Process design and techno-economic analysis of 2'-fucosyllactose enriched distiller's dried grains with solubles production in dry grind ethanol process using genetically engineered Saccharomyces cerevisiae.

2'-fucosyllactose (2'-FL) has been linked positively with piglet gut health. Genetically engineered Saccharomyces cerevisiae strains producing 2'-FL can be used in the dry grind process to enrich Distiller's dried grains with solubles (DDGS) with 2'-FL and supplement swine diets with 2'-FL. The objectives of our study were to modify dry grind ethanol process for 2'-FL enriched DDGS production and evaluate the techno-economic feasibility of the process.

Improving ethanol yields with deacetylated and two-stage pretreated corn stover and sugarcane bagasse by blending commercial xylose-fermenting and wild type Saccharomyces yeast.

Corn stover and sugarcane bagasse are the most widely available agriculture processing biomass and could serve as feedstocks for production of biofuel. In this study, three different technologies are combined to develop a more efficient conversion process for each of these feedstocks. The three technologies are diluted alkaline deacetylation process, combined thermochemical and mechanical shear pretreatment, and fermentation using a combined inoculum of two commercial Saccharomyces yeast strains.

Increasing ethanol yield through fiber conversion in corn dry grind process.

Conversion of corn fiber to ethanol in the dry grind process could increase ethanol yields, reduce downstream processing costs and improve overall process profitability. This work investigates the in-situ conversion of corn fiber into ethanol (cellulase addition during simultaneous saccharification and fermentation) during dry grind process. Addition of 30 FPU/g fiber cellulase resulted in 4.

Fermentation of undetoxified sugarcane bagasse hydrolyzates using a two stage hydrothermal and mechanical refining pretreatment.

In this study, liquid hot water pretreatment was combined with disk milling for pretreatment of sugarcane bagasse. Sugarcane bagasse was pretreated using liquid hot water (LHW) at 140-180 °C for 10 min (20% w/w solids content) and then disk milled. Disk milling improved glucose release 41-177% and ethanol production from glucose/xylose cofermentation by 80% compared to only using LHW pretreatment.

Impact of disk milling on corn stover pretreated at commercial scale.

In cellulosic biofuel production, chemical pretreatment performed at laboratory or pilot scale, followed by mechanical refining, has been demonstrated to be effective to increase feedstock enzyme digestibility. To take the combined pretreatment process one step closer to commercialization, disk milling was performed with commercially pretreated corn stover. Dilute acid pretreated samples with combined severity factors (cSF) of 0.

Improvement of sugar yields from corn stover using sequential hot water pretreatment and disk milling.

Efficient pretreatment is essential for economic conversion of lignocellulosic feedstocks into monosaccharides for biofuel production. To realize high sugar yields with low inhibitor concentrations, hot water or dilute acid pretreatment followed by disk milling is proposed. Corn stover at 20% solids was pretreated with hot water at 160-200°C for 4-8min with and without subsequent milling.

Miscanthus×giganteus xylooligosaccharides: Purification and fermentation.

A procedure was developed to recover xylooligosaccharides (XOS) from Miscanthus×giganteus (M×G) hydrolyzate. M×G hydrolyzate was prepared using autohydrolysis, and XOS rich fractions were acquired using activated carbon adsorption and stepwise ethanol elution. The combined XOS fractions were purified using a series of ion exchange resin treatments.

In Vitro Fermentation of Xylooligosaccharides Produced from Miscanthus × giganteus by Human Fecal Microbiota.

Purified xylooligosaccharides from Miscanthus × giganteus (M×G XOS) were used in an in vitro fermentation experiment inoculated with human fecal microbiota. A commercial XOS product and pectin were used as controls. Decreases in pH by 2.

Vacuum stripping of ethanol during high solids fermentation of corn.

In corn-ethanol industry, yeast stress inducing glucose concentrations produced during liquefaction and subsequent high ethanol concentrations produced during fermentation restrict slurry solids to 32 % w/w. These limits were circumvented by combining two novel technologies: (1) granular starch hydrolyzing enzyme (GSHE) to break down starch simultaneously with fermentation and (2) vacuum stripping to remove ethanol. A vacuum stripping system was constructed and applied to fermentations at 30, 40, and 45 % solids.

Autohydrolysis of Miscanthus x giganteus for the production of xylooligosaccharides (XOS): kinetics, characterization and recovery.

The optima conditions of production and purification of xylooligosaccharides (XOS) from Miscanthus x giganteus (MxG) were investigated. Using autohydrolysis, XOS were produced at 160, 180 and 200°C at 60, 20 and 5min, respectively. XOS yield up to 13.

Contamination issues in a continuous ethanol production corn wet milling facility.

Low ethanol yields and poor yeast viability were investigated at a continuous ethanol production corn wet milling facility. Using starch slurries and recycle streams from a commercial ethanol facility, laboratory hydrolysates were prepared by reproducing starch liquefaction and saccharification steps in the laboratory. Fermentations with hydrolysates prepared in the laboratory were compared with plant hydrolysates for final ethanol concentrations and total yeast counts.

Design and evaluation of an optimal controller for simultaneous saccharification and fermentation process.

