Continuous Survey of the Distribution of RNA Coliphages in Japan

In order to demonstrate the stability and continuity of RNA coliphages (phages) in their natural habitats, we investigated the amount and group types of RNA phages in sewage samples collected continuously from domestic drainage in Japan proper and islands in the seas adjacent to Japan (abbreviated simply as islands, hereafter) over a 5‐yr period from 1973 to 1977. It was found that the frequencies of isolation of RNA phages were fairly high and constant. The group types of RNA phages isolated were also stable in the three cities, Choshi, Niigata, and Toyama in Japan proper. The average for the three cities was group II: III = 3: 1. The investigation in islands revealed that the frequencies of isolation of RNA phages were fairly high as in the case of the above three cities in Japan proper and the group types of RNA phages isolated were also stable. That is to say, group II phages were predominant on Rishiri Island, Rebun I., Iki I., and Tsushima I., which are located relatively near to mainland Japan, while group III phages were predominant on Amamiohshima I., mainland Okinawa, Ishigakijima I., and Iriomotejima I., which are located south of Kyushu. It can thus be said that the RNA phages in the domestic drainage of Japan proper and islands remained more or less stable over at least the 5‐yr period, and an apparent difference in the geographical distribution of RNA phages in Japan exists between Kyushu and Amamiohshima I.