Fungal waste biomass could be used to harvest microalgae for fuels

Waste biomass from fungal fermentation processes could be used to bind to and harvest microalgae being used in other biotechnology applications. A*STAR researchers have successfully demonstrated this procedure with fungal mycelium—the main vegetative part of a fungus such as the tangled mass of underground fibers beneath sprouting mushrooms. 

Suitable fungal biomass might be obtained cheaply or perhaps even freely to offer a sustainable and environmentally sound method for harvesting microalgae. The potential uses of microalgae include burning their biomass as fuel or turning them into mini-factories for making biodiesel or specific chemicals including lipids, sugars or drugs.

"The lack of an economic and effective method for harvesting microalgae is one of the bottlenecks limiting their commercial use in biotechnology," explains Mahabubur Talukder of the A*STAR Institute of Chemical and Engineering Sciences.

Microalgae can be cultured in a broth and existing methods for harvesting them include centrifugation or a precipitation process called flocculation using chemical treatments. All current methods however suffer significant drawbacks, explains Talukder.

For instance, centrifugation is too expensive to be used for low value uses of microalgae, such as biofuel. Similarly inadequate, chemical flocculation contaminates the harvested microalgae with toxic metal salts, causing difficulties in further processing or extraction of desired products. What is needed is a non-toxic and preferably natural and widely available material that can bind to, immobilize and precipitate both freshwater and marine microalgae. This led the researchers to investigate fungal mycelium.