Metagenomics is a recently described technique for cloning functional genes.  It allows isolation and cloning of large segments (30-100 kb) from soil (Rondon et al 2000 AEM 66:2541-47).  It is difficult to study many aspects of soil microbial ecology because the bacteria involved are difficult or impossible to culture.  PCR with specific primers can allow small sections of the genomic DNA to be isolated from soil: for enzyme pathways, larger sections of genomic DNA are needed.  This project, in collaboration with Professor AWB Johnston of UEA, aims to examine genes responsible for different parts of the nitrogen cycle in soil (nitrification, denitrification, nitrogen fixation).  

Cloning the soil metagenome

Initially we have applied metagenomic cloning techniques to Broadbalk soils that have had different N inputs over a very long (>100 year) period and we anticipate that different populations of soil microbes will have been selected and become established over time.  These metagenomic libraries constructed in E. coli can be transferable to a range of Gram negative bacteria that may be capable of expressing genes and pathways not functional in the initial host.  We are currently screening the libraries for a range of functional genes.  (Lesley Ogilvie and Penny Hirsch)

Restriction Analysis of Soil Metagenomic library inserts

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