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3/7/11 11:11 AM Chapter 6: Microbial Growth * Refer to pictures The Requirements for Growth Physical requirements o Temperature Minimum growth temperature Optimum growth temperature Maximum growth temperatue o pH o osmotic pressure Chemical Requirements o C,N, S, P, trace elements, oxygen, organic growth factor Plasmolysis (Fig. 6.4) Psychropiles/psychotrophes Grow between 0-15C and 10-25C Cause food spoilage pH Most bacteria grow bw pH 6.5-7.5 Molds and yeasts grow bw pH 5-6 Acidophiles grow in acidic environment

Exam2Lecture5-1

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Hunter College Microbiology Exam 2 Notes

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Page 1: Exam2Lecture5-1

3/7/11 11:11 AMChapter 6: Microbial Growth

* Refer to pictures

The Requirements for Growth

Physical requirements

o Temperature

Minimum growth temperature

Optimum growth temperature

Maximum growth temperatue

o pH

o osmotic pressure

Chemical Requirements

o C,N, S, P, trace elements, oxygen, organic growth factor

Plasmolysis (Fig. 6.4)

Psychropiles/psychotrophes

Grow between 0-15C and 10-25C

Cause food spoilage

pH

Most bacteria grow bw pH 6.5-7.5

Molds and yeasts grow bw pH 5-6

Acidophiles grow in acidic environment

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Osmotic Pressure

-Hypertonic environments or an increase in slat or sugar cause plasmolysis

-Extreme or obligate halophiles require high osmotic pressure (ie 30% salt – Great Sea, Red Sea)

-Facultative halophiles can tolerate high osmotic pressure (2%-15% salt)

What would happen if cell put into distilled water?

Plasmolysis*

Chemical Requirements for Bacterial Growth

Carbon

Structural organic molecules, energy source

Chemoheterotrophs use organic carbon sources

Autotrophs use CO2

Nitrogen

Amino acids and proteins

Most bacteria decompose proteins (recycle)

Some bacteria use ammonium ions NH4 or nitrate ions

A few bacteria(cyanobacteria) use N2 in nitrogen fixation

Sulfur

In amino acids, thiamine, and biotin

Most bacteria decompose proteins to get sulfur

Some bacteria use SO4-2 or H2S

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Phosporus

In DNA, RNA, ATP and membranes

PO43- is a source of phosporus

Trace Elements

Inorganic elements required in small amounts

Usually as enzyme cofactors

The Effect of Oxygen on Microbial Growth (Table 6.1)

A. obligate aerobe- needs oxygen to survive

B. facultative anaerobe- retain the ability to ferment to undergo anaerobic metabolism. Organisms not on top are

facultative anaerobe. eg. E.Coli

C. obligate anaerobe- cannot use molecule oxygen, but they can use oxygen from water eg. Plastrinium- causes

tetanus and botulism

D. Aerotolerant anaerobe-they don’t use oxygen but can still grow in the presence of it.

E. Microaerophile-can only grow in a very SPECIFIC level of oxygen

Toxic Oxygen

Singlet oxygen: O2- boosted to a higher energy state

Superoxide radicals O2-

When you use oxygen as an electron acceptor

Try to grab electrons from nearest molecule

SOD (enzyme)* o

O2-2+ O2

-2 +2H+ * H2O2 +O2

Peroxide anion O2-2

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catalase or peroxidase – neutralize H2O2

catalase- produce H2O and O2

peroxidase- H2O

Hydroxyl radical (OH-)

Happens in cytoplasm

Through ionizing radiation

All of these could be toxic to humans or bacteria

Organic Growth Factors

-Organic compounds obtained from the environment. Varies from organism to organism

-Vitamins, amino acids, purines, and pyramidines

Biofilms (Fig 6.5)

-Microbial communities

-form slime or hydrogels

bacteria attracted by chemicals via quorum sensing: communication between one cell and another.

Drugs to block the quorum sensing receptors.

“place gets too crowded, people have to leave.”

Important in digestive systems of cows. Need to digest cellulose.

