Lecture 18

Question 1

Describe chemilitoautotrophs

Answer 1

• Energy and reducing equivalent from oxidation of inorganic compounds
• Carbon source are CO2 or CH4
• S-oxidizing bacteria, hydrogen bacteria, nitrifiers, iron bacteria

Question 2

Describe photoautotrophs

Answer 2

• Energy from light, carbon from CO2

Photolitoautotrophs : e- come from inorganic compouds (H2O, H2S, H2…)
- Plants, cyanobacteria, green and purple sulfur bacteria etc

Photoorganoautotrophs: organism that would use organic electron donors, AND fix CO2 at the SAME time may NOT exist

Question 3

Describe photoheterotrophs

Answer 3

• energy from ligh, carbon and electron by assimilation of organic compounds
• P/S bacteria and archea that cannot fix CO2
• Mostly photoorrganoheterotrophs
• Photolithoheterotrophism is possible (in the lab) but may only occur rarely in nature (not known )

Question 4

Describe chemoorganoheterotrophs

Answer 4

• energy and reducing equivalents from oxidation of organic compounds
• Obtain carbon by assimilation of organic compounds

Question 5

Describe chemilithoheterotrophs

Answer 5

• Energy and reducing equivalents form oxidation of inorganic compounds (H2 gas)
• Obtain carbon by assimilation of organic compounds
• Among the chemolithoautotrophic gorups are some exceptions that do not seem to fix CO2 , and this would have to be chemolithoheterotrophs