Microbes in bioenergy research

Question 1

What are some types of biofuels?

Answer 1

Bio-hydrogen 
Bio-ethanol
Bio-methanol
Bio-butanol
Bio-diesel
Bio-methane

Question 2

Why is butanol better than ethanol?

Answer 2

Lower volatility
Higher hydrophobicity
Higher miscibility
Higher energy content per unit

Question 3

How does Clostridium acetobutylicum produce butanol

Answer 3

Through the acetone-butanol-ethanol fermentation pathway
Normally makes lactate, acetate and butyrate in nutrient rich conditions and exports those out of the cell
Under stress and low pH- uptakes the waste products to make butanol and acetone

Question 4

What are the problems with producing butanol in Clostridium?

Answer 4

Makes spores when making butanol and acetone
Butanol is toxic to the bacteria
Culture conditioning means that the tendency to sporulate is lost

Question 5

What are first-generation biofuels?

Answer 5

Grow crops for the purpose of making biofuels

Question 6

What are second-generation biofuels?

Answer 6

Grow crops for food and use leftovers, waste carbon (chitin), and agar from seaweed for biofuel production

Question 7

What are lignocellulosics?

Answer 7

Cellulose, hemicellulose (xylan and glucomannan), and lignin

Question 8

What are cellulosomes?

Answer 8

Huge extracellular protein complexes produced by Clostridia and Ruminococcus

Question 9

What is the structure of cellulosomes?

Answer 9

CipA scaffoldin made up of type I cohesion domains, pro/thr rich linker regions, carbohydrate-binding molecules, and type II dockerin domain
SbdA anchoring scaffoldin made of type II cohesion domain and SLH domain
Cohesion domains bind tightly to dockerin domains
Cohesion I is a dimer
Dockerin I is a monomer

Question 10

What are oxidative cellulases?

Answer 10

Contain copper
Hydrolyse cellulose
Have a methylated histidine at position1 due to post transcription modifications

Question 11

Describe brown algae

Answer 11

Phaeophyta 
Kelp
Vacuoles contain brown/yellow oil/lipid 
Cell walls made of alginic acid 
Store carbon as laminaran
Brokedown by laminarase enzyme

Question 12

Describe red algae

Answer 12

Rhodophyta 
Phycoerythrin pigment 
Cell walls made of agarose
Store carbon as glycogen 
Brokedown by agarase enzyme

Question 13

Describe green algae

Answer 13

Chlorophyta
Cell walls made of mannan
Store carbon as starch
Brokedown by mannanase enzyme

Question 14

Describe golden algae

Answer 14

Chrysophyta
Unicellular
Flagellated
Photosynthetic

Question 15

Describe coralline algae

Answer 15

Related to red algae

Thick magnesium-calcite crust

Question 16

What 2 types of microalgae are useful in making biofuels?

Answer 16

Chlamydomonas

Botrycoccus

Question 17

Describe Chlamydomonas

Answer 17

In stressful conditions (low N) induces TAG biosynthesis
TAGs are compartmentalised into lipid droplet pseudo-organelles
Lipid droplets contain poorly characterised proteins
~250 in each droplet
Major lipid droplet protein ~28 kDa
MLDP transcription increases with TAG induction
Starch accumulation increases with TAG accumulation
Starch-less mutants do not have boosted TAG levels

Question 18

Describe Botryococcus

Answer 18

Unusually green algae secretes oils and hydrocarbons out into growth media
Can grow in fresh or saltwater
Sub categorised into races
Race B makes botrycoccene compounds