Molds And How They Grow

[Music] in an orchard like this one where fruit is ripe and ready for picking many pieces will have fallen to the ground these may very quickly begin to discolor and Decay mold will usually be found on this Fallen fruit it's even seen underwater this mold is one kind of fungus it's one of the principal causes of decomposition and may be found almost anywhere this fluffy colony of mold is hanging beneath the surface of the water several kinds of molds may be found on clothing such as this leather jacket they grow here using the leather for nourishment but leather is only one of the things which may furnish nourishment for molds and there are a great many varieties of molds which take advantage of these different forms of nourishment some molds may be found around a kitchen where food scraps have been left there are varieties which will quickly grow on overripe fruit others Thrive best on bread from which they take food used in growth but molds cannot grow without favorable conditions let's leave a stack of fresh bread out on a shelf to see if we can learn something about the way molds grow after a few days the outer slices still look the same but there is a mold formation on the inner slices why does the mold form here in the middle of the stack rather than on the top we get a clue from the fact that the top piece is hard and dry a laboratory demonstration may show us if moisture has any effect on the growth of mold water is added to one of two slices of bread in glass dishes the dishes are then set aside on a shelf for a few days when we return to the bre rad we see that the slice to which water was added is much more moldy than the other dampness seems to encourage the growth of mold but is dampness the only condition which affects the growth of molds let's do another demonstration one of the moist slices is placed in a refrigerator another is left out on a Shelf at room temperature a third is placed in a warming oven after 3 days the bread slices look very different the one which was left in the refrigerator still seems fresh there is no visible trace of mold here the bread which was left at room temperature is moldy but the slice which was left in the warming oven is covered with mold so temperature too seems to have an effect on the growth of mold now let's look more closely at the parts of a mold even with the uned eye we can see colors and shapes but with a microscope we begin to see the individual Parts more clearly the base of the mold is made up of individual threads called hyy a network of these threads is called a mycelium when the mold is ready to reproduce some of the threads of the melium rise into the air on the tips of these Hy Spore balls form each Spore ball contains thousands of clustered spores the spores are reproductive cells when mature they will scatter into the air the spores are so light that they may remain suspended in the air for months and travel great distances in the wind spores May land and be blown up again and again until they meet conditions favorable for their growth every variety of mold produces spores but each variety has a characteristic shape and color each variety produces spores which may grow and form a new Colony beginning with a microscopic spec like this one a network of melium develops we'll watch with a time-lapse camera The Colony expands in every direction some Hy rise up and form Spore clusters the mold grows and repr juices now that we know something about the conditions under which molds grow and something about their structure let's prepare a mold culture and watch first we need a medium to nourish the mold we'll use rice then we need some spores which we can take from this moldy bread finally we need a place where the rice grains can stay warm and moist with a time lapse camera we can watch the mold growing on the rice let's watch again first the spores grow out to form the interwoven melium then as the mold matures upright Hy with Spore clusters appear the mold has taken nourishment from the rice has grown and reproduced we can also use a medium of Agger on which to raise molds again with the time-lapse camera we can watch as the mold spreads out over the medium let's watch once more and remember the stages of growth and the parts of the mold's anatomy HPA melium Spore ball Spore we can also o prepare a culture on a slide here we see a single mold Spore as it begins growth hiy begin interweaving to form the melium in a side view we can see some high begin to rise up the tips of these Hy develop and become Spore clusters on a single hyper we can see the development of individual spores in almost any part of the world mold spores begin growth whenever they reach a favorable environment some of these molds are harmful many are helpful to man the effects of these molds suggest still further chapters in the story of molds and how they grow n