Microorganisms yield

Recently, it has been demonstrated that the yeast Saccharomyces cerevisiae (DHW S-3) can also be used for the (R)-selective reduction of the acetylsilane rac-48. By analogy with the bioconversions illustrated in Scheme 10, incubation of rac-48 with resting free cells of this microorganism yielded a 1 1 mixture of the corresponding diastereomeric (1-hydroxyethyl)silanes (SiR,CR)-49 and (SiS,CR)-5057. Under preparative conditions, the biotransformation products were isolated in 43% yield (relative to rac-48). The enantiomeric purities of the silanes (SiR,CR)-49 and (SiS,CR)-50 were >98% ee. 

Farbood and Willis(68) in a recent patent application disclosed a process for production of optically active alpha-hydroxy decanoic acid (gamma-decalactone) by growing Yarrowia lipolytica on castor oil as a sole source of carbon. This is a good example of a commercial application of a volatile chemical produced by a microorganism. Yields of up to 6 grams per liter culture media were obtained making this a promising industrial fermentation. 

It was shown that most microorganisms yield characteristic pryolysis products, the pyrograms being readily reproducible under standard culture growing conditions [202— 204]. This enables the chromatograms obtained to be compared with those of known... 

The best preparative results were obtained with Kloeckera corticis (ATCC 20109). Reduction of rac- with growing cells of this particular microorganism yielded a 1 1 mixture of (Si5, CR)-2a and (Si/ ,CS)-2a in 95 % yield the diastereomeric purity of the product was 95 % de. 

The Mosley et al. (38) and Proell et al. (39) studies taken together indicate that monoenes undergo extensive isomerization by ruminal microorganisms yielding a multitude of positional and geometric isomers, and that enzymatic isomerization is... 

Stereochemical Purity In order to make semicrystalline, high-melting PLA, stereochemically pure lactic acid is needed. Not all microorganisms yield such stereochemically pure lactic acid and some even produce a racemic mixture [29]. Therefore, a strain must be chosen that meets the quality demands. Finding such a strain that produces L-lactic acid in an economically feasible manner is relatively easy. Producing D-lactic acid by bacterial fermentation on an industrial scale is far more difficult. 

First, random chain scission of the ester groups of PLA reduces its molecular weight. The speed of chain scission depends on the pH value, temperature, and moisture levels of the environment [66]. Embrittlement of the polymers occurs with the reduction of its molecular weight. Second, low-molecular-weight PLA is metabolized by microorganisms, yielding carbon dioxide, water, and humus [67]. 

Van Dillewijn, P., Wittich, R.M., Caballero, A., and Ramos, J.L. (2008) Type II hydride transferases from different microorganisms yield nitrite and diarylamines from polynitroaromatic compounds. Appl. Environ. Microbiol., 74, 6820-6823. 

Chlorophenyl)thiazol-4-ylacetic acid ( Myalex , see these Reports, Vol. 1, p. 386) is a potent anti-inflammatory agent in animals, but it causes cholestatic jaundice in patients with rheumatoid arthritis, and has consequently not become an established remedy. Its metabolism by microorganisms yields at least eleven (identified) metabolites. Attack occurs at its acetic acid side-chain, which is modified in a number of ways, in contrast to the hydroxylation of the chlorophenyl ring effected by mammals (see these Reports, Vol. 1, p. 392, and Vol. 2, p. 613). ... 

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