Copper and zinc adsorption from bacterial biomass - possibility of low-cost industrial wastewater treatment

Zinc and Copper Oxide Nanoparticles: Pioneering Antibacterial and Antibiofilm Strategies for Environmental Restoration against Antibiotic-Resistant Bacteria

This study explores the challenge of antimicrobial resistance by investigating the utilization of zinc oxide (ZnO) and copper oxide (Cu2O) nanoparticles (NPs) to combat antibiotic-resistant bacteria in wastewater treatment plants (WWTPs). The synthesized metal oxide NPs underwent thorough characterization through various analytical techniques, confirming their nanoparticulate nature. Electronic absorption and X-ray diffraction (XRD) analyses revealed successful reduction processes and crystalline properties, respectively. Fourier transform infrared spectroscopy (FTIR) results indicated the stabilization of nanoparticles in solution. Scanning electron microscopy (SEM) observations revealed well-defined spherical and flower-like morphologies for the zinc and copper oxide nanoparticles, with sizes approximately ranging from 50 nm to 25 nm Notably, the synthesized nanoparticles exhibited heightened efficacy in impeding biofilm formation, with zinc oxide NPs displaying superior antibacterial activity compared to copper. These findings suggest the promising potential of these nanoparticles in controlling antibiotic-resistant organisms, even following WWTP treatment processes. This research contributes to the ongoing advancements in nanotechnology aimed at combating antibiotic resistance, offering new prospects for the development of effective wastewater treatment strategies.

Copper biosorption by Bacillus pumilus OQ931870 and Bacillus subtilis OQ931871 isolated from Wadi Nakheil, Red Sea, Egypt

BACKGROUND

Despite being necessary, copper is a toxic heavy metal that, at high concentrations, harms the life system. The parameters that affect the bioreduction and biosorption of copper are highly copper-resistant bacteria.

RESULTS

In this work, the ability of the bacterial biomass, isolated from black shale, Wadi Nakheil, Red Sea, Egypt, for Cu2+ attachment, was investigated. Two Cu2+ resistance Bacillus species were isolated; Bacillus pumilus OQ931870 and Bacillus subtilis OQ931871. The most tolerant bacterial isolate to Cu2+ was B. pumilus. Different factors on Cu2+ biosorption were analyzed to estimate the maximum conditions for Cu biosorption. The qmax for Cu2+ by B. pumilus and B. subtilis determined from the Langmuir adsorption isotherm was 11.876 and 19.88 mg. g-1, respectively. According to r2, the biosorption equilibrium isotherms close-fitting with Langmuir and Freundlich model isotherm. Temkin isotherm fitted better to the equilibrium data of B. pumilus and B. subtilis adsorption. Additionally, the Dubinin-Radushkevich (D-R) isotherm suggested that adsorption mechanism of Cu2+ is predominately physisorption.

CONCLUSION

Therefore, the present work indicated that the biomass of two bacterial strains is an effective adsorbent for Cu2+ removal from aqueous solutions.

Integrated Omics Approach to Discover Differences in the Metabolism of a New Tibetan Desmodesmus sp. in Two Types of Sewage Treatments

Microalgae are now widely applied in municipal (YH_3) and industrial sewage (YH_4) treatments. Through integrated omics analysis, we studied the similarities and differences at the molecular level between the two different types of sewage treatment processes. The most significantly enriched gene ontology (GO) terms in both types of sewage treatments were the ribosome, photosynthesis, and proteasome pathways. The results show that the pathways of differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were enriched for photosynthesis, glyoxylate and dicarboxylate metabolism, and carbon fixation in photosynthetic organisms. Considering YH_3 vs. YH_4, the metabolism of citrate, sedoheptulose-7P, and succinate was significantly upregulated. In addition, the results showed that the pathways of DEGs and DAMs were enriched in terms of amino acid metabolism and carotenoid biosynthesis in YH_4 vs. YH_3. The metabolism of S-Adenosyl-L-homocysteine was significantly downregulated, 2-oxobutanoate was significantly upregulated and downregulated, and the metabolism of abscisic acid glucose ester (ABA-GE) was also significantly upregulated. Overall, the results of this paper will help to improve the basic knowledge of the molecular response of microalgae to sewage treatments, and help design a response strategy based on microalgae for complex, mixed sewage treatments.

