Acceleration of Fibrous Biomass Degradation by Bacterial Enzymes

Since biomass photosynthesized from C02 and H2O is one of the most predominant storage sites of solar energy, its effective utilization will be essential to overcome the shortage of foods and energy in future. Relaxation of biomass tissue is focused to enhance solubilization by expressing fiber‐degrading enzyme genes in plants. A xylanase gene from Clostridium thermocellum was highly expressed in tobacco plant (4%) without apparent defects in the growth. Another xylanase from Clostridium stercorarium was also expressed well in tobacco suspension cells and degraded the host's insoluble cell wall fraction.A cellulase from a rumen bacterium expressed in tobacco suspension cells promoted protoplast formation efficiency of the transgenic cells. A thermostable (1, 3 - 1, 4)-β-glucanase gene was expressed in the grains of transformed barley after modifying codon usage. The results obtained from these enzyme expressions in plants suggest the relaxation of plant tissue which may enhance solubilization of tough biomass