Screening natural environment

Whether a biocatalyst consists either of an isolate from a natural environment, of a classically improved strain or of a strain improved by various types of genetic engineering, the biocatalyst that is obtained after a screening effort will eventually be applied in a process. In order to obtain sufficient amounts of active biocatalyst, the cells have to be produced by fermentation. 

Often, different results come from screening tests. This may arise from the source of inoculum, whether acclimation has occurred or can occur during the test period (Cowan et al., 1996), and from the microbial population (concentration) in the test medium (Blok and Booy, 1984), depending on whether the screening test is designed to simulate more closely the natural environment or a biological treatment plant. 

Flavonoids as antioxidants have been reviewed several times 45s including an outline of many claims to their beneficial health effects . Due to their complex structures and different classes (eight thousand different compounds are known ), researchers often resorted to qualitative screening methods to evaluate their antioxidant potentials in mixed aqueous/lipid phases. For example, the so-called Trolox equivalent antioxidant capacity (TEAC), the concentration of Trolox with equivalent antioxidant activity of a 1 mM concentration of the substrate, is frequently used in heterogeneous systems. Unfortunately, this can be an unreliable measure of the activity of the substance, especially if initiation is also carried out in the aqueous phase. Nevertheless, there have been some efforts made to evaluate antioxidant activities of specific flavonoids using more quantitative methods in heterogeneous systems in order to mimic natural environments. A few examples are cited below to illustrate some approaches to determine flavonoid activities in micelles or lipid membranes. 

An integral element of the Green Screen is taking into account potential degradation products and metabolites. This is important given that chemicals in the environment are not static, they integrate into human and natural environments. Both decaBDE and BPADP scored lower on the Green Screen because of their breakdown products. 

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