VEM020- GENERAL VETERINARY MICROBIOLOGY

How the microbial cell functions biochemically, including the study of microbial growth, microbial metabolism, and microbial cell structure

Microbial physiology

How genes are organized and regulated in microbes in relation to their cellular functions. This is closely related to the field of molecular biology

Microbial genetics

The evolution of microbes.

Evolutionary microbiology

The role of microbes in human illness, including the study of microbial pathogenesis and epidemiology and the related study of disease pathology and immunology.

Medical microbiology

• Discoveries of the principles of vaccination, microbial fermentation, and pasteurization

• Abolished spontaneous generation

• Discovered pasteurization

• He showed that contaminating yeast cells that produced the lactic acid during fermentation are different morphologically from brewer's yeast is the one responsible for the spoilage.

• The Father of Microbiology

Louis Pasteur

• Developed Koch's Postulate

• Introduced the technique of pure culture, whereby he established the microbial cause of the disease anthrax (1876)

• Introduced both staining and solid culture plates to bacteriology (1881)

• Identified the microbial cause of tuberculosis (1882)

• Popularized Koch's postulates for identifying the microbial cause of a disease and would later identify the microbial cause of cholera (1883).

Robert Koch

Koch's Postulate

1. The pathogenic microorganism must be present in every case of the disease but absent from healthy animals.

2. The suspected microorganism must be isolated and grown in pure culture. 3. The same disease must occur when the isolated microorganism is injected into healthy susceptible animals.

4. The same microorganism must be isolated again from the injected animals.

Koch's Postulate

1. The pathogenic microorganism must be present in every case of the disease but absent from healthy animals.

2. The suspected microorganism must be isolated and grown in pure culture.

3. The same disease must occur when the isolated microorganism is injected into healthy susceptible animals.

4. The same microorganism must be isolated again from the injected animals.

The postulates were formulated by ___________________ and___________________ in 1884 and refined and published by Koch in ____________.

The postulates were formulated by Robert Koch and Friedrich Loeffler in 1884 and refined and published by Koch in 1890.

Koch applied the postulates to establish the etiology of ______________ and _____________.

anthrax and tuberculosis.

Koch's Postulate (21st century) by who?

Fredricks and Relman

Who formulated Rivers' Postulate?

Thomas Rivers

1. A specific virus must be found associated with a disease with a degree of regularity

2. The virus must be shown to occur in the sick individual not as an incidental or accidental finding but as the cause of the disease under investigation. The causal relationship between a virus and a disease.

Rivers' postulate

• Discovered the vaccine for smallpox.

• innovative contribution to immunization and the ultimate eradication of smallpox

• his work is widely regarded as the foundation of immunology—even though he was neither the first to suggest that infection with cowpox conferred specific immunity to smallpox nor the first to attempt cowpox inoculation for this purpose.

Edward Jenner

any organism that is too small to be seen by the unaided eye.

Microorganism

the study of bacteria

Bacteriology

the study of fungi

Mycology

the study of protozoa

Protozoology

the study of algae

phycology

the study of parasites

Parasitology

the study of viruses

Virology

The role of microbes in veterinary medicine.

Veterinary microbiology

The function and diversity of microbes in their natural environments.

Environmental microbiology

The exploitation of microbes for use in industrial processes. Examples include industrial fermentation and wastewater treatment. This field is closely linked to the biotechnology industry.

Industrial microbiology

The study of airborne microorganisms

Aero microbiology

The study of microorganisms causing food spoilage and public health concerns.

Food Microbiology

• The hypothetical process by which living organisms develop from nonliving matter

• archaic theory

• pieces of cheese and bread: mice

• decaying meat: maggots

Spontaneous generation

• He was an Italian scholar

• Contagion is an infection that passes from one thing to another

1546- Girolamo Fracastoro

• Development of microscope

• "animacules"- he coined the organisms he discovered by collecting samples from a paddle of water. (1668)

Antonie van Leeuwenhoek

• Disproved the spontaneous generation.

• Founder of experimental biology

• Father of modern parasitology

• First one to challenge the spontaneous generation.

• Demonstrated maggots on development on meat only occur if a fly laid eggs on it

Francisco Reddi

• He developed the earliest effective vaccine against rabies that was first used to treat a human bite victim on 6 July 1885.

