Exam 2 Flashcards
(168 cards)
1
Q
What are the two ways enzymes can be changed to regulate metabolic activity?
A
AMOUNT (Transcription/Translation) - SLOW (Mins)
ACTIVITY (Posttranslational) - FAST (Secs)
2
Q
NEGATIVE Control of Transcription
A
A regulatory mechanism that stops transcription from a promoter that normally allows transcription
3
Q
POSITIVE Control of Transcription
A
A regulator protein activates the binding of RNA Polymerase to a promoter that is naturally not active.
4
Q
Repression
A
A type of NEGATIVE Control in which transcription is prevented in response to a signal, usually a corepressor binding its repressor and blocking RNAP.
5
Q
Induction
A
A type of NEGATIVE Control in which transcription is INDUCED in response to a signal molecule inactivating a repressor.
6
Q
Inducer
A
Substance that induces enzyme synthesis by binding and inactivating a repressor
7
Q
Effectors
A
Collective term for inducers and corepressors
8
Q
Operon
A
Cluster of genes arranged in a linear fashion whose expression is controlled together.
9
Q
Operator
A
Region of DNA that serves as a binding site for a regulatory molecule
10
Q
Activator Binding Site
A
Specific site on DNA where activator proteins bind. Analogous to the Operator in negative control.
Usually BEFORE the promoter, can be close or several hundred bp’s away.
11
Q
Inducer
A
Like a “Co-activator”, binds to an activator protein to recruit RNAP to the promoter and begin transcription
12
Q
Where on the structure of DNA do DNA-binding proteins typically bind?
A
The MAJOR GROOVE, typically on “inverted repeats”
13
Q
Homodimeric Proteins
A
Proteins made of two identical polypeptides. Describes the proteins that interact with the inverted repeats on DNA in transcriptional regulation.
14
Q
What are 3 classes of protein domains that bind to DNA?
A
- Helix-turn-helix
- Zinc finger
- Leucine zipper
15
Q
Helix-turn-helix domain
A
A type of protein domain that is common in DNA-binding proteins. Contains 2 alpha-helices connected by a turn.
First helix is for RECOGNITION
Second helix is for STABILIZING
Ex: lac and trp repressors of E. coli
16
Q
Zinc finger domain
A
Protein structure that binds a Zn ion. Typically have a recognition helix, turn, and Zn.
17
Q
Leucine zipper domain
A
Leu residues spaced every 7 AA’s on two bound alpha helices each connected to helices that recognize but do not interact directly with DNA
18
Q
Explain how the lac operon works.
A
Both NEGATIVELY and POSITIVELY controlled.
POS: cAMP:CRP bind to activator-binding site, upping XS. cAMP only present in low glucose.
NEG: LacI normally binds to operator, blocking XS. When lac present, allolac (inducer) inactivates LacI, allowing XS only when the cAMP:CRP complex is bound.
19
Q
Global Control Systems
A
regulate expression of many different genes simultaneously
20
Q
Catabolite repression
A
Example of global control. Synthesis of unrelated catabolic enzymes repressed if glucose is present in growth medium.
Basically the cell ensuring that glucose is the only C-source being utilized, and that other pathways are repressed.
**Flagellar genes are also repressed, as the cell doesn’t need to go searching for nutrients.
21
Q
Diauxic Growth
A
A growth pattern with TWO exponential states, exibited when E.coli grow in media with both glu and lac, where glu is limiting. Uses glu up first (growing quickly), then pauses and grows again slowly (using lac).
22
Q
What are some other global control networks?
A
Aerobic/anaerobic respiration Nitrogen utilization Oxidative stress SOS response Heat Shock Response
23
Q
What do regulatory RNA molecules act on?
A
mRNA via base pairing and blocking of XL of mRNA
AKA ANTISENSE RNAs
24
Q
RNA Chaperones
A
Small proteins that bind to both antisense RNAs and ribonuclease E and help the small RNAs maintain correct structure.
Ex: Hfq protein
25
Riboswitches
RNA domains in an mRNA molecule that can bind small molecules to control translation of mRNA. Basically a way for mRNA to regulate its own XL.
Located at 5' end of mRNA
Binding results from folding of RNA into a 3-D structure
26
Attenuation
Transcriptional control that functions by premature termination of mRNA synthesis caused by stem loops in the mRNA.
Stem loops created in trp operon by high levels of trp, eliminating a gap between RNAP and the ribosome, which allow regions 1/2 and 3/4 to loop, terminating transcription.