Grow upwards to increase surface area. Causes bacterial infections.

-share nutrients

-sheltered from harmful factors

- patients with indwelling catheters received contaminated heparin.

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-bacterial numbers in contaminated heparin were too low to cause infection

-84-421 after exposure, patients developed pseudomonas infection

-Pseudomonas fluorescens were cultured from catheters.

-What happened?

They grew and multiplied by themselves.

They are antibiotic resistance.

Heparin might signal biofilm growth

Table 6.2: A chemically defined medium for growing a typical chemoheterotroph, such as E.Coli

Table 6.4: Composition of Nutrient Agar, a Complex medium for the growth of heterotrophic bacteria

Culture Media

-Culture Media: nutrients prepared for microbial growth.

-Sterile: no living microbes

-Inoculum: introductions of microbes intro mediums

-Culture: microbes growing in/on culture medium

Growing a Culture

-nutrients

-pH

-moisture

-oxygen

-initially sterile

Agar

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-Complex polysaccharide

-Used as solidifying agent for culture media in Petri plates, slants, and deeps

-Generally not metabolized by microbes

-Liquefies at 100C

-Solidifies at ~40C

Culture Media (Table 6.2, 6.4)

-Chemically defined media: exact chemical composition is known

-complex media: you don’t know the exact compositions. Include extracts and digests of yeasts, meats or plants

Nutrient Broth

Nutrient Agar

Anaerobic Culture Methods

Anaerobic jar (fig. 6.6)

Anaerobic chamber (fig. 6.8)

Reducing media

-Contains chemicals (thioglycolate or oxyrase) that combine O2.

-Heated to drive off O2.

Figure 6.6, 6.7

Capnophiles

-microbes that require high CO2 conditions

-CO2 packet

-Candle jar

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-multiple methods present

Biosafety Level

1:No special precautions

2: Lab coats, gloves, eye protection

3: Biosafety cabinets to prevent airborne transmission

4: Sealed, negative pressure

Selective Media

-suppress unwanted microbes and encourage desired microbes.

-chemically defined: salt media is preventing some bacterial species while allowing others to grow

-Staphylococcus aureus- metabolizes manatose to make acidic environment (yellow)

- Staphylococcus epidermidis- growing but basic

Differential Media

-make it easy to distinguish colonies of different microbes

Enrichment Culture

-encourages growth of desired microbe

-assume a soil sample contains a few phenol-degrading bacteria and thousands of other bacteria

inoculate phenol-containing culture medium with soil and incubate

transfer 1 mL to another flask of the phenol medium, and incubate

transfer 1 mL to another flask of the phenol medium and incubate

only phenol-metabolizing bacteria will grow after much dilutions later.

Binary Fission (Fig 6.12A)

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Cell Division

Bacterial Growth Curve

Obtaining Pure Cultures

-A pure culture contains only one species or strain

-A colony is a population of cells arising from a single cell or spore or from a group of attached cells.

-A colony is often called a colony-forming unit (CFU)

-The streak plate method is used to isolate pure cultures

Preserving Bacterial Cultures

-deep freezing: -50C to -95C

-Lyophilization (freeze-drying): frozen (-54 to 72C) and dehydrated in a vacuum.

The Growth of Bacterial Culture

Reproduction in Prokaryotes

Binary fission

Budding

Conidiospores (actinomycetes)-chains when they reproduce

Fragmentation of filaments

Bacterial growth happens exponentially- based on generation number and binary fission can figure out

how many cells are being made.

Generation Time

If 100 cells growing for 5 hours produced 1,720,320 cells:

o Number of generation= [log #of cells (end) –log #cells (beg)]/(0.301) log of 2

o Generation time= (60min x 5hours)/ number of generations= 21 min/generation.

