High-level expression of thermostable cellulolytic enzymes in tobacco transplastomic plants and their use in hydrolysis of an industrially pretreated Arundo donax L. biomass

Table 1 Enzyme yield in transplastomic tobacco plants and partial purification of plastid-based cellulolytic enzymes

Enzyme	Whole plant leaves (g FW)	% yield (TSP)^a	Specific activity^b						Fold purification
			Crude extract					Enriched extracts
			Old leaf	Whole plants leaves				Enriched extracts
			U/mg	U/mg	U/g plant	U/plant	U (millions)/t DW	U/mg
Endo-β-1,4-xylanase	45.5	35.7	34.2	27.2	163.3	7429.7	1484	105.4	3.9
β-Glucosidase	45.2	60.9	97.2	62.6	1450.8	65,574.6	13,189	255.4	4.1

g FW gram of fresh weight leaves, TSP total soluble proteins, U/mg unit per milligram of crude or enriched extract, U (millions)/t DW unit per ton of dry weight leaves
^aDetermined by Western blotting analysis using a dilution series of purified Flag protein
^bDetermined by enzymatic standard assay. Data are relative to crude and enriched extracts by heat treatment (see “Methods” section for details)

ISSN: 2731-3654