| Organisms |
Advantages |
Disadvantages |
| Algae |
•Wide distribution (particularly in moist environment).
•Multiple modes of cultivation available (e.g., open ponds, photobioreactors).
•Fast growing.
•High cell density.
•Fast CO2 uptake.
•High cellular lipid content.
•Production of high-value byproducts (e.g.,proteins, aquaculture nutrients, fertilizers).
•Genetic modification tools available. |
•Light requirement (e.g., intensity, wavelength).
•Water requirement.
•Large amount of phosphorous required as a fertilizer.
•Biodiesel fuels derived from algae have poor cold flow properties and low oxidative stability. |
| Cyanobacteria |
•Grow easily with basic nutritional requirements.
•Cultivation is simple and inexpensive.
•Higher photosynthetic levels and growth rates compared to algae and higher plants.
•Contain considerable amount of lipids (mainly in the thylakoid membranes).
•Wide range of fuels potentially obtained from cyanobacterial biomass (e.g., H2, ethanol, photanol, diesel, methane).
•Genetic modification tools available. |
•Temperature (optimum growth temperature 20-30°C), pH (optimum pH 7-9) and light intensity affect productivity.
•After carbon, nitrogen (e.g., nitrate, urea, ammonia) is the most limiting nutrient for biomass production.
•Agitation (e.g., aeration, pumping and mechanical stirring) is necessary, increasing the operating cost of cell cultivation. |
| β-Proteobacteria |
•Aerobic microorganisms and easier cultivation compared to clostridia.
•Diverse carbon sources and carbon utilization pathways.
•Natural ability to store carbon intracellularly as PHA.
•Genetic modification tools available. |
•Gas fermentation is still under development. |
| Clostridia |
•Diverse range of carbon substrates (e.g., simple or complex carbohydrates, CO2/H2 and CO).
•Diverse pathways for production of useful metabolites/industrial products (e.g., ethanol, acetate, acetone, lactate, butanol, 2,3-butanediol, valeroate, caproate, carpylate and Closthioamide).
•Tolerance to toxic metabolites and substrates.
•Genetic modification tools available. |
•Anaerobic cultivation could be expensive.
•Gas fermentation is still under development. |
| Archaea |
•Natural ability to produce CH4 (methanogenesis) by methanogens.
•Natural ability to accumulate PHA in some archaeal species.
•Excellent sources of thermostable enzymes (e.g., carbonic anhydrases).
|
•Gas fermentation is still under development.
•Difficult to emulate growth conditions.
•Genetic modification tools unavailable for most archaeal species. |
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