Lecture 1/2: Introduction

Question 1

What is ecology?

Answer 1

the study of organisms and their interactions with the environment and other organisms

Question 2

what is Microbial Ecology?

Answer 2

The study of interactions between:

• microbes and microbes
• microbes and macroscopic organisms
• microbes and the environment

therefore, microbial ecology is the study of the interactions between microbes and their abiotic and biotic environments.

Question 3

What environmental components are essential fofr all life?

Answer 3

C,H,O,N,P,S

Question 4

What are the general objectives for the study of microbial populations? (4)

Answer 4

1. Detect
2. Identify
3. Quantify (number of microbes)
4. Characterize (what they eat and ecological interactions)

Question 5

what is an organotroph

Answer 5

oxidizes carbohydrates like CH2O, CH4 (eats carbon)

Question 6

what is a lithotroph

Answer 6

oxidizes H2, H2O, H2S, NH4+ (rock eaters).

Question 7

the electron donor may be the energy source for chemotrophs if:

Answer 7

energy is conserved in reactions that remove electrons

Question 8

what is the purpose of electron donors and acceptors in the cell?

Answer 8

to energize cell membranes and create a membrane potential.

Question 9

challenge when studying microbes:

Answer 9

differentiation between live and dead cells

Question 10

what is a stromatolite

Answer 10

• they were dominant before there were any algae or corals to cover the stromatolites (didn’t have to compete with other organisms)
• they would form a biofilm where sand and other things would accumulate so you can observe layer upon layer in a given stromatolite.

Question 11

earths atmosphere at formation vs presently:

Answer 11

at formation:
- high CO2, low N2 and O2, some CH4, H2S, NH3
- reducing conditions , high temperatures

presently:
- 0.03% CO2, 79% N2, 21%O2
- oxidizing conditions (13 deg C)
- atmosphere has changed over time due to microbial activity

Question 12

microbial growth curve

Answer 12

• exponential growth
• lag phase: adjustment to new media before logarithmic growth
• log phase: exponential growth
• stationary phase: growth is limited by depletion of nutrients, accumulation of waste products, cell death…

Question 13

what do microbes need to survive:

Answer 13

• liquid water
• energy source
• something to oxidize and reduce (to keep membrane potential)
• source of carbon
• source of N,P,S (CHONPS) critical nutrients

Question 14

why do we need nitrogen, phosphorous and sulfur respectively

Answer 14

nitrogen: for RNA and DNA

phosphorous: nucleotides, DNA and RNA

sulfur: some amino acids… methionine start codon!!