 We have a look on some important groups of the fungi. There are certain phyla, we talk about just some important ones, which are commonly known. There is one phylum called Zygomycota. Zygomycota are some of the important phyla of the fungi and they actually destroy our breads. They are called the bread molds. Rhizopus, for example, the black bread mold, that is, which makes our bread a rusty appearance. When we put it in a humid place at room temperature for a longer period, then there is a group called Eschomycota, Eschomycetes sometimes, the family. They are the sac-like fungi. They are fruiting bodies or they are spore producing structures. They are like sacs. And also, the Eschomycetes group, the Eschomycota phylum, also include the yeast. And we know that yeast are very important organisms. We produce many of the baking products using the yeast. Yeast also have certain important characteristics and we talk about it in some time. Then comes the phylum Basidio Mycota. These are called the club fungi. A very important group of fungi is included in this group called the mushrooms. We know that some mushrooms are edible, that is, we can eat them. They are a good source of proteins because their body consists of proteins. But we know that there are a lot many fungi, the mushrooms, which are highly poisonous. If someone eats them, they may instantly die. So it is really very difficult to find out that a particular type of mushroom, is it poisonous or not poisonous? And of course, the experts can identify them. And fungi are cultured for food, the edible fungi. And they are very costly part of the food, sometimes used in salads. And sometimes we make various foods out of them. There are various dishes of mushrooms, we know that. There are other fungi called puff balls, bracket fungi, the rusts and smarts, which are included in the club fungi, that is, the Basidio Mycota phylum. Rusts, we know that many times, are different materials. We call them, they become rusty. That is, there is some brownish dark colored mass appears upon them. These are the fungi, which grow upon different things when the environment is humid and it's moist. Then comes another group, the phylum Deutromycota. These are called sometimes also, the fungi imperfectly. These are the fungi, which have some characteristics, which are different from the other fungi. So that we call them fungi imperfectly. Penicillium is one of the most important fungus in this group. And we know that penicillium are the fungi, from which scientists derived penicillin. And penicillin was the drug, which actually saved more than thousands of life. We must say hundreds of thousands of lives during the World War II, when it was discovered. Before that, people die out of wound infections. And penicillin was the most important ones to treat those infections. So fungi are also source of very important medicines. Here you can see in a diagram, a fungus, a bread mold in bread, in and on a bread. We can see the surface of the bread. In the diagram, we can see that some part of the fungus, the hyphae, these are present inside the bread and the some part of the same fungus is present outside of the bread. They are inside of the bread, hyphae are spreaded in the bread. At that place, this collection of hyphae inside will be called a mycelium. And the part which is present outside are actually their spore producing structures. We also call them fruiting bodies. So the hyphae, they are inside and the spore producing structures, the fruiting bodies are present outside. And we can see them in the form of a green or a brown, rusty colored, say scum, present on the surface of the bread. Look at another diagram. It shows you the production of, actually the process of sexual reproduction in hyphae. When the hyphae of two different mating types, they grow side by side. For example, on a bread, as you have seen in the previous diagram. When they come across, the tips of these branches develop into gametangela. That is a gamet-like structures. And then the gametangela, they fuse and they make the gametes. These gametes fuse and produce a zygote. Zygote is also called sometimes zygospore, it have two n number of chromosomes. And this is the structure which as we can see and we can observe in the diagram, which is more harder. And it can face more harsh environments. During the harsh environments, it can survive. And when the favorable conditions come, then this structure, the zygospore, carry out meiosis and produces n number of chromosomes. That is, it divides by meiosis into the cells, which have n number of chromosomes. And then they produce the mycelia, which are haploid, again, fungi. They grow almost everywhere. They are present in most of the humid and dry places all over the world. This is a diverse group. Number of described species in somewhere between 69,000 to 100,000. There is an estimate of about 1.5 million species in total of all the fungi present on the planet Earth. They are present in soil, they are present in water, they are present on foods, they are present in our own animal and plant bodies. There are some special groups of fungi, we talk about them, lichens. Lichens are very important groups of fungi. Actually, lichen is our term used for a symbiotic relationship between an algae and a fungi. That is an algal group and a fungal group. The algae, because they are producers, they provide food to the fungi and fungi, give them protection. And they also decomposes various materials, which could be used by the algae. Usually, these lichens are very, very stable structures. And they can tolerate harsh environments. Usually, whenever after destruction of an old ecosystem, a new ecosystem is coming into being, then the lichens are usually the very first inhabitants of those ecosystems. We can say they are important reducers and decomposers of ecosystems. They are heterotrophs and mainly they decomposes the dead organic matters. They convert these dead organic matters into usable forms for the plants. They are one of the most important decomposers groups on the planet earth. As we know that the other decomposers are some animals like earthworms. And most of the decomposers, they are bacteria. But fungi are equally important because they are very widely distributed and they mainly feed upon the dead organic matter, the decaying organic matter. So they are the most important part of the food chain because they have to convert the dead organic matter into those forms which are usable by the producers, the plants. So they make the usable materials available for the plants. They convert sometimes some other materials into less toxic forms as well. As we know that fungi, they are food source, mushrooms. Most of the people like the salads with the mushrooms, there are various types. Some are very poisonous, some are edible and those which are edible are grown for making salads and other types of foods. They are very important protein source. In particularly those areas where the animal meat or we can say the animal source of protein is scarce or less, these are very important form of proteins. But they are themselves costly because it is difficult to grow. These fungi and this is also difficult to actually identify them from the poisonous species because it is spoilage of our foods. For example, the bread molds, they cause spoilage of vegetables, they cause spoilage of fruits. So they are beneficial and they are harmful. Certain fungi are also source of medicines. For example, penicillium is a source of medicine. We produce penicillin from the penicillium which is a fungus. There are many fungi which produces or we can extract different types of medicines out of them. There is a group of fungi called truffles. These are very commonly used in medicines and they grow inside the soils. And this is interesting to just know that these produces some specific smell and these smells could be sensed by the dogs and pigs. So dogs and pigs are when these fungi are grown in the soil for medicinal purposes, the farmers have to use the dogs and the pigs which actually sense that in which part of the soil actually inside the soil the truffles are growing. There are pathogenic fungi. Pathogenic fungi means any organism is called pathogenic when it can cause a disease. There are a lot many pathogenic fungi which are pathogens for plants, which are pathogens for human beings, which are pathogens for animals.