Using microorganisms to brew biofuels

Rao, Reeta P.; Dufour, Nicholas; Swana, Jeffrey

doi:10.1007/s11627-011-9374-3

Cited by 6 publications

(1 citation statement)

References 128 publications

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“… 2) 3) Saccharomyces cerevisiae, the most commonly used microorganisms for ethanol production, can efficiently ferment glucose, but cannot utilize xylose for ethanol production. 4) Therefore, co-fermentation of glucose–xylose mixtures using two kinds of ethanol-producing microorganisms 5) or a genetically engineered yeast strain capable of fermenting both sugars 6) 7) 8) has been extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

Reusable Floating Beads with Immobilized Xylose-Fermenting Yeast Cells for Simultaneous Saccharification and Fermentation of Lime-Pretreated Rice Straw

Guan

Zhao

et al. 2019

J. Appl. Glycosci.

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Novel bioreactor beads for simultaneous saccharification and fermentation (SSF) of limepretreated rice straw (RS) into ethanol were prepared. Genetically modified Saccharomyces cerevisiae cells expressing genes encoding xylose reductase, xylitol dehydrogenase, and xylulokinase were immobilized in calcium alginate beads containing inorganic lightweight filler particles to reduce specific gravity. For SSF experiments, the beads were floated in slurry composed of lime-pretreated RS and enzymes and incubated under CO 2 atmosphere to reduce the pH for saccharification and fermentation. Following this reaction, beads were readily picked up from the upper part of the slurry and were directly transferred to the next vessel with slurry. After 240 h of incubation, ethanol production by the beads was equivalent to that by free cells, a trend that was repeated in nine additional runs, with slightly improved ethanol yields. Slurry with pre-saccharified lime-pretreated RS was subjected to SSF with floating beads for 168 h. Although higher cell concentrations in beads resulted in more rapid initial ethanol production rates, with negligible diauxic behavior for glucose and xylose utilization, no improvement in the ethanol yield was observed. A fermentor-scale SSF experiment with floating beads was successfully performed twice, with repeated use of the beads, resulting in the production of 40.0 and 39.7 g/L ethanol. There was no decomposition of the beads during agitation at 60 rpm. Thus, this bioreactor enables reuse of yeast cells for efficient ethanol production by SSF of lignocellulosic feedstock, without the need for instruments for centrifugation or filtration of whole slurry.

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Section: Introductionmentioning

confidence: 99%

Reusable Floating Beads with Immobilized Xylose-Fermenting Yeast Cells for Simultaneous Saccharification and Fermentation of Lime-Pretreated Rice Straw

Guan

Zhao

et al. 2019

J. Appl. Glycosci.

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Molecular Biology Based Innovations in Lignocellulose Biorefinery

Sharma¹,

Bibra²

2022

Lignocellulose Bioconversion Through White Biotechnology

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Review on technology of making biofuel from food waste

Zeng

Wang

2022

Intl J of Energy Research

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The disposal of food waste has become an environmental issue of great concern with the increasing consumption of materials. The conversion of food waste into biofuels using biotechnology is a very promising approach. Food waste can be converted into fuels such as bio-methane, bio-hydrogen, bio-ethanol, and bio-diesel by different biotechnologies. Food wastes as raw materials for biofuel preparation are mainly classified into protein, fat, starch, sugar, and cellulose. Carbohydrate-rich wastes such as straw, bagasse, grape and apple pomace, and kitchen garbage can produce biofuels, which can be converted into biofuels through anaerobic digestion, aerobic digestion, and microbial fermentation processes. Co-substrates are increasingly used to increase biofuel production and to overcome the shortcomings of a single substrate. The main raw materials for each biofuel are different. Anaerobic digestion technology can be utilized for the production of biomethane, and the digestion efficiency can be changed by the adjustment of the substrate combination, and reactor configuration. The process of methane production by anaerobic digestion mainly includes hydrolysis, acid production, acetic acid production, and methane production. The main raw materials used for methane preparation are livestock manure (pig manure, chicken manure, cow manure, etc.), straw and kitchen waste. Each raw material has a different methane yield and environmental friendliness. Fermentation technology of Saccharomyces cerevisiae can be used to produce bio-ethanol, which consists mainly of raw material pretreatment, enzymatic digestion (saccharification), fermentation, and ethanol production. Cellulosic raw materials (including hemicellulose) are the most promising raw materials for ethanol production on earth, mainly straw, wood chips, peanut shells, and corn. Coupled biomass dark and photo-fermentation technologies can be utilized to produce bio-hydrogen, which includes degradation, dark fermentation, photo-fermentation, and hydrogen production. Food waste containing lipids, proteins, and complex carbohydrates is a good substrate for the dark fermentation stage. The main raw materials for hydrogen production are kitchen wastewater, sugars (glucose), starch (cassava), and cellulose (water hyacinth and rice straw). Hydrothermal liquefaction, hydrothermal gasification, and hydrothermal carbonization technologies can be utilized to produce bio-oil or bio-char. The raw materials for bio-oil/biochar are mainly Edible vegetable oil, nonedible vegetable oil, animal oil, waste edible oil, coffee residue, peanut shell, brewer's grains, grape pomace, sugarcane peel, straw,

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Using microorganisms to brew biofuels

Cited by 6 publications

References 128 publications

Reusable Floating Beads with Immobilized Xylose-Fermenting Yeast Cells for Simultaneous Saccharification and Fermentation of Lime-Pretreated Rice Straw

Reusable Floating Beads with Immobilized Xylose-Fermenting Yeast Cells for Simultaneous Saccharification and Fermentation of Lime-Pretreated Rice Straw

Molecular Biology Based Innovations in Lignocellulose Biorefinery

Review on technology of making biofuel from food waste

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