Introduction of Microbiology

Course : B.Sc. Biotechnology, Biochemistry

Sem II

Sub: Basic Microbiology

Unit 1.1

Microbiology• Microbiology

• Greek word : mikros - "small"; bios - "life“ and logia- Science

• Is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms.

• This includes eukaryotes such as fungi and protists, andprokaryotes which are bacteria and archaea.

• Viruses, though not strictly classed as living organisms, are alsostudied.

History of Microbiology

Lucretius, a Roman philosopher Fracastoro, a 16th century physician

• Before they were visibly observed, microbes were suspected not only to exist, but also to cause disease.

• 1590 - Hans Jansen developed the first useful apparatus with compound lenses.

• Robert Hooke first observed and described microbes Inventor of the 17th century Coined the term “cells” to describe the “little boxes” He observed in examining cork slices with a compound

microscope In 1665, published the book Micrographia documenting

his various observations In 1678, he was asked to confirm van Leeuwenhoek’s

observations

• Leeuwenhoek

Developed single lens microscopes

1673 to 1676 - publishes his discovery of “animalcules”

• Bacteria

• Protozoa

• “Vinegar eels”

• From before the time of Aristotle (384-322 B.C.), people believed that life could arisefrom non-living matter, i.e., spontaneous generation.

• “Evidence” includes:

Mice from grain

Beetles from dust

Worms and frogs from mud

Maggots from rotting meat

• In the late 1600s, Francesco Redi challenged this view through a series of experimentsinvolving rotting meat.

• Redi’s experiments, and those by others, refuted the spontaneous generation theoryfor larger organisms.

• These experiments did not, however, dispel speculation that the theory still held truefor microorganisms.

• Proponents cited evidence of microbial growth in boiled extracts of hay or meat.

• By the late 1800s, Pasteur and Tyndall conclusively disprovedthe theory of spontaneous generation

• Louis Pasteur

• Father of Microbiology

• Contributions include:

• Wine fermentation

• Microbial diseases of grapes and silkworms

• “Pasteurization”

• Rabies vaccine

• In 1861, Pasteur provided definitive proof againstspontaneous generation using swan necked flasks.

• John Tyndall

English physicist - first scientist to study greenhousegases and climate change

Demonstrated the existence of heat-resistantbacteria, thereby extending Pasteur’s findings

Giants of the early days of microbiology and their major contributions

Scope of Microbiology

• Microbiology has an impact on

Medicine

Agriculture

Food science

Ecology

Genetics

Biochemistry

Immunology

Production of antibiotics

• Most of the antibiotics are produced frommicroorganisms.

• Industrial microbiology concerns itself with theisolation of antibiotic producing microorganisms fromnatural environments such as soil or water.

• Many antibiotics are isolated from naturalmicroorganisms by the process of fermentation.

Antibiotics Microbial scourse

Penicilin Penicillium species

Streptomycin Streptomyces griseus

Chloramphenicol Streptomyces venezuelae

Tetracycline Streptomyces rimosus

Neomycin Streptomyces fradiae

Production of human hormones

• Bacteria have been inserted with human genes that control the production of insulin, Human growth hormone and interferon.

• The bacteria can produce these in mass quantities that human cannot.

1. Human insulinAmongst the earliest uses of biotechnology inpharmaceutical manufacturing is the use ofrecombinant DNA technology to modify Escherichiacoli bacteria to produce human insulin.Genentech researchers produced artificial genes foreach of the two protein chains that comprise theinsulin molecule.

2. Production of vitaminBacteria like E. Coli present in human colon are involved in

synthesis of vitamins like vitamin b12, folic acid, biotin and K, which may beused by the host. Such bacteria are often used for commercial preparationof vitamins like riboflavin.

3. Production of Antiseptic• Antiseptics are antimicrobial substances that are applied to living

tissue/skin to reduce the possibility of infection, sepsis or putrefaction.• Some antiseptics are true germicides, capable of destroying microbes

(bactericidal) whilst others are bacteriostatic and only prevent or inhibittheir growth.

