Application of cinder gel-beads/reeds combination strategy for bioremediation of pyrene- and indeno(1,2,3-cd)pyrene-contaminated estuarine wetlands.

Pseudomonas putida PYR1 and Acinetobacter baumannii INP1 isolated from Liaohe estuarine wetlands were entrapped in cinder beads to make cinder gel-beads. They were combined with reeds for bioremediation of pyrene- and indeno(1,2,3-cd)pyrene-contaminated estuarine wetlands. The results showed that the removal percentages of pyrene and indeno(1,2,3-cd)pyrene (69.2 and 89.8 % respectively) in 40 days using cinder gel-beads/reeds were obviously higher than those using cinder gel-beads(52.6 and 70.0 %) and reeds (33.5 and 78.6 %) alone, about four times those of the control (13.8 and 31.1 %). The removal efficiency of pyrene was in the order cinder gel-beads/reeds > cinder gel-beads > reeds > control, which was different from cinder gel-beads/reeds > reeds > cinder gel-beads > control of indeno(1,2,3-cd)pyrene. This result indicated that the functional mechanism to remove indeno(1,2,3-cd)pyrene with six benzene rings was different from that of pyrene. The synergistic effect of reeds and cinder gel-beads for indeno(1,2,3-cd)pyrene removal was weaker than that of pyrene. But the absorption and transformation of reeds with high efficiency were beneficial to indeno(1,2,3-cd)pyrene removal from wetlands. Additionally, microbial analysis with high-throughput sequencing presented that Gammaproteobacteria were dominant PAH-degrading groups in bioremediation with immobilized bacteria. This strategy can serve as a model system for the removal of more complex or structurally related organic compounds from contaminated sites.