Catalyzes the reversible phosphorolytic cleavage of trehalose. Phosphorolysis is specific for trehalose, but D-xylose, D-galactose, L-arabinose, D-fucose, L-fucose, D-glucosamine and 2-deoxy D-glucose can act as substitutes for D-glucose in the synthetic reaction. alpha,alpha-trehalose + phosphate = beta-D-glucose 1-phosphate + D-glucose Inhibited by Cu(2+), Hg(2+), Mg(2+), Mn(2+), Pb(2+) and Zn(2+). kcat is 110 sec(-1) for trehalose. kcat is 110 sec(-1) for phosphate. kcat is 140 sec(-1) for D-glucose. kcat is 140 sec(-1) for beta-D-glucose 1-phosphate. Optimum pH is 7.0-7.5 for phosphorolysis, and 6.0-7.0 for synthetic reaction. Optimum temperature is 70 degrees Celsius. Glycan degradation; trehalose degradation. Homodimer. Belongs to the glycosyl hydrolase 65 family.