Bacteria - Friend Or Foe (1954)

Department Ted seems to be having a little trouble can't you get it focus on the field and 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 oh I'm trying say Here I am it look good you know what god they are know all I know that they came out of that test too but you gave him then they're one of the kinds of bacteria that cause 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 wilt 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 Anton van Leeuwenhoek 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 his own teeth in contrast here using a modern microscope we see other microorganisms taken from tartar after the time of Leeuwenhoek generations worth its great importance would be made in the study of bacteria it was the famed chemist Louis Pasteur of France who in the 1850s proved that bacteria caused fermentation plain medical changes that go on in nature Pasteur also proved that bacteria never developed 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 mo but this discovery was made by Koch a German contemporary of path to earth this discovery is the basis of the germ theory of disease Robert Koch and his assistants also learned to prepare and use nutrient materials nutrient materials are usually jelly like emulsions or fluids which favour the growth of bacteria Koch made other discoveries that helped lay the foundations of modern bacteriology since the time of Koch 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 sacrifice and still others autotrophs parasites depend upon living plants or animals for food here are some parasitic bacteria most bacteria that cause human disease are parasitic sepra fights live upon dead plants or animals or their products saprophytic bacteria produce enzymes that cause the chemical break P 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 sacrifice 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 a period Frank depending upon the structure or shape of bacteria there are four main kinds the cox i that are round like these that are common in the air the bacilli that are rod shaped like these from gas gangrene the spur illah that are spiral like these taken from a sample of well water and the filament is formed such as these thread-like one structure or shape is one of the principal characteristics used by bacteriologists to classify or identify different kinds of bacteria the life essences 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 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 conditions 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 usually this temperature is about 30 to 37 degrees centigrade 37 degrees centigrade is about equal to the normal human body temperature in case the temperature is unfavorable some bacteria especially the rod-like 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 forms for it at the ends of the rod instead of at the centres 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 rod like bacteria not many disease producing bacteria go through a spore form besides protective mechanisms some bacteria are equipped to move about the hair or clip like parts attached to these bacterium cells are called Vaghela different types of bacteria have different types of flagella such flagella can be moved to propel a living bacterium through blood or other solutions not all bacteria have certain since the time of Leeuwenhoek progress in bacteriology has been phenomenal his successors such as pastor of france and koch 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 multitude that our friends in order to make human life more helpful and increase our standard of living