• The method involved inoculation with homogenates of RABV-infected rabbit spinal cord that had been desiccated progressively in sterile air. Initially, the recipient received a subcutaneous injection of homogenate that was fully inactivated. This was followed by injection of material derived from infections of the spinal cord desiccated for shorter periods that contained progressively more virulent preparations of the virus.

Louis Pasteur et., al

• Developed the porcelain filter to produce bacteriologically - sterile water to produce culture media.

• In 1884 he developed a type of filtration known today as the Chamberland filter or ChamberlandPasteur filter, a device that made use of an unglazed porcelain bar. The filter had pores that were smaller than bacteria, thus making it possible to pass a solution containing bacteria through the filter, and have the bacteria completely removed from the solution.

• Chamberland was also credited for starting a research project that led to the invention of the autoclave device in 1879.

Charles Chamberland

demonstrated that tobacco mosaic disease In Tobacco plants can be transferred to another plant. (Using Chamberland's porcelain filter).

Dimitri Ivannovsky and Martinus Beijerinck

• In 1887 to investigate "wildfire," a disease that was infecting tobacco plantations of the Ukraine and Bessarabia.

• In 1890 he was commissioned to study a different disease that was destroying tobacco plants in Crimea.

• Using a filtering method for the isolation of bacteria, Ivanovsky discovered that filtered sap from diseased plants could transfer the infection to healthy plants.

• Further research led Ivanovsky to conclude that the causal agent was an exceedingly small parasitic microorganism that was invisible even under great magnification and that could permeate porcelain filters designed to trap ordinary bacteria.

• He differed from later researchers of viruses only in his supposition that the pathogenic agent in question was a minuscule bacterium, rather than an entirely new and different type of organism.

• He published his findings in an article, "On Two Diseases of Tobacco" (189

Dimitri Ivannovsky

• one of the founders of virology and environmental microbiology.

• His results were in accordance with a similar observation made by Dmitri Ivanovsky in 1892.

• Like Ivanovsky before him and Adolf Mayer, predecessor at Wageningen, Beijerinck could not culture the filterable infectious agent; however, he concluded that the agent can replicate and multiply in living plants.

• He named the new pathogen virus to indicate its non-bacterial nature. Beijerinck asserted that the virus was somewhat liquid in nature, calling it "contagium vivum fluidum" (contagious living fluid).

Martinus Beijerinck

Identified the first filterable agent from animals, The virus of foot and mouth disease.

Loefler and Frosch

Described Filterable agent Yellow fever Virus.

Walter reed and his team

demonstrated the oncogenic potential of the filterable agent.

Ellerman and bang

observed that bacteria were susceptible to a filterable agent

Frederick Twort

made a similar observation as Twort named these viruses "BACTERIOPHAGE".

Felix de herelle

succeeded in growing vaccinia virus using a guinea pig cornea embedded in clotted plasma.

Steinhardt and his colleagues

used mice as a host species for propagating viruses

Furth and Sturnia

were successful in propagating the fowl pox virus on the chorioallantois membrane of embryonated eggs.

Woodruff and Goodpasture

observed vaccinia virus using a light microscope

Buist

employed the newly developed electron microscope and a metal shadowing technique to identify tobacco mosaic virus in purified preparations

Kaushe and his co-workers

obtained tomato bushy stunt virus.

Harrison and his co-workers

Demonstrated crystallization of TMV

Stanley

showed that TMV contained Nucleic acid as well as proteins

Bawden and pirie

suggested that Viral nucleic acids were surrounded by a shell of identical protein subunits.

Watson and Crick

proposed a universal system on which the modern classification of viruses

Lwoff and his colleagues

the modern classification of viruses is based:

• The type of nucleic acid

• The symmetry of the virus

• The presence and absence of an envelope

• The diameter of the nucleocapsid or the number of capsomeres

• Temin and Baltimore helped elucidate retrovirus replication.

An organism with a primordial nucleus has a much simpler morphology than eukaryotic cells and lacks a true membrane delimited.

Prokaryote

Greek "pro", before, and "karyon", nut or kernel

Prokaryote

All bacteria are procaryotic!

[Greek eu, true, and karyon, nut or kernel] have a membrane-enclosed nucleus.

