(I.c&d) General Characters and their importance of Prokaryotes, Eubacteria, Archaebacteria, Eukaryotic Microorganisms-(Fungi, Algae, protozoa) , Viruses, viroid and prions.
General Characters and their importance of
1.Prokaryotes,
2.Eubacteria,
3.Archaebacteria,
4.Eukaryotic Microorganisms-(Fungi, Algae, protozoa) ,
5.Viruses, viroid and prions.
1.General Characters and their importance of Prokaryotes:
The prokaryotic (Gr., pro-primitive, karyon-nucleus) cells are the most primitive cells from morphological point of view. They occur in bacteria and blue green algae. Prokaryotes are small, single cell organisms, usually less than a micrometer (abbreviated µm; 1000 µm=1 millimeter, abbreviated mm) are generally not longer than Зµm.
Prokaryotic cells have different characteristic features. The characteristics of the prokaryotic cells are mentioned below.
They lack a nuclear membrane.
Mitochondria, Golgi bodies, chloroplast, and lysosomes are absent.
The genetic material is present on a single chromosome.
The histone proteins, the important constituents of eukaryotic chromosomes, are lacking in them.
The cell wall is made up of carbohydrates and amino acids.
The plasma membrane acts as the mitochondrial membrane carrying respiratory enzymes.
They divide asexually by binary fission. The sexual mode of reproduction involves conjugation.
2.General Characters and their importance of Eubacteria:
Eubacteria are considered to be "true bacteria,".
They are characterized by a lack of nuclear membrane, single circular chromosome and have cell walls composed of peptidogycan.
The word "eubacteria" derives from the words "eu," which means "true" and "bacteria."
Eubacteria are prokaryotes, which mean they have a primitive nucleus.
The nuclear material of bacteria is not bound by a distinct nuclear membrane, as in eukaryotes. Also, bacterial genetic material, or the DNA, is present as a single circular chromosome.
The cell wall of bacteria is composed of peptidoglycan, as opposed to cellulose, like in plants.
They are single celled organisms, and mostly reproduce through binary fission.
Eubacteria are either motile, or non-motile.
Eubacteria can form spores, which allows them to survive for a long time in adverse conditions.
Eubacteria are further classified as either gram positive bacteria, or gram negative bacteria, depending on whether or not they take in a gram stain.
Eubacteria and Archaebacteria evolved from a common ancestor, but have enough differences to merit two separate domains in the classification of living beings
3.General Characters and their importance of Archaebacteria:
- Archaebacteria are obligate anaerobes and they survive only in oxygen-free environments.
- They are known as extremophiles, as they are able to live in a variety of environment. Some species can live in the temperatures above boiling point at 100 degree Celsius or 212 degree Fahrenheit. They can also survive in acidic, alkaline or saline aquatic environment. Some can withstand a pressure of more than 200 atmospheres.
- The size of archaebacteria ranges from one-tenth of a micrometer to more than 15 micrometers.
- Some of archaebacteria have flagella.
- Like all prokaryotes, archaebacteria don’t possess the membrane-bound organelles. They don’t have nuclei, endoplasmic reticula, Golgi complexes, mitochondria, chloroplasts, or lysosomes. The cells consist of a thick cytoplasm that contains all the compounds and molecules required for metabolism and nutrition. Their cell wall doesn’t contain peptidoglycan. The rigid cell wall supports the cell and allows an archaebacterium to maintain its shape. It also protects the cell from bursting when present in a hypotonic environment.
- Archaebacteria have lipids in their cell membranes. They are composed of branched hydrocarbon chains, connected to glycerol by ether linkages.
- Since these organisms don’t have nuclei, the genetic material floats freely in the cytoplasm. They consist of ribosomal RNA (rRNA). Their DNA contains a single, circular molecule, which is compact and tightly wound. No protein is associated with DNA.
- The archaebacterial cell may contain plasmids, which are small, circular pieces of DNA. They can duplicate independent of a larger, genomic DNA circle. Plasmids often code for antibiotic resistance or particular enzymes.
- Archaebacteria reproduce by an asexual process known as binary fission. During this process, the bacterial DNA replicates. The cell wall pinches off in the center, due to which the organism is divided into two new cells. Each cell consists of a copy of circular DNA. Some species can multiply from one cell into two in as less time as 20 minutes.
- The interactions between archaebacteria and other life forms are either symbiotic or commensal as archaea are not known to pose pathogenic hazard to other organisms.
