Study of the potential relationship between the morphology of infectious somatic coliphages and their persistence in the environment

The proportions of different morphological types of infectious somatic coli phages were determined in faecally polluted freshwaters. Myoviridae, follow ed by Siphoviridae, were the most frequently isolated morphological types i n raw sewage, treated sewage and river water collected a few metres downstr eam from a sewage outfall. However, in rover water collected further downst ream from the pollution point, in river water after 'in situ' inactivation experiments and in chlorinated raw and treated sewage significant changes i n the proportions of the different somatic coliphage morphological types oc curred. In all cases, Siphoviridae, especially those with flexible and curl ed tails, became more abundant to the detriment of Myoviridae.