A whole-cell biocatalyst system was developed in our research laboratories to directly produce ethanol from cellulose in a single step; initially we used a model amorphous cellulose (Phosphoric acid swollen cellulose, PASC).  This whole cell biocatalyst was constructed with LY01, which is one of the most developed ethanologenic Escherichia coli strains, as a host cell.  The cellulase genes, celCCA, celCCE and β-glucosidase, were prepared from the mesophilic strain Clostridium cellulolyticum.  To enhance the stability and activity of the cellulosic enzymes, these enzymes were co-displayed with the anchor protein PgsA on the surface of the host cell.  For inducing the synergism of enzymes, this recombinant cellulolytic microorganism co-expressed endoglucanase, cellobiohydrolase, and β-glucosidase, simultaneously.  The saccharification product, monosaccharides, can be uptaken immediately by the host cell and produce ethanol so that the inhibition of the catalytic activity of enzymes due to high substrate (sugars) concentration, can be effectively minimized.  In this research, we also applied the whole-cell biocatalyst system in a bioethanol production process with the lignocellulosic biomass as a substrate.  With the enzymatic hydrolysis of natural biomass, there are several factors, which  determine the hydrolysis rate, e.g. crystallinity, degree of polymerization, particle size, pore volume, and accessible surface area.  Since cellulose hydrolysis occurs on the surface of cellulose, we especially focus on the relationship between particle size of cellulose and hydrolytic rate in whole-cell biocatalyst system.   The results are very promising.