家鷄雛の無菌飼育に関する研究

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As the working of intestinal flora is so complicated and delicate and its fundamental study consequently entails a great deal of difficulty that its physiological significance has not yet been fully clarified in spite of the achievements of many bacteriologists since Louis Pasteur. Metschnikoff's theory that men would not age and their life span could be extended if they are fed with yoghurt lacks concrete experimental evidences to support it. The most adequate method for studying activities of intestinal bacteria would be to use animals whose body contains no germs at all. Studies on intestinal bacteria have been carried out in this department for years. An attempt at raising germ-free chicks made by Akazawa and his collaborators was successful, and it was reported by Tanikawa, Akazawa and etc. in 1942 that germ-free rearing of animals had been successfully carried out for the first time in Japan. In the present experiments, the authors first performed checking up on the results of the previous experiments availing themselves of the equipment developed by Akazawa. Finding this early equipment inadequate, the authors started improving it and finally succeeded in developing an equipment of their own idea. The new equipment has been installed in an experimental facilities incorporating new devices. The present equipment for germ-free rearing of chicks consists of a cylindrical chamber and a germicidal trap which is attached to one side; the cylinder is 75 cm high and 50 cm in diameter and its base is a steam-heated hot water bath which is used for sterilizing and heating purposes. After preliminary experiments on the control of temperature, humidity and ventilation of the chamber and the proper diet to be fed to the germless animals, the regular experiments were performed in the following process: Nearly fullterm embryos were placed inside a steam-cleansed chamber after their encasing shells had been sterilized. The chicks thus hatched in proper temperature were raised in sterile seclusion, being given sterile chick feed and water. Measurement of weight was done with a scale placed in the chamber. The experiments on germ-free raising of chicks in the present equipment which can be operated with comparative ease proved to be a complete success. The results of the experiments have evidenced that the germless chicks develop into normal adults provided that they are reared in ordinary conditions. The fact that the chicks which are free from intestinal bacteria have been kept alive, will refute the claim that intestinal bacteria are essential to the survival and growth of animals. It is clear, however, that intestinal bacteria of the animals placed in natural environment influence the physical conditions of hosts in one way or another. The availability of the germ-free animals for experiments will open up new vistas to the wide variety ofresearches;・experiments on the relationship between various organisms in the intestinal canal carried out in germ-free animals will help solve the problems on antagonism and symbiosis of various forms of intestinal bacteria, on digestion and absorption of food, on synthesis and decomposition of vitamins, on autointoxication caused by some uneliminated toxin generated by a certain kind of intestinal flora and on immunuzation.
千葉大学の論文
1955-03-28

家鷄雛の無菌飼育に関する研究

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