Bisphenol A is an organic compound used in the production of many plastic products throughout the industrial world. Since 2008, companies and governments have been questioning its safety and it has garnered considerable attention lately for being an environmental pollutant and for having adverse effects on human endocrine systems, resulting in potential birth defects and other health problems. Bisphenol A is not soluble in water, so factories that operate near rivers or lakes tend to deposit a great deal of this toxic material into the water, along with many other pollutants, that cannot be easily removed. The work of Shimoda et al. (2011) is one study in a sea of recent research into bioremediation, a cheap and safe process that essentially uses microorganisms to remove harmful chemicals from a particular medium through biotransformation. The researchers involved in this study used a microalgal species, Amphidinium crassum, and immobilized cells from a plant species, Catharanthus roseus, to biotransform bisphenol A, and recorded promising results. Biotransformation refers to the effect an organism has on any chemical compound and in this case the two plant species broke the bisphenol A down into glucosides, which is a glucose containing compound the plant can store to metabolize for energy later. This is accomplished by glycosylation, a process common to many plants. The results of this study show clearly that each species is capable of removing bisphenol A from aquatic environments, leaving behind a harmless, soluble organic compound and producing energy for itself, giving further evidence to the usefulness of bioremediation.—Edward McLean
Shimoda, K., Yamamoto, R., Hamada H. 2011. Bioremediation of Bisphenol A by Glycosylation with Immobilized Marine Microalga Amphidinium crassum. Advances in Chemical Engineering and Science, 2011, 1, 90-95.
In this short-and-to-the-point study, Shimoda et al. used the natural process of glycosylation to produce their results, but needed an impressive amount of cultured cells to carry out the experiment. For each trial, they used a centrifuge to separate algal or immobilized cells out of the water, in which they had been incubating for two weeks, until 9 g of plant material had been collected. Using lab manufactured sea water (free of organic compounds) as solution, the plant cells were exposed to bisphenol A and incubated for five days at a time, with measurements being taken daily. The solution was analyzed each day using high-performance liquid chromatography (HPLC), a common method used in biochemistry that separates organic compounds and allows researchers to identify and quantify particular chemicals. Many organic compounds can be biotransformed by plants through the process of glycosylation. The chemical that forms as a result of glycosylation is known as a glucoside, and each plant makes its own unique compound. In this experiment, Shimoda et al. measured the amount of bisphenol A that had been biotransformed by recording the amount of the glucoside that the plant cells synthesized each day and how much less bisphenol A remained. Several trials using both species all returned the same positive results, and within just five days of incubation, up to 17% of the bisphenol A that had been added to the solution had been removed, while the lowest yield still showed a promising 4% removal.
Breakthroughs in bioremediation are happening at an astonishing rate, and many companies and environmental agencies are recognizing the wide-ranging applications of bioremediation, especially because these methods are often inexpensive and harmless. The metabolic machinery that has evolved naturally on this planet is elegant and often far better equipped to handle pollutants than our most dazzling inventions. As a result, the safest way to detoxify our water and soil is through the careful, regulated application of beneficial microorganisms to affected areas. The authors conclude their study optimistically, while mentioning companion studies being carried out by colleagues in the field, noting several other species that might be useful in other bioremediation efforts. Let’s hope many more follow in their footsteps as increased funding for such practices becomes available.