Life without microbes

The relationship between the animal host and its resident population of microorganisms has fascinated scientists for many years. As long ago as 1885 Louis Pasteur, in a now famous dissertation to the French Academy of Science, speculated on the possibility of life without microbes and suggested ways in which it might be investigated. He even outlined a method by which he thought chicks might be produced and maintained in a bacteriOlogically sterile condition a procedure that is very similar to the one we use today .. Modern microbiological techniques have demonstrated that the association between host and its gut microbes is very close indeed. Many components of the indigenous micro flora actually adhere to the mucosa, and it is this characteristic that enables them to resist being swept on in the digesta and to establish them elves in a particular site. Once a flora has been acquired it is very difficult to remove. Although there are reports of animals and human patients being rendered almost or completely germfree by treatment with massive doses of antibiotics, for studies of life without microbes it is much more satisfactory to derive the animals in the first place in a sterile condition. This is possible because embryos developing in the uterus of a healthy mother, or in the egg of a healthy hen, are microbiologically sterile. Provided they can be conveyed into a sterile environment without contamination they will never become associated with microorganisms. Around the turn of the century several groups of workers attempted to put Pasteur's ideas into practice, but the technological difficulties were, in those days, formidable and the success rate was not high. The development of the present gnotobiotic techniques began several decades ago. The first isolators were adapted autoclaves. In Japan, Miyakawa's apparatus used tongs operated by remote control to handle the animals inside, whereas in the USA the Reyniers model was fitted with long-sleeved rubber gloves. Both were very costly and rather cumbersome, but Gustafsson in Sweden produced a light-weight stainless-steel model that could be wheeled into an autoclave for sterilization. This was considerably cheaper and easier to handle, but it was Trexler's use of plastic