Requires RNA Binding Protein
27
Two-Component regulatory systems
Most common type of signal transduction system. Made up of a SENSOR KINASE (in membrane) and a RESPONSE REGULATOR (in cytoplasm).
Has feedback loop to terminate signal.
28
Quorum Sensing
Mechanism by which bacteria assess their population density
29
What purpose does quorum sensing play for bacteria?
It ensures sufficient number of cells are present before initiating a response that requires a certain cell density to have an effect (e.g. toxin production in pathogenic bacterium)
30
Autoinducer
A molecule produced by each species of bacterium that diffuses freely across the cell envelope and, when in high enough concentrations (due to many neighbors), triggers the transcription of specific genes.
Ex: Acyl homoserine lactone (AHL)
31
Stringent Response
When a cell is starved for AA-charged tRNA's, RelA protein on the ribosome causes GTP + ATP --> pppGpp --> ppGpp which signals for the cell to decrease tRNA and rRNA synth while upregulating AA biosynthesis.
32
How is sporulation signaled in Bacillus?
Extreme external conditions cause SpollAA to lose its P group, becoming active and binding SpollAB, which allosterically discharges a sigmaF from SpollAB, which interacts with several sigma factors to eventually form an endospore.
33
What are the two major forms of Caulobacter cells?
Swarmer cells = dispersal
| Stalked cells = reproduction
34
What are the three proteins involved in Caulobacter differentiation and what do they do?
DnaA: Recruits DNAP to the ori, associated with stalked cells
GcrA: Associated with stalked cells, expressed during DNA replication
CtrA: Counters DnaA and is expressed in swarmer cells.
35
Silent Mutation
A mutation that does not change the frame or AA sequence of a peptide
36
Nonsense Mutation
A mutation that changes an amino acid codon to a STOP codon
37
Missense Mutation
A mutation that changes an amino acid codon to a different amino acid codon
38
Reversion
Alteration in DNA that reverses the effects of a prior mutation
39
Frameshift Mutations
Usually deletions or insertions of 1 or 2 base pairs that result in a shift in the reading frame. Usually completely destroy gene function
40
Revertant
Strain in which original phenotype is restored
41
Genotypic Revertant
Mutation is at the same site as original mutation and restores original DNA sequence
42
Phenotypic Revertant
Mutation restores phenotype, but is not the original DNA sequence (takes advantage of degenerative nature of genetic code), puts in an "acceptable" amino acid, not necessarily the same one. Could also be at a different site, but still recovers phenotype.
43
What is the standard rate of errors in DNA replication?
10^-7
| 1 error in ~10^7 bp
44
How many bp are in an average gene?
10^3
45
What is the difference between a SCREEN and a SELECTION?
Screen: Can look at ~100 cells on a plate. Expose everyone to conditions, all survive, but the ones you want will look different.
Selection: Can look at ~10^8 cells on a plate. Expose all cells to same conditions, only the ones you want will grow.
46
What are the two main types of radiation?
Ionizing (X-rays, cosmic rays, gamma rays)
Non-Ionizing (UV)
47
What are the effects of NON-IONIZING radiation on DNA?
Pyrimidine dimers (T-T, A-A)
48
What are the effects of IONIZING radiation on DNA?
Ionization of water into free radicals, which damage all macromolecules in the cell. No specific changes.
49
How does mismatch repair work?
dam methylase methylates the A in the GATC sequence on parent strands. This marks it as the "parent". New strands are compared to that one, and when there is a mismatch, MutS binds it, MutH binds the nearest GATC, and MutL forms a complex while MutH excises the space between two GATC's on the new strand, which is then re-made by DNA pol III.
50
How does photo repair work?
When T-T dimers occur, photolyase binds them, is activated by light photons, and re-monomerizes them.
51
How does methyl transferase repair work?
When DNA becomes methylated (and isn't supposed to), methyl transferase comes in and transfers the methyl group to itself, which deactivates it and leaves DNA repaired.
52
How does base excision repair work?
When a base becomes damaged structurally, it is removed by DNA glycolase, AP endonuclease comes in and along with deoxyribophosphatase (dRPase), excises the sugar-phosphate backbone. Then, DNA polymerase comes in and repairs the gap.
53
How does recombination repair work?
It is very complex (17 proteins!), but the damaged region is borrowed from a good chromosome and lined up with the bad, and used to resynthesize the damaged areas.