- A characteristic unique to archaea is the composition of their cell walls. The archaebacteria cell wall is made of pseudomurein, which is made up of a combination of N-acetyltalosaminuronic acid and N-acetylglucosamine. This kind of cell wall makes archaebacteria immune to the effects of Lysozyme, which is an enzyme produced by a host’s immune system to attack and disable cell walls of pathogenic bacteria.
4.General Characters and their importance of Eukaryotic Microorganisms-(Fungi, Algae, protozoa) :
A.Characteristics of Fungi
The diversity of this kingdom makes it difficult to provide a simple fungi definition. Despite their superficial similarities to plants, fungi are more closely related to animals.
They do not have chlorophyll and cannot make their own food like plants.
Fungi obtain food by absorbing carbon and other nutrients from dead or decaying organic material or living organic material in the case of fungal parasites.
Instead of eating food and then digesting it, fungi first digest their food externally by secreting enzymes to break it down.
Pre-digestion allows fungi to break down tough plant fibers into simpler, more readily consumed molecules of glucose.
Parasitic fungi eat in much the same way. Within a living host, they use enzymes to digest living tissue before absorbing the nutrients they need from the tissue
Examples of Fungi
Kingdom Fungi comprises four main groups of fungi.
Phylum Basidiomycota includes mushrooms.
Phylum Ascomycota includes a wide variety of organisms ranging from yeasts . Some species of yeast are used in baking bread, while others cause rashes on moist tissues, such as diaper rash and athlete’s foot. Some fungi in this group feed on grains and destroy crops. Around 75 percent of fungi belong to this phylum.
There are fewer than 1,000 species in phylum Zygomycota. These organisms include bread molds, which manifest as grayish-green fuzz on old, decaying bread. Some member of this phylum feed on decaying animals, as well as dead plants, while others parasitize living hosts.
Phylum Deuteromycota are called incomplete fungi because they reproduce only by releasing spores. The other groups of fungi reproduce both by spores and by cells joining together through meiosis. A well-known fungus from this phylum is Penicillium, used to make the antibiotic drug penicillin.
B.Characteristics of Algae
Algae are classified in the Kingdom Protista, which has a variety of unicellular, multicellular and colonial organisms.
Algae are eukaryotic organisms, meaning they have complex structures inside the cell membrane.
A eukaryotic cell's most important organ is the nucleus, which houses the cell's genetic information and differentiates it from prokaryotic cells.
Algae require a moist environment and can live in salt or fresh water, soil and on the surface of rocks.
These tiny plants lack typical roots, leaves and stems; however, they have chloroplast organs, which are membrane-bound and create energy to power the cell through photosynthesis .
Types of Algae
There are an overwhelming variety of algae, with the current number of documented alga species at 127,203 as of March 2011, according to AlgaeBase.
The term "algae" covers a wide range of distantly related organisms.
The scientific community has eased species identification by creating seven different groups that categorize species with similar chemical processes, color, anatomy and behavior.
Yellow-green algae are colonial species that grow in freshwater, and brown algae are commonly known as seaweed.
Unicellular varieties are euglenoids, golden-brown algae and fire algae.
The green and red types of algae both range in size from microscopic to macroscopic.
C. Characteristics of Protozoa
The group includes members of the Kingdom Protista that do not have chloroplasts and therefore have no color.
All protozoa were thought to be eukaryotic and unicellular.
It is now known that the organisms classified as protozoa are not closely related.
Although the term does not meet all current classification needs, it is still used for describing the general characteristics of a very diverse group.
Protozoa can reproduce both sexually and asexually, are eukaryotic and either ingest or absorb their nutrients from the surrounding environment.
Types of Protozoa
Protozoa are divided into four phyla: Sarcodina, Mastigophora, Ciliophora and Sporozoa.
The phylum Sarcodina includes amebae and related organisms. Unicellular and motile, they gather food by surrounding it with the cell membrane through the use of arm-like pseudopods.
Ciliophora are motile through the use of hair-like projections of the cell membrane called cilia,
while those from Mastigophora use flagella for motility. Though most are free-living organisms, there are also many parasitic protozoa. Parasites can infect an organism through contact with hosts, soil or water, and many can be deadly to humans. Parasitic protozoa range in size from microscopic to 16mm in length.
5. General Characters and their importance of Viruses, viroid and prions:
Prions are infectious protein particles responsible for a group of transmissible and/or inherited neurodegenerative diseases. Prions are extremely resistant to chemicals, heat, and radiation.
Viruses are a unique group of infectious agents whose distinctiveness resides in their simple, acellular organization.
They can reproduce only within living cells because they are obligate intracellular parasites.
