Abstract

Though actinomycets are of universal occurrence in nature, their existence was noticed only two centuries after Antoni van Leeuwenhoek, who is considered to be the Father of Microbiology, first observed bacteria in his microscope'. The first report on an actinomycete was made by Ferdinand Cohn in the year 1875 and since then several reports have appeared on their occurrence in soil, composts and manure heaps and also as plant, animal and human pathogens and detailed investgations have been carried out. As a result it occupies at present a very prominent position in industrial and agricultural microbiology. Studies on actinomycetes started in the United States when Dr. Selmen A. Waksman, at present Director of the Institute of Microbiology, Rutgers University, entered this field. In the spring of 1914, Waksman, while studing different groups of microorganisms in the soils of New Jersey Agricultural Experimental Station, came across the interesting but little-known group of 'ray fungi'. The reason for this neglect was brought out in his first paper on the subject in the following words: "The actinomycetes grow very slowly; they begin to develop from the bottom of the plate, and to the casual observer the colonies formed look like those of bacteria, even after 5-6 days' incubation; only the somewhat mealy or rough surface will disclose the fact that they are not bacteria. It requires careful observation to tell whether those white, pink or grey colonies are bacteria or not. Many counts of bacteria might have been confused, when this point was not known, and the fungi and actinomycetes were not taken into consideration".

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