Cytodex dextran beads as a substrate for observing the effects of selenium on bacterial morphology

Abstract

Selenium, through the process of bioconcentration, can accumulate to reach toxic levels in the tissues of birds, fish and other wildlife. To date, little research has focused on the effect os selenium on bacteria and in particular, on the nitrifying bacteria which provide a considerable beneficial impact on the environment. Preliminary studies in our laboratory, have indicated that selenium can disrupt the nitrogen cycle by inhibiting the conversion of nitrite to nitrate by Nitrobacter spp. The effect of selenium on Nitrobacter is as of yet unknown. This break in the normal cycle allows nitrite, which is highly toxic in low levels to aquatic animals, to accumulate in the environment. This study was undertaken to investigate the effects of selenium assimilation, by nitrifying bacteria, on the nitrogen cycle and any resultant morphological changes in cell structure.