1
Biology 2420 –
Chapter 1 – Introduction to Microbiology –
The Main Themes of Microbiology
Talaro, P. 2 –
5
Microbiology – the study of organisms too small to be seen with the naked eye. You
need a microscope
The microbial world – microorganisms
1. Bacteria (and cyanobacteria)
10
2. Viruses
3. Protozoa
4. Algae
5. Fungi (Molds, Yeasts)
15
Talaro, P. 8-11 –
Why study microbiology? What good is it?
1. Understand how the microbiological world impacts on your day to day life.
 Food chain – microorganisms eaten by larger animals eaten by us – fish,
shellfish.
20
 Geochemical processes – cycling of nitrogen, oxygen, carbon (oil and gas)
(limestone), sulfur – rotting of organic matter (mineralization), frees up
nutrients for growth. Disposal of wastes – sewage treatment.
 Assist in digesting food – cellulose digesters in horses and cattle, in termites.
Vitamin K synthesis in human intestines.
25
 Industrial microbiology – pickles, sauerkraut, soy sauce, yogurt, beer, wine,
antibiotics, hormones
 Genetic engineering – make microbes do things that they don’t do in nature but
are useful to humans – research, industry, medicine
2
 Research – as model systems to see some of life’s most basic processes –
genetic, biochemical pathways, regulation, differentiation.
30

Health related – “big picture” – microbes that cause infectious disease – less
than 1% of total microbes out there, but important in some of the worst killers
and cripplers in human history – plague, cholera, smallpox, diphtheria, polio,
etc.
35
WHY IS MICROBIOLOGY IMPORTANT TO YOU?
1. If you don’t pay attention to this stuff, you will kill or injure yourself or someone else.
Many health care workers have died at work and not known it for the next 6 to 12
40
months. More than 10% of health care personnel are pierced each year by sharp and
usually contaminated instruments. One in ten, each year, every year. Feeling lucky?
2. Understanding results communicated to you by the lab. “Your patient has Gram
positive cocci in chains”. What does that mean?? If you don’t walk the walk and talk the
45
talk, you are going to come across as unfit for service. Your colleagues are going to be
very intelligent people, and you’d better come across as one also, or you won’t be
employed in healthcare for long.
3. Only 50% of your work is operational – the other 50% concerns your role as an
50
educator and a patient advocate. For example, you need to understand immunity – the
importance of immunizations against influenza, polio, DPT. You will be consulting with
physicians about your daily observations. You certainly will be reviewing doctors orders
and communicating your opinion if anything incorrect is being done. If you cannot or prefer not to perform your duties in this manner, that needs to come out now in enough
55
time for you to find a new career option.
3
4. Impress and astound your fellow workers and your superiors. This can lead to merit
raises, promotions, new job opportunities inside the workplace or from workplace to
workplace. There are all manner of rewards for the microbially conscious!!
4
Talaro, P. 11-18 – For the history of microbiology, read about Pasteur and
his major accomplishments. I especially want you to know about
spontaneous generation on P. 15 and how Pasteur finally disproved this,
and about the germ theory of disease, as explained on P. 18, right.
Talaro, P. 18 –
In biology, it is necessary to bring order to the wide diversity of living
organisms that can be studied. This is because when one microbiologist
communicates with others they have to know what it is that is being talked
about. Common names won’t do. This is especially true in a clinical
environment where confusion about identities can have devastating results
for the patient, and where patient records can travel vast distances from their
point of origin.
A taxon is a sensible grouping. Taxonomy is thus the science of
classification – it not only eliminates this kind of ambiguity, but also allows
us to see certain common characteristics that related organisms have.
Linnaeus started the first organized taxonomic scheme in the 1700’s – his
system of binomial nomenclature (P. 20) is used to this day. In this
system, an organism has 2 names, a capitalized genus (first name) and a
lowercase species (last name). Members of species that have differing
characteristics, but not different enough to make them a new species, are
examples of subspecies, or in microbiology, strains. Once used, the genus
can be abbreviated with a capital letter. The species name is never
capitalized or abbreviated.
5
Talaro, Fig. 1.13, P. 20, –
Higher taxonomic terms include:
Domain, Kingdom, Phylum (Division in the plants), Class, Order, Family,
Genus, Species
One common memory device is
“King Philip came over from Greece on Sunday”
The species level is the only natural name the organism has – based
on its own characteristics.
Back to Linnaeus and his kingdoms – he recognized only 2 kingdoms
– the two we still think of commonly as the plant kingdom and the animal
kingdom. As long as there were only these two, the Linnaean system
worked well at this level. But along comes microbes, and Linnaeus threw up
his hands in disgust. He quite literally did not know what to do with them,
and in the end assigned them to Chaos, and ignored them. Well, obviously,
that wasn’t good enough for biology as it matured. In this century, new
criteria were gradually introduced – the two most important ones being –
1. Whether the microorganisms were prokaryotic or eukaryotic – the cell
plan
2. The different ways microorganisms have of getting or making food – the
nutritional profile
Consumers - ingestive
Producers – photosynthetic
Absorbers – absorptive, saprobic, saprobes
6
Talaro, P. 21 – Whittaker’s Five Kingdom System of Classification
So, finally in 1969, R.H. Whittaker of Cornell University in New
York State proposed his 5 kingdom taxonomic system.
Talaro, Fig. 1.14, P. 22 –
Whittaker’s system is shaped like a three fingered hand.
At the heel of the hand are the Monera – composed of all prokaryotic
microorganisms – bacteria (old and new), the blue green or cyanobacteria,
and the archaea. Also included here are the rickettsiae, spirochetes,
chlamydia and mycoplasma. All are unicellular, lacking true nuclei, and
complex cellular organelles. Reproduction is by binary fission.
Protists make up the palm of the hand. Whittaker used Haeckel’s old
name for his kingdom Protista, but unlike Haeckel, Whittaker includes only
those microorganisms that are eukaryotic, either unicellular or organized
into simple colonies. They do not develop from embryos or spores. The
various fingers of the hand are the Kingdoms Plantae, Animalia, and Fungi.
Microbiology is not appropriate for most plants and animals – too big. But
fungi are important microbes. Can be unicellular or multicellular.
Fungi are always eukaryotic and always get their food by absorption from
dead organic sources. Fungi are filamentous and reproduce by means of
spores.
BUT NOT VIRUSES!!!!!
There is no Whittaker kingdom for viruses!!!
7
Talaro, Fig. 1.15, P. 23 –
You should also be aware that the field of taxonomy is in a state of great
flux and turmoil nowadays. New taxonomic schemes have arisen since
Whittaker’s day, one of which is shown on P. 23 in Talaro, Fig. 1.15. The
in depth examination of these new schemes is beyond the scope of this
course, but you should at least be cognizant that a new taxon – the Domain
– has been proposed, a taxon even higher than kingdom.
Since 1969 it has become increasingly apparent that there are major and
fundamental differences between the bacteria that live in modern, moderate
environments, and which possess complex metabolism, and those bacteria
that live in weird places, at weird temperatures, and possess weird nutritional
lifestyles. The Domain Bacteria contains the normal, everyday bacteria, as
well as mitochondria and chloroplasts. The Domain Archaea contains the
prokaryotic microorganisms that live in weird places, at weird temperatures,
and possess weird nutritional lifestyles. The Domain Eukarya contains the
old Whittaker kingdoms Protista, Fungi, Plantae and Animalia.