CELLULOSE AND XYLAN UTILIZATION IN THE LOWER TERMITE RETICULITERMES SPERATUS

The distribution of the enzymes of cellulose and xylan metabolism name ly endo-beta-1,4-glucanase, beta-glucosidase, endo-beta-1,4-xylanase a nd beta-xylosidase activities, in Reticulitermes speratus (Kolbe) was measured both in the salivary glands and in the major gut sections and along the length of the gut in freshly collected termites, The majori ty of the endo-beta-1,4-glucanase activity (77.8%) was found in the sa livary glands which also contained 23.9% of the beta-glucosidase activ ity, At least 70% of the remaining activity was located in the anterio r section of the hindgut, A small amount of endo-beta-1,4-xylanase act ivity (2.4%), but no beta-xylosidase activity, was present in the sali vary glands, The majority of these activities were in the anterior sec tion of the hindgut, The RQ of freshly collected termites at 25 degree s C was 1.03+/-0.01, Maintaining termites for 16 days on wood, cellulo se and xylan showed that the RQ values of termites fed on wood or xyla n were not significantly different from those of freshly collected ter mites but significantly increased when maintained on cellulose, The KQ of starved termites after ii days was 0.81+/-0.02. There were three e ffects on protozoan populations of feeding termites xylan for 20 days, One species, Dinenympha parva was not affected, while five others, Py rsonympha grandis, Holomastigotes elongatum, Dinenympha rugosa, Dineny mpha leidy and Dinenympha porteri survived for 20 days but slowly decr eased in numbers, The numbers of P. grandis and D. leidy surviving for 20 days were significantly different from those in starved termites. The third group comprising the two large species. Teratonympha mirabil is and Trichonympha agilis and three small species, Pyrsonympha modest a, Dinenympha exilis and Dinenympha nobilis disappeared within 15 days as in starved termites, It is suggested that protozoa in the first tw o groups are xylanolytic, Protozoan populations on wood and cellulose diets were not markedly affected, Selective removal of the protozoa by u.v. irradiation led to the loss of xylanolytic activity and a life s pan comparable to starved termites, (C) 1997 Elsevier Science Ltd.