Microbial overview i
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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.
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).
• 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!
• 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.
• Prokaryotes• Peptidoglycan cell
walls• Binary fission• For energy, use
organic chemicals, inorganic chemicals, or photosynthesis
• Prokaryotic• Lack peptidoglycan• Live in extreme
environmentsInclude:
– Methanogens– Extreme halophiles– Extreme thermophiles
• 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
• Eukaryotes• Absorb or ingest
organic chemicals• May be motile via
pseudopods, cilia, or flagella
Trypanosoma
Giardia
• Eukaryotes• Cellulose cell walls• Use photosynthesis
for energy• Produce molecular
oxygen and organic compounds
Diatoms
• 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
• Eukaryote• Multicellular
animals• Parasitic
flatworms and round worms are called helminths.
• Microscopic stages in life cycles.
–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.
• 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.
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.
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.
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
Organism Time needed to
consume body weight
Human 180 DaysPig 20 DaysYeast 30 MinutesLactobacillus 10 MinutesMicrococcus 3 Minutes
• 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.
• 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.
• One of major human problems: getting rid of microbes, or preventing their growth.
• Practical problem for food, beverage, cosmetic, pharmaceuticals, other industries.
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
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
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)
