Anaerobic fermentations

Alcoholic Fermentation. Certain types of starchy biomass such as com and high sugar crops are readily converted to ethanol under anaerobic fermentation conditions ia the presence of specific yeasts Saccharomyces cerevisia and other organisms (Fig. 6). However, alcohoHc fermentation of other types of biomass, such as wood and municipal wastes that contain high concentrations of cellulose, can be performed ia high yield only after the ceUulosics are converted to sugar concentrates by acid- or enzyme-catalyzed hydrolysis ... 

Substrate Compounds Aerobic Anaerobic Fermentation Oxidation Co-oxidation... 

Product formation stoichiometry can be used to estimate the upper bounds for product yields in processes. A relatively simple example is the anaerobic fermentation of glucose by yeast. Here, carbon dioxide and ethanol are the only products. Modification of (E -3.9) then becomes ... 

Anaerobic fermentation Water-l-sugar Carbon dioxide Yeast... 

PG activity was assayed from cells grown in a medium containing 1% glucose in one-litre self-induced anaerobic fermentation for 5 days by increase of reducing sugars. Enzyme activity increased from pH 3.0 to pH 5.0 (citrate buffer) and decreased drastically above 5.0 (phosphate buffer), but activity was not affected differentially by the two buffers used (data not shown). PG activity increased almost linearly from 20°C to 40°C but above this optimum, activity was lost rapidly and the enzyme was completely inactivated at 60°C and 70°C after 10 and 6 min, respectively (data not shown). No PL, PGL or PME were detected. 

Vogel TM, D Grbic-Galic (1986) Incorporation of water into toluene and benzene during anaerobic fermentative transformation. Appl Environ Microbiol 52 200-202. 

Brune A, S Schnell, B Schink (1992) Sequential transhydroxylations converting hydroxyhydroquinone to phloroglucinol in the strictly anaerobic, fermentative bacterium. Pelobacter massiliensis. Appl Environ Microbiol 58 1861-1868. 

Gorny N, B Schink (1994a) Hydroquinone degradation via reductive dehydroxylation of gentisyl-CoA by a strictly anaerobic fermenting bacterium. Arch Microbiol 161 25-32. 

The term three-phase fluidization, in this chapter, is taken as a system consisting of a gas, liquid, and solid phase, wherein the solid phase is in a non-stationary state, and includes three-phase slurry bubble columns, three-phase fluidized beds, and three-phase flotation columns, but excludes three-phase fixed bed systems. The individual phases in three-phase fluidization systems can be reactants, products, catalysts, or inert. For example, in the hydrotreating of light gas oils, the solid phase is catalyst, and the liquid and gas phases are either reactants or products in the bleaching of paper pulp, the solid phase is both reactant and product, and the gas phase is a reactant while the liquid phase is inert in anaerobic fermentation, the gas phase results from the biological activity, the liquid phase is product, and the solid is either a biological carrier or the microorganism itself. 

A continuous centrifugal bioreactor, in which cells are fluidized in balance with centrifugal forces, has been designed to allow high density cell cultivation and superior aeration without elutriation of the suspended cells (van Wie et al., 1991). Reactor performance was hampered by elutriation of biomass by evolved gas in an anaerobic fermentation, indicating that it may not be suitable in its present state for three-phase fermentations. Immobilization of the cells on denser particles may overcome this problem. 

ANTHANE/ANODEK [Anaerobic Methane/Anaerobic O. de Konickx] A process for generating methane by the anaerobic fermentation of industrial organic wastes. Invented by the Institute of Gas Technology, Chicago engineered by the Studiebureau O. de Konickx, Belgium, and commercialized since 1977. 

Sulfate is needed as an electron acceptor for the sulfate reduction process, but normally, it is available in unlimited concentrations in wastewater. If this is not the case, iron sulfate may support the process. The anaerobic fermentation processes still proceed, and the odorous organic substances produced are generally not affected by the addition of iron salts. 

Anaerobic fermentation (in the absence of air) is less common, for instance anaerobic digestion of organic wastes is practiced to make methane. 

Anaerobic fermentation can occur in the pH range of between 5 and about 9, while the methane bacterial operate in a much narrower range of between 6.5 and about 7.6, with the optimum range at about 7.0. 

---