Factors affecting fermentation

Factors affecting the accumulation of ansamitocins P-2, P-3, and P-4 in JSbocardia sp. C-15003 have been studied (246) the addition of isoleucine, propionate, ptopionaldehyde, or -ptopyl alcohol to the fermentation medium resulted in the increased production of P-2 the addition of valine, isobutyrate, isobutyraldehyde, or isobutyl alcohol increased the production of P-3, reaching more than 90% of the total ansamitocins produced and the addition of leucine, isovalerate, isovaleraldehyde, or isoamyl alcohol increased the production of P-4. 

FACTORS AFFECTING THE MOLD GROWTH AND FERMENTATION PROCESS... 

Several factors affect the overall economics of PHA production. These include PHA productivity, PHA content, yield of PHA on carbon source, carbon substrate cost, and recovery method employed. Figure 1 shows the production costs of P(3HB) by various P(3HB) contents and P(3HB) productivities [29]. The effect of P(3HB) productivity on the production cost is only related to the cost of the fermentation equipment [18]. However, the P(3HB) content has multiple effects on the volume of the fermentation equipment and the recovery process [17,18]. The increase of P(3HB) yield on carbon source and the use of less expensive carbon substrates reduce the cost of carbon substrate [17, 29]. Development of an efficient recovery method, which will be different for each bacterium employed, is also important to overall economics of PHA production. When the actual fermentation processes employing many different re-... 

Extraction of PHA from plants is likely to be a major factor affecting the production cost of PHA from crops and, therefore, the economic viability of this approach. In contrast to production of PHA from bacterial fermentation, where the production system is designed to produce only PHA, an agricultural production of PHA is likely to be most viable only through the recovery of not only PHA but also all other useful components of the harvested crop, i.e., oil, proteins, and carbohydrates. This fact, combined with the lower level of PHA accumulation in plants in comparison to micro-organism, is likely to make PHA recovery from plants a challenging task. 

Many factors affect the production of biogenic amines in fermented meats, including the natural microflora present and their ability to decarboxylate, manufacturing processes, type and quality of meat, and the length of maturation (Shalaby, 1995). 

Figure 6.1 Factors affecting ethanol production from glucose using baker s yeast (S. cerevisiae) in a gas-solid fluidized bed fermenter. Reproduced from Hayes (1998) with permission.

Room temperature ionic liquids have potential as extractants in recovery of butyl alcohol from fermentation broth water solubility in ionic liquid and ionic liquid solubility in water are important factors affecting selectivity of butyl alcohol extraction from aqueous solutions (Fadeev and Meagher, 2001). 

Nomura, Y., Yamamoto, K., andlshizaki, A. 1991. Factors affecting lactic acid production rate in the built-in electrodialysis fermentation an approach to high speed batch culture. J. Ferment. Bioeng. 71, 450-452. 

Hofvendahl, K. and Hahn-Hagerdal, B. 2000. Factors Affecting the Fermentative Lactic Acid Production from Renewable Resources. Enzyme Microb. Technol., 26, 87-107. 

Houtman, A. C., Morais, J., Du Plessis, C. S. (1980) Factors affecting the reproducibflity of fermentation of grape juice and of the aroma composition of wines. I Grape maturity, sugar, inoculation concentration, aeration, juice turbidity and ergosterol. Vitis, 19, 37-54. 

The unique flavors of wines are due not only to grape flavors but also to those formed during the primary yeast fermentation and any secondary bacterial or yeast fermentation that can occur. Many of the factors affecting fermenta-tions-related flavors remain controversial (e.g., spontaneous versus inoculated yeast fermentations) or are still not well understood. The effects of grape composition, seasonal variations, and the identification of odor impact compounds need much more investigation. However, novel enzymatic syntheses are leading to an increased understanding of the pathways by which fermentation flavors are formed. These topics are discussed in Chapters 6-9. 

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