Project description:Here, we established a successive Fe0-enhanced microbe system to remove azo dye (a typical organic pollutant) by Shewanella decolorationis S12 (S. decolorationis S12, an effective azo dye degradation bacterium) and examined the gene expression time course (10, 30, 60, and 120 min) in whole genome transcriptional level. Comparing with the treatment without ZVI, approximately 8% genes affiliated with 10 different gene expression profiles in S. decolorationis S12 were significantly changed in 120 min during the ZVI-enhanced microbial azo reduction. Intriguingly, MarR transcriptional factor might play a vital role in regulating ZVI-enhanced azo reduction in the aspect of energy production, iron homeostasis, and detoxification. Further investigation showed that induced [Ni-Fe] H2ase genes (hyaABCDEF) and azoreductase genes (mtrABC-omcA) contributed to ZVI-enhanced energy production, while reduced iron uptake (hmuVCB and feoAB), induced sulfate assimilation (cysPTWA) and cysteine biosynthesis (cysM) related genes were essential to iron homeostasis and detoxification. This study disentangles underlying mechanisms of ZVI-enhanced azo reduction in S. decolorationis S12 and lays a foundation for further optimization of integrated ZVI-microbial system for efficient organic pollution treatment.
Project description:Rhizoremediation, the biotechnology of the utilization of rhizospheric microorganisms associated with plant roots for the elimination of soil contaminants, is based on the ability of microorganisms to metabolize nutrients from plant root exudates, in order to survive the stressful conditions of the rhizosphere, and thereby, to co-metabolize or even mineralize toxic environmental contaminants. Novosphingobium sp. HR1a is a bacterial strain able to degrade a wide variety of polycyclic aromatic hydrocarbons (PAHs). We have demonstrated that this bacterium is able to grow in vegetated microcosms and to eliminate phenanthrene in the presence of clover faster than in non-vegetated systems, establishing a positive interaction with clover. We have studied the molecular basis of this interaction by phenomic, metabolomic and transcriptomic analyses, demonstrating that the positive interaction between clover and Novosphingobium sp. HR1a is a result of the bacterial utilization of different carbon and nitrogen sources (such as sugars, amino acids and organic acids) released during seedling development, and the capacity of exudates to induce the PAH degradation pathway. These results are pointing out to Novosphingobium sp. HR1a as a promising strain for the bioremediation of PAH-contaminated soils.
Project description:Aromatic diketones are a major product of formic acid lignin depolymerization. Novosphingobium aromaticivorans can degrade these diketones, but the enzymes used in this process were unknown. We used RNA-Seq to identify aromatic dimer dehydrogenases as potential candidates for the initial reduction of the aromatic G-diketone, then verified this using in vitro enzyme assays.
