Antibiotics remove Caduceia versatilis from the Cryptotermes cavifrons (Kalotermitidae : Isoptera) hindgut and increase production of calcium-rich crystals

The microbial community of the hindgut of the wood-eating termite Cryptoter mes cavifrons contains many different bacterial types associated with the w ood-digesting protists (Caduceia versatilis, and the multinucleate Snyderel la tabogae and Stephanonympha sp.). Bacterial symbionts are common on the s urface membranes, in the cytoplasm and in the nuclei of the protists. The b acterial distribution pattern is species-specific in these protists. Crypto termes cavifrons fed a mixture of penicillin and streptomycin over one mont h were compared to untreated termites. After four weeks of treatment, no C. versatilis or Stephanonympha remained; S. tabogae persisted as the only la rge protist present. Calcium-rich organic crystals of unknown composition a ccumulated in far greater quantities in the guts of the antibiotic-treated termites relative to controls. Snyderella tabogae cells from termites livin g in the original wood sample were 10 percent shorter and had 30 percent fe wer nuclei than those fed paper with or without antibiotics or NaCl.