All viruses have a nucleocapsid composed of a nucleic acid genome surrounded by a protein capsid.
Some viruses have a membranous envelope that lies outside the nucleocapsid.
The nucleic acid of the virus can be RNA or DNA,single-stranded or doublestranded, linear or circular.
Capsids may have helical, icosahedral, or complex symmetry.
Although each virus has unique aspects to its life cycle, a general pattern of replication is observable.
The typical virus life cycle consists of five steps: attachment to the host cell, entry into the host cell, synthesis of viral nucleic acid and proteins within the host cell, self-assembly of virions within the host cell, and release of virions from the host cell.
Viruses are cultured by inoculating living hosts or cell cultures with a virion preparation.
Purification depends mainly on their large size relative to cell components, high protein content, and great stability. The virus concentration may be determined from the virion count or from the number of infectious units.
Viruses are classified primarily on the basis of their nucleic acid’s characteristics, reproductive strategy, capsid symmetry, and the presence or absence of an envelope.
References:
https://www.yourarticlelibrary.com/zoology/cell/prokaryotic-cells-7-most-important-characteristics-of-prokaryotic-cells/30453
https://byjus.com/biology/prokaryotic-cells/#:~:text=Characteristics%20of%20Prokaryotic%20Cell&text=They%20lack%20a%20nuclear%20membrane,chromosomes%2C%20are%20lacking%20in%20them.
https://www.quora.com/What-is-eubacteria-What-are-its-characteristics
http://www.biology.lifeeasy.org/2255/what-are-the-characteristics-of-eubacteria
https://biologywise.com/characteristics-of-archaebacteria
https://sciencing.com/characteristics-protozoa-algae-8124201.ht
Prescott L.M., Harley J.P., AND Klein D.A. (2005). Microbiology, 6th Edition.
MacGraw Hill Companies Inc.
Importance of study of Microbiology and relevance in
Biotechnology (Brief discussion of application of Microbiology in
various fields)
Microbiology is the study of biological organisms that are too small to be seen with the naked eye (without using such tools as the magnifying glass or microscope etc)
Microbiology has proved to be one of the most important disciplines in biology, making it possible to identify how some of these organisms cause diseases, discover cures for such diseases and even use some microbes for industrial purposes etc.
Applications of Microbiology
Microbiology is one of the most applied branches of science. Its outstanding applications in the field of food microbiology, medical microbiology, industrial microbiology, soil microbiology, water and wastewater microbiology, microbial technology (biotechnology), extraction of metals and environmental microbiology including the use of microorganisms as biosensors is as given below.
1. It provides us with information about different types of microorganisms enabling us to understand their structure and functions; identifications and differentiations; their classifications; nomenclatures (naming), requirements regarding their nutrition; their isolation and purification; as plant and human pathogens; to derive phylogenetic relationships (relationships according to developmental stages in the evolution of an organism) and to understand the origin of life itself.
2. Microorganisms as food: Besides comestible fungi like mushrooms, microorganisms are also being used as single cell protein in the form of yeasts, bacteria, cyanobacteria, fungi as human food or animal feed. The production of the algal microbes as Chlorella (green alga and Spirulina (cyanobacterium) are being produced in Japan, Taiwan, Mexico, Israel, Thailand and America. Production of cellulose or lignocellulose utilizing microorganisms serves as human food as such or in the form of their products. Microbial products are also used as animal feed.
3. Microorganisms are used in production of a large number of, fermented foods such as leavened bread, sourdough bread, fermented milk products and flavours. The fermented milk products are yoghurt, cheese and several other products.
4. The important fermented vegetables are sauerkraut (from cabbage) and Kimchi (from other fermented vegetables in Korea).
5. Fermented meats and fermented fish are used in different parts of the world due to their increased retentivity, otherwise the meats and fish are highly perishable
6. Beer, vinegar, soya sauce, rice wine too are fermented products.
7. Microbiology has been very useful in preservation of food by heat processing, by pasteurization and appertization (commercially sterile food), by calculating thermal death values, prevention of spoilage of canned foods, aspectic packaging, irradiation, UV radiation, ionizing radiation, high pressure processing, i.e., pascalization, low temperature storage (chill storage and freezing), chemical preservatives (organic acids, esters, nitrite, and sulphur dioxide). In food microbiology one learns about bacterial and nonbacterial agents of food borne illness. Among the helminthes and nematodes are: Platyhelminthus (i.e. liver flukes and tapeworms) and roundworms (e.g., Trichinella spiralis). The protozoa that cause food borne diseases are Giardia lamblia and Entamoeba histolytica.
