Introduction Definition those in which microbial growth and
Introduction Definition those in which microbial growth and product formation occur on the surface of solid substrates Biofilm formation and SSF Solid substrates serve as substratum Less liquid movement
Introduction Solar energy was not efficiently utilized. Ø Solar radiation striking the earth is equivalent to 178, 000 terawatts per year (15, 000 times of global consumption) Ø Only light within the wavelength range of 400 to 700 nm (photosynthetically active radiation, PAR) can be utilized by plants (45%) Ø Only 25% of the PAR absorbed by the photosynthetic system Ø Theoretical maximum efficiency 11%, in fact, 3 -6% of total solar radiation
Biomass resource of the world Grains (rice, wheat) Starch sugar crops Sugar cane Corn Potatoes Crops Biomass Aquatic plants See weeds Water-hyacinth, Chlorella Rubber plants Para rubber tree Guayule rubber tree Oil plants Palms, etc. Petroleum plants Heliopora, Yukar Woods Rice straw, chaff, wheat straw Agricultural wastes Sugarcane bagasse Corn, stover Unused resources Forestal wastes Sawdust Pulp waste Thinned woods Municipal wastes, industrial wastes Livestock wastes Excreta of livestock
Biomass resource utilization Fuel alcohol production from cellulosic biomass Improved methane fermentation from industrial and agricultural residues Biological H 2 production from water and various wastes Oil production through thermochemical liquefaction of microalgal biomass
Cellulosic wastes Cellulose Ø Plant cell walls Ø Universal and the most abundant and renewable source of carbon and energy in nature Ø 2 x 1011 tons per year from photosynthesis Hemicellusoe Ø Composed of 5 and 6 -C ring sugar Ø Supportive matrix for the cellulose Lignin Ø Hold fibers and cellulose Ø Amorphous
Cellulosic biomass Constitution Cellulosic biomass Cellulose Hemicellulose Lignin Ash Bagasse 41 24 18 2 Rice straw 35 35 6 8 Wood 40 -55 20 -35 25 -30 0. 2 -2 Structure Cellulose Hemicellulose Lignin Chain form linear or baranched complex, crosslinked Chain length ~10, 000 50 -300 varies widely Chain unit b-D glycopyranose b 1, 4 glycans phenylpropane Bond type 1 -4 glycosidic b 1 -4 : xylans glucomannans various types
Structure of plant cell walls http: //www. botany. hawaii. edu/faculty/webb/
Structure of cellulose
Structure of hemicellulose
Cellulose-degrading enzyme system Endo-b-1, 4 -glucanase (EC 3. 2. 1. 4) Exo-b-1, 4 -glucanase (EC 3. 2. 1. 91) b-glucosidase (EC 3. 2. 1. 21) http: //www. science. siu. edu/microbiology/micr 302/ figure%2010. 05. jpg
Xylan-degrading enzyme system The backbone enzymes Side chain-debranching enzymes Ø endo-β-1, 4 -xylanase (EC 3. 2. 1. 8) Øα-L-arabinofuranosidase (EC 3. 2. 1. 55) Ø β-D-xylosidase (EC 3. 2. 1. 37) Øα-glucuronidase (EC 3. 2. 1. 139) Ø acetylxylan esterase (EC 3. 1. 1. 72) Ref. Sunna, A. , and G. Antrankian. 1997.
Application of cellulase Cellulose reuse Food industry Textile industry Cellulase Xylanase Feed Additives Household industry Pulp and Paper Ref: http: //www. patent. womplex. com/1. html http: //valleyenzymes. com/enzymes/vtrconc. html
Characteristics of Solid Substrates Traditional Agricultural products, such as rice, wheat, millet, barley, corn and soybeans Non-Traditional Agricultural, forest, animal and food-processing wastes, such as sweet potato residues, rice bran, animal discharge… Solid substrates can be viewed as gas-liquid-solid mixtures Water content varied in solid substrates tightly bound, less tightly bound, free state in capillary region Most are in complex polymeric forms requiring enzymatic hydrolysis
Characteristics of Solid State Fermentation Occur at or near the substrate surface with low moisture Able to provide a selective environment at low moisture for mycelial organisms that produce a variety of extracellular enzymes, surface bound or free grow at high nutrient concentration near solid surfaces Organisms include a large number of filamentous fungi and a few bacteria, such as the actinomycetes, one strain of Bacillus Favor extracellular enzyme synthesis in growth-associated metabolism Microbial physiology is modified by chemical composition and physical structure of substrates by local variation in temp, p. H, nutrients, dissolved-gas concentration
Classification of Solid State Fermentation According to physical state of substrate Without agitation: tempeh, natto With occasional agitation: miso, soy sauce With continuous agitation: aflatoxin Suspended solids in packed columns through which liquid is circulated: rice wine, beer &more According to the nutrient state Solid is the major nutrition source Solid is nutritionally inert (uncommon)
Country Name Ingredients Shape Microorganism China Chu granular or cake Rhizopus Amylomyces Korea Nuruk Wheat, barley, millet, rice (whole grain, grits or flour) Wheat, rice, barley (whole grain, grits or flour) soybean (whole seed) wheat, rice(whole grain, grits or flour) rice (flour) rice, glutinous rice (flour) bran rice Meju Japan Indonesia Malaysia Phillipines Thailand India Koji Ragi Bubod Loopang Marchaa large cake large ball granular small cake powder flat cake Aspergillus Rhizopus yeasts Aspergillus Bacillus Aspergillus Amylomyces Endomycopsis Mucor, Rhizopus Saccharomyces Amylomyces Aspergillus Hansenula anomala Mucor fragilis Rhizopus arrhizus
Advantages of Solid state fermentation Minimal nutrient supplementation Fermentation vessel is small relative to product yield Low moisture reduces the problem of contamination Agitation inhibits mold sporulation Minimal product purification Product yields may be much higher than liquid state
Disadvantages of Solid state fermentation High power required if continuous agitation involved The addition of water in early stage Risk of bacterial contamination Spore inocula may be quite large Need harvest aspetically Considerable development required to make process feasible at a large scale
Solid-State Fermentation Processes Traditional Foods Oriental foods Soy source, Miso, Hamanatto, Chinese Cheese Water content (WC) Cooked soybean 60% WC (ideal for bacterial growth) mixed with roasted wheat 45% WC (adequate for fungal growth) Acid treatment p. H 3. 5 -4. 5 inhibit the growth of undesirable organism Two major processing stages: Koji phase: an aerobic solid state fermentation by one or more fungal species Moromi: an anaerobic submerged culture fermentation with mixed population
Solid-State Fermentation Processes Enzymes cellulase, amylase, pectinase, protease, lipase Primary metabolites Citric acid and gluconic acid Secondary metabolites Antibacterial agents: Mycotoxin, Aflatoxin, Ochratoxin WT Lignocellulosic wastes Ethanol production Detoxification of cassava
Solid-State Fermentation Processes Rice wine Rice koji used as starter culture Brown rice Milled and polish Washed and steeped Solublize nutrients and swell the grains Steamed 30 -60 min 30 -35% WC Inoculated with spores of A. oryzae at 30 o. C and 80 -90% RH Fermentation time 44 -48 h
Rice wine producing procedure
Sorghum liquor producing procedure more about wine: classification, production, drunk 1, 2
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