Encapsulating Fungal Enzymes for Safer Oil Remediation

Mycoremediation is a form of bioremediation that uses fungi to break down and extract contaminants from the environment. Ligninocellulosic enzymes (including lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase) produced by wood-rotting fungi can also break down complex carbon-based chains found in heavy crude oils and other persistent environmental pollutants such as dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCBs) and dioxins. This makes mycoremediation a promising treatment alternative for soils and sediments contaminated with crude oil wastes, textile effluents, organochloride agrochemicals, pulp effluents and other pollutants. 

However, using live fungal cultures is problematic. Fungal organisms must have specific substrates and environmental conditions in order to produce the necessary enzymes. Introducing live non-native species may also present its own environmental risks. Applying the enzymes rather than the live cultures is considered to be safer and enables more precise application and dosage. Because the protein molecules in the enzymes degrade quickly when exposed to unfavorable environmental conditions, a solution was needed to stabilize the enzymes for storage and transport and activate them once they are applied. 

Battelle developed an encapsulation technology to protect the enzymes from physical and chemical degradation. Fungal enzymes are extracted from the fungi in the lab and encapsulated in a special polymer. The biodegradable shell is engineered to swell and break open in the presence of water and/or by the action of microbes on the polymer. This allows the enzyme to be kept in a stable formulation. The shells also provide necessary ions and activators for the enzyme to stay in the active state and reduce the potential for denaturation. This ensures that the enzymes will be delivered exactly when and where they are needed, without the risk of introducing a potentially invasive fungal species into the environment. The shell design may be altered to target different contaminants of interest. 

Studies conducted at Battelle have demonstrated that the encapsulated fungal enzymes are highly effective for biodegradation of heavy weathered crude oil with alkane chains representing fractions higher than C35. The enzymes break down the heavy hydrocarbon chains into shorter chains that can be more easily biodegraded by naturally occurring microbes. The technology has since been patented and is now available for remediation efforts at sites contaminated by petroleum hydrocarbons. Battelle is currently conducting tests to demonstrate its efficacy for sites contaminated by agrochemicals, PCBs and munitions constituents.