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Bacterial Growth Curve

Phases of Growth (log graph, not linear)

1. Lag phase

-not much bacterial growth

-no exponential growth

2. Log phase

-exponential growth

-assuming optimal conditions

-reaches point of capacity

3. Stationary phase

-# cells growing = # cells dying

-no exponential growth

4. Death phase

-nutrients have been used up

-exponential decrease

Direct Measurement of Microbial Growth

1. Serial Dilutions

1:10 – 9 mL broth in each tube

1:100

1:1000

1:10,000

1:100,000

2. Plate Counts

a) pour plate method

b) the spread plate method

3. Plate Counts

After incubation, count colonies on plates that have 25-250 colonies (CFUs)

4. Counting Bacteria by Membrane Filtration

Fig 6.18

5. Direct Microscopic Count

-Serial dilution must be performed

-number of bacteria/mL= #of cells counted/ volume of area counted

6. Turbidity

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Direct Methods Indirect Methods

-plate counts

-filtration

-MPN

-direct microscopic count

-turbidity

-metabolic activity

-dry weight

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3/14/11 11:11 AMThe terminology of microbial control-Sepsis-microbial contamination

-Asepsis- the absence of significant contamination

-Aseptic surgery-prevent microbial contamination of wounds

Sterilization- removing all microbial life

Commercial sterilization- killing C. botulinum endospores

Disinfection- removing pathogens

Antisepsis- removing pathogens from living tissue

Degerming- removing microbes from a limited area

Sanitization- lowering microbial counts on eating utensils

Biocide/germicide- kills microbes

Bacteriostasis- inhibiting growth, NOT killing

Population Death Rate is Constant

A Microbial Death Curve (fig 7.1 A)

Actions of Microbial Control Agents alternation of membrane permeability

damage to proteins

damage to nucleic acids

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Heat Thermal death point (TDP)-lowest temperature at which all cells in a culture are killed in

10 min.

Thermal death time (TDT)- time during which all cells in a culture are killed.

Decimal Reduction Time (DRT) Minutes to kill 90% of a population at a given temperature (fig 7.2)

Moist Heat Sterilization Moist heat denatures proteins

Autoclave: steam under pressure

Steam Sterilization Steam must contact item’s surface

Pasteurization Reduces spoilage organisms and pathogens

Equivalent treatments

63 C for 30 min

High temperature short time- 72C for 15 sec

Ultra high temp- 140 C for <1 sec

Thermoduric organisms survive

Dry Heat Sterilization Kills by oxidation

o Dry heat

o Flaming

o Incineration

o Hot-air sterilization

Hot Air Autoclave

Equivalent treatments 170 C, 2 hr 121 C, 15 min

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Filtration HEPA removes microbes > 0.3 uM

Membrane filtration removes microbes > 0.22 uM

Physical Methods of Microbial Control Low temp inhibit microbial growth

o Refrigeration

o Deep freezing

o Lyophilization

High pressure denatures proteins

Dessication prevents metabolism

Osmotic Pressure causes plasmolysis

Radiation Ionizing radiation (X rays, gamma rays, electron beams)

o Ionizes water to release OH

o Damages DNA

Nonionizing radiation (UV, 260 nm)

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o Damages DNA

Microwaveso Kill by heat; not especially antimicrobial

Principles of Effective Disinfection Concentration of disinfectant

Organic matter

Time

pH

Use Dilution Test Metal rings dipped in test bacteria are dried

Dried cultures are placed in disinfectant for 10 minutes @ 20C.

Rings are transferred to culture media to determine whether bacteria survived treatment.

Disk Diffusion MethodPhenols and Phenolics

Disrupt plasma membranes

Bisphenols

Hexacholorphene triclosano Disrupt plasma membranes

Biguanides Chlorhexidine

o Disrupt plasma membranes

Halogens Iodine

o Tinctures: in aq. Solution

o Iodophors: in organic molecules

o Alter protein synthesis and membranes

Chlorineo Bleach: HOCl (hypochlorous acid)

o Chloramine: chlorine + ammonia

o Oxidizing agents

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3/21/11 11:11 AMTRANSCRIPTION-NUCLEUS

