5^th World Bioenergy Congress and Expo

Biography

Biography: Weilan Shao

Abstract

Many   interesting   and   important   tests   are   stopped   at   protein preparation from a target gene, and the industrial applications of lignocellulases  are hindered by the high costs of enzyme production. A gene expression system of E. coli, pHsh, was constructed to enhance the production of recombinant enzymes by using the consensus promoter of heat shock (Hsh) proteins. The target gene in pHsh is under the control of an alternative sigma factor, σ32, and its expression is induced by a temperature up-shift. The presence of pHsh increases σ32 concentration in E. coli cells, which could strengthen the transcription of heat shock chaperons.  Therefore,  pHsh  exhibits  advantages  in  allowing  healthful growth of recombinant cells, increasing production of target protein, and decreasing   inclusion   body   formation.   Based   on   pHsh   system   and mediated   by  a  thermostable   DNA  ligase,   in  situ  error-prone   PCR technique has been developed to perform directed evolution in a step of PCR amplification and plate selection. Combining the techniques of pHsh expression, site-directed mutagenesis, and directed evolution, we are able to modify genes coding for lignocellulases  with desired properties,  e.g. the  genes  encoding  extremely  thermostable  xylanase  and  laccase  have been improved, and enzymes can be efficiently produced for biobleaching pulp at high temperatures.  These advanced techniques  will enhance the biodegradation  of lignocellulosic  biomass for the industrial  applications of bioenergy.