Related Experiment Video
Updated: May 29, 2026
14:53
Techniques for the Evolution of Robust Pentose-fermenting Yeast for Bioconversion of Lignocellulose to Ethanol
Published on: October 24, 2016
Bioconversion of corn stover derived pentose and hexose to ethanol using cascade simultaneous saccharification and
1Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA.
Bioprocess and Biosystems Engineering
|September 13, 2011
Summary
This study introduces cascade simultaneous saccharification and fermentation (CSSF) for converting corn stover sugars to ethanol. The method reduces enzyme use by 50% while achieving 60% of the theoretical maximum ethanol yield.
Area of Science:
- Biotechnology
- Biochemical Engineering
- Renewable Energy
Background:
- Corn stover is a rich lignocellulosic biomass containing pentose and hexose sugars.
- Efficient conversion of these sugars to ethanol is crucial for sustainable biofuel production.
- Current methods often require high enzyme loadings and face challenges in separating sugar fractions.
Purpose of the Study:
- To develop and evaluate a cascade simultaneous saccharification and fermentation (CSSF) process for enhanced ethanol production from corn stover.
- To reduce enzyme input and improve overall process efficiency.
- To achieve high ethanol yields from both pentose and hexose fractions.
Main Methods:
- A two-phase sequential SSF process was designed: Phase 1 for pentose conversion using xylanase, endo-glucanase, and Escherichia coli (KO11); Phase 2 for hexose conversion using cellulase, β-glucosidase, and Saccharomyces cerevisiae (D(5)A).
- Enzymes were recycled from the fermentation broth across multiple stages.
- Untreated corn stover was used as the feedstock.
Main Results:
- The CSSF process achieved up to 60% of the theoretical maximum ethanol yield based on total sugars.
- Enzyme loadings were reduced by 50% (v/v).
- A final ethanol concentration of 27 g/l was reached.
Conclusions:
- The CSSF strategy offers an efficient and cost-effective method for converting lignocellulosic biomass to ethanol.
- Enzyme recycling and sequential sugar conversion significantly improve process economics.
- This approach holds promise for sustainable biofuel production from agricultural residues.
Related Concept Videos
01:27Production of Alcohol
Continuous fermentation is a key strategy in industrial ethanol production, particularly when efficiency, scalability, and high yields are essential. This approach allows for uninterrupted operation and optimized resource utilization. The primary feedstock, corn starch, undergoes enzymatic hydrolysis facilitated by α-amylase and glucoamylase. These enzymes break down the starch into fermentable sugars such as glucose, which are readily assimilated by fermentative microorganisms.Fermentation...
01:22Bioreactor Controls-III
Strain improvement is a foundational strategy in industrial microbiology aimed at maximizing microbial productivity, particularly because natural isolates typically yield commercially valuable products in very low concentrations. Although optimizing the culture medium and environmental conditions can improve yields, these adjustments are inherently limited by the organism’s genetic potential. As a result, the focus shifts toward genetic modifications to enhance biosynthetic capacity. The...
01:25Production of Organic Acids
Lactic acid, an important organic acid extensively applied in food, pharmaceutical, and biodegradable polymer industries, is primarily produced via microbial fermentation. This method is favored over chemical synthesis due to its environmental sustainability and capacity for enantiomerically pure product formation. Among various microbial processes, the fermentation of starch-based substrates stands out due to the abundance and renewability of raw materials like corn and potatoes.Hydrolysis of...
01:25Biofuels
The microbial conversion of organic matter into biofuels holds potential as a renewable energy source. Among biofuel sources, microalgae are recognized as a highly efficient and adaptable feedstock for biodiesel production, owing to their rapid biomass accumulation, elevated lipid productivity, and capacity to proliferate in diverse aquatic systems, including freshwater, marine, and wastewater habitats. Unlike terrestrial crops, microalgae do not compete for land and can achieve significantly...
01:26Biosynthesis of Polysaccharides
Polysaccharides such as glycogen and starch are synthesized from nucleoside diphosphate sugars, primarily uridine diphosphate glucose (UDPG) and adenosine diphosphate glucose (ADPG). These activated glucose donors act as key intermediates in carbohydrate metabolism and biosynthesis. UDPG primarily involves glycogen synthesis in animals and many bacteria, while ADPG plays a fundamental role in starch synthesis in plants and certain bacteria.UDPG is formed when glucose-1-phosphate reacts with...
01:20Fates of Pyruvate
Pyruvate is the end product of glycolysis, where glucose is oxidized to pyruvate, simultaneously reducing NAD+ to NADH. Two molecules of ATP are also produced by substrate-level phosphorylation.
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...
In aerobic organisms, pyruvate is metabolized via the citric acid cycle to produce reduced coenzymes NADH and FADH2. These coenzymes are then oxidized in the electron transport chain to produce ATP and, in the process, regenerate the NAD+ and FAD. As seen in some cell types and organisms, fermentation...