(5)Industrial and Environmental Uses of Recombinant Microorganisms

Biomass

Waste from food/agricultural industries, now valuable.

Bioremediation

Using biological agents to remove toxic substances.

Xenobiotic

A compound foreign to a biological system.

Mesophilic bacterium

Grows best at moderate temperatures (20-45°C). Their enzymes function optimally at these temperatures.

Psychrophilic bacterium

Grows best at low temperatures (below 20°C). Their enzymes are adapted to function in cold environments.

Superbug (Pseudomonas putida)

The first patented bacterium (created by Ananda Chakrabarty) was used to degrade crude oil. It was developed by combining plasmids from different Pseudomonas strains, each capable of degrading different hydrocarbons.

Starch

biopolymer with linear (amylose) and branched (amylopectin) homopolymers.

Amylose

linear chains of 100- 400,000 D-glucose residues linked by α-1,4-bonds

Amylopectin

short linear chains of approx. 17 to 23 glucose units, linked by α-1,4-bonds and joined by α-1,6 -linkages and some 1,3-linkages to form a highly branched structure that contains 10,000-40,000,000 glucose residues

Lignocellulose

Primary cellulosics: plants for cellulosic content (cotton, timber, hay).
Agricultural waste cellulosics: post-harvest materials (rice hulls, corn stovers, straw).
Municipal waste cellulosics: waste paper, cardboards.

Lignin

3D, globular, irregular, insoluble polymer (>10,000 MW).
Phenyl propane subunits with irregular chains. Bonds are hard to hydrolyze.

Hemicellulose

Short-chain, heterogenous polymers with hexoses and pentoses.
Xylans: hardwood. Glucomannans: Softwoods

Cellulose

Abundant polymer with long chains of D-glucose in β-1,4 configuration. Hydrolyzable to glucose.
Crystalline structure, insoluble and resistant to hydrolysis.

Cellulase

Requires breakdown into structural components via acid, base, high temperature/pressure. Bacteria/fungi degrade using cellulase (multiprotein complex).
Component enzymes:
Endoglucanase
Exoglucanase
Cellobiohydrolase
β-glucosidase/cellobiase

Cellulosome

A multi-enzyme complex produced by some microorganisms that efficiently degrades cellulose. It consists of:
Scaffoldin: A structural protein that binds the cellulases.
Cellulases: Including endoglucanases, exoglucanases, and β-glucosidases.

ABE Fermentation

Bacterial fermentation to produce acetone, butanol, and ethanol from starch.
Anaerobic process using Clostridia (e.g., Clostridium acetobutylicum).
Produces solvents in a 3:6:1 ratio (acetone:butanol:ethanol).