biofuel 111 Biomass 92 Biofuels 89 cellulose 70 biomass 67 Lignin 54 Cellulose 51 lignin 47 Fermentation 46 Saccharification 45 Ethanol 44 enzyme activity 42 Enzymes 41 Technology: general issues 41 fermentation 39 hydrolysis 39 Metabolism 38 gene expression 38 Crops 37 enzyme 37 Glucose 36 Lignocellulosic biomass 36 Yeast 36 metabolism 36 Genes 35 Biochemistry 34 Enzymatic hydrolysis 34 Plants (botany) 34 fungus 31 ethanol 30