Mirobiology

Mirobiology


Microbiology is a branch of biology concerned with study of microscopic organisms and is one of the largest and most applied of all biological sciences, in addition to study the natural history of microbes, that deals with every aspects of microbe-human and environmental interaction, these interactions include: ecology, genetics, metabolism, infection, disease, chemotherapy, immunology, genetic engineering, industry and agriculture.
The term microbiology was given by French chemist Louis Pasteur (1822- 1895). Microorganism was first living things to appear on earth more than three billion years ago and the term microbe was first used by Sedillot (1878).
Microbiology branches
Medical microbiolog
Industrial microbiology
Food microbiology
Soil microbiology
Plant microbiology
Medical Microbiology is studied under fallowing headings:
1- Bacteriology
2- immunology
3- Genetics
4- Virology
5- Parasitology
6- Mycology
Microbiology

The an American microbiologist Carl Richard Woese ( 1928 – 2012) classiefied the organisms into three kingdom Eukaryote cells, prokaryote cells including(Eubacteria and Archeabacteria)

Kingdom of Prokaryotaes contains Eubacteria (derived from the Greek "bakt rion”, meaning “small staff”) and Archaebacteria. There are many characters of bacteria:
1- Bacteria are small unicellular organisms, microscopic in size about 0.5 -5 ?m length 0.2- 2 ?m in width and .
2- They lack a true nucleus and complex membrane bounded organelles except the ribosome.
3- Bacteria replicate asexually by binary fission, genetic material exists as a single double-stranded DNA in a nuclear region or nucleoid and not associated with histones.
Bacterial cell

4-Most species of bacteria are heterotrophic; they acquire their food from organic matter. A few bacterial species are parasitic, living within host organisms and cause disease. Certain bacteria are autotrophic, they synthesize their own foods in process of photosynthesis using pigments dissolved in their cytoplasm like green sulfur bacteria and the purple bacteria.

5- Morphology of bacterial cell are not always constant because it affected by many factors such as composition of media and external environment factors like temperature, pH values, radiation, starvation and dryness.
Most bacteria appear in variations of four different shapes:
1- Spherical bacteria (coccus) are usually round or oval elongated having several groups arranged according to the manner in which the resulting cells attaches together after division such as cluster for example Staphylococcus aureus.
Morphology
2- Rod shape (Bacilli) the shape of cells like rod or bacilli having many shapes on the base of cell arrangement for example streptobacilli like Bcillus anthrax.

Morphology of bcteria
Morphology
3- Spirilla the bacteria is a corkscrew shape with rigid cell wall and hair like projections called flagellum that help in movement of bacteria ex. Treponema pallidium.
Question


Which type of compound microscope can be examined bacteria T. Pallidium

Morphology
4- Filamentous bacteria
The body of this type consists of mycelium which resembles a mass of branched thin non – septate hyphae similar to that of fungi such as Actinomycetes.
5- Bacteria play many beneficial roles in the environment:
Some species of bacteria live on roots of plants and “fix” nitrogen from the air into organic compounds that are useful to plants. Other bacteria are responsible for decomposing dead bodies in the environment; these bacteria recycle the essential elements in the ecosystems.
In the food industry, bacteria are used to prepare many products such as cheeses, fermented dairy products, in other industries bacteria are used to produce antibiotics, chemicals, dyes, numerous vitamins, enzymes and a number of insecticides.
In the human intestine, bacteria synthesize several vitamins not widely obtained in food, especially vitamin K; also bacteria often break down certain foods that otherwise escape digestion in the body.
Koch’s postulate


Unfortunately, many bacteria are pathogenic cause many human disease such as tuberculosis, gonorrhea, syphilis, food poisoning, plague, tetanus, typhoid fever, pneumonia and Anthrax. Robert Koch was proved the germ theory by procedures known as Koch s postulates (Fig).They provided a set of principles whereby a specific microorganisms could be related to a specific diseases:
Koch’s postulate
1- M.O must be present in every case of the disease but absent from healthy organisms.
2- The suspected M.O must be isolated and grown in a pure culture.
3- The same disease must result when the isolated M.O is inoculated into a healthy host.
4- The same M.O must be isolated again from the diseased host.

**Atypical bacterial types
There are some small forms of bacteria can be seen only with the electron microscope were Rickettsiae , Chlamydiae and Mycoplasma .
Rickettsiae are intermediate forms between bacteria and viruses,
they resemble some of bacteria in morphology, spherical or rod – shaped, rigid cell wall, also contain both genetic materials DNA and RNA,
but differing only in being of much smaller size but larger than viruses. Rickettsiae like viruses intracellular parasites in arthropods carried such as fleas, mites and ticks. Rickettsiae causes typhus fever

2-Commensalisms
A- type of symbiosis in which one of members of this association benefit and the other is not harmed for example the relationship with Staphylococcus epidermidis, a consistent inhabitant of the skin of human, by produces lactic acid that protects the skin from colonization by harmful microbes that are less acid tolerant
3- Parasitism
In biology, the term parasite refers to an organism that grows feeds and is sheltered on or in different hosts; this is a negative association because one member benefit and the other be harm. The parasite is termed obligate when it can live only in a host for example viruses and Rickettesia and as facultative when it can live both in a host as well as in free form as saprophytic life for eaxmple Bacillus anthraces. Parasites that live inside the body are termed endoparasite whereas those that exist on the body surface are called ectoparasite.
Question of lecture

All bacteria are microorganisms but not all microorganisms are bacteria? This statement true or false
The answer

Yes, because there are another organisms found like viruses, protozoa and fungi are M.O cannot be visualized by eyes but under microscope.







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