Lecture 10: Limits of Life

Question 1

high temperature limit

Answer 1

the methanopyrus kandleri

capable of growth at 122C

Question 2

low temperature limit

Answer 2

the planococcous halocryophilus

capable of growth at -15C

Question 3

high pressure limit

Answer 3

colwellia marinimaniae

capable of growth at 1400 bar

Question 4

how do thermophiles adapt their proteins?

Answer 4

salt bridges

hydrogen bonds

disulfide bridge

hydrophobic interactions

Question 5

how do thermophiles enhance their protein stability?

Answer 5

increasing the number of intramolecular bonds

decreasing the size of their proteins/ loop domains

Question 6

how do piezophiles adapt their proteins?

Answer 6

high pressures favour systems with the smallest volume

so piezophiles have evolved proteins which are pressure insensitive and more densely packed

piezophilic proteins reduce their ‘void volume’

Question 7

what about the low temperature limit for life?

Answer 7

protein unfolding and dynamics set the limits to life at high temperatures and pressures

same not true for low temperature limit for life

unsure if there’s one thing which sets this limit

Question 8

studies around the low temperatures limit for life

Answer 8

price and sowers(2004)
“our results disprove the view that the lowest temperatures limit at which life is possible is ~-17C”

clarke et al(2013)
“we propose that the vitrification temperature represents a general lower thermal limit to life on earth”

Question 9

challenges for life in low temperatures

Answer 9

reduced enzyme kinetics/ biomolecular dynamics

low nutrient availability

low water activity

Question 10

extreme life and biotechnology

Answer 10

PCR- testing for covid

bioremediation of waste

bio-detergents for washing clothes at low temperatures