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INTRODUCTION TO MICROBIOLOGY

Microbiology means the studying and the learning of the organisms in the surrounding environment around us which are too tiny and small and are not clearly visible with our naked eye or unaided eye when they exist and taken as individually. These organisms that cannot be observed with our naked eye and can only be observed through the microscopes are called as the microorganisms.These microorganisms are not visible to the human naked eye, because these organisms are less than 0.1mm in size, which means that they are smaller in size than the visual range of the humans.The microorganisms can be found everywhere on the planet Earth.The microorganisms are the most abundant and the diverse group of organisms on the Earth.Many different and various groups of microorganisms have inhabited the Earth at present.They possess different adaptations,specialized and differentiated functions,various forms and structures, different shapes and sizes, and numerous habitats to ensure their survival and existence on the Earth.Some of the different groups of microorganisms that exist on the Earth are Bacteria,Archaea Bacteria, Cyanobacteria or Blue Green Bacteria, Protists, Algae, Fungi, Mollicutes(Mycoplasmas and Phytoplasmas), Viruses, Viroids, Prions etc.

The units which are used to measure the microorganisms and their structural components are nanometers and micrometers.Due to the larger sizes of some microorganisms, they are more quickly and readily visible than the other smaller types of microorganisms.The microorganisms can be distinguished almost everywhere on the Earth. Thus, they are ubiquitous on the earth. This means that they are found everywhere on the earth including in soil, water, air, in interior surfaces and on exterior surfaces of the earth.Most of the microorganisms act as the primary producers of the food chains in the fresh and marine water habitats, as most of them possess the ability to perform photosynthesis.Therefore, they form the basis of the food chains in the aquatic water bodies.The microorganisms that live in the soil, which are commonly known as the soil microorganisms possess the ability to decompose and to digest the waste products and materials in the environment and also they assist in the recycling of the chemical elements and compounds in between the soil, water, air and the living organisms.These soil microorganisms decompose and break down complex organic matter into simple organic matter and then into simple organic and inorganic molecules and after that, into their constituent most basic elements either by physical breakdown or by biochemical transformation of these complex compounds.These organisms that cannot produce their own food and depend on the non living, dead, organic, decaying and waste matter are called as Saprotrophs or as Saprophytes.In order to survive, they obtain their energy by feeding on these dead and decaying waste organic materials.Most of the Fungi such as Rhizopus, Mucor, Agaricus, Penicillium, Aspergillus,Morchella and Saccharomyces(Yeast), some bacteria such as soil bacteria, some protozoans and some algal species such as photosynthetic algae like green algae exhibit saprophytic mode of nutrition.Some microorganisms are suspended and released into the atmosphere or air as bioaerosols and these microbes and microorganisms possess the capability to travel and spread long distances with the help of the wind current and precipitate.These bioaerosols are composed of bacterial cells, their cellular fragments and remnants, fungal spores and their hyphae, viral particles, viroids, mollicutes, prions, their metabolic waste and by-products.Therefore, the pathogenic bioaerosols are capable of transmitting and spreading of most of the infectious diseases in living organisms.Only a trace number of microorganisms which are associated with the other living organisms such as plants, animals and human beings are pathogenic and cause infectious diseases.Majority of the microorganisms are advantageous, useful, important, beneficial and harmless.But, all viruses are very harmful and disadvantageous to the living organisms that are attached with. All viruses cause infectious diseases to living organisms.Some of the microorganisms are well adapted to live or inhabit in the extreme environmental conditions which are unfavourable and can even be lethal for the other living organisms.These microorganisms are known as the extremophiles.These extremophiles can be discovered and found inside the crust of the Earth, in deep seas at high pressures such as in the deepest point of the Earth which is the Great Mariana Trench which is about 11034m in depth,in extremely acidic or in extremely basic conditions,in hydrothermal and alkaline vents, in frozen sea water,in volcanoes,in hot water springs,in upper atmosphere and outer space.