RecA is very important in this process.
54
How does the SOS regulatory system work?
In large-scale DNA damage, this system allows replication to proceed and cell to replicate, but errors are more likely. Translesion synthesis allos DNA to be synthesized without a template.
55
Transformation
When DNA is incorporated into a recipient cell and brings about genetic change.
56
Competent
Word used to describe cells that are capable of taking up DNA and being transformed
57
What happens when cells are not naturally competent?
WE MAKE THEM COMPETENT. BY SHOCKING THEM. (Electroporation)
58
Transduction
Use of bacteriophages to transfer DNA to a new cell.
59
What are the two modes of transduction and how do they differ?
GENERALIZED Transduction: DNA from any old portion of the host genome is sent over via the "VIRION"
SPECIALIZED Transduction: A SPECIFIC region of DNA from the host chromosome is integrated directly into the virus genome
60
Bacterial conjugation
A way for one bacterium to transfer genetic materiall (via a plasmid) to another. The mechanism is encoded in the plasmid, so the recipient does nothing in the process except receive the plasmid.
61
What is the F plasmid?
The FERTILITY plasmid. It contains transposable elements that allow the plasmid to join into the host chromosome.
62
What is the origin of transfer?
AKA oriT, is a site on all plasmids where the circle is cut and the single strand is then sent to a new cell while DNA synthesis occurs.
63
What is the function of the pilus?
ONLY to bring bacteria together, NOT TO TRANSFER DNA.
64
Transposable elements
DNA chunks that can move from one location in the genome to another via TRANSPOSITION.
Types: Insertion Sequences and Transposons
65
How do Insertion Sequences and Transposons differ?
Insertion sequences are typically just a single copy of a gene of interest (transposase).
Transposons are typically two insertion sequences with something interesting in between (gene for Ab resistance). Only one of the two IS is used in transposition.
66
What are the two mechanisms of transposition and how do they differ?
CONSERVATIVE: transposon is excised from one location and reinserted elsewhere (Tn5). # of transposons stays constant.
REPLICATIVE: New copy of transposon is produced and inserted elsewhere. # of transposons present doubles.
67
Define Metabolism
The sum of all reactions which occur in a cell. Consists of two types of processes: Catabolism and anabolism.
68
Catabolism
How complex molecules are broken down into smaller, simpler molecules with the release of ENERGY and reducing power (e-)
69
Anabolism
Synthesis of complex molecules from simpler ones. Requires energy and often reducing power.
70
What are the typical products of catabolism?
Organic Acids: lactic, acetic
Alcohols: Ethanol, methanol, butanol
Gases: H2 and CO2
71
When do yeast utilize oxygen during bread/beer making?
They first grow aerobically in order to synthesize a key sterol in their membranes, then mostly anaerobically.
72
Fermentation
Energy yielding process whereby organic molecules serve as both electron donors and electron acceptors.
73
What is a molecule that tends to build up in fermentation?
NADH after reduction of NAD+
74
What is an important intermediate in fermentation?
PYRUVATE
75
Homofermentation
A type of lactic fermentation where the organism ONLY produces lactic acid/lactate.
76
Heterofermentation
Type of lactic fermentation that yields multiple products, including Lactate, CO2, and ethanol.
77
From where is the energy derived for fermentation?
Substrate-level phosphorylation
78
What are the net products of the TCA cycle?
4 NADH + 1 FADH as source of e- for ETS
GTP
79
What do phospholipases do?
Attack the Glycerol-Fatty Acid bonds to break off the fatty acids in lipid catabolism.
80
What is the gist of oxidative phosphorylation?
Use NADH reducing power to pump protons out and eventually make ATP.
Water is also produced.
81
What are the inputs and outputs of oxidative phosphorylation?
In: NADH
Out: H+, H20
82
What is the gist of photophosphorylation?
Energy captured by photopigments, electrons get energized, then passed through electron transport chain. Iron complexes common.
83
What two functions does the membrane serve in electron transport chains?
Separate charge
| Hold respiration components
84
What are the two components of ATP synthase?
F0: intermembrane part, has protons loaded from outside, rotates around with shaft to move F1 subunits.
F1: Bottom portion, connected by the shaft to the F0 portion. The shaft changes the conformation of F1 so that ADP and P can be joined.
85
What can move to the different proteins in the ETS?
