Bacteria : Friend and Foe (1953)

[Music] [Applause] Ted Jones is visiting one of the Laboratories at the City Health Department his brother Frank has recently taken a position as a bacteriologist with the Department Ted seems to be having a little trouble can't you get it focused on the field then try using the fine adjustment knob and do it more slowly you're likely to miss the cells you're looking for even though they may be there okay I'm trying say here they are hey look good you know what kind they are no all I know is that they came out of that test tube that you gave me then they're one of the kinds of bacteria that caus food to spoil Ted has just seen one of the many kinds of bacteria bacteria are found almost everywhere in our environment some float around in the air some are in water or other liquids still others thrive in the soil bacteria are plants but they are not green like the plants we usually see some kinds are indispensable for example countless bacteria are at work in this Clover Field they are growing in the little nodules at the plant roots bacteria in these nodules take nitrogen from the air and change it into a form of plant food other kinds of bacteria are responsible for milk or cream becoming sour the development of flavor and other qualities in cheese and the disintegration of dead plants and animals in fact the effects of bacteria are so important that Life as we know it would be impossible without them most bacteria are friends of man some even produce chemicals called antibiotics that are used to help fight different diseases only a few kinds of bacteria cause disease probably the first person to observe bacteria was Anon van Leen hook inventor of one of the first successful microscopes after looking through his crude microscope he made drawings of the microorganisms he saw these represented organisms from tartar scraped from from his own teeth in contrast here using a modern microscope we see other microorganisms taken from tartter after the time of Leen hook Generations were to pass before another achievement of great importance would be made in the study of bacteria it was the famed chemist Louie pastur of France who in the 1850s proved that bacteria cause fermentation this explained many of the chemical changes that go on in nature Pastor also proved that bacteria never develop out of dead organic matter alone as some people had believed he emphasized that bacteria can only come from other bacteria soon afterward it was found that bacteria can spread disease from a sick animal to a healthy animal but this discovery was made by Koch a German contemporary of pastur this discovery is the basis of The Germ theory of disease Robert kooch and his assistants also learned to prepare and use nutrient materials nutrient materials are usually jellylike emulsions or fluids which favor the growth of bacteria coch made other discoveries that helped lay the foundations of modern bacteriology since the time of coke much has been learned and many other kinds of bacteria discovered today if Ted could collect all known kinds of bacteria he would have thousands and the facts that have been discovered about them are exceedingly numerous he wonders how a beginner can ever learn about so many kinds of bacteria Frank explains that it takes a systematic approach for example bacteria may be separated into groups according to what they live upon the nature of the food they require some bacteria are parasites others sap aites and still others autot tropes parasites depend upon living plants or animals for food here are some parasitic bacteria most bacteria that cause human disease are parasitic saprophytes live upon dead plants or animals or their products saprophytic bacteria produce enzymes that cause the chemical breakdown we call decay there are more kinds of saprophytic bacteria than of any other type autotrophs get their energy from minerals or other inorganic materials the autotrophic bacteria seen here live upon a form of iron through oxidation they change one form of iron into another and use the energy that is released unlike the large majority of plants most bacteria have no chlorophyll with which to manufacture food parasites sapry and autotrophs all take in food through their cell walls to pass through these cell walls the food must be soluble in some instances insoluble foods are converted into soluble materials by chemicals released by the bacteria themselves all bacteria require soluble food to live Ted thinks the information seems complicated but Frank speaking from experience explains that the basic facts about bacteria are quite simple and very useful besides facts about the food getting of bacteria Frank describes another type of information that is especially useful in bacteriology depending upon the structure or shape of bacteria there are four main kinds the coxy that are round like these that are common in the air the basili that are rod-shaped like these from gas Gang Green the spirilla that are spiral like these taken from a sample of wellwater and the filamentous forms such as these threadlike ones structure or shape is one of the principal characteristics used by bacteriologists to classify or identify different kinds of bacteria the life processes of bacteria are simple we've already seen how bacteria obtain food now we will consider their reproduction which takes place through simple division of the cells in drawings we can see that bacterium cells are continually growing when a cell reaches maturity it divides again this goes on and on about every half hour as long as the food supply holds out or until some unfavorable condition slows down or stops their development the reproduction rate of bacteria may be greatly affected by temperature in a laboratory the temperature can be controlled in an electric incubator as Frank explains there's always a temperature that's best for growing bacteria area usually this temperature is about 30 to 37° C 37° centigrade is about equal to the normal human body temperature in case the temperature is unfavorable some bacteria especially the rodlike kinds have a special means of protecting themselves they do it by forming spores notice the Spore forming in the center of one of these bacterium cells some other kinds of bacteria form spores at the ends of the rods instead of at the centers either way a Spore has a special wall around itself that seems to protect the bacterium inside from such adverse conditions as cold heat sunlight or disinfectant later when conditions improve the Spore may change back again into the rodlike bacterium not many disease producing bacteria go through a Spore form besides protective mechanisms some bacteria are equipped to move about the hair or whip-like parts attached to these bacterium cells are called fella different types of bacteria have different types of flagella such fella can be moved to propel a living bacterium through blood or other Solutions not all bacteria have such means of locomotion since the time of Leen hook progress in bacteriology has been phenomenal his successors such as pastor of France and coch of Germany have made discoveries and invented techniques indispensable in successfully preparing nutrient materials growing cultures and subjecting the cultures to tests that help identify and classify bacteria today in bacteriology Laboratories work is conducted that leads to the control of the relatively few bacteria that are foes of mankind and to the more effective use of the multitudes that are friends in order to make human life more healthful and increase our standard of [Music] living