Metagenomic enzyme screening

KimJ, Grate JW, Wang P. Nanobiocatalysis and its potential apphcations. Top Catal 2012 55 1055-6. Ko K-C, Lee JH, HanY, Choi JH, SongJJ.A novel multifunctional cellulolytic enzyme screened from metagenomic resource representing ruminal bacteria. Biochem Biophys Res Commun 2013 441 567-72. 

Recently, metagenomic library screening provided a few more nitrilases, whose genes were obtained from clones growing on cinnamonitrile or a nitrile mixture. One of the enzymes was selected for the monohydrolysis of 2-methylglutaronitrile into... 

Proteases are hydrolytic enzymes with important application in industries, in particular, in detergent and in the food industry. A metagenomic study in which 100 000 plasmid clones were screened for proteolytic activity found one positive done, which was determined to be novel by sequencing analysis [84]. 

The recently developed methodology for enzyme discovery that is based on random DNA isolation and subsequent screening (metagenome mining) is... 

Figure 2.3 Metagenomic cloning experiments. Isolation of genomic DNA directly from environments (soil, plants, mixed environments or thermal-vent worms are the examples Illustrated here) can recover DNA fragments which could encode for enzymes. The DNA fragments can be ligated to plasmids or DNA linkers, and then subjected to functional screening (expression cloning) and/or sequence analysis. Amplification by PCR can sometimes be used to yield libraries enriched with clones containing selected sequence motifs relating to families of enzymes...

But there is still another point, not yet discussed but with considerable potential, which may also impact eventually on technical asymmetric catalysis. Even though biocatalysts are efficient, active, and selective, there still remains one big disadvantage At present, there is not yet an appropriate enzyme known or available for every given chemical reaction. It is estimated that about 25 000 enzymes exist in Nature, and 90% of these have still to be discovered [28, 29]. New biocatalysts are made available nowadays not only from screening known organism but also via screening metagenomic libraries and directed evolution techniques [30]. 

Lorenz P, Liebton K, Niehaus F, Eck J (2002) Screening for novel enzymes for biocatalytic processes accessing the metagenome as a resource of novel functional sequence space. Curr Opin Biotechnol 13 572-577... 

Most recently, this group applied the metagenome screening strategy for fhe identification of improved DERA enzymes [75]. More than 15 DERA enzymes were discovered, of which one was used to optimize the process mentioned (Scheme 4.17E) on a 100 g scale. Using a fed-batch strategy, which is necessary because of substrate inhibition, Burk et al. obtained a final product concentration (16) of 93 g I. (>99.5% ee, de 96.6%). Concomitantly, the amount of enzyme was reduced to 2% (wt/wt). 

Litthauer D, Ginster A, Skein EVE (2002) Pseudomonas luteola hpase a new member of the 320-residue Pseudomonas lipase family. Enzyme Microb Technol 30 209-215 Lopez-Serrano P, Cao L, van Rantwijk F et al. (2002) Cross-linked enzyme aggregates with enhanced activity application to lipases. Biotechnol Lett 24 1379-1383 Lorenz P, Liebeton K, Niehaus (2002) Screening for novel enzymes for biocatalytic processes accessing the metagenome as a resource of novel functional sequence space. Curr Opin Biotechnol 13 572-577... 

The screening of a metagenomic library derived from loam soil afforded a novel two-component SMO, which has been heterologously expressed in E. coli [52], This biocatalytic system was able to perform selective sulfoxidations of alkyl aryl sulfides, providing the recovered (R)-sulfoxides with good to high selectivities and moderate conversions after 16h. Ethyl phenyl sulfide was the best substrate for this enzyme, as the final sulfoxide was obtained with 92% ee. It therefore represents an interesting SMO alternative. 

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