Microbiology/Virology

 

Microbiology is the study of microorganisms. Microorganisms include viruses, prokaryotes and simple eukaryotes. At present, most of the work in microbiology is done by biochemical and genetic methods. Since many pathogens (such as the four major pathogens that cause plant diseases: viruses, fungi, nematodes and bacteria) can be considered as microorganisms in the broad sense, microbiology is also closely related to pathology, immunology and epidemiology. Microbiologists have made fundamental contributions to biology and medicine, especially in the fields of biochemistry, genetics, and cell biology.

 

 

Overview of microorganisms

 

History

 

1. Before the Development

Before the development of microbiology, microbes had been perceived by man for many centuries. The Roman scholar Marcus Varro mentioned the first principle in his book on agriculture. He warned that no pasture or house should be built near a swamp, because there were invisible floating objects in the air, which could cause disease if they entered the body through the mouth or nose.

In 1546, Girolamo Fracastoro proposed that infectious diseases are caused by seedlike entities that can be transmitted by direct or indirect contact or by vectors.

 

2. The Birth of Microbiology

The development of microbiology began with the invention of the microscope. In 1665, an Englishman, Robert Hooke, invented the microscope and observed the outline of cells (the cell walls of fungi, but was considered to be a simple plant at the time, until in the 20th century proved to be fungus), in 1673 the Dutch Levin Hawke used their improved microscope to observe real cells, while recording the morphology of a variety of microorganisms.

a. 1798 - Edward Jenner, an Englishman, inoculated against smallpox with cowpox.

b. 1864 - Frenchman Pasteur invented Pasteur's method of disinfection.

c. 1867 - Joseph Lister, an Englishman, was the first to use phenol as a disinfectant on patients' wounds and invented a way to avoid infection during surgery.

d. 1876 - German Ferdinand Cohen discovered endophytes.

e. 1884 - Danish Hans Christian Gram invented Gram stain.

f. At the end of the 19th century - German Robert Kehoe proposed Kehoe's rule, purified culture, and discovered Bacillus Athracis and Tubercle Bacillus.

g. 1925 - British Professor Alexander Fleming discovered the antibiotic penicillin.

 

Since the 1940s, the research results of microbiology have been applied to medicine, industry, agriculture and so on. In biological research, molecular biology, biochemistry, cytology, genetics and other disciplines often use microorganisms as research materials.

 

 

Microbiology

 

Research Methodology

 

1. Microscopic Examination

The bacteria could be preliminarily identified by Gram stain. Bacteria can be divided into Gram-positive and Gram-negative according to different colors after Gram staining. Because bacteria contain cocci and bacilli, they can be classified into the following four categories by microscopic observation: GPC (Gram-positive cocci), GNC (Gram-negative cocci), GPB (Gram-positive bacilli) and GNB (Gram-negative bacilli).

 

2. Other Method

Microbes have many properties that make them ideal model organisms for scientific research:
    a. They are small and do not consume a lot of resources.
    b. Some microbes have very short generations (the optimal time for a cell to divide is about 30 minutes for E. coli and 12 to 24 hours for Mycobacterium tuberculosis).
    c. Individual cells can survive relatively easily.
    d. Unicellular eukaryotes reproduce by mitosis, whereas prokaryotes usually reproduce asexually by two divisions, so that genetically identical populations (clones) can be studied.
    e. Most microorganisms can be kept frozen for a long time. Even if 90% of the cells die in the freezing process, millions of cells can still survive in a milliliter of culture medium.

 

Main Branch of Microbiology

 

The branch of microbiology can be divided into pure science and applied science. Microbiology can be divided into bacteriology, virology, etc., and medical microbiology, environmental microbiology, applied microbiology, etc. according to the research direction.


    The taxonomy of microbiology focuses on the observation of the morphology, physiology, distribution, variation, heredity and evolution of a group of microorganisms.

 

Features

 

1. Small volume, large specific surface area

Microorganisms whose size is measured in μm, but whose specific surface area (surface area/volume) is large, must have a huge nutrient uptake, metabolic waste excretion and environmental information receiving surface. This characteristic is also the key to distinguishing microbes from all large organisms.

 

2. More absorption, faster transformation

This characteristic provides a sufficient material basis for rapid growth and reproduction and the production of a large number of metabolites

 

3. Growth and rapid reproduction

High growth and reproduction speed, such as E.coli divides once in 20-30 minutes, if not divided, the bacteria increase by 2.2x10^43 in 48 hours, nutrient consumption, metabolic accumulation, and growth rate are limited. This property can convert a large number of substrates into useful products in a short time and shorten the research cycle. There are also disadvantages, such as disease and grain mildew.

 

4. Strong adaptability and easy variation

Remarkably adaptable to extreme environments, genetic material that is prone to variation. More importantly, there are many physiological metabolic types and metabolites of microorganisms.

 

5. Wide distribution and variety

It has a wide distribution area and a wide distribution environment. There are many physiological metabolic types, many metabolites and many kinds. Microbes can be found in any environment where other organisms can live, and they can be found in extreme environments where no other organisms can live.

 

6. Liable to mutate, produce mutation

The large specific surface area of microorganisms makes microorganisms more susceptible to environmental conditions. Under the changes of ultraviolet rays, biological mutagens and some nutritional factors in the environment, the individual consciousness and genetic structure of microorganisms are forced to change, resulting in variants. According to the statistics of natural conditions, the microorganism mutation probability is one over one million. Since microorganisms are easy to produce mutants, people use this characteristic of microorganisms to carry out microbial mutagenesis, and then screen microbial strains with certain objective characteristics, such as improving yield, nutritional defects, etc.

 

Effect

 

1. It acts in the natural cycle of matter

2. Air and water purification, sewage treatment

3. Industrial and agricultural production: thallus, metabolites, metabolic activities

4. For services of life sciences

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