Protons AND electrons to NDH
Protons AND electrons to FP
ONLY electrons to NH Fe (p+ pumped out of FP)
86
What is a fluorescent dye that detects viable cells?
CTC (stains red)
| DAPI (stains DNA, blue)
87
What is FISH?
Fluorescence in situ hybridization. Can see live cells with fluorescent markers.
Probes can be designed for any sequence -> Domain, phylum, species.
88
How does pyrosequencing work?
Isolate DNA, nebulize it with pressurized gas to shear it to desired length, ligate via adaptor sequence to beads, add annealing primer, amplify sequence using PCR, add single beads to picotiter plate wells, add enzymes + luciferin, add dNTPs one at a time to see if light emitted (pair made, ATP synthd, light emitted)
89
How does 16S rRNA Sequencing work?
Extract DNA from enviro, isolate DNA, amplify 16S rRNA, sequence it (via pyro, etc)
90
What are some metabolomic techniques and what do they tell us?
DNA array: Tell us what genes being expressed
cDNA libraries: same thing but based on isolated mRNA (bc only genes expressed will be seen as mRNA)
LC-MS: find out what metabolites are being made
91
What adaptations do organisms have for hot environments?
Ether-linked membrane lipids, membrane monolayers.
92
What adaptations do organisms have for cold temperatures?
Ester-linked membrane lipids, lipid bilayers
93
Who are the major players present at acid mines? (7)
```
Nitrospira (Leptospirillum groups 2 and 3) - fix nitrogen for community
Firmicutes (Sulfobacillus, sulfolobus)
Arman-1 and Arman-2
Ferroplasma acidarmanus (an archaea)
Thermoplasma (archaea)
Euglena Mutabilis (protist)
Ascomycota (fungi)
```
94
What does Sulfolobus spp. do that is metabolically interesting in acid mines?
Use polythionates and elemental sulfur to produce sodium sulfate and sulfuric acid.
Use oxygen as terminal electron acceptor to make more acid.
95
What does Leptospirillum ferrooxidans look like? Describe its metabolism and abundance.
Gram Negative, Spiral shaped
Chemolithoautotroph, oxidizes Fe2+ with oxygen
Membranes impermeable to p+ aside from ATP synthase. Uses ETC to neutralize protons!
Dominant species
96
What is special about the metabolism/physiology of Ferroplasma acidarmanus?
Iron-oxidation, no cell wall, lives in pH range 0.1 - 2.5!
97
What is special about Euglena mutabilis?
Oxygenic photosynthesis
Survive down to pH 1.7
Accumulate Fe-rich granules
Cause formation of stromatolites
98
Who are the major degraders in soil environments?
BASIDIOMYCETES (White/Brown rot fungi)
99
How do starch and cellulose differ?
Starch uses 1,4 ALPHA linkages
Cellulose uses 1,4 BETA linkages
100
How do white/brown rot fungi such as Phanerochaete chrysosporium degrade lignin?
Using PEROXIDASES, create peroxide to attack chemical bonds.
Break off aromatics that decay into phenolics, which are then degraded.
101
What are Syntrophs?
Organisms that live off of the products of other organisms.
102
How is the degradation of acids (an unfavorable reaction) carried forward?
Syntrophic methanogens use the products and export the gases, making the reactions favorable!
103
Why are many syntrophs difficult to culture?
They have a very dependent metabolism. They NEED somebody else to be providing them with the right stuff.
104
What is rice cluster 1?
A phylogenetic cluster of uncultured methanogens that reside in rice paddy soils and contribute 20-50% of the methane produced by rice paddy soils (which contribute 10-25% of global methane emissions).
105
What are CoM and CoB?
They are unique cofactors to methanogenesis, used in the final step to take methyl-CoM to CH4.
106
What are the different Light Harvesting pigments that we discussed?
Chlorophyll / bacteriochlorophyll
Bacteriopheophytin
Carotenoids
107
What is the general structure and function of chlorophyll?
Pheophyrin ring, coordinated to a central Mg atom. Usually many coordinated to a protein.
Function: harvest photons and transfer the energy to electrons/proteins.
108
What is the usual structure and function of carotenoids?
Unsaturated alkyl chain (30-50 C's), 0-2 cyclic rings.
| Provide protection from reactive byproducts. MAY be important in light harvesting.
109
How do carotenoids protect cells?
They quench triplet-state chlorophyll to prevent damage caused by high-energy e- in the Mg of chlorophyll. They can also quench singlet oxygen.
