Microorganisms are very tiny living organisms. They are microscopic and may be unicellular or multicellular (Madigan and Martinko 2006). The microorganisms include all prokaryotes and some eukaryotes. They are usually not visible to the naked eye, but some macroscopic ones can be seen with naked eye also (Max Planck Society Research News Released Accessed 15 September 2012).
Microorganisms include bacteria, archaea, protozoa, fungi, algae and some members of the kingdom Animalia such as rotifers and planarians. Viruses also fall under this category, i.e., microorganisms but some researchers even consider viruses as non living (Rybicki 1990) (LWOFF 1956).
Microorganisms inhabit every sphere of this planet Earth. They inhabit the most extreme environments where no other living organisms can survive. Such microbes are known as “Extremophiles”. These may include the following:
a) Acidophiles:- these include those organisms which can survive in highly acidic conditions or at very low pH which is generally less than 2. Acidophiles belong to all the three classes namely Archaea, Bacteria and Eukarya. Example: Acetobacter aceti, Dunaliella acidophila, Acidianus infernus etc.
b) Basophiles:- this class include organisms which can thrive in extremely alkaline conditions with a pH of more than 10. These are also known as Alkaliphiles. Example: Halorhodospira halochloris, Natromonas pharaonis, Thiohalospira alkaliphira etc.
c) Thermophiles:- these are those organisms which thrive easily at very high temperatures such as 45 degree Celsius and up to 122 degree Celsius. At such high temperatures no other living organisms are found to survive except this certain class of microorganisms. Examples: Sulfobolus solfataricus, Sulfobolus acidocalda...
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...ttributed to the fact that they are too expensive and the range of toxic materials that they can decontaminate is very less.
This has led the researchers to look for alternative solutions. This is how the use of microorganisms for bioremediation first started. This use of microorganisms provides an environment friendly technique of remediation of harmful substances without having any alternative effect which may disturb the homeostasis of environment in any manner.
Many microorganisms live in the body of human beings and other animals also. Most common of these is bacteria Lactobacillus which is found in the human mouth, intestine and vagina of females. Lactobacillus has the ability to bind to detoxify some of the most harmful radionuclides and toxic metals. Due to this property, Lactobacillus is now also used in packed frozen foods and fermented preparations also.
Escherichia coli is a member of the family Enterobacteriaceae. It is a bacterium with a cell wall that has many components. Escherichia coli can live without oxygen which means that it is a facultative anaerobe. It is also capable of fermenting lactose under anaerobic conditions, and in the absence of alternative electron acceptors. There are effects and various factors that limit its growth rate. Its morphology consists of a rod-shaped gram negative bacteria that is commonly found in soil, water, vegetation, human intestines, as well as the intestines of animals. Its presence can be good or bad.
Amoebae of the genus Naegleria are identified in part by their ability to create a temporary flagellate phase once exposed to nutritional scarcity. N fowleri is confirmed to be a typical eukaryotic protist by electron microscopy examination (Patterson et al., 1981).
Since Woese’s research, Archaea have been divided into two main phyla, the Eutyarchota and Crenarchaeota, with the majority being extremophiles. This supports the hypothesis that Eubacteria and Archaea had a thermophilic common ancestor that was able to tolerate the hot conditions on Earth. Nelson et al (1999) also found that Thermotoga maritima bacteria had 24% genes of archaeal origin when analysed, supporting the theory of Thermatoga’s early branching from Archaea in the Tree of Life.
1. Living things can be either uni-cellular (one cell) or multi cellular. A bacteria is one type of unicellular.
Protists are members of Protista, one of the five main kingdoms of organisms. They are eukaryotic, multicellular and unicellular creatures that are either microscopic or very large in size, and are found in moist and marine environments. Being mostly micro in size, 5 micrometers to 2 to 3 millimeters is the prevalent size for protists. Despite not being categorized in any other animal kingdoms due to their complex structures and heavy diversity, they still are very much like fungi, animals and plants in their characteristics (Corliss, "General Features").
