Analysis of Phenol Biodegradation in Antibiotic and Heavy Metal Resistant Acinetobacter lwoffii NL1

Phenol is a common environmental contaminant. The purpose of this study was to isolate phenol-degrading microorganisms from wastewater in the sections of the Chinese Medicine Manufactory. The phenol-degrading Acinetobacter lwoffii NL1 was identified based on a combination of biochemical characteristics and 16S rRNA genes. To analyze the molecular mechanism, the whole genome of A. lwoffii NL1 was sequenced, yielding 3499 genes on one circular chromosome and three plasmids. Enzyme activity analysis showed that A. lwoffii NL1 degraded phenol via the ortho-cleavage rather than the meta-cleavage pathway. Key genes encoding phenol hydroxylase and catechol 1,2-dioxygenase were located on a megaplasmid (pNL1) and were found to be separated by mobile genetic elements; their function was validated by heterologous expression in Escherichia coli and quantitative real-time PCR. A. lwoffii NL1 could degrade 0.5 g/L phenol within 12 h and tolerate a maximum of 1.1 g/L phenol, and showed resistance against multiple antibiotics and heavy metal ions. Overall, this study shows that A. lwoffii NL1 can be potentially used for efficient phenol degradation in heavy metal wastewater treatment.

Mechanistic Insight of Biochar-layered Double Hydroxide Composite for Efficient Removal of Aqueous Pb(II) and Cu(II)

To explore the heavy metal adsorption mechanisms by biochar-based materials, MgAl-layered double hydroxide (MgAl-LDH) was loaded on a commercial coconut shell biochar (BC) to obtain the composite (BC-LDH) for adsorptive decontamination of Pb(II) and Cu(II) in water. The removal capacities of BC-LDH (294 and 38.6 mg/g) was higher than BC (13.3 and 11.4 mg/g) and LDH (126 and 22.7 mg/g) for aqueous Pb(II) and Cu(II). The pseudo-second-order equation and the Langmuir model could better illustrate the adsorption process, respectively. The interaction mechanisms between BC-LDH and heavy metals were classified as mineral precipitation (Qpre), cation exchange and isomorphic replacement (Qexc), electrostatic attraction (Qele), and surface complexation (Qcom) according to the characterization results. The quantitative analysis indicated that the contributions of the above mechanisms of BC-LDH for Pb(II) and Cu(II) followed the order of Qpre > Qele > Qexc and Qpre > Qexc > Qele, respectively. Compared with BC, the Qpre increased and Qele decreased significantly, certified the combination of BC and LDH provided a kind of viable composite in heavy metal wastewater treatment.

The performance of wastewater treatment by two-species immobilized lignin-degrading mycelial pellet GX-1310

This study found a new type of immobilized mycelial pellet GX-1310, which can better treat industrial wastewater. Among them, Aspergillus fumigatus G-13 (degradable lignin) was combined with Bacillus cereus X10-1-2 (having the ability to produce cellulase), and the two synergistically produce strong degradation ability. Taking combined mycelial pellet as the research object, its ability to treat papermaking wastewater, heavy metal wastewater and dye wastewater was investigated. The combined mycelial pellet was superior to the single fungal mycelium in the degradation of lignocellulose, removal of heavy metal ions and adsorption capacity of dyes. And the combined mycelial pellet has a wide range of application conditions (temperature range 28-34°C and pH range 4-8), which can maintain high processing capacity for papermaking wastewater, heavy metal wastewater and dye wastewater. After three batches of wastewater treatment, the combined mycelial pellet still maintains high activity and can continuously treat wastewater. The study fixed the single fungal mycelium together with cellulose-degrading bacteria, the strains producing different enzymes were combined to form a multi-functional combined mycelial pellet. This method provides a new way for industrial wastewater treatment.