110
How are pigments positioned in the cell?
Light-harvesting pigments near the outside. Pigments in rxn center positioned to allow efficient transfer of light energy.
111
What are the main pigments in reaction centers?
```
BChl creates excited electron
Carotenoids
Bacteriopheophytin
Non-heme iron
Quinones
```
112
What is the purpose of proteins in reaction centers?
To hold the pigments in the optimal positions to facilitate the light reactions.
NOT to help collect light.
113
What is the rate-limiting step in light-harvesting reactions?
Excitation of electrons by photons
114
What phylum do Purple Bacteria belong to?
PROTEOBACTERIA (alpha, beta, and gamma)
115
What is interesting about Purple bacteria?
They carry out anoxygenic photosynthesis.
They use H2S, H2, or organic acids as e- donors.
They oxidize to sulfur or sulfate.
C-SOURCES: CO, CO2, or organic acids (succinate)
They can grow with or without light.
116
Where is the Purple Bacteria's photosystem housed?
IntraCellular Membrane - ICM
117
How many light harvesting complexes do purple bacteria have?
TWO: Core and Peripheral.
118
How do Green Bacteria obtain energy?
Light ONLY. They are OBLIGATE phototrophs. However, they are NOT closely related to other phototrophs.
119
What is the phylogeny of Green Bacteria?
2 DISTINCT groups: From each other and from other phototrophs.
120
Can green bacteria grow in the presence of oxygen?
NO, strict anaerobes
121
Can green bacteria grow in the dark?
NO, obligate photoautolithotrophs
122
What do green bacteria use as electron donors?
ALL can use H2S,
SOME can use H2 or thiosulfate (S2O3)
123
What is the light-harvesting complex of green bacteria called and how is it structured?
CHLOROSOME
Elliptical structure just under cytoplasmic membrane. Has monolayer membrane. Crystalline lattice of BChl means efficient light collection.
Baseplate proteins funnel electrons to reaction center.
124
Why can green bacteria grow where other bacteria can't?
They can harvest wavelengths of light that other bacteria can't. They live under the purple bacteria and cyanobacteria in lakes.
125
Where can cyanobacteria be found?
Everywhere from deserts to trop rain forests, oceans and even thermal hot springs
126
What is cyanobacteria's metabolism like in regards to light and oxygen?
OBLIGATE phototrophs
| Carry out OXYGENIC photosynthesis - supply Oxygen to enviro
127
What proteins are in cyanobacterial light-harvesting machinery?
Phycobiliproteins
Phycoerythrin (550 nm)
Phycocyanin (620 nm)
Allophycocyanin (650 nm)
128
How does the reaction center in cyanobacteria compare to those in green and purple bacteria?
Two photosystems:
PSI looks like green RC
PSII looks like purple RC
129
What environmental factor typically dicates microbial populations in lakes?
Nutrient levels, especially nitrogen and phosphorus.
130
What are the 5 major phyla of bacteria present in lakes?
```
Beta-proteobacteria
Alpha-proteobacteria
Bacteriodetes
Cyanobacteria
Actinobacteria (50%)
```
131
What is acl-BI?
An Actino isolated from Lake Mendota that was found to have one of the smallest Actino genomes known. Has low G/C ratio.
132
What is the physiology of acl-BI like?
Metabolizes xylose and ribose, has many repair mechanisms for its genome, and has rhodopsin.
133
What are extreme halophiles and what is special about them?
Salt-loving microbes, many morphologies (even square), chemoheterotrophs, all grow in oxygen.
NOT IN FRESH WATER
134
How do extreme halophiles like Halobacterium spp. deal with high salt environments?
Acidic cell wall, K+ pump to balance Na+, less hydrophobic AA's
135
What is bacteriorhodopsin and when is it expressed?
It is a light-driven proton pump that is expressed under oxygen-limiting conditions.
Contains retinal
136
How does bacteriorhodopsin work?
Light causes conformational shift of retinal (and protein), surrounding protein deprotonates, and proton is pumped out.
137
What is actinorhodopsin and how common is it in fresh water?
It is similar to bacteriorhodopsin and 35% of freshwater isolates have it. Mainly used as a method of energy generation.
138
What is Microcystis aeruginosa and why is it important in lakes?
It is a unicellular obligate phototroph that secretes Microcystins, which are dangerous hepatoxins that kill fish, humans, and livestock.
139
What is Anabaena and why is it important in lakes?