• Antibacterial are antiseptics that only act against bacteria.• Microbicides which kill virus particles are called viricides.• Some common examples of antiseptics are alcohols, Quaternary

ammonium compounds, Boric acid, Chlorhexidine Gluconate, Hydrogenperoxide, Iodine, phenol etc.

Medical Microbiology

• Medical Microbiology helps in the diagnostic protocol foridentification of causative agents of various humanaliments, alimentes & subsepuents preventive measures.

• Genetic engineering

• Microorganisms can now be genetically engineered tomanufacture large amounts of human hormones.

• Microorganisms play a central role in recombinantDNA technology and genetic engineering. Importanttools of biotechnology are microbial cells, microbialgenes, and microbial enzymes.

Pharmaceutical Microbiology

• Pharmaceutical Microbiology – is the part of industrialmicrobiology that is responsible for creating medications.

• The making of life-saving drugs, antibiotics e.g.Penicillin’s, ampicillin, chloramphenicol, ciprofloxacin,tetracyclines, and streptomycin belong to the sector ofpharmaceutical microbiology.

• There are many useful products made by microbes.

Industrial microbiology• Industrial microbiology making of ethanol, acetic acid

lactic acid, citric acid, glucose, syrup, high-fructosesyrup.

Waste-Treatment Microbiology

• Waste-Treatment Microbiology includes treatment ofdomestic and industrial effluents or wastes bylowering the COD.

• Without microbes we would have an over abundanceof dead things.

• Microbes are also used to clean up oil, toxic waste,and dynamite and sewage treatment.

Immunology

• Immunology is the branch of medicine and biology concernedwith immunity.

• Immunology studies the system of body defenses that protectsagainst infection.

• It includes serology, a discipline that looks for the products ofimmune eactions in the blood and tissues and aids in diagnosisof infectious diseases by that means, and allergy, the study ofhypersensitive responses to ordinary, harmless materials.

Food Microbiology • that microorganisms were responsible for the chemical changes

that take place in foods and beverages.

• Microorganisms play an important role in

• Food preservation

• Food spoilage

• Food poisoning

• Food fermentation

• Food hygine

• Food-born disease

• Food quality control

• 1.5 million tons of baker’s yeast (Saccharomycescerevisiae) are produced worldwide every year.

• Cheese production also has ancient origins.

• Beverage Microbiology making of beer, sandy, wine,and a variety of alcoholic beverage e.g. whisky, brandy,rum, gin, vodka, etc.

Fermented Food Substrate Microorganisms

Idli Rice and blackgram Leuconostoc mesenteroids, Streptococcus faecalls

Yoghurt Milk Streptococcus thermophillus, Lactobacillus bulgaricus

Kefir Milk Lactobacillus and Yeast

Cheese Milk Penicillium sp, Lactobacillus sp

Fields of Microbiology

Phycology• Phycology (from Greek word, phykos, "seaweed"; and -logia) is the

scientific study of algae.• Phycology/ Agologist is a branch of life science and often is

regarded as a subdiscipline of botany.• Algae are important plants as primary producers in aquatic

ecosystems.• Most algae are eukaryotic, photosynthetic organisms that live in a

wet environment.• They are distinguished from the higher plants by a lack of true

roots, stems or leaves. They do not flower.• Many species are single-celled and microscopic (including

phytoplankton and other microalgae); many others are multicellularto one degree or another, some of these growing to large size (forexample, seaweeds such as kelp and Sargassum).

• Phycology includes the study of prokaryotic forms known as blue-green algae or cyanobacteria.

• A number of microscopic algae also occur as symbionts in lichens.

Mycology

• Mycology is the branch of biology concerned with the study offungi, including their genetic and biochemical properties, theirtaxonomy and their use to humans as a source for tinder,medicine (e.g., penicillin), food (e.g., beer, wine, cheese, ediblemushrooms), and entheogens, as well as their dangers, such aspoisoning or infection.

• From mycology arose the field of phytopathology, the study ofplant diseases, and the two disciplines remain closely relatedbecause the vast majority of "plant" pathogens are fungi.

• Historically, mycology was a branch of botany because,although fungi are evolutionarily more closely related toanimals than to plants, this was not recognized until a fewdecades ago.

Virology

• Virology is the study of viruses – submicroscopic, parasiticparticles of genetic material contained in a protein coat – andvirus-like agents.

