Enhanced biodegradation of sediment-bound heavily weathered crude oil with ligninolytic enzymes encapsulated in calcium-alginate beads.

The degradation of crude and weathered crude oil following the application of crude and calcium-alginate encapsulated ligninolytic enzymes was studied using in situ microcosms. Changes in the chemical composition of the oil were monitored in crude enzyme extracts, as well as a sediment matrix, for as long as 70 days. Compound-specific effects of ligninolytic enzymes applied to the sediments were observed over time through changes in concentration of total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAHs) and fractions of saturates, aromatics, resins and asphaltenes (SARA). As the oil weathered, most TPH and PAH fractions showed a rapid decrease in concentration. As sediment oil concentrations decreased following treatment with ligninolytic enzymes, the microbial population was enriched with hydrocarbon-degrading species. This trend demonstrates that the oil fractions initially not bioavailable for microbial degradation, were subsequently released to the sediment via catalytic conversion with laccase and manganese peroxidase, and the oil continues to be biodegraded by microbial populations.

Physiological Peculiarities of Lignin-Modifying Enzyme Production by the White-Rot Basidiomycete Coriolopsis gallica Strain BCC 142.

Sixteen white-rot Basidiomycota isolates were screened for production of lignin-modifying enzymes (LME) in glycerol- and mandarin peel-containing media. In the synthetic medium, Cerrena unicolor strains were the only high laccase (Lac) (3.2-9.4 U/mL) and manganese peroxidase (MnP) (0.56-1.64 U/mL) producers while one isolate Coriolopsis gallica was the only lignin peroxidase (LiP) (0.07 U/mL) producer. Addition of mandarin peels to the synthetic medium promoted Lac production either due to an increase in fungal biomass (Funalia trogii, Trametes hirsuta, and T. versicolor) or enhancement of enzyme production (C. unicolor, Merulius tremellosus, Phlebia radiata, Trametes ochracea). Mandarin peels favored enhanced MnP and LiP secretion by the majority of the tested fungi. The ability of LiP activity production by C. gallica, C. unicolor, F. trogii, T. ochracea, and T. zonatus in the medium containing mandarin-peels was reported for the first time. Several factors, such as supplementation of the nutrient medium with a variety of lignocellulosic materials, nitrogen source or surfactant (Tween 80, Triton X-100) significantly influenced production of LME by a novel strain of C. gallica. Moreover, C. gallica was found to be a promising LME producer with a potential for an easy scale up cultivation in a bioreactor and high enzyme yields (Lac-9.4 U/mL, MnP-0.31 U/mL, LiP-0.45 U/mL).

In-situ subaqueous capping of mercury-contaminated sediments in a fresh-water aquatic system, Part II-evaluation of sorption materials.

The function and longevity of traditional, passive, isolation caps can be augmented through the use of more chemically active capping materials which have higher sorptive capacities, ideally rendering metals non-bioavailable. In the case of Hg, active caps also mitigate the rate and extent of methylation. This research examined low cost, readily available, capping materials for their ability to sequester Hg and MeHg. Furthermore, selected capping materials were evaluated to inhibit the methylation of Hg in an incubation study as well as the capacity of a selected capping material to inhibit translocation of Hg and MeHg with respect to ebullition-facilitated contaminant transport in a column study. Results indicated that bauxite had a better capacity for mercury sorption than the other test materials. However, bauxite as well as soil capping materials did not decrease methylation to a significant extent. Materials with larger surface areas, higher organic matter and acid volatile sulfide (AVS) content displayed a larger partitioning coefficient. In the incubation experiments, the presence of a carbon source (lactate), electron acceptor (sulfate) and the appropriate strains of SRB provided the necessary conditions for Hg methylation to occur. The column study showed effectiveness in sequestering Hg and MeHg and retarding transport to the overlying water column; however, disturbances to the soil capping material resulting from gas ebullition negated its effectiveness.