Surfactant Enhanced Biphenyl Bioavailability Study

In this study a microbial system for biphenyl biodegradation is set up in order to investigate the effects of surfactants on biodegradation of hydrophobic organic compounds. Four strains which can grow on biphenyl as the sole carbon and energy sources are selected out, in which Alcaligenes eutrophus DJ1 and Pseudomonas SMS02 are chosen as degradation strains. After studing the bioavailability of three nonionic surfactants (OP-10, Tween-80, and Triton X-100), they are added into the biodegradation system of biphenyl. The major experimental results are listed as follows: l)The lag time of Alcaligenes eutrophus DJ1 and Pseudomonas SM302 decrease from 255h and 216h to 24h and 3.5h, respectively, and the cells grow better one by one generation after four batchs of domestication. 2)Both strains can grow in presence of the nonionic surfactants of OP-10, Tween-80, Triton X-100 as the sole carbon source, among which OP-10 and Tween-80 are more suitable than Triton X-100 due to their high bioavailability. 3)When the concentrations of surfactants are below their critical micelle concentrations (CMCs), their effects of promoting the solubility of biphenyl are undetectable. If the concentrations of surfactants are beyond CMCs, they will promote the solubility of biphenyl in direct proportion. 4) The biodegradation rates of biphenyl increase to more than three times by adding surfactants above their CMCs into the microbial system, while little effects are observed at the cases of addition of surfactants below their CMCs. As a conclusion it could be drawn that the bioavailability of biphenyl can increase with the help of nonionic surfactants at high concentrations beyond their CMCs in the microbial system.