• It focuses on the following aspects of viruses: their structure,classification and evolution, their ways to infect and exploit hostcells for reproduction, their interaction with host organismphysiology and immunity, the diseases they cause, the techniquesto isolate and culture them, and their use in research andtherapy.

• Virology is considered to be a subfield of microbiology or ofmedicine.

Bacteriology• Bacteriology is the branch of biology that deals with the study of

minute organisms called bacteria (singular bacterium).

• Bacteria: a single-celled, often parasitic microorganism withoutdistinct nuclei or organized cell structures. Various species areresponsible for decay, fermentation, nitrogen fixation, and manyplant and animal diseases.

• They are:

Prokaryotes

Single-celled organisms

Size: microscopic.

E.g. E. coli is 1.3 um wide x 1.0 um long.

6250 E. coli to make 1 inch

Medical microbiology

• This branch deals with the pathogenic microbes, their lifecycle, physiology, genetics, reproduction etc., many of themicrobes also provide remedies for microbial diseases. Allthese aspects are studied in this branch.

• Some of the diseases like tuberculosis, leprosy, typhoid etc arecaused by microbes and cure for them is provided by othermicrobes in the form of antibiotics.

Agricultural microbiology

• It is dealing with the various aspects of agriculture.

• In this branch the role of microbes in agriculture is studiedfrom the point of view of both harm and usefulness.

• Many microbes - fungi, bacteria and viruses cause a numberof plant diseases.

• From the point of view of benefit - N2 fixing activity, use ofmicrobes as biofertilizers and several other aspects arestudied.

Industrial microbiology

• The role of microbes in Industrial Production is studied.

• Many microbes produce industrial alcohols, and acids as apartof their metabolism.

• The study of fermentation by microbes has contributed agreat lot to alcohol manufacturing. Breweries have greatlybenefited by understanding the role of specific microbes infermentation.

Food and Dairy microbiology

• Various aspects such as food processing, food preservation,canning, Pasteurization of milk, study of food borne microbialdiseases and their control is studied.

• Micro-flora of fruits and vegetables are also studied.

• It deals with the fermentations and fermented products likeyogurt, cheese, sauerkraut, sausage, baker’s yeast, soy sauce,beer, wine, etc.

• These microbiologists involve in prevention of deterioration andspoilage of the food products and have a continuous hygienechecks on the food products to prevent any food poisonings.

• Application of enzymes in food and dairy industry is studied.

Aquatic microbiology

• Microbiological examination of water, water purification,biological degradation of waste are studied in this branch.

Aero microbiology

• Dispersal of disease causing microbes through air microbialpopulation in air, their quality and quantity in air comes underthe perview of this branch.

Environmental microbiology

• This is one of the most important branches of micro biology.

• It involves in the study of ecological study which includes air,water, food and environment as such.

• These microbiologists check the factory wastes which can causepollution of the air or water thus increasing the rate of poisoningor diseases in the environment.

• The role of microbes in maintaining the quality of theenvironment is studied here.

• Microbial influence in degradation and decay of natural waste,their role in biogeochemical cycles are all studied.

• Some of the recent researches have shown that certain bacteriacan help in cleaning the oil spill and this gives added significanceto the study of environmental microbiology.

Geochemical microbiology

• Role of microbes in coal, gas and mineral formation,prospecting for coal, oil and gas and recovery of minerals fromlow grade ores using microbes is included here.

• This is the most significant branch which may even change thecourse of life as we know today. Microbes are used as genecarriers to deliver specific genes to function in a differentenvironment.

• New, genetically engineered microbes can produce drugs(human insulin) or in agriculture N2 fixing ability may betransferred to all the plants. The Potentialities of bio-technology are immense.

Biotechnology

Immunology

• Studied in this branch are the immune responses inorganisms.

• How toxins are produced,

• How the antigens influence the formation of antibodies,

• How protective vaccination helps in combating the diseases,

• How immune system collapses (as in AIDS) are some of thequestions for which immunology as a branch of microbiologyis trying to find out answers.

Medical Microbiology

• Involves in identifying, treatment or prevention of somediseases caused by bacteria, virus, and fungi.

