Methods of Bioremediation Used to Reduce Heavy Metals in Agriculture

Retired professor and Director of the Endophyte Lab at Oregon State University, A. Morrie Craig, Ph.D., has more than 40 years studying the microbiological processes that affect agriculture. More recently, Dr. Morrie Craig wrote a paper regarding the effects of phytobioremediation on agriculture, which involves using micro-organisms to clean the soil.

In general, bio-remediation is a complicated process that reduces the number of pollutants in soil and water. Finding ways to clean both water and soil is important because, unless the food is grown organically, the agricultural process dictates the use of heavy metals in fertilizers and pesticides. In fact, sulfides, oxides, silicates, and chromite (all minerals) are found in fertilizers and pesticides (only chromite).

The two ways that bio-remediation processes can reduce pollutants are bio-absorption and bio-accumulation. Furthermore, the micro-organisms involved in these processes are prokaryotes (bacteria) and eukaryotes (micro-algae, fungi, and yeast).

Bio-absorption is a passive process where microorganisms are mixed with a substance containing heavy metals. The micro-organism then absorbs the chemicals from water or soil-and thus removes the harmful pollutant.

Bio-accumulation is a little more complicated and is an active form of reducing the impact of pollutants in water or soil. While it might seem contradictory, the process involves the aggregation of metals within the substance.

However, proteins within the micro-organism bind to metals, detoxifying soil, or water. Also referred to as tolerance, these metal-binding proteins (typically found in bacteria and yeast) detoxify the source through changing the chemical structure of the heavy metals (pollutants).

Both processes are vital in that they provide those within the agricultural industry with ways to produce food safe for human consumption. Additional benefits of bio-remediation include its cost-effectiveness, it is non-toxic and non-corrosive, works quickly, non-hazardous, and it reduces special equipment needs found in other technologies designed to reduce pollution.