Functional screening of a winter and a spring genomic DNA libraries obtained from soils in a winter wheat crop

摘要

Soils are very rich environments where the diversity of microorganisms is very high. These microorganisms play important role in the degradation of organic matter with enzymes able to degrade it. The aim of this work is to discover by functional screening new enzymatic activities of microorganisms from soils collected in winter and spring in a winter wheat crop. The genomic DNA was extracted from both soils to construct two libraries in Escherichia coli. These libraries were then screened for several enzymes such as lipase, beta-glucosidase, cellulase, α-amylase,… At this time, 2 beta-glucosidases and 3 lipases have already been found in the winter library and 3 beta-glucosidases and 1 lipase in the spring library. Sequence analyses with the BLASTX program revealed that two beta-glucosidases have less than 65% of sequence identity with known beta-glucosidases, one have 64% of identity with a known beta-galactosidase and one have 59% of identity with a glycoside hydrolase. The fifth seems to be a phosphorylase kinase (54% identity) which have a glucoamylase domain responsible for the activity. This ORF is interrupted by a transposase. Three of the four lipases have less than 60% of sequence identity with known lipases/esterases. The fourth show 55% of identity with a known beta-lactamase.