivity and eliminate the need for seed fermentors, little information is available to guide process design or optimization. Therefore, in this paper, we focuse...

Enzymes play important roles in hydrolyzing lignocellulosic biomass to sugars. Previous studies suggested that the accessibility and reactivity of cellulase and non-cellulase enzymes varied depending on substrates and pretreatment technologies. In this study, typical commercial cellulases (Spezyme CP, GC 220, and Accelerase 1000) and non-cellulases...

Coastal Bermuda grass (GBG) was pretreated using an autohydrolysis process with different temperatures and times, and the pretreated materials were enzymatically hydrolyzed using a mixture of cellulase, xylanase and beta-glucosidase with different enzyme loadings to evaluate sugar yields. Compared with untreated CBG, autohydrolysis pretreatments at...

This study used the fungus, Phanerochaete chrysosporium, to pretreat cotton stalks with two methods, shallow stationary and agitated cultivation, at three supplemental salt concentrations. Pretreatment efficiencies were compared by evaluating lignin degradation, solid recovery and carbohydrate availability over a 14-day period. Shallow stationary c...

The potential of microbial pretreatment of cotton stalks by Phanerochaete chrysosporium to degrade lignin and facilitate fuel ethanol production was investigated under two culture conditions: submerged cultivation (SmC) and solid state (SSC) cultivation. Although microbial pretreatments showed significant lignin degradation (LD) (19.38% and 35.53%...

White rot fungi degrade lignin and have biotechnological applications in conversion of lignocellulose to valuable products. Pretreatment is an important processing step to increase the accessibility of cellulosic material in plant biomass, impacting efficiency of subsequent hydrolysis and fermentation. This study investigated microbial pretreatment...

Enzymes play an important role in the breakdown of lignin during microbial pretreatment of lignocellulosic feedstocks. However, quantification of the various enzyme activities with assays developed for enzyme extracts from pure cultures can be challenging. In this study, spectrophotometric assays used for the quantification of peroxidases in enzyme...

Lignocellulosic biomass has been recognized as a widespread, potentially low cost renewable source of mixed sugars for fermentation to fuel ethanol. Pretreatment, as the first step towards conversion of lignocellulose to ethanol, remains one of the main barriers to technical and commercial success of the processing technology. Existing pretreatment...