Microbial overview i

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Billions per gram of fertile soil

Billions per gram of fertile soil

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•Microbes can grow at temperatures from < 0°C (the snow alga, Chlamydomas nivalis) to 110°C (Pyrolobus fumarii). •A microbe that can grow in water over 100°C.• The P. fumarii grows under the sea at hydrothermal vents where the water pressure is very high.

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Note the large amount of material being precipitated out of the super-heated water (about 300C) as it comes in contact with ocean water at the sea floor (4C).

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Steam (C)Water at atmospheric pressure 1.0 bar 98-100 2.4 bar 125 3.0 bar 134

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• Most of the organisms we will examine will grow at 20-50°C.

• Microbes are also present in saturated salt lakes, in acid mine drainage that is below pH 1,

• In environments devoid of oxygen, in soil, and on you!

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• Micro-organisms are microscopic in size. • The smallest body that can be seen with the

naked eye is about 100 μm. • All medically related bacteria are smaller than

this and a microscope is therefore necessary• When spread on solid media, bacteria (and

fungi) form macroscopically visible structures contain at least 108 cells, known as colonies.

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Classification

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Archaea = العتيقة

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• Prokaryotes• Peptidoglycan cell

walls• Binary fission• For energy, use

organic chemicals, inorganic chemicals, or photosynthesis

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• Prokaryotic• Lack peptidoglycan• Live in extreme

environmentsInclude:

– Methanogens– Extreme halophiles– Extreme thermophiles

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• Eukaryotes• Chitin cell walls• Use organic chemicals

for energy• Molds and mushrooms

are multicellular consisting of masses of mycelia, which are composed of filaments called hyphae

• Yeasts are unicellular

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• Eukaryotes• Absorb or ingest

organic chemicals• May be motile via

pseudopods, cilia, or flagella

Trypanosoma

Giardia

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• Eukaryotes• Cellulose cell walls• Use photosynthesis

for energy• Produce molecular

oxygen and organic compounds

Diatoms

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• Acellular• Consist of DNA or RNA

core• Core is surrounded by a

protein coat• Coat may be enclosed in

a lipid envelope• Viruses are replicated

only when they are in a living host cell

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• Eukaryote• Multicellular

animals• Parasitic

flatworms and round worms are called helminths.

• Microscopic stages in life cycles.

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Microbial characteristics

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–Various diagnostic test systems are used to detect specific bacteria in clinical systems, including,

– reaction with antibodies in ELISA formats,

– immunofluorescence and–Increasingly PCR-based technology.

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• Typing of bacterial isolates is necessary for epidemiological investigations in outbreaks and for surveillance, and a variety of phenotypic and genetic methods has evolved for the identification of strains.

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archeaEubacteria

Protozoan

with alteration

AnO2 O2AnO2 O2

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Bacteria and Archaea are present in all environments that support life. Procaryotes have the usual nutritional requirements for growth of cells, but many of the ways that they utilize and transform their nutrients are unique. This bears directly on their habitat and their ecology.

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Early Earth was AnO2, Cyanobacteria build up of O2 in atmosphere from 0% to 20% around 2 billion years ago (BYA).

Lithotrophic and fermentative modes of metabolism were the first to develop in early prokaryotes.

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2O2- + 2H+ SOD H2O2+O2

2H2O2 Catalase 2H2O +O2

SOD=Superoxide dismutase

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Neutrophiles （ 5 to 8 ）

Acidophiles （ below 5.5 ）

Alkaliophiles （ above 8.5 ）

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ENDEMIC ( مستوطن disease present :(مرضor usually prevalent in a population or geographic area at all times

EPIDEMIC ( شائع disease occuring :(وبائيsuddenly in numbers clearly in access of normal expectancy

PANDEMIC (فاشية): a widespread epidemic distributed or occuring widely throughout a region, country, continent, or globally

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Organism Time needed to

consume body weight

Human 180 DaysPig 20 DaysYeast 30 MinutesLactobacillus 10 MinutesMicrococcus 3 Minutes

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• 1. The invisible world of microbes underlies and shapes what we call the "visible world".

• 2. Microbes have extraordinary genetic and metabolic diversity.

• 3. Microbial metabolism can create anaerobic environments, and anaerobic microbes can use these environments.

• 4. Different microbes are adapted to survive and use an enormous range of environments, both inanimate and animate.

• 5. Among all life forms on earth, microbes have the widest range of genetic and evolutionary diversity.

MICROBES & ECOLOGY

• Many microbes (bacteria and fungi) are decompsers (saprotrophic) and break down organic matter.

• Decomposers release nutrients form dead organisms and return them to the ecosystem.

• These free nutrients are recycled & used by other organism for growth, repair, & continuation.

MICROBES & INDUSTRY

• Microbes are used in many industrial products and processes.

• Some examples are the development of medicines (e.g. antibiotics), the production of chemicals (alcohols, organic acids, acetone), the production of various enzymes, vitamins, hormones, steroids, and perfumes.

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• Microbes are widely used in food production.

• Examples of microbial food products are:

• Cheese, sour cream, yogurt, butter milk, vinegar, bread and soy sauce.

• Typically involves bacteria and/or yeast.

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• One of major human problems: getting rid of microbes, or preventing their growth.

• Practical problem for food, beverage, cosmetic, pharmaceuticals, other industries.

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Disease can come about in several overlapping ways

1. Some bacteria are entirely adapted to the

pathogenic way of life in humans. They are

never part of the normal flora but may cause

subclinical infection, e.g. M . tuberculosis

2. Some bacteria which are part of the normal

flora acquire extra virulence factors making

them pathogenic, e.g. E. coli

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Disease can come about in several overlapping ways

3. Some bacteria which are part of the normal

flora can cause disease if they gain access to

deep tissues by trauma, surgery, e.g. S.

epidermidis

4. In immunocompromised patients many free-

living bacteria and components of the normal

flora can cause disease, especially if introduced

into deep tissues, e.g. Acinetobacter

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Growth/Culture condition

The majority of microbes persist attached to surfaces within a structured biofilm ecosystem and not as free floating organisms.

Microbiol. Mol. Biol. Rev. 64:847-867 (2000)