Ethanol from corn is produced using dry grind corn process in which simultaneous saccharification and fermentation (SSF) is one of the most critical unit operations. In this work an optimal controller based on a previously validated SSF model was developed by formulating the SSF process as a Bolza problem and using gradient descent methods. Validation experiments were performed to evaluate the performance of optimal controller under different process disturbances that are likely to occur in practice.

A simultaneous saccharification and fermentation model for dynamic growth environments.

Many mathematical models by researchers have been formulated for Saccharomyces cerevisiae which is the common yeast strain used in modern distilleries. A cybernetic model that can account for varying concentrations of glucose, ethanol and organic acids on yeast cell growth dynamics does not exist. A cybernetic model, consisting of 4 reactions and 11 metabolites simulating yeast metabolism, was developed.

Starch hydrolysis modeling: application to fuel ethanol production.

Efficiency of the starch hydrolysis in the dry grind corn process is a determining factor for overall conversion of starch to ethanol. A model, based on a molecular approach, was developed to simulate structure and hydrolysis of starch. Starch structure was modeled based on a cluster model of amylopectin.

Ultrafiltration of thin stillage from conventional and e-mill dry grind processes.

We used ultrafiltration (UF) to evaluate membrane filtration characteristics of thin stillage and determine solids and nutrient compositions of filtered streams. To obtain thin stillage, corn was fermented using laboratory methods. UF experiments were conducted in batch mode under constant temperature and flow rate conditions.

Heat transfer fouling characteristics of microfiltered thin stillage from the dry grind process.

We investigated effects of microfiltration (MF) on heat transfer fouling tendencies of thin stillage. A stainless steel MF membrane (0.1 micron pore size) was used to remove solids from thin stillage.

Nutrient recovery from the dry grind process using sequential micro and ultrafiltration of thin stillage.

The effectiveness of microfiltration (MF) and ultrafiltration (UF) for nutrient recovery from a thin stillage stream was determined. When a stainless steel MF membrane (0.1microm pore size) was used, the content of solids increased from 7.

Characterization of microbial trophic structures of two anaerobic bioreactors processing sulfate-rich waste streams.

A multi-compartment anaerobic bioreactor, designated the anaerobic migrating blanket reactor (AMBR), did not perform well in terms of chemical oxygen demand (COD) removal after an increase in sulfate load, compared to a conventional upflow anaerobic sludge blanket (UASB) reactor. The trophic structures of the bioreactors were characterized by analyzing the electron flows, formation and consumption of fermentation intermediates and terminal product (methane and hydrogen sulfide) formation. Critical performance parameters were linked to operational perturbations such as increase in sulfate load and changes in flow reversal schemes in the AMBR.

Effect of resistant starch on hydrolysis and fermentation of corn starch for ethanol.

Starch samples with 0% or 30% amylose were subjected to four different liquefaction enzyme treatments (at various temperature and pH conditions) followed by simultaneous saccharification and fermentation (SSF). Resistant starch (RS) measurements were conducted for the initial starch sample, after liquefaction and after SSF. Initial RS was higher for 30% amylose starch samples (16.

Thin stillage fractionation using ultrafiltration: resistance in series model.

The corn based dry grind process is the most widely used method in the US for fuel ethanol production. Fermentation of corn to ethanol produces whole stillage after ethanol is removed by distillation. It is centrifuged to separate thin stillage from wet grains.

Use of formalin-fixed tissues to determine fumonisin B1-induced sphingolipid alterations in swine.

Fumonisin B1 is a mycotoxin that causes lethal pulmonary edema in swine. Sphinganine, sphingosine, and the sphinganine to sphingosine ratio are important biomarkers for fumonisin B1 exposure. Currently, tissues selected for sphinganine and sphingosine analyses are frozen at -80 degrees C until analyses take place.

Microbial diversity and dynamics in multi- and single-compartment anaerobic bioreactors processing sulfate-rich waste streams.

We investigated bacterial and archaeal community structures and population dynamics in two anaerobic bioreactors processing a carbohydrate- and sulfate-rich synthetic wastewater. A five-compartment anaerobic migrating blanket reactor (AMBR) was designed to promote biomass and substrate staging, which partially separates the processes of methanogenesis and sulfidogenesis in the middle and outer compartment(s) respectively. The second reactor was a conventional, single-compartment upflow anaerobic sludge blanket (UASB) reactor.

Element concentrations of dry-grind corn-processing streams.

The dry-grind corn process is one of two technologies used to convert corn into ethanol. In this process, all kernel components are processed through several sequential steps, including fermentation. Only one coproduct (distillers' dried grains with solubles [DDGS]) is available for marketing.

Improvement in fermentation characteristics of degermed ground corn by lipid supplementation.

With rapid growth of fuel ethanol industry, and concomitant increase in distillers dried grains with solubles (DDGS), new corn fractionation technologies that reduce DDGS volume and produce higher value coproducts in dry grind ethanol process have been developed. One of the technologies, a dry degerm, defiber (3D) process (similar to conventional corn dry milling) was used to separate germ and pericarp fiber prior to the endosperm fraction fermentation. Recovery of germ and pericarp fiber in the 3D process results in removal of lipids from the fermentation medium.