INTERACTIONS BETWEEN SOIL BACTERIA AND THE MOLLUSCAN ALIMENTARY TRACT

Abstract

The alimentary tract is a major site of interaction between an animal's ecosystem and its physiology. It may be intermittently or permanently populated by microorganisms from its environment that could be beneficial or pathogenic in their influence. The bacterial populations of the snail (H. aspersa) and the woodlouse (O. asellus) have therefore been estimated in terms of colony forming units. gm body weight⁻¹. The bacteria in the snail appear to be similar to those found in soil and show wide resistance to antibiotics. The main types are gram negative rods tentatively identified as belonging to Pseudomonas, Xanthomonas, Acinobacter, Vibrio and Enterobacteriaceae. Some gram positive and endospore forming bacteria of Bacillus, Staphylococcus and Micrococcus spp were also present. The numbers of bacteria increase towards the posterior of the alimentary tract although the numbers in the digestive gland are more constant.