a1 Biological Sciences Department, College of Natural Sciences, University of Agriculture, Abeokuta, Nigeria
a2 Microbiology Department, College of Natural Sciences, University of Agriculture, Abeokuta, Nigeria
Microbial isolates from the gut region of larvae and adults of the variegated grasshopper Zonocerus variegatus (Linnaeus) were screened for extracellular production of the enzymes lipase, amylase, esterase, protease, linamarase and cellulase. Using the pour-plate culture technique, 15 bacterial, 4 yeast and 5 mould isolates were tested. None of the bacterial isolates showed lipase activity, but virtually all showed esterase and protease activities. Many bacterial isolates demonstrated linamarase and cellulase activities, and a few of them amylase activity. Of the yeast isolates, a few had amylase activity. None of the mould isolates showed enzyme activity, except Aspergillus sp., which showed lipase activity. Evidently, the gut of Z. variegatus contains micro-organisms that are able to produce digestive enzymes. Of significance is the biosynthesis of linamarase (β-d-glucosidase) by the grasshopper's gut bacteria, which probably contributes to the insect's neutralization of the toxic effects of cyanogenic glycosides present in cassava (Manihot esculenta), one of its major food plants.
(Accepted September 16 2009)