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Comparison of the screening methods for metagenomeic libraries |
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| Function-based screening |
Sequence-based screening |
SIGEX |
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| Screening principle |
• Detecting changes by enzymatic reactions (e.g. halo formation around the colonies) |
• PCR or Southern hybridization based on the DNA sequence consensus |
• Trapping the operon induced by a substrate and sorting using FACS |
| Advantages |
• Secures a complete form of gene or gene cluster required for desired traits • Potentially obtains completely novel genes. |
• Overcomes the limitations of the heterologous expression |
• Fast and economical • Any substrates that can be introduced into cytoplasm can be used in its native forms. |
| Disadvantages |
• Must satisfy the expression conditions (transcription, translation, folding, secretion) in heterologous hosts |
• Requires a database and analyses of the DNA sequence consensus. • Does not guarantee the acquisition of complete forms of genes or gene clusters. |
• Sensitive to the orientation of the genes with desired traits • Cannot use substrates that do not migrate to cytoplasm • Sensitive to the initial FACS setting |
| Examples |
antibiotics [9, 19-22], genes involved antibiotic resistance [9, 23, 24], agarases [15], amidases [13], amylases [15, 21, 25, 26], esterase/lipases [8, 15, 21, 27, 28], xylanases [29], 4-hydoxybutyrate dehydrogenase [30] alcohol oxidoreductases [14], pectate lyases [31] |
amylases [26], polyketide synthases [32, 33] |
Benzoate-degratative or catechol degradative operon, P450 enzyme [16] |
Yun and Ryu Microbial Cell Factories 2005 4:8 doi:10.1186/1475-2859-4-8 |
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