Are we human, or are we…

The diversity of microbes

Diversity of MicrobesMicrobes are ubiquitous on our

planet◦Found in every environment

imaginable50% of all biomass is thought to

be made up of microbesBacteria and other microbes help

our world function as we know it◦Fermentation nitrogen fixation◦Biopharmaceuticals decomposition◦Digestion food production

Diversity of Microbes

1 trillion vs 10 trillion30k genes vs 30 million

Diversity of Microbes5 Kingdoms system has been used since

1959Grouping stated with Linnaeus (1700s)

Can be grouped into eukaryotes and prokaryotes

Late ‘80s Carl Woese used rRNA to identify differences in prokaryotes

Led to a new classification system, the 3 Domains

Diversity of MicrobesThe 3 Domains are:

◦ Eubacteria: typical prokaryotes◦ Archaea: extremophiles

◦ Eukarya: single and multicellular organisms with a membrane bound nucleus

5 kingdoms based on structural differences, 3 Domains molecular differences

Variations in rRNA sequences led to a clear distinction within the three domains and provided another evolutionary piece of evidence

Be familiar with the table on page 514

Diversity of MicrobesThe split into the 3 domains was

really to help explain discrepancies that were seen within the 5 kingdoms

Each of the 5 kingdoms would fit within one of the three domains

Main problem archaea were classified within the same kingdom as bacteria◦Molecularly more closely related to

eukaryotes (all based on rRNA structures)

Diversity of Microbes--ArchaeaThese are the extremophiles—

they live in very harsh conditionsThese conditions are thought to

be similar to life on early EarthThey can split into three main

groups:◦Methanogens—used CO2 to produce

CH4

◦Thermophiles—heat loving, usually acidic

◦Halophiles—salt loving, 10x greater than oceans

Diversity of Microbes--BacteriaTypically found in arrangements with three

different shapes◦ Spherical (cocci)◦ Rods (bacilli)◦ Helices (spirilla)

Can occur as single cells or groups of cells◦ Staphylococcus—bunch of spheres◦ Streptococcus—chain of spheres◦ Diplococcus—pair of spheres

These arrangements are used in part to identify bacteria

Diversity of Microbes--BacteriaBesides shape, one major way to

differentiate between bacteria is cell wall morphology

Gram staining is an easy way to differentiate between these differences

Gram (+) Gram (-)

Purple Pink

Lots of peptidoglycan Little peptidoglycan

No outer membrane Outer membrane

More susceptible to antibiotics

Less susceptible to antibiotics

Diversity of Microbes--BacteriaBacteria have a way in which they can

communicate with one another◦ Quorum sensing relies on chemical signals

Not all QS is cool…most pathogenic microbes also use QS to release toxins that cause illness

Diversity of Microbes--VirusesViruses are not alive, but still

considered microbesCome in a variety of shapes and with

multiple methods of replicatingSame general packaging regardless of

type of virus◦ Protein coat (encapsulated or not)◦ Nucleic acid (ssDNA/RNA or dsDNA/RNA)◦ Internal enzymes

Diversity of Microbes-eukaryotes

Not all microbes are prokaryotes

MEMBRANE BOUND NUCLEUS

YEASTFermentation alcohol and CO2

AMOEBAPseudopodia & food

vacuoles (intracellular digestion)

PLASMODIAParasitic heterotrophs

PARAMECIUMCiliate heterotrophs; food vacuole + lytic

enzymes vacuole

EUGLENAHeteroautotrophs,

chlorophyll and photoreceptors

CHLORELLASingle celled green algae

Chlorphyll, non-motile, cellulose

Diversity of MicrobesThe world around you functions as a result

of microbes in ways which we usually don’t recognize

Two good examples of this would be the Nitrogen Cycle and Waste Water Treatment

Section F.2 in the book discusses microbes in the environment, be sure to know the details from that section

With all these examples, the natural metabolism of microbes is used in some way to benefit us

Diversity of MicrobesMicrobes can be producers, decomposers,

and nitrogen fixers“fixing” a gas simply takes it from a gaseous

state to a form which can be used by organisms

The nitrogen cycle is responsible for taking nitrogenous wastes from plants and animals and turning it into nitrogen gas (N2)

It is also responsible for taking nitrogen gas and converting it into nitrates, nitrites, and ammonia which can be used metabolically by plants which are then consumed by animals

Diversity of MicrobesAMMONIA

NH3

Gaseous NitrogenN2

1

NITRATES/NITRITES

2

3

4

5

6

7

1) Fixation 2) Nitrification 3) active transport of Nitrate ions 4) consumption 5) death and excretion 6) putrefaction 7) denitrification

Diversity of MicrobesWhat happens to the water in your toilet

after you flush?◦ How would you feel knowing that it will be

recycled and you could drink it later?It’s because of microbes, specifically

saprotrophs, that this is possibleWater from bath tubs, showers, toilets,

washing machines, dishwashers, and business and industry all sent to treatment plants

Water is treated and eventually reused◦ Solid wastes are removed (in inorganic), consumed (by

microbes), and concentrated and sent to a landfill (sludge)

Diversity of Microbes

Diversity of MicrobesMany food production processes require

microbesBeer, wine, bread, sauerkraut/kimchi, yogurt,

and soy sauce are all produced using microbes◦ Make sure you can explain the production of soy sauce by using Aspergillus

oryzae

Processes are also in place to preserve food to prevent spoilage by microbes◦ Canning/Pickling – uses pH (acids) and salt to

prevent spoiling

◦ Preserves—uses high sugar concentration

◦ Pasteurization—uses heat and a sealed environment

Diversity of MicrobesFood poisoning can occur if preservation

techniques are done poorly or if fresh food is left to spoil

Salmonella infections are common food-borne illnesses

Studies have shown 80% or more of chicken at grocery stores are contaminated

Fully cooking food will prevent illnessMost infections result from undercooked

food, irrigation with contaminated water, or cross-contamination

Diversity of MicrobesWith salmonellosis symptoms (cramps,

diarrhea, fever) will develop 12 to 72 hours after infection

Severe dehydration can result in hospitalization

Without treatment, infection can spread to blood and lead to death (not typical)

Antibiotics will take care of the infectionTo fully diagnose salmonellosis fecal samples

must be tested for the presence of the bacterium

~40,000 cases reported in the U.S. each year