Recombinant cellulolytic bacillus subtilis as the platform for one-step production of biofuels and biochemical from pretreated biomass

Abstract 143

Y-H Percival Zhang [1],,
Xiao-Zhou Zhang [1]
Chun You [2]
Hui Ma [1]

Consolidated bioprocessing (CBP) is a low-cost cellulosic biomass processing by integrating cellulase production, cellulose hydrolysis, and sugar fermentation into a single step.

Although significant efforts have been made to create recombinant cellulolytic microorganisms, real recombinant cellulolytic microorganism that can produce sufficient secretory active cellulases, hydrolyze cellulose, and utilize soluble sugars for supporting cell growth and cellulase synthesis without help of organic nutrients was not available before our efforts.

We demonstrated that over-expression of Bacillus subtilis endoglucanase BsCel5 enables non-cellulose-utilizing Bacillus subtilis to grow on cellulose and pretreated lignocellulosic biomass as the sole carbon source without addition of costly organic nutrients.

After directed evolution and screen on solid cellulose through a novel powerful and highly efficient enzyme engineering platform, both the expression/secretion level and specific activity of BsCel5 has been increased successfully. We also optimized and co-expressed secretory family 5, 9 and 48 cellulases in a single B. subtilis strain.

One-step production of ethanol, micro-biodiesel and lactate from cellulose and pretreated biomass in the minimal medium without adding any organic nutrient has been demonstrated.

The recombinant cellulolytic B. subtilis would be an ultra-low-cost platform for producing biofuels (e.g., ethanol, butanol, fatty alcohols) and other value-added products (e.g., lactate, fumaric acid) from non-food biomass, with obvious advantages over other developing CBP microorganisms.

(1) Gate Fuels Inc, Blacksburg, VA 24061, United States
(2) Biological Systems Engineering, Virginia Tech, Blacksburg, VA 24061, United States