Mechanism of microbial utilization of biphenyl sorbed to polyacrylic beads.

A microbial consortium mineralized biphenyl sorbed to polyacrylic beads faster than the slow rate at which much of the compound was desorbed. Pure cultures of bacteria isolated from the consortium mineralized biphenyl in solution but not the sorbed compound. However, combinations of two strains did degrade biphenyl. The consortium did not reduce the surface tension in media containing sorbed biphenyl or biphenyl in solution, and addition of synthetic and microbially produced surfactants to pure cultures did not result in utilization of sorbed biphenyl by isolates able to use the soluble molecule. Cells from the consortium that were attached to continuously washed beads degraded the substrate. We suggest that bacteria may act on sorbed compounds without the necessity of an initial desorption and that the mechanism may involve cells attached to the particles rather than the excretion of a surfactant.