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 : CH + HO CHCHOH 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 6. 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 & 95C starch is liquefied MILLING Feed stocks passed through Hammer mill - Fine powder ( meal) FERMENTATION Sugars ethanol & CO Continuous flow of mash through several fermenterfully fermented & leaves the tank Batch process mash in one fermentor for 48 hrs (beer) before distillation is started yeast 7. 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 8. Co- Products Distillers grain : used wet or dry highly nutritious livestock feed CO : 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. 9. 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 10. 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. 11. Advantages of Z.mobilis over S.cerevisiae Higher sugar uptake & ethanol uptake Lower biomass production Higher ethanol tolerance Doesnt 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. 12. 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. 13. 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 : CO( preparation of dry ice) & H (fuel) Product recovery : fractional distillation 14. 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 15. 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