Microbial-mediated metal(loid) immobilization in mulch-covered tailings.

Mulch coverage of mining tailings can create anaerobic conditions and consequently establish an anoxic environment that promotes the metabolic processes of anaerobic microorganisms. This anoxic environment has the potential to decrease heavy metal mobility and bioavailability. While tailings exposed to sunlight have been extensively studied, research on the effects of microbial-mediated geochemical cycling of heavy metals in mulch-covered tailings is scarce. This study aimed to examine the effects of mulch coverage-induced alterations in the structures of tailing microbial communities on the biogeochemical processes associated with heavy metals. Mulch coverage significantly reduced the pH of the tailings and the tailings exhibited heavy metal bioavailability. Random forest analysis demonstrated that mulch coverage-induced changes in the As/Cd-contaminated fractions and nutrients (total organic carbon and total nitrogen) were the most crucial predictors of microbial diversity and ecological clusters in the tailings. Notably, different from direct metal(loid) immobilization, mulch coverage can facilitate heavy metal immobilization in tailings by promoting microbial-mediated Fe, S, and As reduction. Overall, this study demonstrated that mulch coverage of tailings contributed to a reduction in heavy metal mobilization, which can be attributed to shifts in microbial-mediated Fe, S, and As reduction processes.The study provides valuable insights into the potential of mulch coverage as a remediation strategy and underscores the importance of microbial-mediated processes in managing heavy metal pollution in tailing systems.

Elimination of pathogenic multidrug resistant isolates through different metal oxide nanoparticles synthesized from organic plant and microbial sources.

Beta-hemolytic multidrug-resistant bacteria (MDR) are highly regarded as a major public health risk because they are resistant to at least 10 antibiotics in different groups with different mechanisms of action. The present study shows that among 98 bacterial isolates collected from laboratory fecal samples: 15 were beta-hemolytic and tested against 10 different antibiotics. 15 beta-hemolytic; 5 isolates exhibit strong multidrug resistance traits. Isolate 5 Escherichia coli (E. coli), Isolate 7 (E. coli), Isolate 21 (Enterococcus faecium), Isolate 27 (Staphylococcus sciuri), and isolate 36 (E. coli) are largely untested antibiotics. Substances (clear zone >10 mm) Its growth sensitivity to different types of nanoparticles was further evaluated by the agar well diffusion method. AgO, TiO2, ZnO, and Fe3O4 nanoparticles have been separately synthesized by microbial and plant-mediated biosynthesis. By evaluating the antibacterial activity of different nanoparticle types against selected MDR isolates, the results showed that global MDR bacterial growth was inhibited differently depending on the nanoparticle type. TiO2 was the most potent antibacterial nanoparticle type, followed by AgO, while Fe3O4 showed the least efficacy against selected isolates. The MICs of microbially synthesized AgO and TiO2 nanoparticles were 3 µg (67.2 µg/mL) and 9 µg (180 µg/mL) for isolates 5 and 27, respectively, indicating that biosynthetic nanoparticles via pomegranate of antibacterial activity at a higher MIC than microbial-mediated ones, it recorded (300 and 375 µg/ml, respectively) of AgO and TiO2 nanoparticles for isolates 5 and 27. Biosynthesized nanoparticles were examined by TEM, the average sizes of microbial AgO and TiO2 nanoparticles were 30 nm and 70 nm, respectively, and the average sizes of plant mediated AgO and TiO2 NPs were 52 nm and 82 nm respectively. Two most potent extensive MDR isolates (5 and 27) were identified as E. coli and Staphylococcus sciuri by 16s rDNA technology, and the sequencing results of the isolates were deposited with NCBI GenBank under accession numbers ON739202 and ON739204, respectively.

Initial Formation and Accumulation of Manganese Deposits in Drinking Water Pipes: Investigating the Role of Microbial-Mediated Processes.

Microbial Mn(II) oxidation occurs in areas with insufficient disinfectants in drinking water distribution systems. However, the overall processes of microbial-mediated Mn deposit formation are unclear. This research investigated the initial Mn(II) oxidation, deposit accumulation, and biofilm development in pipe loops fed with nondisinfected finished water for 300 days. The results show that it took 20 days for microbial Mn(II) oxidation and deposition to be initiated visibly in new pipes continuously receiving 100 µg/L Mn(II). Once started, the deposit accumulation accelerated. A pseudo-first-order kinetic model could simulate the disappearance of Mn(II) in well-mixed pipe loop water. The observed rate constant reached 2.81 h-1 [corresponding to a Mn(II) half-life of 0.25 h] after 136 days of operation. Without oxygen, Mn(II) in the water also decreased rapidly to 1.0 µg/L through adsorption to deposits, indicating that after the initial microbial formation of MnOx, subsequent MnOx accumulation was attributable to a combination of microbial and physicochemical processes. Compared to the no-Mn condition, Mn(II) input resulted in 1 order of magnitude increase in biofilm formation. This study sheds light on the increasingly rapid processes of Mn accumulation on the inner surfaces of water pipes resulting from the biological activity of Mn(II)-oxidizing biofilms and the build-up of MnOx with strong adsorption capacity.

Microbial synthesized cadmium oxide nanoparticles induce oxidative stress and protein leakage in bacterial cells.