8. Microbial diseases: Microorganisms are the causative agents of a large number of diseases which have been described under a separate chapter.
9. Industrial Microbiology: A large number of products of microbial metabolism after microbial processing of raw materials are produced on industrial scale. A separate chapter has been given on ‘Industrial Microbiology’.
10. Energy from microbial sources: A number of substrates can be used as a source of energy as biogas from methanogenic microorganisms. The microbes like Methanobacterium and Methanococcus can utilize CO2 as an electron acceptor finally producing methane. A new species of Methanobacterium, i.e., M. cadomensis strain 23 has been evolved in Japan for faster production of methane. Ethanol can also be used for the production of gasohol by mixing 80 per cent gasoline and 20 per cent ethanol.
11. Degradation of cellulose and lignin: Trichoderina reesei can be used to degrade cellulose since it produces extracellular cellulase. The white rot fungus Sporotrichum pulverulentum is a cellulase negative organism but a mutant of it has been prepared which can degrade kraft and wood lignocellulase actively. It has been possible to produce biological pulp without any chemical treatment for delignification.
12. Mining and extraction of metals: Thiobacillus ferrooxidans and combination of Leptospirillum ferroxidans and Thiobacillus organoparpus can be used to degrade pyrite (FeS2) and chalcopyrite (CuFeS2). The archaeal species Sulfolobus acidocaldarius and S. brierlevi are capable of oxidizing sulphur and iron for energy depending on C02 or other simple organic compounds for carbon. The pyrite and chalcopyrite are also degraded by these archaeobacterial species.
13. Recombinant DNA and genetic recombination: Recombinant DNA is a wonderful product of genetic engineering, i.e., manufacturing and manipulating genetic material in vitro. The process of joining DNA from different sources is genetic recombination. A large number of restriction enzymes/restriction endonucleases have been obtained from various microorganisms that can cut or cleave double stranded DNA leaving staggered ends.
14. Hybridoma and preparation of monoclonal antibodies: Hybridoma is a cell made by fusing an antibody-producing B-cell with a cancer cell. The resulting hybrid myeloma or hybridoma cells have properties of both parent cells immortality and the ability to secrete large amounts of a single specific type of antibody. This was discovered by Kohler.
15. Harvesting DNA biotechnology for public health engineering programmes: Such programmes include production of interferon which is an antiviral protein produced by certain animal cells in response to a viral infection, production of human insulin production of somatotropin a human growth hormone and production of a large number of other hormones and vaccines. The vaccines for cholera, diphtheria, tetanus, pertussis, viral hepatitis type A, type B, influenza, mumps, measles (rubella) plague, poliomyelitis, rabies, rubbela, typhoid, typhus and yellow fever have been developed so far.
16. Microbial technology of nitrogen fixation exploiting symbiotic microorganisms in association with lower or higher plants and asymbiotic or nonsymbiotic (by nitrogen fixing microorganisms independently). Detailed information is covered under a separate chapter on ‘biofertilizers’. In nature, in legume root nodules a red pigment containing protein called leghaemoglobin is involved in the process of nitrogen fixation. The key enzyme responsible for biological conversion of molecular nitrogen to ammonia is nitrogenase.
17. Making faster and smarter computers: The Archaeobacterium Halobacterium halobium grows in nature in solar evaporation ponds having high concentration of salts. Such salty ponds are found around San Francisco Bay located on the Western coast of USA. It has been found that the plasma membrane of Halobacterium halobium fragments into two fractions, when the cell is broken down. These two fractions are red and purple. The purple fraction is important in making computer parts (chips). The purple colour is due to a protein which is 75% of purple membrane and has been referred to as bacteriorhodopsin. Robert Birge at Syracuse University’s Centre of Molecular Electronics has grown Halobacerium halobium in 5-litre batches and has extracted the protein bacteriorhodopsin from the cells and developed the computer chips which are made up of a thin layer of bacteriorhodopsin. The chips so made from the bacterial source can store more information than the conventional silicon chips and process the information faster more like a human brain. The only drawback is that one needs to store the protein chips at -4°C. But Birge believes that this problem will be overcome soon
Reference:
https://madhavuniversity.edu.in/applications-of-microbiology.html#:~:text=Its%20outstanding%20applications%20in%20the,as%20biosensors%20is%20as%20given
https://ispub.com/IJMB/10/1/14136#:~:text=Microbial%20biotechnology%20is%20an%20important,research%20in%20the%20agricultural%20sciences.
https://microbenotes.com/scope-and-applications-of-microbiology/
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