Bioconversion factor

A number of factors described as influencing carotenoid bioavailability were regrouped under the SLAMENGFll mnemonic. Species of carotenoid. Linkages at molecular level. Amount of carotenoids consumed in a meal. Matrix in which the carotenoid is incorporated. Effectors of absorption and bioconversion. Nutrient status of the host. Genetic factors. Host-related factors, and Interactions among these variables. Only the factors that affect the micellarization of the compound in the gut are discussed and summarized in Table 3.2.1. 

Studies in humans and animals suggest that carotenoid absorption depends on several factors including vitamin A status. Sklan and others (1989) demonstrated that vitamin A supplementation reduced (3-carotene and canthaxanthin absorption in chickens. Dietary carotenoids absorption and bioconversion to vitamin A varied inversely with the vitamin A status of Philippine children (Ribaya-Mercado and others 2000). Some studies (Lecomte and others 1994 Albanes and others 1997) have suggested a possible negative effect of alcohol consumption on carotenoid absorption however,... 

Tanumihardjo SA. 2002. Factors influencing the conversion of carotenoids to retinol bioavailability to bioconversion to bioefficacy. Int J Vitam Nutr Res 72 40-5. 

West CE and Castenmiller JJM. 1998. Quantification of the SLAMENGHI factor for carotenoid bioavailability and bioconversion. Int J Vit Nutr Res 68 371-377. 

One of the major expenses incurred in the application of enzymes for bioconversion processes is the cost of enzyme production (1). The total cost of production includes the cost of fermentative production as well as downstream processing requirements. Both of these factors must be optimized and integrated for maximum cost-effectiveness. 

CSBR). In this case the bioconversion is run under approximately steady-state conditions where the position of reaction equilibrium lies toward the products of the conversion. In this case the concentration of product (proportional to Sj — S0 ) at a given reactor residence time becomes a function of both the flow rate (Q) into the reactor and reactor volume, in addition to the factors discussed above for batch mode reactors (i.e., catalyst parameters and density, inlet substrate concentration S and outlet substrate concentration S0). 

A number of factors must be considered in the area of stereoselectivity (31). Distinct differences are noted between stereoisomers in absorption/ uptake, activity at the target or receptor site, pathways and rate of bioconversion, and pharmacokinetics. All of these factors are applicable in the case of triadimefon and are examples of processes that may be manipulated to enhance disease control effectiveness. 

West CE and Castenmiller JJ (1998) Quantification of the SLAMENGHl factors for carotenoid hioavailability and bioconversion. International Journal of Vitamin and Nutrition Research 68,371-7. 

A few economic factors concerning the dilute acid process are discussed here in comparison to the enzymatic process. It must start with the yield that has been the focus of the reactor analysis and development. Production of fuels and chemicals from biomass is substrate cost intensive with feedstock costs representing roughly one half of total production costs 142, 55]. It is of paramount importance in most bioconversion processes to maximize the yield of the product from the biomass substrates. The most advanced dilute acid process has brought the saccharification yield to above 80% as verified by NREL bench-scale experiments [10]. The actual yield of the enzyme saccharification is dependent on the effectiveness of the pretreatment. However, it rarely surpasses 90% even with a highly efficient pretreatment. The enzymatic process also requires additional substrate because it has to be produced from cellulosic biomass. The amount of biomass feedstock needed for enzyme production is estimated to be about 9% of the total. With these in consideration, the yield of the acid saccharification is about even with that of the enzymatic process. What can... 

Plant cellulose is always associated with hemicellulose and lignin that protect against microbial attack. Scrap paper is a better substrate for bioconversion because it has already undergone a pulping step that removes most of the hemicellulose and lignin. Other factors are ... 

For these reasons, SSF is the preferred process option for the bioconversion of the cellulose fraction of lignocellulosic materials to ethanol. The SSF process involving lignocellulosic materials has been reviewed [66]. The following factors are important for an efficient SSF process ... 

As a new option, for the bioconversion of poorly soluble substrates the classical EMR-concept can be extended to an Emulsion Membrane Reactor , comprising a separate chamber for emulsification (with a hydrophilic ultrafiltration membrane), an EMR-Ioop with a normal ultrafiltration module, and a circulation pump. This approach has been successfully demonstrated for the enzymatic reduction of poorly soluble ketones [107]. Using this device, e.g., for the enantioselective reduction of 2-octanone to (S)-2-octanol (e.e. >99.5%) with a carbonyl reductase from Candida parapsilosis under NADH-regeneration with FDH/for-mate, the total turnover number was increased by a factor 9 as compared with the classical EMR. 

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