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Fig. 8.10

Eukaryotes: nucleus

Prokaryotes: cytoplasm

Fig 8.11 : RNA Processing in Eukaryotes

DNA RNA transcript mRNA

Exons- are expressed

Introns- intervening sequences

Has to be removed

In order to be translated for protein synthesis

snRNPs

TRANSLATION- CYTOPLASM

Fig 8.2

-mRNA is translated in codons (three nucleotides)

-translation of mRNA begins at start codon: AUG (meth)

-Translation ends at nonsense codons: UAA, UAG, UGA

-64 sense codons on mRNA encode the 20 amino acids

the genetic code is degenerate

tRNA carries the complementary anticodon

Page 17: Exam2Lecture5-1

The Genetic Code (fig 8.8)

Note the degeneracy

Simultaneous Transcription and Translation (fig 8.10)

Cannot happen in eukaryotes

DNA/RNA stuck in nucleus

The process of Translation (fig 8.9)

AUG codon tRNA anticodon ribosomal units attaches

EPA sites

New protein

The Regulation of Gene Expression

Regulation

-Constitutive genes are expressed at fixed rate

~60-80% of genes

-Other genes are expressed only as needed

Repressible genes

Inducible genes

Catabolite repression

Operon

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Fig 8.12

DNA Regulatory gene Promoter* Operator*

*Not genes: causes polymerase to bind

Operator: acts as a stop light

Structural Genes: Z Y A enzymes that ferments lactose (E. Coli)

Regulatory gene: also a repressible protein (turns on AND off)

Induction

-Fig 8.12

-Lac operon when there is no lactose.

-RNA polymerase binds at promoter, repressor binds the operator

- Lac operon when there is lactose PRESENT

Allolactose binds the repressor protein shape- no longer binds the operator.

RNA polymerase can go ahead and make structural genes Z Y A

Repression

-Fig 8.13

-Structural genes: E D C BA

encoding for different genes: tryptophan synthesis

Repressor protein is ALWAYS ono Cannot bind at O, operator site

Once tryptophan is made

Binds inactive repressor protein

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Blocking RNA polymerase

Tryptophan: co repressor

Allolactose: co- inducer

Catabolite Repression

Fig 8.14a & b

- Constitutively active genes

-Preference energy source is GLUCOSE

growth rate is much faster than LACTOSE

-When glucose runs out, cAMP builds up

cAMP= alarm mode

Lag time

Then, metabolizes LACTOSE

Lactose PRESENT, no GLUCOSEcAMP Inactive CAP Active CAP Promoter (extra red flag encouraging RNA polymerase to bind

there: promoting lactose metabolism)

Fig. 8.15

LACTOSE +GLUCOSE Present Inactive CAP

RNA polymerase cannot bind

Inducer- allolactose

Mutation

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-A change in the genetic material

-Mutations can be neutral, beneficial, or harmful

Neutral: Triplet code codes for the same amino acido Non-gene encoding regions: neither beneficial or harmful

-Mutagen: agent that causes mutations

-Spontaneous mutations: occurs in the absence of mutagen.

Fig 8.17a, b,c,d

Base substitution (point mutation)- change in one base

Sickle cell disease

Missense mutation- Constitutively active genes result in change in amino acid

Nonsense mutation- results in a nonsense codon. Peptide sequence cuts short, protein isn’t being made.

Frameshift mutation- insertion or deletion of one or more nucleotide pairs

Huntington’s Disease: accumulates in nerve cells

The Frequency of Mutation

Spontaneous mutation rate = 1 in 10^9 replicated base pairs or 1 in 10^6 replicated genes.

Mutagens increase to 10^-5 or 10^-3 per replicated gene

Chemical Mutagen (fig 8.19a)

Nitrous Acid

Nucleotide analog: looks like correct DNA base but they are NOT

Radiation

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Ionizing radiation (X rays and gamma rays) causes the formation of ions that can react with nucleotides

and the deoxyribose-phospate backbone

Wave that breaks covalent bonds

UV Radiation and Repair (fig 8.20)

Photolyases separate thymine dimmers

Nucleotide excision repair DNA polymerase makes the repair

Selection*

Positive (direct) selection detects mutant cells because they grow or appear different.

