Functional analysis of phenoloxidase activity towards the model substrate pyrogallol. (a) pH dependence of pyrogallol oxidation determined using whole guts of worker termites. (b) Distribution of pyrogallol oxidation activity across the termite gut using 14,000 g supernatants from homogenized tissues of the foregut plus salivary gland (FG), midgut (MG), and hindgut (HG). (c) Feeding by live termites for 7 days on papers treated with lignin alkali at concentrations ranging from 0% to 0.625% w/v. (d) Pyrogallol oxidation activity in whole termite guts after feeding on various concentrations as depicted in (c). Bars with the same letters are not significantly different by least significant difference (LSD) t tests (P < 0.05).