Lecture Notes About Microorganisms

MICROORGANISMS 1. Criteria for Living Creatures There are several criteria for living creatures, including the following: a. Living creatures exchange substances or metabolism, namely taking in food substances and getting rid of food waste. b. Living things experience growth; At first it was small then it got bigger. c. Living creatures reproduce or reproduce; At first the number was small, then the number became large. d. Living creatures have responses to external influences, which responses are useful for their survival. e. Living creatures move, although sometimes it is difficult to observe. Many microorganisms have no movement at all, but they is still a living creature, because it meets the other four criteria. 2. Definition and Characteristics of Microorganisms Microbes or microorganisms are living organisms that are very small in size, difficult to observe without magnification (microscope, electron microscope). Therefore, the existence of microbes could only be known after the invention of the microscope.As is known, the human eye cannot observe objects whose diameter is less than 0.1 millimeter.Living cells, namely biological structural units, are almost all located within these size limits, while the body as a living unit is large in size. Many microbes only consist of one cell, so all living tasks are assigned to that cell. This is different with living bodies which consist of many cells; Here generally there is a division of tasks between cells or groups of cells, or in other words there is organization and coordination between cells or groups of cells. So microbes as living organisms have very complex metabolic tasks, because all their life tasks are assigned to one cell. 3. Coverage of Microorganisms Microorganisms are living creatures whose size is several microns or even smaller, namely 1 micron = 0.001 mm. So living things that are included or included in the group of microorganisms are:  Viruses  Bacteria.  Fungi (thread fungus)  Yeast (Yeast)  Algae (low level algae).  Protozoa (unicellular animals) 4. Various Forms of Life Association of Microorganisms  Not Interfering with Each Other (Neutralism) It is very possible that in the soil or in animal waste there are many species that can live together without harming each other, but also not benefiting each other.  Rivalry or Competition The need for the same food substances can cause competition between species. The species that adapts best is the species that will thrive.  Living in Opposites (Antagonism) Antagonism states an asocial relationship. One species produces something that is poisonous to the other species, so that the growth of the latter species is greatly impaired by it. The substance produced by the first species may be an excrete, it may also be a food waste; What is clear is that this substance "opposes" the life of other microorganisms. For this reason, these opposing substances are called antibiotics.  Commensalism or Metabiosis If two species live together, then one species benefits, while the other species is not harmed by it, then the relationship between the two species is called commensalism. Species that benefit are called commensals, while species that provide benefits are called hosts. Commensals cannot survive without a host.  Mutualism Mutualism is a form of symbiosis between two species, where each partner benefits. If separated, each of them is not or less able to survive. Lichenes are an example of symbiosis between fungi and algae; Living together brings benefits to both parties.In the termites' digestive organs, there are Protozoa (Flagellates) which can digest cellulose, while the Protozoa themselves are guaranteed to survive by the Termites. Likewise, in the stomachs of ruminants there are various microorganisms that can convert cellulose into glucose.  Synergism If two species live together and carry out activities that do not interfere with each other, but instead their respective activities are in a sequence that is mutually beneficial, then the living relationship between the two species is called synergism. The yeast (dough) for making tape consists of a collection of Aspergillus, Saccharomyces, Candida, Hansenula species, and possibly also Acetobacter.  Parasitism The relationship that exists between viruses or bacteriophages and bacteria is a relationship that only benefits one party. Viruses cannot live outside bacteria or other living cells. On the other hand, bacteria or other cells that become hosts will die because of it.  Predatorism The relationship that exists between amoeba and bacteria is called predatorism. Ameba is a predator, while bacteria is prey. The death of the prey means the life of the predator. The difference with parasitism is in size only; Parasites are smaller than hosts, while predators are larger than the organisms they prey on. 5. Some media for the life of microorganisms  Microorganisms Found in Milk Even though milking is done using machines whose cleanliness can be guaranteed, milk that is 100% free of microorganisms is rare or completely non-existent. The bacteria that are almost always present in milk are bacteria that produce milk acid; These bacteria are mostly from the Lactobacteriaceae family.  Microorganisms in Soil Medium Inorganic and organic components are good substrates or mediums for the life of microorganisms. Soil-dwelling microorganisms are a mixture of populations of (a) protozoa such as ameba, flagellates, ciliates, (b) bacteria (Clostridium, Rhizobium)