Distribution and abundance of bacteria in the gut of a soil-feeding termite Procutiermes aburiensis (Termitidae, Termitinae).

The alimentary canal of a representative species of soil-feeding termite was examined for associations with bacteria. Enumerations made in the principal regions of the intestine by direct observation and expressed for comparative purposes as total microbial standing crop showed a net three- to fourfold increase between the foregut (crop) and rectum. Filamentous organisms, putatively actinomycetes, contributed significantly to the flora in most regions of the gut and were more abundant, relative to non-filamentous forms, than in freshly ingested soil. Transmission and scanning electron microscopy of the gut wall showed that the actinomycetes formed novel associations with the host in the mesenteron, mixed segment and colon. Non-filamentous organisms, chiefly rods, colonized the walls of the first proctodaeal segment and the colon, in addition to filaments, and were present in large numbers in the contents of the third proctodaeal segment.