Friday, June 25, 2010

Functional metagenomics reveals mechanisms of antibiotic resistance

The CopyControl™ Fosmid Library Production Kit has established itself as the molecular tool of choice in studying many facets of environmental metagenomics. Donato et al. at the University of Wisconsin-Madison explored several antibiotic resistance genes from soil microbes in an apple orchard. The study focused on Streptomyces bacteria, long known to be a reservoir of multiple antimicrobial resistance markers. Older techniques, such as cultivation of microbes from soil and determining resistance based on the ability to grow these microbes can fall short in locating these resistance genes, primarily due to the inability to cultivate some of these bacteria. Functional metagenomics, which involves inserting large fragments of foreign DNA into E. coli and assaying the resulting clones for expressed functions, allows the study and isolation of various activities encoded by genes from microbes that are otherwise uncultivatable.

Among 13 antibiotic-resistant clones, the authors isolated two genes that encode novel bifunctional proteins. One putative bifunctional protein confers resistance to ceftazidime and contains a natural fusion between a predicted transcriptional regulator and beta-lactamase. The ability to archive these activities in a genomic library enhances their future study under many different conditions.

ResearchBlogging.orgDonato, J. et al. (2010). Metagenomic Analysis of Apple Orchard Soil Reveals Antibiotic Resistance Genes Encoding Predicted Bifunctional Proteins Applied and Environmental Microbiology, 76 (13), 4396-4401 DOI: 10.1128/AEM.01763-09

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