GK-12 WORKSHOP DECEMBER 7 , 2011

Fun with Fermentation

What is fermentation?

Any of a group of chemical reactions that split complex organic compounds into relatively simple substances without oxygen.

Example: Sugar ethanol and carbon dioxideEnzyme: Any of numerous complex proteins

that are produced by living cells and catalyze specific biochemical reactions

(Merriam Webster)

Catalyze: Cause or accelerate

Yeast Enzymes

Ethanol Production

GLBRC, 2010

Glucose

Glucose is a simple sugarCarbohydrate-Carbon, Hydrogen, and OxygenProduced by plantsGlucose linked together by bonds makes

starches and cellulose

Starch

Glucose linked together by bondsWhat are some examples of starch?What is the purpose of starch?

Cellulose

Glucose linked together by bondsWhere is cellulose?What is the purpose of cellulose?

Fermentation in a bag

Materials Sugar Ground Corn Grass clippings Yeast 50 mL or ¼ cup of hot water Snack size Ziploc bags or balloons

Fermentation in a bag

Instructions Add 1 teaspoon of the feedstock, 1 teaspoon of yeast,

and 50 mL of warm water to the Ziploc bag Close the bag, try to remove as much air as possible Allow the bag to set for at least 15 minutes

Pre Experiment Questions

Which bag contains the most CO2 after a certain period of time?

Do you think the amount of CO2 production is different based on the feedstuff tested?

Why do you think the amount of CO2 production will be different?

Which feedstuff do you think will produce the most CO2?

Which feedstuff do you think will produce the most ethanol?

Why does fermentation vary among feedstuffs?

Sugar=glucoseCorn=starchGrass=cellulose

Starch vs Cellulose

https://wikispaces.psu.edu/display/Biol230WCE/Properties+of+Macromolecules+II-Nucleic+Acids,+Polysaccharides+and+Lipids

Alpha 1,4 vs Beta 1,4

Alpha 1,4 bond is broken by common enzymes, such as amylase, or acid treatments

Beta 1,4 bond is not easily broken, humans and animals do not have the enzyme necessary to cleave this bond

Based on the results of this experiment can yeast break the alpha 1,4 or the beta 1,4 bond?

Questions

Which feedstuff fermented the most? How do you know?

What gas accumulated in the bag and based on the reaction equation what else was produced?

Why did the amount of fermentation vary among the feedstuffs?

In general what do you think is the carbohydrate content is for the feedstuffs tested?

How is corn used for ethanol production?

Corn is starchStarch is glucose linked by alpha 1,4 bondsYeast cannot break the alpha 1,4 bondsEnzymes or acid first break the alpha 1,4

bonds and free single glucose moleculesEnzymes: amylase

Why use cellulose?

Cellulose makes up over half of plant biomassThis makes cellulose very abundantCellulose has potential to be the largest

biofuel source

Why Switchgrass?

BiomassEasy to grow

Marginal Lands High Temperature Drought Tolerate

Perennial

The trouble with cellulose…

Cellulose is wrapped in lignin and hemicellulose

These components have to be detangled in order to get to the cellulose

This process is called pretreatment

GLBRC, 2010

Pretreatment

Most expensive part of the processActive research looking for enzymes or

chemicals to help with the processMany bacteria and fungi can produce

cellulase enzymesOr scientist will genetically modify yeast or

other organisms

GLBRC, 2010

New Research

Before a pretreatment (cooking switch grass in hot water for 10 minutes) only 10% of cellulose was available for fermentation after pretreatment 90% of cellulose was made available for fermentation

Fall switchgrass given a pretreatment and fermentation with special yeast could produce as much as 800-1,000 gallons of ethanol per acre per year, compared with 150-250 gallons per year without pretreatment.

Corn ethanol from grain produces about 500-600 gallons per acre per year

http://www.purdue.edu/newsroom/research/2011/110831LadischSwitchgrass.html

End