Microorganisms ethanol fermentation

The product may be located inside a microorganism (intracellular) or outside in the growth medium (extracellular), or alternatively, the product could be the whole cell material. The nature of the product may be solid or dissolved in the aqueous phase. For example, the product is found in the aqueous phase for a fuel ethanol fermentation, within the cell for a therapeutic protein, while the product is the whole cell in the case of single cell protein. The location of the product influences the choice of a bioseparation method which may favor the efficient recovery of either the solid or liquid phase. The relative difficulty of separating intracellular products from other unwanted insoluble materials may influence the subsequent processing steps once the solids phase has been recovered from the fermentation broth. 

Thibault et al [14] investigated experimentally the production of ethanol by fermentation under CO2 pressure, but they were not successful due to the negative effect of pressure on the microorganisms used. L ltalien et al [15] attempted to improve the ethanol fermentation under hyperbaric conditions with limited success. The separation of ethanol from fermentation broth, however, was not investigated thoroughly. 

There are many minor industrial problems associated with the ethanol fermentation processes to be solved nowadays, when optimal operation is a target. Among them, there is the lack of process robustness in the presence of fluctuations in operational conditions, which leads to changes in the kinetic behavior, with impact on yield, productivity, and conversion. These changes are very common in ethanol plants, where they occur not only because of the variations in the quality of the raw material but also beeause of variations of dominant microorganisms in the process. 

The critical concentrations of the inhibitor were dependent on the microorganisms used in the ethanol fermentation. Yeast strains have been proven to be more tolerant than bacterial bioethanol producers [e.g. Zymomnas mobilis and recombinant E. coZi). Martin and Jonsson reported that 7.5 g HMF or 3.0 g furfural or 1.2 g HMF plus 1.0 g furfural extended the lag phase of S. cerevisiae ATCC 211239 over 24... 

Biological—Biochemical Processes. Fermentation is a biological process in which a water slurry or solution of raw material interacts with microorganisms and is enzymatically converted to other products. Biomass can be subjected to fermentation conditions to form a variety of products. Two of the most common fermentation processes yield methane and ethanol. Biochemical processes include those that occur naturally within the biomass. 

The growth of cells on a large scale is called industrial fermentation. Industrial fermentation is normally performed in a bioreactor, which controls aeration, pH and temperature. Microorganisms utilise an organic source and produce primary metabolites such as ethanol,... 

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