Recherche pétrolière et gazière

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In-planta expression of HT lignocellulose digesting enzymes: a green & economic strategy for advanced biofuel production

Bilal Ahmad Mir

The growing demand for energy and concerns about
Greenhouse gas emissions have stimulated a worldwide
interest in the exploitation of lignocellulosic plant biomass,
the most abundant renewable and low-cost organic
raw material for production of biofuels and biomaterials.
In planta expression of lignocellulose digesting enzymes
is a promising approach to reduce the production costs
associated with biomass pretreatments and enzymatic hydrolysis.
However, this approach faces a number of challenges,
including auto-hydrolysis of developing cell walls,
plant growth and yield penalties, low expression levels
and the limited stability of expressed enzymes at the high
temperatures generally used for biomass processing to release
fermentable sugars. In planta consolidated bioprocessing
using hyperthermophilic (HT) lignocellulose-degrading
enzymes is a promising strategy for conversion
of lignocellulose into fermentable sugars because these
enzymes will continue to function during the ‘heat-up’
phase of a steam explosion process used for lignocellulose
pretreatment. The high level functional expression of recombinant
HT enzymes in bioenergy feed-stocks could
reduce, or even obviate, the need for exogenous enzyme
additions prior to fermentation, substantially reducing
the cost of the complete processing operation.