Potential Of Fungal Biotechnology

It has been recognized for decades that many microorganisms have a physiology, which allows them to act on

Table 2 Pretreatment standards based upon Best Practical Control Technology (BPT) for existing sources of metal finishing wastewaters. Discharges for releases of 10,000 or more ga (38,0001) a day in the United States. (40 CFR (Code of Federal Regulations of the U.S.) 413)

Metal ion

Maximum for any 1 day

Average daily value for 30 consecutive days

Cu

3.38 mg/l

2.07 mg/l

Ni

3.98

2.38

Cr

2.77

1.71

Zn

2.61

1.48

Pb

0.69

0.43

Cd

0.69

0.26

Ag

0.43

0.24

toxic metal ions and to alter them in such a way that renders those ions less harmful. In fact, genetic adaptation to survival of microorganisms in heavy metal-rich environments is not at all unusual in nature (Nies 1999; Ow 1996).

One aim of biotechnology is to put that special physiology to use and produce a commercial product (cell or cell component) for remediating heavy metal contamination. Biological materials that can accomplish this mission may be therefore termed biotraps and can be grouped into three major categories based on function:

a. Biosorption or the process by which individual cells or cell components bind or take up metals a. Adsorption of ions onto a surface, including ion exchange and complexing with ligands, and b. Uptake into the cell and sequestration by cytoplasmic components, b. Transformation by oxidation/reduction into a less toxic or volatile form, and c. Precipitation by forming insoluble salts, or by a combination of these processes.

This review discusses general heavy metal bioremediation processes rather than have to deal with each group of organisms individually.

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