This document summarizes microbial production of various solvents like ethanol, acetone, butanol, and glycerol. It describes the common uses of solvents and details the processes of ethanol production through both petrochemical and biological fermentation methods. The biological fermentation process involves steps like saccharification, liquefaction, milling, fermentation, and distillation. It also discusses the advantages of using bacteria like Z. mobilis and C. ljungdahlii over yeast for ethanol production, as well as the production methods for acetone, butanol, and glycerol.

1. MICROBIAL PRODUCTION OF
SOLVENTS

2. SOLVENT
Liquid that dissolves any kind of solute.
Common solvents
* Ethanol
* Acetone
* Butyl alcohol
* Glycerol etc..

3. COMMON USES
 Dry cleaning (tetrachloroethylene)
 Paint thinner (toluene, turpentine)
 Nail polish removers & glue solvents( acetone,
ethyl acetate, methyl acetate)
 Spot removers(hexane, petrol ether)
 Detergents( citrus terpenes)
 Perfumes (ethanol) &
 Chemical synthesis..

4. Ethanol production
Petrochemical – hydration of ethylene
Biological – fermenting sugars with yeast
Chemical ethylene hydration :
 Raw materials: petrochemical feedstocks
 Process : acid- catalyzed hydration of ethylene
 Reaction : C₂H₄ + H₂O CH₃CH₂OH
 Catalyst : phosphoric acid – adsorbed onto a
porous support(diatomaceous earth/charcoal)

5. Biological fermentation :
Dry mill process or wet mill process.
DRY MILL PROCESS
Overall reaction involved
 fermentation of starch portion of corn into sugar
 distillation into alcohol

7. Steps involved in dry mill process
SACCHARIFICATION
Cooled mash + glyco amylase - Liquefied sugars to fermentable sugars (dextrose)
LIQUEFICATION
Meal + water +alpha amylase -Cookers (120 -150)˚c & 95˚C – starch is liquefied
MILLING
Feed stocks passed through Hammer mill - Fine powder ( meal)
FERMENTATION
Sugars ethanol & CO₂
Continuous flow of mash through several fermenter–fully fermented & leaves the tank
Batch process – mash in one fermentor for 48 hrs (beer) before distillation is started
yeast

9. DENATURING
Ethanol used for fuel must be denatured or made unfit for human consumption, with
a small amount of gasoline (2-5%) This is done at ethanol plant
DEHYDRATION
Alcohol from top of the column – dehydration system (remaining water removed)
Most ethanol plants use molecular sieve to capture last bit of water in the ethanol
Alcohol product at this stage (anhydrous ethanol – pure, without water) – 100% proof
DISTILLATION
Fermented mash(beer)–10% alcohol & all non-fermented solids from corn & yeast cells.
Mash – pumped into continuous flow, multi-column distillation system – alcohol
Alcohol leaves the top of final column at 96% strength & residue mash (stillage)
transferred from base of the column to the co-product processing area

11. Co- Products
Distillers grain :
used wet or dry – highly nutritious livestock feed
CO₂ :
Given off in great quantities during fermentation
Many ethanol plants collect ,compress & sell it for use in other
industries.
 Most ethanol from microbial fermentation-preparation of beverages.
 Ethanol production from sugary substrates-expensive than naturally
available petroleum.
 Microbial conversion of sugar to alcohol is limited by the toxicity of
alcohol which cannot accumulate in the fermenter beyond a limit.
 The recovery process which involves distillation requires energy input.

12. Ethanol production by bacteria
 Bacteria which can ferment sugar faster than yeast have
been found
eg. Zygomonas mobilis &
Thermophilic Thermobacter ethanolicus.
 As sugary substrates are expensive & are used for food, it
may be possible to use cellulosic materials & photosynthetic
MOs.
 Process:
1. Cellulose Sugar
2. Sugar Alcohol
Clostridium sp.
Zygomonas mobilis (or)
Thermobacter ethanolicus

13.  The anaerobic bacterium Clostridium ljungdahlii, (in
commercial chicken wastes) can produce ethanol from
single carbon sources including
* synthetic gas,
* a mixture of CO and H
that can be generated from the partial combustion of
either fossil fuels or biomass.
 If these techniques coupled with genetic engineering
techniques - possible to produce cheap ethanol to meet
the organic solvents & automative fuel requirements of the
world.

14. Advantages of Z.mobilis over S.cerevisiae
 Higher sugar uptake & ethanol uptake
 Lower biomass production
 Higher ethanol tolerance
 Doesn’t require controlled addition of oxygen during the
fermentation
 Amenability to genetic manipulations
Limitations compared to yeast
 Difficulties in converting large amount of complex CHO
polymers like cellulose, hemicelluloses and starch to ethanol.
 Its utilizable substrate range is restricted to glucose, fructose and
sucrose.
 Its resulting in by-products such as sorbitol, acetoin, glycerol
and acetic acid.
 Formations of extracellular levan polymer.

15. ACETONE & BUTYL ALCOHOL
 Chaim Weizmann, England in the early part of this
century when
acetone: production of explosives &
butanol: making synthetic rubbers.
 N-butanol is used in brake fluids, urea-formaldehyde
resins & in lacquers used as protective coatings in
automobiles.

16. Organism:
1. Clostridium acetobutylicum – 1st organism – industrial
production of acetone from starch.
2. Clostridium saccharoacetobutylicum – convert molasses
into acetone & butanol.
 submerged cultures
 Substrate: sterile diluted molasses or cooked corn meal.
 pH : 7.2
 Type of fermentation: anaerobic
 By-products : CO₂( preparation of dry ice) & H (fuel)
 Product recovery : fractional distillation

17. GLYCEROL
Main uses :
 solvent in food colouring agents
 Lubricant in toothpastes, candies, cake icings
 Cosmetic & pharmaceutical industries
 Production of explosives & propellants.
Production:
 organism : yeast - Saccharomyces cerevisiae or
bacteria – Bacillus subtilis

18. BY
R.ABARNA
BTH-12-001
THANK YOU