Cyanobacteria are one of the largest and most important groups of bacteria on the earth. Often called ‘the blue-green algae’ Cyanobacteria is in fact, not an algae at all. Algae are eukaryotic, whereas cyanobacteria, is a bacteria, and is prokaryotic. The name algae is used to refer to any aquatic organisms capable of photosynthesis, so the term is considered general, though in this case, inaccurate. Being tiny and normally unicellular, cyanobacteria grow in large colonies, making them visible to the human eye, and often dominate aquatic habitats such as shorelines. Over their 3.5 billion year reign, Cyanobacteria have helped to successfully establish the earth’s atmosphere, making it possible for human life forms to thrive and some of the oldest known fossils in the world are cyanobacteria, earning it the title of one of the great survivors of all time.
These organisms need temperatures to be at least 113°F for reproduction. There are organisms that require even hotter temperatures, as hot as 176° F. These organisms are referred to as hyperthermophiles. No multicellular animal or plants have been found to tolerate these types of conditions. These discoveries were made in the late 1960’s. Extremeophiles can be found on volcanic hydrothermal vents located on the bottom of the ocean floor. The most heat resistant of these microbes, Pyrolous fumarii, grow in the walls of the hydrothermal vents, also known as black
Microbial biofilms are populations of microorganisms that are concentrated at an interface and typically surrounded by an extra cellular polymeric slime matrix. Biofilms can form on both solid surfaces such as teeth or dental implants and soft tissue such as gums and cheek walls.
Prokaryotes have been around for at least 3.5 billion years, considering that the earth is over 4.5 billion years old. They are the earliest known organisms to ever inhabit the earth. Still small and insignificant they may seem, they have been able to endure and evolve on their own for over 2 billion years. They have produced a substantial impact on all life as we know on earth, and they have been able to go on to survive and adapt to an ever evolving land.
The study of microorganisms is called microbiology. Viruses, Bacteria, Protozoa, Fungi and Worms all come under this category. They have an incredible impact on our daily lives, even though these organisms are tiny and can only be seen when under a microscope. Named microbes for short, it is estimated that there are about 5 million trillion, trillion microbial cells Earth. The largest mass of living material on earth is constituted collectively by microbes. They are tied to the activities of all living things as they degrade organic matter and also provide key nutrients. However, some microbes are considered pathogenic. (The University of Manchester, 2015)
Normal microbiota are bacteria that naturally habitat the human body without causing harm. There are two forms, residential and transient. Residential microbiota are the organisms that have been with you since the day you were born and shall remain with you for the rest of your life; meanwhile, transient microbiota are the harmless bacteria that you come in contact with on a daily basis. These can easily be removed from the body meaning that transient microbes only stay with you for a short period of time. Both forms of normal microbiota are usually found on the surface of the skin, mucous membranes, digestive tract, upper respiratory system, intestines,
Protists are not animals, plants, or fungi. They have their very own kingdom called The Kingdom Protista. Protists are a very diverse group. There are over 200,000 of them. They get classified into three main groups, and then get classified further into phyla Protists can be found in everyday surroundings, and they have a big impact on all organisms on Earth.
As stated by Prescott, Harley and Klein (1990) microbiology is the study of organisms that are usually too small to be seen with the naked eye.
Prokaryotes include several kinds of microorganisms, such as bacteria and cyanobacteria. Eukaryotes include microorganisms as fungi, protozoa, and simple algae. Virus cells often consist of just a nucleic acid either DNA or RNA in a protein capsule. Viruses are considered neither prokaryotes nor eukaryotes because they lack the characteristics of living things, except the ability to replicate (which they accomplish only in living cells).
Different types of bacteria have different range of temperature they are able to survive. They are generally divided into three types: psychrophiles, mesophiles and thermophiles. Psychrophilic bacteria are able to survive in low temperatures ranging from about -10 to 20°C while thermophilic bacteria are able to thrive in high temperatures ranging from 40 to 75°C. These two types of bacteria are also known as extremophiles due to their ability to survive in extreme conditions. Mesophilic bacteria are bacteria that thrive in temperatures ranging from 10 to 45°C and usually have an optimum growth temperature of about 37°C (M. Furlong, n.d.).