Negative (indirect) selection detects mutant cells because they do not grow

Replica plating- (recorded) Fig 8.21- Looking for a auxotrophic mutation- being able to metabolize something

Ames Test for Chemical Carcinogens

Fig 8.22

Amount of mutation that forms- increased incidents of cancer

Media lacking histidine Incubation into Colonies of revertant bacteria

Salmonella + Rat liver extract

Genetic Recombination

-Vertical gene transfer: occurs during reproduction between generations of cells

-horizontal gene transfer: Gene transfer between organisms without reproduction

-Exchange of genes between two DNA molecules

Crossing over occurs when two chromosomes break and rejoin

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Fig 8.23

Fig 8.25

-Circular chromosome

-DNA gets into the bacterial cell

-One piece of DNA will replace the other

-Result: Genetically transformed cell

Fig 8.24 Griffith Experiment

-Bacteria was encapsulated

-Injected encapsulated bacteria into mouse dies.

-injected nonencapsulated bacteria into mouse sick.

-dead bacteria into mouse lives

-Mixed bacteria mouse dies due to genetic transformation

Fig 8.26 Bacterial Conjugation

-One bacteria on one species can contact another species and can change genetic material

Fig 8.27a.b,c Conjugation of E. Coli

F+ (has f factor), F-, Hfr (f+ recombined with chromosome)

Hfr + F- Hfr cell + Recombinant F- cell

Fig 8.28 Transduction by a Bacteriophage

-Usually talks about viruses

-Transfers DNA from one host to another

Plasmids

Conjugative plasmid-carries genes for sex pilli and transfer of the plasmid

Dissimilation plasmids-R factors-

R factors, a Type of Plasmid (fig 8.29)

Origin of replication

Similar map to bacterial chromosome- like a clock

Transposons (Fig 8.30a b c)

Segments of DNA that can move from one region of DNA to another

Contain insertion sequences for cutting and resealing DNA (transposase)

Complex transposons carry other genes

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Chapter 9 3/21/11 11:11 AMBiotechnology and Recombinant DNA

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Biotechnology- use of microorganisms, cells, or cell components, to make producto Foods, antibiotics, vitamins, enzymes

Vector- self replicating DNA used to carry the desired gene to a new cell

Clone- population of cells arising from one cell, each carries the new gene

Recombinant DNAo Insertion or modification of genes to produce desired proteins.

Fig 9.1 : A Typical Genetic Modification Procedure

1. Vector, such as plasmid is isolated (human insulin gene)

2. GO back into the bacteria

3. Make many copies

OR Protein products of gene

GMOs, or foods, hormones

Table 9.2 : Used in pharmaceutical industry

Interesting Facts

Restriction Enzymes

Cut specific

PCR

Inserting Foreign DNA into cell

DNA can be inserted into a cell byo Transformation

Page 25: Exam2Lecture5-1

o Electroporation

o Protoplast fusion fig 9.5b

o Gene Gun

o Microinjection fig 9.6, 9.7

o

Obtaining DNA

Complementary DNA (cDNA) is made from mRNA by reverse transcriptase (fig 9.9)

Synthetic DNA is made by a DNA synthesis machine

Selecting a Clone (fig 9.11)o Putting obtained DNA into a special vector

o Vector inserted into bacteria

o Grown in a special plate

o Grows in certain color/ certain environment

o Obtain DNA of sequence

Making a Product (vector for gene expression or the gene itself)

E.Colio Used because it is easily grown and its genomics are known

o Cells must be lysed to get product

Sacchromyces cerevisiaeo Used because it is easily grown and its genomics are known.

o May express eukaryotic genes easily

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Plant cells and whole plantso May express eukaryotic genes easily

o Plants are easily grown

Mammalian cellso May express eukaryotic genes easily

o Harder to grow

Therapeutic Applications

Human enzymes and other proteins

Subunit vaccinesNon pathogenic viruses carrying genes for pathogen’s antigens as DNA vaccinesGene therapy to replace defective or missing genes

