Microbiology Questions for BSc in Botany Students.  Today, I would like to discuss here the most important topics of microbiology from chapter :01. I would like to talk about

  • Introduction of microbiology 
  • Definition of microbiology 
  • History of  microbiology 
  • Scope And Development  of microbiology
  • Distribution of microorganisms
  • Spontaneous generation and biogenesis
  • Germ theory of dieses           

(1) Which are termed as microbes?
/ What is microorganisms? /Define the term Microorganisms.    

Microorganisms/Microbes  :A microorganism or microbe is an organism which is microscopic, which means too small to be seen by the unaided human eye. The study of microorganisms is called microbiology. Microorganisms include bacteria, fungi, archaea, protists and viruses, and are among the earliest known life forms.

(2) What is microbiology? /Define the Term microbiology  
Microbiology: Microbiology is a science that deals with tiny organisms that can't be seen by naked eyes.   
(3) Describe the germ theory of diseases    
Germ theory of Disease   :The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to see without magnification, invade humans, other animals, and other living hosts. Their growth and reproduction within their hosts can cause disease. "Germ" may refer to not just a bacterium but to any type of microorganism or even non-living pathogen that can cause disease, such as protists, fungi, viruses, prions, or viroids. Diseases caused by pathogens are called infectious diseases. Even when a pathogen is the principal cause of a disease, environmental and hereditary factors often influence the severity of the disease, and whether a potential host individual becomes infected when exposed to the pathogen.

(4)What are the contribution of Antony Von Leeuween-hook and Ronald Ross in the field of Microbiology?

Contribution of Antony Van Leeuwenhoek: 
The Microscope and Discovery of Microorganisms. Antonie vanLeeuwenhoek was one of the first people to observe microorganisms, using a microscope of his own design, and made one of the most important contributions to biology. Robert Hooke was the first to use a microscope to observe living things.

Contribution of Sir Ronald Ross: Sir Ronald Ross was a British medical doctor who received the Nobel Prize for Physiology or Medicine in 1902 for his work on the transmission of malaria, becoming the first British Nobel laureate, and the first born outside Europe. His discovery of the malarial parasite in the gastrointestinal tract of a mosquito in 1897 proved that malaria was transmitted by mosquitoes, and laid the foundation for the method of combating the disease.

(5)write the scope of microbiology.

Scope of microbiology: 

Genetics:Mainly involves engineered microbes to make hormones, vaccine, antibiotics and many other useful products for human being.

Agriculture:  The influence of microbes on agriculture; the prevention of the diseases that mainly damage the useful crops.

Food Science: It involves the prevention of spoilage of food and food borne diseases and the uses of microbes to produce cheese, yoghurt, pickles and beer.

Immunology: The study of immune system which protect the body from pathogens.

Medicine:  deals with the identification of plans and measures to cure diseases of human and animals which are infectious to them.

Industry:  it involves use of microbes to produce antibiotics, steroids, alcohol, vitamins and amino acids etc.

(6)Write kock's postulates for the identification of new pathogen.

Kock's Postulates:  In 1890 the German physician and bacteriologist Robert Koch set out his celebrated criteria for judging whether a given bacteria is the cause of a given disease. Koch's criteria brought some much-needed scientific clarity to what was then a very confused field.

Koch's postulates are as follows:

(i)The bacteria must be present in every case of the disease.
(ii)The bacteria must be isolated from the host with the disease and grown in pure culture.
(iii)The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
(iv)The bacteria must be recoverable from the experimentally infected host.

(6) write down the contribution of scientists.
Contributions of Scientists on the field of microbiology: 

Louis Pasteur:
(1)He is the father of medical microbiology.
(2)Swan Neck Flask experiment: Pasteur conducted a now infamous experiment in which he used S shaped neck flask. This experiment is known as Swan Neck flask experiment. By this experiment, he proved that, living things only can come from a living things.
(3) Pasteurization: Pasteur in 1897 suggested that mind heating at 62.8°C(145°F) for 30 minutes rather than boiling is enough to destroy the undesirable organisms without ruining the taste of the products, the process is known as pasteurization.
(4)Pasteur invented the process of pasteurization, fermentation and the development of effective vaccines( rabies and anthrax).
(5)Pasteur demonstrated diseases of silkworm was  due to protozoan parasite.
(6) He coin the term "Microbiology" "aerobic"; "anaerobic".
(7)He developed live attenuated vaccine of Disease.

Louis Pasteur 

Antony Van Leeuwenhoek: 
(1) He is the first man who observed living things.
(2) He described the tiny microbes that he called animalcules.
(3) All the main unicellular microbes,protozoa,algae,yeast and bacteria were described by him.

Robert Koch:
(1)He demonstrated the role of bacteria in causing diseases
(2)He perfected the technique of isolating bacteria in pure culture.
(3)Robert koch used gelatin to prepare solid media but it was not an idea because
(i)Since gelatin is a protein,it is digested by many bacteria capable of producing proteolytic exo enzyme gelatinase that hydrolyses the protein to amino acids.
(ii)It melts when temperature rises above 25°C 

Ronald Ross(1857-1932) 
(1) Eliminate the "Polluted Water Theory " about malaria
(2) Discovered the organism responsible for malaria disease.
(3) Discovered the role of femle Anopheles mosquito in the malaria transmission in 1848.

