BACTERIA: CLASSIFICATIONSTAINING NUTRITIONRECOMBINATION

Last Day• We looked at how to describe

bacterial colonies and make purity plates for our specimens

• Looked at the different structures of bacteria, and briefly at classification

– What is the difference between Gram Positive and Gram Negative?

– The amount of peptidoglycan in the…

– Cell wall

• Reminder, all retests must be done by Wednesday, April 22!!

Outlook for Today

• Further look at bacterial classification

• Gram staining procedure

• Gram staining our organisms!

• Bacterial Nutrition

• Recombination and Replication

Time permitting: observing our Gram stains!

Outlook for Future

• Antibiotic resistance talk – April 23rd

• Bacteria Unit Test – Tentatively May 1

• Term Reports Due Friday – Please have all assignments you want updated for this term done by THURSDAY

• Evol/DNA retests – Today or tomorrow!

• Virus Retest – Wednesday or Thurs!

• Bacteria Quiz – structure, media, nutrition, classification, recombination MONDAY, APRIL 27. (FOR MARKS)

Bacterial classificatio

n

• Last Day – We learned about the difference between Gram positive and Gram negative organisms

• But we can classify bacteria even further

Kingdom Eubacteria

• There are 12 different phyla of bacteria according to evolutionary relationships

• There are only 4 we will be focusing on in this unit

– Table 24-1 in your textbook

– Cyanobacteria

– Spirochetes

– Gram-positive bacteria

– Proteobacteria

Phylum Cyanobacteri

a

• Once known as Blue-green algae

– Now classified as Eubacteria, as they do not contain any membrane bound organelles

• Photosynthetic (Use sunlight to produce energy, give off oxygen as a waste product) prokaryotes

– Responsible for the oxygen in Earth’s atmosphere today!

• Can grow in chains and form heterocysts

– Used to fix Nitrogen (converting atmospheric Nitrogen into ammonia for use by plants)

Phylum Cyanobacteri

a

• An accumulation of nutrients (nitrates and phosphates) can lead to an overgrowth of cyanobacteria known as eutrophication or population/algal bloom

– Following eutrophication, many cyanobacteria die off and are decomposed by heterotrophic bacteria

– Heterotrophic bacteria consume available oxygen in water, causing other marine life to die.

Phylum Spirochetes

• Gram positive

• Spiral shaped

• Heterotrophic

– Cannot fix carbon, must use organic carbon for growth

• Aerobic or Anaerobic

– Grow in presence of oxygen or in absence of oxygen

• Move in cork-screw like rotation

Phylum Spirochetes

Treponema pallidum

• Can live:

• Freely

– No need for host organism

• Symbiotically

– Lives on/in host organism, both organisms benefit from relationship

• Parasitic

– Live on/in host organism, only bacterium (parasite) benefits, while causing harm to host

• Syphyllis

Phylum Gram

Positive Bacteria

Streptococcus sp.

• Despite it’s name… not all members in this phylum are Gram positive

– Some GN organisms in this phyla because of their molecular similarities

• Actinomycetes

– GP bacteria that produce many of the antibiotics we know today

• Many human infections

– Staphylococcus

– Streptococcus

• Lactobacillus sp.

– Grows in all of us!

– Makes milk turn into yoghurt

– Found in our oral cavity and intestinal tract

– Help with oral health… but can also be associated with tooth decay

Phylum Gram

Positive Bacteria

Lactobacillus sp.

Phylum Proteobacteri

a

•Gram Negative bacteria

•Can be

–Enteric

–Chemoautotrophs

–Nitrogen Fixing bacteria

Enteric Bacteria

• Inhabit animal intestinal tracts

• Escherichia coli

–Produces Vitamin K, and assists with breakdown of food

• Salmonella spp.

–Responsible for many cases of food poisoning

Chemoautotrophs

• Extract energy from minerals, by oxidizing them.

• Iron-oxidizing bacteria

– Grown in high iron concentration lakes

– Can be used in bio-mining

– More on that later!

Nitrogen fixing

bacteria

• Produce Nitrogen (N2) – the primary gas in our atmosphere!

• Live on many types of plants – plants provide them with nutrients, bacteria provide plants with forms of nitrogen they can use

– What kind of relationship do we call this?

– Symbiotic

To do now: • Gram stain instruction lecture

• ½ of class – Work on 24.1/24.2/finish off notes Review Silently, so classmates can focus on gram strain procedure

• Switch after first group is done.

To do now: • With your partner

• CAREFULLY follow the Gram stain procedure provided for you.

• When done, you can read ahead in 24.2

NUTRITION + GROWTH

Heterotrophs and

autotrophs

• Heterotrophs

– Use organic matter as a source of nutrition

– Saprophytes

– Feed on dead and decaying material

• Autotrophs

– Obtain their energy from sunlight or minerals.

Photoautotrophs• Use the sunlight as an

energy source .

– cyanobacteria

Chermoautotrophs

• As we have just learned, oxidize inorganic minerals to obtain energy

Living Environments

• Obligate anaerobe

– CANNOT live in the presence of oxygen

– Clostridium tetani (causes tetanus)

• Facultative anaerobes

– Can live with or without oxygen

– E.coli

• Obligate aerobes

– Cannot survive WITHOUT Oxygen

– Mycobacterium tuberculosis (causes tuberculosis [TB])

Temperature Requirement

s

• Different species of bacteria grow best at all different temperatures

– Most grow best in 30-35oC range

– Thermophillic bacteria grow best in high temperatures (40-110oC)

• Most bacteria grow best at pH 6.5-7[Neutral]

– Lactobacilli (yoghurt, Sour cream) prefer acidic environments (ph6 or lower)

GENETIC RECOMBINATION

Table 24-3 in text

•Ways bacteria can acquire and express new genetic information

Transformation • When a bacterial cell takes in DNA from the external environment.

• New material substitutes out existing, similar material and becomes part of the bacterial chromosome

Conjugation

• Bind together, one bacteria can exchange genetic information with another

• Genetic Donor must contain special plasmid and pillus

• Binds to recipient bacterium, forms a conjugation bridge

• Plasmid replicates in donor cell, then replicated plasmid transfers over conjugation bridge into recipient cell

• After DNA transfer, cells detach

Transduction • Bacteria and viruses working together!

• Virus takes up fragments of bacterial DNA.

• After Virus replicates, and is released, it will find new bacteria to transfer DNA into.

• Old bacterium's genes can be expressed in new bacteria