RNA Interference (RNAi) Interference with RNA, cannot be used for translation

Transcript control: cleaved. A way to gene silencing vs. gene knock out

The Human Genome Project Nucleotides have been sequenced

Human Proteome Project may provide diagnostics and treatmentso Reverse genetics: block a gene to determine its function

Scientific Applications Understanding DNA

Sequencing organisms’ genomes

DNA fingerprinting for identification (fig 9.17)

Forensic Microbiology PCR

Primers for a specific organism will cause amplification if that organism is present

Reverse-trancription (RT-PCR): Reverse transcriptase makes DNA from viral RNA or

mRNA. Real time PCR is different

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Chapter 10: Classification 3/18/11 11:11 AMTaxonomy

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The science of classifying organisms

Provides universal names for organism

Provides a reference for identifying organisms

Systematics, or Phylogeny The study of evolutionary history of organisms

All Species inventory (2001-2005)o To identify all species of life on Earth.

o Identify which of those species might have diagnostic use and evolutionary history.

Placing Bacteria1735 Kingdoms Plantae and Animalia

1857 Bacteria and fungi put in Kingdom, Plantae – “Flora”

1866 Kingdom Protista proposed for bacteria, protozoa, algae, and fungi

1959 Kingdom Fungi

1961 Prokaryote defined as cell in which nucleoplasm is not surrounded by a nuclear membrane

1968 Kingdom Prokaryotae proposed

1978 Two types of prokaryotic cells (Bacteria and Archea) found- 3 Domain classification recommended

Fig 10.1/ Table 10.1

The 3-domain System (fig 10.1)Endosymbiotic Theory

Pre-eukarya looked like prokaryote

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Plasma membrane invaginated DNA

Fossilized Prokaryotes Determine common ancestors thru imprints of bones and shells

Microorganisms are hard to find in fossilized formo Black rock: Filamentous bacteria

o Upper right: cyanobacteria ~3 bil years ago

Phylogenetics Each species retains some characteristics of its ancestors

Grouping organisms according to common properties implies that a group of organisms

evolved from a common ancestoro Anatomy

o Fossils

o rRNA

Scientific Nomenclature Common Names

o Vary with language and geography

Binomial Nomenclature (genus + specific epithet)o Used worldwide

o Escheria coli

o Homo sapiens- same all-knowing

Taxonomic HierarchyDomain (bacteria is a domain not a Kingdom)

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Kingdom* no kingdoms for bacteriao Phylum

Class

Order

Familyo Genus

Species

The Taxonomic Hierarchy

Fig 10.5 Appreciate Taxonomic Hierarchy- not inclusive

Classification of Prokaryotes

Prokaryotic species: a population of cells with similar characteristicso Culture: grown in laboratory media

o Clone: Population of cells derived from a single cell

o Strain: genetically different cells within a clone. Same species, but specific subtype

Phylogenetic Relationships of Prokaryotes

Fig 10.6

Classification of Eukaryotes

Eukaryotic species: a group of closely related prganisms that breed among themselveso Animalia

Multicellular, no cell walls, chemoheterotrophico Plantae

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Multicellular, cellulose cell walls, usually photoautotrophico Fungi

Chemoheterotrophic; unicellular OR multicellular, cell walls of chitin,

develop from spores or hyphal fragments.o Protista

A catchall kingdom for eukaryotic organisms that do not fit other kingdoms

Grouped into clades based on rRNA

Classification of Viruses

Viral species: population of viruses with similar characteristics that occupies a particular

ecological niche. They do not fit in Domain, not living organism. Has its own classification

system.

Classification and Identification

Classification- placing organisms in groups of related species. Lists of characteristics of

known organisms.

Identification- Matching characteristics of “unknown” organisms to lists of known

organisms.o Clinical lab ID

o Seen in hospitals

o Helps with classification ( p. 283 )

Dichotomous Keys

Identification Methods

Morphological characteristics- useful for identifying eukaryotes

differential staining- gram staining, acid-fast staining

biochemical tests- determines presence of bacterial enzymes

Identifying a Gram- Negative, Oxidase – Negative Rod (fig 10.8 )Numerical Identification (fig 10.9)

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More Methods of IdentificationSerology- use of antibiotics for testing purposes

Aggluntination, ELISA, Western Blottingo Based on how they are detected

Phage Typing Plate with lawn of bacteria. Each square of grid, add a different phage.