The bactericidal activity of metal oxide nanoparticles (NPs) offers extensive opportunities in bioengineering and biomedicines. Bioengineered transition metals used in various forms against lethal microbes. In this study, Cadmium Oxide nanoparticles (CdO-NPs) were prepared through the co-precipitation method using fungal strain Penicillium oxalicum and cadmium acetate solution. The structure and elemental composition of the prepared NPs were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Antibacterial activity was assessed through well diffusion method against Staphylococcus aureus (S. aureus), Shigella dysenteriae (S. dysenteriae), and Pseudomonas aeruginosa (P. aeruginosa). In addition, reactive oxygen species (ROS), reducing sugars and protein leakage contribution was examined against selected strains. The XRD analysis proved that the synthesized CdO-NPs possess a crystalline structure with an average crystalline size of 40-80 nm. FTIR confirmed the presence of organic compounds on the particle surface, while UV showed stability of the particles. SEM and EDS confirmed that CdO-NPs were successfully prepared and spherical. The maximum zone of inhibition against S. dysenteriae and P. aeruginosa was found and showed a less optical density of 0.086 after 18 h. ROS, reducing sugar, and protein leakage assay showed a significant difference as compared to control. Based on the present study, it is recommended that microbial mediated synthesized nanoparticles can be used as biomedicines for the treatment of different types of bacterial infections.

How nutrient loading leads to alternative stable states in microbially mediated N-cycle pathways: A new insight into bioavailable nitrogen removal in urban rivers.

Excessive nutrients have disrupted pathways of microbial-mediated nitrogen (N) cycle in urban rivers and caused bioavailable N to accumulate in sediments, while remedial actions sometimes fail to recover degraded river ecosystems even when environmental quality has been improved. It is not sufficient to revert the ecosystem to its original healthy state by restoring the pre-degradation environmental conditions, as explained by alternative stable states theory. Understanding the recovery of disrupted N-cycle pathways from the perspective of alternative stable states theory can benefit effective river remediation. Previous studies have found alternative microbiota states in rivers; however, the existence and implications of alternative stable states in microbial-mediated N-cycle pathway remain unclear. Here, high-throughput sequencing and N-related enzyme activities measurement were combined in the field investigation to provide empirical evidence for the bi-stability in microbially mediated N-cycle pathways. According to the behavior of bistable ecosystems, the existence of alternative stable states in microbial-mediated N-cycle pathway have been shown, and nutrient loading, mainly total nitrogen and total phosphorus, were identified as key driver of regime shifts. In addition, potential analysis revealed that reducing nutrient loading shifted the N-cycle pathway to a desirable state characterized by high ammonification and nitrification, probably avoiding the accumulation of ammonia and organic N. It should be noted that the improvement of microbiota status can facilitate the recovery of the desirable pathway state according to the relationship between microbiota states and N-cycle pathway states. Keystone species, including Rhizobiales and Sphingomonadales, were discerned by network analysis, and the increase in their relative abundance may facilitate the improvement of microbiota status. The obtained results suggested that the nutrient reduction should be combined with microbiota management to benefit the bioavailable N removal in urban rivers, therefore providing a new insight into alleviating adverse effects of the nutrient loading on urban rivers.

Interplay between PCOS and microbiome: The road less travelled.

Polycystic ovarian syndrome (PCOS) is a complicated neuro-endocrinal, reproductive, and metabolic condition. It encompasses patterns such as hyperandrogenism, recurrent cysts triggered by steroidogenic functional aberrations in the ovaries, overweight, chronic inflammation, and more. The underlying cause of this heterogeneous illness is obscure, although it is suspected to be driven by a blend of environmental and hereditary factors. In recent years, the connection between the microbiome and PCOS has been acknowledged and is thought to be involved in the genesis of the syndrome's emergence. Microbiota vary in different pathological features of PCOS, and fundamental pathways linked to their involvement in the commencement of diverse clinical presentations in PCOS open up a new avenue for its management. Prebiotic, probiotic, synbiotic, and fecal-microbiota-transplant, by promoting eubiosis and nullifying the effect caused by the altered microbial profile in PCOS women, can aid in management of diverse phenotypes associated with the syndrome. These microbiota-mediated treatments improve PCOS women's metabolic, inflammatory, and hormonal profiles. However, more studies are needed to elucidate the mechanisms that drive this positive effect.

Incorporating the soil environment and microbial community into plant competition theory.

Plants affect microbial communities and abiotic properties of nearby soils, which in turn influence plant growth and interspecific interaction, forming a plant-soil feedback (PSF). PSF is a key determinant influencing plant population dynamics, community structure, and ecosystem functions. Despite accumulating evidence for the importance of PSF and development of specific PSF models, different models are not yet fully integrated. Here, we review the theoretical progress in understanding PSF. When first proposed, PSF was integrated with various mathematical frameworks to discuss its influence on plant competition. Recent theoretical models have advanced PSF research at different levels of ecological organizations by considering multiple species, applying spatially explicit simulations to examine how local-scale predictions apply to larger scales, and assessing the effect of PSF on plant temporal dynamics over the course of succession. We then review two foundational models for microbial- and litter-mediated PSF. We present a theoretical framework to illustrate that although the two models are typically presented separately, their behavior can be understood together by invasibility analysis. We conclude with suggestions for future directions in PSF theoretical studies, which include specifically addressing microbial diversity to integrate litter- and microbial-mediated PSF, and apply PSF to general coexistence theory through a trait-based approach.