Simultaneous removal of nitrate, tetracycline, and Pb(II) by iron oxidizing strain Zoogloea sp. FY6: Performance and mechanism.

Based on the prevalence of combined antibiotics and heavy metals contamination in the aquatic environment, this study utilized a microbial approach to achieve simultaneous removal of nitrate (NO3--N), tetracycline (TTC), and Pb(II). Zoogloea sp. FY6 could achieve an optimal NO3--N removal efficiency of 91.5% under C/N ratio of 2.0, at a pH of 6.3, and Fe(II) concentration of 20.23 mg L-1 based on response surface methodology. Additionally, strain FY6 was further found to achieve 89.9 and 81.7% removal of TTC and Pb(II) at 6 h under the optimal conditions. Finally, the results of Fluorescence excitation-emission matrix, X-ray diffraction, Fourier transform infrared spectrometer, and X-ray photoelectron spectroscopy further proved that the biologically formed nanoscale iron oxides and biological action jointly led to the removal of TTC and Pb(II). This study provided a theoretical basis for the application of microbially driven process to remove multi-pollutants in micro-polluted water bodies.

Single-step removal of calcium, fluoride, and phenol from contaminated water by Aquabacterium sp. CZ3 via facultative anaerobic microbially induced calcium precipitation: Kinetics, mechanism, and characterization.

Confronting the complex contaminated water, Aquabacterium sp. CZ3 could perform microbially induced calcium precipitation (MICP) under facultative anaerobic condition using phenol as supplementary carbon source. Strain CZ3 exhibited a remarkable ability to remove nitrate, fluoride, calcium and phenol with removal rates of 100.00, 87.50, 66.24 and 100.00%, respectively. The Modified Gompertz model was used for kinetic analysis to determine the optimum conditions for denitrification and degradation of phenol. The mechanism of anaerobic MICP was enhanced by measuring the self-aggregation properties of the isolates. The mechanism of fluoride removal was identified as co-precipitation and adsorption by characterization analysis of the bioprecipitation. Furthermore, the changes in soluble metabolites under phenol stress explained the utilization of phenol as a co-substrate by microorganisms. This is a novel report on phenol degradation by anaerobic MICP, which provides a theoretical basis for expanding its practical application.

Denitrification strategy of Pantoea sp. MFG10 coupled with microbial dissimilatory manganese reduction: Deciphering the physiological response based on extracellular secretion.

In this study, the manganese (Mn) reduction-coupled denitrification strategy of dissimilatory Mn reducing bacteria was insightfully investigated. Different parameters (MnO2 level, pH, and temperature) were optimized by kinetic fitting to improve denitrification and Mn reduction effects. The 300 mg L-1 MnO2 addition achieved 98.72% NO3--N removal in 12 h, which was 54.62% higher than blank group without MnO2. Scale-up studies showed that the metabolic activity of the bacteria was effectively enhanced by the addition of MnO2. Besides the deepening of humification in the system, tryptophan-like protein and polysaccharide as potential electron donor precursors revealed remarkable contributions to the extracellular secretion-dependent denitrification process of DMRB. The effect of EPS on Mn reduction depends mainly on the capture of MnO2 by the LB-EPS layer versus its dissolution in the TB-EPS layer. Ultimately, the EPS possess a dual effect of accelerated denitrification and Mn reduction efficiency due to the enhanced EET process.