Observe virus clearing of bacterial lawn- what type of viruses can infect this particular cell

Fatty Acid Profiles- FAME (fatty acid methyl ester)

Flow Cytometry Machine with microscopic probe. Solution sucked into a tube, passed into a laser picture.

Take cell then use electrical conductivity- size, shape, density (more or less organelles,

inclusions), cell surface

Fluorescence- pick out one cell at a time

DNA Base Composition- GC, AT ratio can be figured out. Indicative of relation.

DNA Fingerprinting- RFLP’s (chapter 9) restriction length polymorphisms are regions of DNA that has

repeats in them. takes advantage of knowing DNA sequence.

PCR- increasing frequency for amplification.

Nucleic Acid Hybridization

Southern Blotting, DNA Chip, FISH

Building a CladogramThe Prokaryotes (check pic)

Domain Bacteria

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Phylum Proteobacteria:o gram-negative, chemoheterotrophic

Class:o Alphaproteobacteria

o Betaproteobacteria

o Gammaproteobacteria

o Deltaproteobacteria

o Epsilonproteobacteria

The Gammaproteobacteria

Pseudomonadaleso Pseudomonas

Opportunistic pathogens

Metabolically diverse

Polar flagella

Vibrionaleso Found in coastal water

Vibrio cholerae causes cholera

V. parahaemolyticus causes gastroenteritis

Enterobacteriales (enterics)o Petrichous flagella; facultatively anaerobic

Enterobacter

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Erwinia

Escherichia

Klebsiella

Proteus

Salmonella

Serratia

Shigella

Yersinia

The Epsilonproteobacteria Slender gram-negative rods Helicobacter

o Multiple flagella

o Peptic ulcer

o Stomach cancer

Campylobactero One polar flagella

o Gastroenteritis

Nonproteobacteria Gram- Negative Bacteria Photosynthesizing bacteria

Oxygenic Photosynthetic Bacteria: Phylum- Cyanobacteriao Gliding motility

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o Fix nitrogen

Anoxygenic Photosynthetic Bacteriao Purple sulfur, Purple nonsulfur: proteobacteria

o Green sulfur, Green nonsulfur

Phototropic Oxygenic photosynthesis

Anoxygenic photosynthesis

The Gram-Positive Bacteria Phylum: Firmiculates

o Low G+ C

o Gram +

Phylum: Acitnobacteriao High G+C

o Gram +

o Pleomorphic (many shapes)

o Actinomyces, Corynebacterium, Frankia, Gardnerella, Mycobacterium, Nocardia,

Propionibacterium, Streptomyceso They look like protista but they are BACTERIA

Nonproteobacteria Gram- Negatives Planctomycetes

o Gemmata obscuriglobus

Double internal membrane around DNA ( fig 11.23)

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Life Cycle of the Chlamydias (fig 11.24a)

Sprochetes- note axial filamentso Borrelia

o Leptospira

o Treponema

Fusobacteria o Fusobacterium

Are found in the mouth

May be involved in dental disease

Looks like toothpick

Domain Archaea Extremophiles

o Hyperthermophiles

Pyrodictium

Sulfolobuso Methanogens

Methanobacteriumo Extreme halophiles

Halobacterium

Microbial Diversity Bacteria size range

o Thiomargarita (750 uM)

o Nanobacteria (0.02uM) in rocks

PCR indicates up to 10,000 bacteria per gram of soil

Many bacteria have not been identified because theyo Haven’t been cultured

o Need special nutrients

o Are a part of complex food chains requiring the products of other bacteria

o Need to be cultured to understand their metabolism and ecological role.

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3/7/11 11:11 AMFocus on Phyla- What distinguishes one phyla from another.