Bioremedation:

To clean up the environment from toxic chemicals is called Bioremedation.

The main contaminants in polluted soils are:

1. Polycyclic Aromatic Hydrocarbons (PAH’s) viz. residues from the processing of oil, tar, coal and comparable substances.

2. Polychlorinated Biphenyls (PCB’s) used as cooling agents in transformers.

3. Dioxines: These are by-products of chemical manufacturing and are found in fly-ashes from combustion processes.

The general approaches to bioremediation are to enhance natural biodegradation by natural organisms (intrinsic bioaugmentation).

In-situ bioremediation involves treating contaminated materials at the site

 Ex-situ involves the removal of the contaminated material to be treated elsewhere

The easiest method of treating contaminated soil is to simply add organic matter to as many toxic metals will readily form compounds with the organic materials found in compost

 

MUSHROOMS AND BIOREMEDIATION

White-rot fungi is used for advantages for pollutant degradation. lignin decomposing white-rot fungi show extraordinary abilities to transform recalcitrant pollutants like polycyclic aromatic hydrocarbons (PAH’s)

WHITE-ROT FUNGI DEGRADATION SYSTEM

The main mechanism of biodegradation employed by this group of fungi is the lignin degradation system of enzymes. The major components of lignin degradation system include lignin peroxidase (LiP), manganese peroxidase (MnP), H2O2 producing enzymes.

Phanerochaete flavido-alba

Phanerochaete flavido-alba has been able to decolorize Olive oil mill wastewater (OMW), a major waste product of olive oil extraction for subsequent use in bioreme diation assays.

pleurotus ostreatus (Jacq. Fr.) P. Kumm

Recent studies have shown that P. ostreatus is able to degrade a variety of polycyclic aromatic hydrocarbons (PAH). It has the ability to degrade PAH in non-sterile soil both in the presence and in the absence of cadmium and mercury.

 
Pleurotus tuber-regium (Fries) Singer

Pleurotus tuber-regium (Fries) Singer   is to ameliorate crude oil polluted soil and the resulting soil sample supported seed germination and seedling growth of Vigna unguiculata. They reported a significant improvement in percentage germination, plant height and root elongation.

Due to the bioremediation of cutting fluids contaminated soil by P. tuber-regium, the soil's nutrient content improved, heavy metals were bioaccumulated, TPH and lignin were degradation, and polyphenol oxidase and peroxidase activity increased.

The application of white-rot fungi in bioremediation is expected to be relatively economical because the fungi can be grown on a number of inexpensive agricultural or forest wastes such as rice straw, corn cobs and sawdust. The fungal inoculum can also be mass-produced by current simple techniques used to produce fungal spawn. For economical and ecologically sound methods for environmental remediation, the use of mushrooms is a very good approach and solution.

The challenges faced in the field application such as contamination by other fungi especially Penicillium sp., Aspergillus spp. needs to be also looked into and solutions recommended.