Lec 9

Question 1

(LOW pH ENVIRONMENTS)

Mining of pyrite (FeS2) deposits results in…

Answer 1

…S2- oxidized to SO42- + H+

Question 2

Lower pH mobilizes…

Answer 2

…metals

Question 3

…in which specialized microbial communities develop

Answer 3

Acidic effluent with high metal content known as Acid Mine Drainage (AMD)…

Question 4

low ph microbes =

Answer 4

acidophiles

Question 5

Acidophiles contain many…

why?

Answer 5

…H+ pumps in the cellular membranes

–> To continuously pump hydrogen ions out because they want to keep the H+ out for the most part

Question 6

Acidophiles inner pH is about

Answer 6

6 (neutral)

Question 7

(ACIDOPHILIC PROTEIN ADAPTATIONS)

Only a few…

Answer 7

…general mechanisms by which proteins can achieve acid stability – not consistent among all acidophiles

Question 8

(ACIDOPHILIC PROTEIN ADAPTATIONS)

At low pH, charged residues become…

Answer 8

…protonated –> charge changes

Question 9

(ACIDOPHILIC PROTEIN ADAPTATIONS)

Proteins contain an overabundance of…

Answer 9

…acidic residues which minimizes low pH destabilization that is induced by a buildup of positive charge

Question 10

(ACIDOPHILIC PROTEIN ADAPTATIONS)

Other mechanisms include…

Answer 10

…minimization of solvent accessibility of acidic residues or binding of metal cofactors

Question 11

(High pH / ALKALINE HOT SPRINGS)
ph =
temp =

Answer 11

> 7 - 12

up to 100*C

Question 12

alkaline =

Answer 12

high pH

Question 13

Alkaline adaptations:

Answer 13

• Cytoplasmic polyamines with charged amino acids
• Acidic molecules in the membrane
• Na+ ion channels (and pumps H+ ions in to balance pH & homeostasis)

Question 14

(High pH enviro)

Soda Lakes: microbial diversity is…

Answer 14

…understudied (cyanobacteria & algae)

Question 15

(APHOTIC ENVIRONMENTS)

example:

Answer 15

desert carbonate cave

Question 16

Carbonate caves are devoid of

Answer 16

phototrophic primary production

Question 17

(Carbonate caves)

Can receive fixed organic carbon from…

Answer 17

…drip water that form speleotherms

Question 18

(Carbonate caves)
have unexpectedly high…
dominated by…
10% metagenome comprised of…

Answer 18

…bacterial diversity
…heterotrophic growth
….archaeal species

Question 19

Desiccate (dry) and UV stressed environments example:

Answer 19

…atacama desert, chile

Question 20

Organisms that live in dry/UV stressed environments are found…

Answer 20

…to be associated with rocks (litobiotic)

• Found cyanobacteria and green algae
• Also found heterotrophic bacteria as well

Question 21

Cyanobacteria species are _______ and ________ tolerant

Answer 21

dessication and radiation

Question 22

Survival strategies of desert microbes include:

Answer 22

1.) Ability to protect and repair DNA damaged by UV
2.) Maintenance of proteins and membrane integrity via EPS sheath
(May help understand life on other planets such as Mars)

Question 23

Deinococcus radiodurans =

Answer 23

microbe w/ world record for most tolerant to UV raditation

Question 24

UV Radiation Repair: (2)

Answer 24

1. ) Multiple genomes and repair mechanisms

2. ) Mn2+ complexes as antioxidants (Mn protects proteins/macromolecules from any damage caused by oxidation (from UV))

Question 25

Hypersaline =

Answer 25

> 5% NaCl

Question 26

(Hypersaline microbes) Their problem= Their Adaptations =

Answer 26

= They are living in a very salted environment = the water in the cells will want to go out = cell shrivel and die = focused on maintaining an equilibrium between the outside and inside of the cell so you don’t get water loss

Question 27

(Hypersaline microbes) (Overcoming High Salt Conditions) 2 Strategies: also Cellular machinery contains ... DNA contains...

Answer 27

1. ) Osmoprotectants 2. ) High K+ levels in cytoplasm ...a high number of charged amino acids on their surfaces, allowing the retention of water molecules ...high GC content – more resistant to denaturing conditions