Properties of Digestive Carbohydrase Activities Secreted by Two Cockroaches, Panesthia cribrata and Periplaneta americana

Abstract

Carbohydrase activities in the xylophagous Panesthia cribrata and the omnivorous Periplaneta americana were localised in the foregut and midgut and are endogenous. Levels of activities involved in the hydrolysis of cellulose and hemicellulose were higher in P. cribrata, while those directed against starch and sucrose, by comparison, were elevated in P. americana. Two endo-β-1,4-glucanase (EC 3.2.1.4) and two endo-β-1,4-xylanase (EC 3.2.1.8) components and additional components active against laminarin or lichenin, were secreted in the gut of P. cribrata. Two major β-glycosidase components, β-GD1 and β-GD2, were also secreted. β-GD1 was a β-fucosidase (EC 3.2.1.38), a β-mannosidase (EC 3.2.1.25) and a β-glucosidase (EC 3.2.1.21), which rapidly hydrolysed cellobiose, laminaribiose, and lactose. β-Galactosidase (EC 3.2.1.23) activity may also be partially associated with β-GD1. β-GD2 was a β-xylosidase (EC 3.2.1.37), an α-L-arabinosidase (EC 3.2.1.55) and a β-glucosidase, but was less active against β-linked disaccharides than was β-GD1. One β-N-acetylhexosaminidase (EC 3.2.1.52) and three α-galactosidase (EC 3.2.1.22) components were also secreted by P. cribrata. Two of the α-galactosidases may be associated with trehalase (EC 3.2.1.28) activity. A single sucrose α-glucosidase (EC 3.2.1.48) component hydrolysed sucrose, maltose and other α-linked disaccharides. β-fructofuranosidase (EC 3.2.1.26) activity is not secreted by P. cribrata.