• The medical microbiologists research on different diseases,their causes, development and pathogenesis.

• Every human needs good, purified water for survival.

• These microbiologists ensure and monitor the quality of thewater supplied to the domestic areas.

Bacteriology

• It dealing with the Study of bacteria.

• This subdivision of microbiology involves the identification,classification, and characterization of bacterial species.

Major groups of Microorganisms

Introduction

• Microorganisms are named based on their particular physiological and nutritional characteristics.

• Based on Temperature:

1. Psychrophile

2. Psycrotroph

3. Mesophile

4. Thermophile

5. Hypothermophile

Based on Temperature

Tyepes of MicrobeOptimum growth

TeperatureGrowth Temp Range

Psychrophile 15 oC 0-20 oC

Psycrotroph 5 oC 0-25 oC

Mesophile 37 oC 10-45 oC

Thermophile 50 oC -

Hypothermophile 80 oC -

Based on pH requirementspH• The pH scale is a measure of hydrogen ion (H+) concentration. Low pH corresponds

with high concentrations of hydrogen ion, neutral pH with equal numbers of hydrogenand hydroxyl ions (OH-), and high pHs correspond to low concentrations of hydrogenion

Optimum pH• Optimum pH is that pH at which a given organism grows best. The range over which• most organisms can grow tends to vary over no more than a single pH unit in either• direction (e.g., from pH 6 to pH 8 for an organism whose pH optimum is pH 7)

Acidophiles• Organisms whose optimum pH is relatively to highly acidic, which means growing best

in acidic pH

Neutrophiles• Organisms whose optimum pH ranges about pH 7, plus or minus approximately 1.5 pH

units

Alkaphiles• Organisms whose optimum pH is relatively to highly basic, which grow best in high pH

Based on oxygen requirements• Organisms differ in their requirements of molecular oxygen (i.e., O2) as

well as other atmospheric gasses (e.g., carbon dioxide). Categories of organisms as per their oxygen requirements include:

Obligate aerobe• Organisms that are unable to grow in the absence of oxygen or they

require oxygen for their growth. Some times this group of organism may be called strict aerobes as they can not grow without oxygen.

Facultative aerobe• Organisms that can grow in the absence normal level of oxygen that is

other wise required.

Microaerophile• These are organisms that grow best when small amounts of oxygen are

present. That is, less than atmospheric concentrations, but more than those concentrations tolerable by obligate anaerobes

Obligate anaerobe• Organisms that are strict anaerobe and require complete

absence of oxygen for their growth, which mean they cannot grow in the presence of oxygen.

Facultative anaerobe/Facultative aerobe• Facultative anaerobes can grow either in presence or

absence of oxygen. These organisms tend to exist in environments in which oxygen concentrations are uncertain.

Aerotolerant anaerobe• These are organisms that are able to grow in the presence

of oxygen though they do not require it for their growth.

Based on oxygen requirements

Capnophiles• These are organisms whose optimum growth requires relatively high concentrations

of carbon dioxide

Osmotic pressure• The concentration of dissolved substances in the environment can impact on the

growth and survival of bacterial cells.• Osmophilic organisms are microorganisms adapted to environments with high

osmotic pressures, such as high sugar concentrations.

Plasmolysis• Environments containing large concentrations of dissolved substances draw water out

of cells, causing shrinkage of the cytoplasm volume, a phenomenon termedplasmolysis.

• Plasmolysis interferes with growth and this is why highly osmotic environmentsprevent bacterial growth (e.g., brine, the high sugar concentrations in jellies and jams,salting of meats)

Halophiles• Organisms that require high concentrations of dissolved salts to grow are termed

halophiles.• Depending on organism, the salt concentrations required range from those of

seawater on up to those of brine.

ReferencesBooks:

1. Biology of microorganisms By M. T. Madigan, J. M. Martinko, D. A. Stahl and D. P. Clark

Websites:

1. http://en.wikipedia.org/wiki/Virology

2. http://en.wikipedia.org/wiki/Mycology

3. http://en.wikipedia.org/wiki/Phycology

4. http://www.gitam.edu/eresource/environmental/em_maruthi/introduction.htm#4