It is a filamentous Cyanobacteria that is an obligate photoautotroph. Under low N conditions, they form HETEROCYSTS, which are specialized cells that fix N for the cell.
140
What are Bacteroidetes and why are they important in lakes?
They include Flavobacteria and Chitinophaga, two important degraders. They also have extreme phenotypic and metabolic diversity.
141
Why are Flavobacteria important in lakes?
They can ferment carbohydrates.
Produce succinate, acetate, and formate.
142
Why are Chitinophaga pinensis important in lakes?
They degrade CHITIN (insect bodies), glucose, lactose.
| Produce acid
143
Why are Alphaproteobacteria important in lakes?
Widely distributed, grow well in low nutrients (and high).
LD12 (relative of SAR11) is dominant in lakes
144
Why are Betaproteobacteria imortant in lakes?
They are numerically dominant in lakes by DAPI staining.
Ex: Limnohabitans curvus: grows in nutrient rich med, chemoheteroorganotroph.
145
What phyla of bacteria dominate the oceans?
ALPHA (SAR11, 86), beta, gamma proteobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, Actinobacteria
146
What is SAR11 and why is it special in oceans?
Peligobacter ublique
| Oligotroph, SLOW grower, "Metabolically Capable", Proteorhodopsin, Chemoheterotroph
147
What is Prochlorococcus and why is it special?
It is a cyanobacterium that is one of the two most abundant oxygenic phototrophs.
Makes unique divinyl derivatives of chlorophyll a and b
Can grow in low light/deep depths
Mostly in MIDDLE LATITUDES
148
What is Synechococcus and why is it special?
It is the OTHER abundant cyanobacteria in the ocean.
Found in ALL oceans, but different groups
Obligate photoautotrophs.
149
What is special about Thermus thermophilus?
Thermophile, Obligate Heterotroph, Deep sea vents
150
What is special about Persephonella marina?
Deep Sea vents, Microaerophile (3% Oxygen), Strictly chemolithoAUTOtrophic
151
What are two types of metabolisms common in the deep sea?
Methanogens
Methylotrophs
152
What is special about Geoglobus ahangari?
Thermophile, Uses Fe3+ as terminal e acceptor, important acetate sink
153
What is special about Thermococcus atlanticus?
Obligate anaerobe, thermophile, heterotroph, grows on proteinaceous substrates
154
Why are tube worms interesting to microbiologists?
They take up CO2 and H2S using hemoglobin protein and receive organic matter from a SULFUR OXIDIZING SYMBIONT.
155
How do rhizobial nodules form in root hairs?
Root grows, bacteria attach, root hair curls, infection thread generated, bacteria enter.
156
What is special about Frankia alni in plant environments?
It is an Actinobacteria that infects alder trees and fixes nitrogen - has nif genes!
157
What are nif genes?
Genes that encode the ability to fix nitrogen. The enzymes are Dinitrogenase reductase and dinitrogenase, along with regulatory genes and electron transport.
158
What are the two groups of bacteria (metabolically) that comprise nitrification?
Ammonia-oxidizing bacteria
| Nitrite-oxidizing bacteria
159
What is special about Nitrosomonas?
BETA-proteobacterium that does ammonia oxidation. Extensive membrane system for ETS.
160
What is special about Nitrobacter winogradskyi?
Carries out Nitrite Oxidation, is an ALPHA-proteobacterium, extensive membrane for ETS.
161
What is Anammox, who does it, and why is it important?
ANaerobic AMMonia OXidation (NH4+ +NO2- -> N2 + 2H2O
Done by order Brocadiales
70% of N2 flux in ocean!
162
What type of organism makes the biggest contribution to CO2 emissions?
MICROBES!
163
What is special about Alcanivorax borkumensis?
It degrades straight-chain and branched alkanes found in oil spills.
164
What is special about Cycloclasticus spp?
They degrade polycyclic aromatic hydrocarbons found in oil spills. Not the only one to do this.
165
Who is able to degrade PCBs?
MANY bacteria
166
Why are we unable to culture most bacteria?
```
Key missing nutrient
Competition
Codependency
Slow Growth
Medium Toxicity
```
167
What is the Scout Hypothesis?
An unknown fraction of cells are in a non-growing dormant state, and only randomly awaken to begin normal growth.
168
How are we beginning to culture the unculturables?
Cross feeding
Detoxification
Cell Dormancy
Simulated Environments