Lord Joseph Lister: 
(1) He is the father of antiseptic  surgery
(2) He concluded that wound infections too were due to microorganisms.
(3)He also devised a method to destroy the microorganisms in the operation theatre by spraying a fine mist of carbolic acid into the air.

John Tindal:
1)He discovered highly resistant bacterial structures, later known as endospore.
(2)Prolonged boiling or intermittent heating was necessary to kill these spores,to make the infusion completely sterilized, a process known as Tyndanllisation. 

(7)Explain "the swan neck flask" experiment.
Hypothesis : Pasteur conducted a now infamous experiment in which he used a glass flask with an S shaped neck. This S shaped flask became known as the ‘swan neck flask’.  He partly filled the body of the flask with an ‘infusion’ - a nutrient rich broth. He then boiled the infusion killing any germs already present in the liquid - this process is known as pasteurisation.

The steps of Pasteur's experiment are outlined below:
(1)Pasteur prepared a nutrient broth.

(2) He placed equal amounts of the broth into two long-necked flasks. He left one flask with a straight neck. The other he bent to form an "S" shape. This S shaped flask became known as the ‘swan neck flask"

(3) he boiled the broth in each flask to kill any living matter in the liquid. The sterile broths were then left to sit, at room temperature and exposed to the air, in their open-mouthed flasks.

After several weeks, Pasteur observed that the broth in the straight-neck flask was discolored and cloudy, while the broth in the curved-neck flask had not changed.
He concluded that germs in the air were able to fall unobstructed down the straight-necked flask and contaminate the broth. The other flask, however, trapped germs in its curved neck,­ preventing them from reaching the broth, which never changed color or became cloudy.
If spontaneous generation had been a real phenomenon, Pasteur argued, the broth in the curved-neck flask would have eventually become reinfected because the germs would have spontaneously generated. But the curved-neck flask never became infected, indicating that the germs could only come from other germs.

(8)Write down the history of microbiology  

History of microbiology  :

I. Discovery 
- 1665 Robert Hooke - observed cells in sections of cork
~ (1680s) Leeuwenhoek - “animalcules” observed in rain water, other sources.
Spontaneous Generation = life from non-life, disproving this belief:
~ 1670 Redi - demonstrated larva present on meat was from eggs
~ 1765 Spallanzani and others used sealed flasks and treated air to prevent microbial growth
however, others such as Needham claimed a vitalistic force in air was necessary for
spontaneous generation to occur.
- 1860’s Louis Pasteur - “Father of Microbiology” used swan necked flasks 
to disprove spontaneous generation. Also, observed that heat could kill these microbes. This led to the development of Pasteurization. (also see Tyndall)

II. Pure Culture Concept
pure culture = 1 type of organism grown in culture, once this was accomplished,
microbes could be studied individually.

III. Germ Theory of Disease - proved role of microorganisms in causing disease.
A) - 1870’s Robert Koch - demonstrated 6 different infections in mice caused by 6 different bacteria; demonstrated anthrax was caused by bacteria

1884 - 4 postulates (Koch’s) 
1) organism present in diseases cases, absent in healthy animals
2) can be isolated from diseased animal and grown in pure culture
3) disease can be reproduced by inoculation of healthy animal with cultured organism
4) organism can be re-isolated from experimentally infected animal and returned to culture (pure)

B) Koch’s work and others led to the “Golden Age of Microbiology”
1) causes of many diseases were determined
2) improved culture methods
3) improved staining techniques

C) Lister in 1860s, developed aseptic surgical techniques, used carbolic acid
(phenol) to treat dressings.

IV. Cell Theory

V. Role of Microorganisms in Chemical Transformations
A) 1837, demonstrated that Yeast generated alcohol

glucose + H2O ---> ethanol + CO2

B) 1857 - 1876, Pasteur demonstrated such fermentations were microbial processes
C) 1897 Buchner discovered enzymes

VI. Areas developed from Microbiology
Development of microbiology led to the following areas:
1) Immunology
2) Chemotherapy
3) Virology
4) Molecular Biology

A) Immunology
1) 1796 Jenner - immunity to smallpox conferred by inoculation with cowpox
2) 1881 Pasteur - used “attenuated” virus for immunization against rabies
3) 1884 Metchnikoff - observed phagocytosis = cellular theory of immunity
4) 1890 Emil von Behring - immunity in cell free portions of blood = humoral theory

B) Chemotherapy
1) 1908 Ehrlich - treatment for syphilis (salvarsan = arsenic derivative)
2) 1929 Fleming - penicillin
3) 1944 Waksman - streptomycin
4) 1950’s - many antibiotics discovered

C) Virology
1) 1892 Iwanowski - showed an agent passing through a filter caused a disease in plants
2) 1931 - cultivation of viruses in chick embryos
3) 1949 - cultivation in cell cultures

D) Molecular Biology
1) Monoclonal antibodies - 1975 Kohler and Milstein fused myeloma and antibody producing cells = hybridoma which generates monoclonal antibodies
2) Genetic engineering - 1973 Chakrabarty transferred genes from one organism to another