Effect of lead on mustard plant.

Lead contamination is a problem in eastern Missouri; an area often termed the "lead belt". Lead may accumulate in soil, posing a hazard for children in contact with the soil. Ingestion of bioavailable lead causes lead poisoning, which leads to impairment of mental function. Lead is classified as a persistent contaminant, since it binds tightly with the soil. Land that is left untreated will continue to be hazardous for many years. Current methods of cleanup can be costly and ineffective for long-term treatment. One possible method of cleanup is the use of lead altering bacteria in conjunction with lead resistant plants. The mustard plant in particular has shown to have some lead resistant qualities to it. When grown in soil containing substantial amounts of lead it has been able to thrive and reach maturity within a normal time frame. Our experiments showed that a 0.5 mM Pb solution stunted the growth of the plant by at least 43% compared to those plants with no lead added. From this discovery we decided to add three different lead resistant bacterial strains to the contaminated soil to see if the bacteria could enhance plant growth at all. Variovorax paradoxis, Pseudomonas fluorescens, and an unknown Pb resistant bacteria were each added to the soil of a mustard plant both with lead and without lead. The plants that grew the closest to normal were the ones in lead contaminated soil with the Variovorax paradoxis bacteria while addition of the other strains showed a decrease in plant growth and in some cases no growth at all.

* Kulhanek, L. and T. Giblin. Department of Natural Sciences, Stephens College.