Eukaryotic

they are more complex morphologically and are usually larger than procaryotes.

Eukaryotic

Algae, fungi, protozoa, higher plants, and animals are eukaryotic.

cell division prokaryotes

binary fission

cell division eukaryotes

mitosis

prokaryotic cell size:

0.2-2.0 um in diameter

eukaryotic cell size:

10-100 um in diameter

• Unicellular • smaller and less complex than eukaryotic cells (RBC)

• have rigid cell walls containing a peptidoglycan layer.

Bacteria

occur as rods, cocci, and helical forms and occasionally as branching filaments

Bacteria

most bacteria are between _______ and __________ in length.

0.5 μm and 5 μm in length.

what do motile bacteria possess so which they can move through liquid media

Flagella

majority of it can grow on suitable inert media.

bacteria

what are those bacterias which are unable to multiply on inert media, require living cells for in vitro growth

Rickettsiae and Chlamydiae

• consists of nucleic acid, either DNA or RNA

• enclosed in a protein coat called a capsid.

• some viruses are surrounded by envelopes.

Virus

virus are much smaller than bacteria, and typically range in size from __________to __________

in diameter.

20 nm to 300 nm

spherical, others are brick-shaped or bullet - shaped and a few have an elongated appearance

virus

it can multiply only within living cells.

• Both prokaryotic and eukaryotic cells are susceptible to infection by it

viruses

• Yeasts, molds, and mushrooms • either unicellular or multicellular

fungi

Multicellular fungi produce filamentous microscopic structures called

molds

yeasts, which are unicellular, have a spherical or ovoid shape and multiply by

budding

ability to secrete potent enzymes that can digest organic matter.

• moisture is present and other environmental conditions are favorable

fungi

an organic substrates which, if present on crops or in stored food such as grain or nuts, can cause disease in animals and humans.

mycotoxins

infectious agents composed exclusively of a single piece of circular single stranded RNA which has some double-stranded regions.

VIROIDS

mainly cause plant diseases but have recently been reported to cause human diseases.

VIROIDS

The only human disease known to be caused by a viroid

hepatitis D

proteinaceous infectious particle

PRIONS

Prions are infectious agents composed exclusively of a single sialoglycoprotein called

PrP 27-30.

smaller than viruses have been implicated in the neurological diseases of animals and humans that are termed transmissible spongiform encephalopathies.

PRIONS

a method of multiplying microbial organisms by letting them reproduce in a predetermined culture medium under controlled laboratory conditions

A microbiological culture or microbial culture

are foundational and basic diagnostic methods used as research tools in molecular biology.

Microbial cultures

a nutrient material prepared for the growth of microorganisms in a laboratory.

Culture Medium

Microbes that are introduced into a culture medium to initiate growth

Inoculum

microbes that grow and multiply in or on a cultural medium

Culture

Most fungi require extra carbohydrates and an acidic environment for optimal growth.

Cultivation of Fungi

Cultivation of Fungi: medium employed for these organisms is potato dextrose agar, also known as

Sabouraud dextrose agar.

• are obligate intracellular parasites.

• They cannot grow in any cultural media.

Cultivation of Virus

three methods used for the cultivation of the viruses:

1. Animal Inoculation

2. Tissue Culture

3. Embryonated Egg

the cultivation of viruses occurs by using different types of animals.

Animal Inoculation

e mainly done for highly specialized parasites of certain organs. e.g., tracheal ring culture is done for isolation of Coronavirus.

Organ cultures

Fragments of tissue can be grown as explant in plasma clots. Rarely used.

Explant culture

mostly used tissue culture

normal cells freshly taken and grown under controlled conditions.

Cell culture

Cells are grown in vitro glass or treated plastic in a suitable growth medium.

Cell culture

type of tissue culture

• Organ cultures

• Explant culture

• Cell culture

used for the cultivation of viruses.

Embryonated egg inoculation

Inoculation on what membrane that produces visible lesions.

chorioallantois membrane

Inoculation in the _____________ produces a rich yield of Influenzas, and Paramyxovirus

allantoic cavity

Inoculation in the ___________ is employed for the primary isolation of the______________ virus.

amniotic cavity: Influenza virus.

Inoculation is used for the cultivation of some viruses.

Yolk sac:

It is mainly used for vaccine production

Allantoic cavity