Bacillus coagulans XY2 ameliorates copper-induced toxicity by bioadsorption, gut microbiota and lipid metabolism regulation

Excessive copper pollutes the environment and endangers human health, attracting plenty of global attention. In this study, a novel strain named Bacillus coagulans XY2 was discovered to have a great copper tolerance and adsorption capacity. B. coagulans XY2 might maintain copper homeostasis through multisystem synergies of copper resistance, sulfur metabolism, Fe-S cluster assembly, and siderophore transport. In mice, by promoting the expression of SREBF-1 and SREBF-2 and their downstream genes, B. coagulans XY2 significantly inhibited the copper-induced decrease in weight growth rate, ameliorated dyslipidemia, restored total cholesterol and triglyceride contents both in serum and liver. Furthermore, B. coagulans XY2 recovered the diversity of gut microbiota and suppressed the copper-induced reduction in the ratio of Firmicutes to Bacteroidota. Serum metabolomics analysis showed that the alleviating effect of B. coagulans XY2 on copper toxicity was mainly related to lipid metabolism. For the first time, we demonstrated mechanisms of copper toxicity mitigation by B. coagulans XY2, which was related to self-adsorption, host copper excretion promotion, and lipid metabolism regulation. Moreover, working model of B. coagulans XY2 on copper homeostasis was predicted by whole-genome analysis. Our study provides a new solution for harmfulness caused by copper both in human health and the environment.

Harnessing the Potential of Bacillus altitudinis MT422188 for Copper Bioremediation

The contamination of heavy metals is a cause of environmental concern across the globe, as their increasing levels can pose a significant risk to our natural ecosystems and public health. The present study was aimed to evaluate the ability of a copper (Cu)-resistant bacterium, characterized as Bacillus altitudinis MT422188, to remove Cu from contaminated industrial wastewater. Optimum growth was observed at 37°C, pH 7, and 1 mm phosphate, respectively. Effective concentration 50 (EC50), minimum inhibitory concentration (MIC), and cross-heavy metal resistance pattern were observed at 5.56 mm, 20 mm, and Ni > Zn > Cr > Pb > Ag > Hg, respectively. Biosorption of Cu by live and dead bacterial cells in its presence and inhibitors 1 and 2 (DNP and DCCD) was suggestive of an ATP-independent efflux system. B. altitudinis MT422188 was also able to remove 73 mg/l and 82 mg/l of Cu at 4th and 8th day intervals from wastewater, respectively. The presence of Cu resulted in increased GR (0.004 ± 0.002 Ug−1FW), SOD (0.160 ± 0.005 Ug−1FW), and POX (0.061 ± 0.004 Ug−1FW) activity. Positive motility (swimming, swarming, twitching) and chemotactic behavior demonstrated Cu as a chemoattractant for the cells. Metallothionein (MT) expression in the presence of Cu was also observed by SDS-PAGE. Adsorption isotherm and pseudo-kinetic-order studies suggested Cu biosorption to follow Freundlich isotherm as well as second-order kinetic model, respectively. Thermodynamic parameters such as Gibbs free energy (∆G°), change in enthalpy (∆H° = 10.431 kJ/mol), and entropy (∆S° = 0.0006 kJ/mol/K) depicted the biosorption process to a feasible, endothermic reaction. Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-Ray Spectroscopy (EDX) analyses revealed the physiochemical and morphological changes in the bacterial cell after biosorption, indicating interaction of Cu ions with its functional groups. Therefore, these features suggest the potentially effective role of B. altitudinis MT422188 in Cu bioremediation.