Abstract
The advancement of biotechnology, including gene-technology, and life science in recent years is remarkable. Bacteria such as Escherichia coli (E.coli) contributed enormously to that advancement and are essential for research in those fields. We have developed simple handling methods for E.coli and for the observation of the chemotaxis of that bacteria for biological education in high schools. For sterilization, an autoclave was not neccessary; the incubation of the culture medium in boiling water bath for one hour and the clean-up of equipment by use of 70% ethanol were enough. For the growth of E.coli, shaking bath was not neccessary; non-shaking incubation of the culture medium with shallow depth was sufficient. For harvesting E.coli, centrifugation was not neccessary, we could harvest through filteration of the medium by use of ordinary filter paper. The chemotaxis of E.coli was easily observed as follows: (1) Uniformly spread E.coli on a semi-solid agar plate came together at the circumference of the small filter paper containing the attractant during the incubation at 30℃ for several hours and we could recognize a muddy ring formed by the attracted bacteria. (2) For the observation of attracted E.coli under a microscope by Adler's method, a U-shaped glass tube, which is very difficult to make by oneself, is neccessary. Through our improvement, we could very easily observe bacterial chemotaxis by use of hole-side glass. We shall describe quantitative assays of the bacterial chemotaxis in the following paper.
