External redox couple enhanced anammox sludge activity at low temperature: Insight into intracellular resource synthesis.

Anaerobic ammonium oxidation (anammox), an energy-efficient deamination biotechnology, faces operational challenges in low-temperature environments. Enhancing the metabolic activity of anammox bacteria (AnAOB) is pivotal for advancing its application in mainstream municipal wastewater treatment. Inspired by the metabolic adaptability of AnAOB and based on our previous findings, this work investigated the enhancement of intracellular ATP and NADH synthesis through the exogenous supply of reduced humic acid (HAred) and H2O2 redox couple, aiming to augment AnAOB activity under low-temperature conditions. Our experimental setup involved continuous dosing of 0.0067 µmol g-1 volatile suspended solid of H2O2 and 10 mg g-1 volatile suspended solid of HAred into a mainstream anammox reactor operated at 15 °C with an influent TN content of 60 mg/L. The results showed that HAred / H2O2 couple succeeded in maintaining the effluent TN at 10.72 ± 0.91 mg l-1. The specific anammox activity, ATP and NADH synthesis levels of sludge increased by 1.34, 2.33 and 6.50 folds, respectively, over the control setup devoid of the redox couple. High-throughput sequencing analysis revealed that the relative abundance of Candidatus Kuenenia after adding HAred / H2O2 couple reached 3.65 % at the end of operation, which was 5.14 folds higher than that of the control group. Further metabolomics analysis underscored an activation in the metabolism of amino acids, nucleotides, and phospholipids, which collectively enhanced the availability of ATP and NADH for the respiratory processes. These findings may provide guidance on strategy development for improving the electron transfer efficiency of AnAOB and underscore the potential of using redox couples to promote the mainstream application of anammox technology.

Light-Driven Electron Uptake from Nonfermentative Organic Matter to Expedite Nitrogen Dissimilation by Chemolithotrophic Anammox Consortia.

Nonphotosynthetic microorganisms are typically unable to directly utilize light energy, but light might change the metabolic pathway of these bacteria indirectly by forming intermediates such as reactive oxygen species (ROS). This work investigated the role of light on nitrogen conversion by anaerobic ammonium oxidation (anammox) consortia. The results showed that high intensity light (>20000 lx) caused ca. 50% inhibition of anammox activity, and total ROS reached 167% at 60,000 lx. Surprisingly, 200 lx light was found to induce unexpected promotion of the nitrogen conversion rate, and ultraviolet light (<420 nm) was identified as the main contributor. Metagenomic and metatranscriptomic analyses revealed that the gene encoding cytochrome c peroxidase was highly expressed only under 200 lx light. 15N isotope tracing, gene abundance quantification, and external H2O2 addition experiments showed that photoinduced trace H2O2 triggered cytochrome c peroxidase expression to take up electrons from extracellular nonfermentative organics to synthesize NADH and ATP, thereby expediting nitrogen dissimulation of anammox consortia. External supplying reduced humic acid into a low-intensity light exposure system would result in a maximal 1.7-fold increase in the nitrogen conversion rate. These interesting findings may provide insight into the niche differentiation and widespread nature of anammox bacteria in natural ecotopes.

Therapeutic effects of 5,2'-dibromo-2,4',5'-trihydroxydiphenylmethanone (LM49) in an experimental rat model of acute pyelonephritis by immunomodulation and anti-inflammation.

Antibiotics are still the primary therapy for acute pyelonephritis (APN); rarely, natural polyphenols are also used. LM49 is a novel marine bromophenol derivative displaying strong anti-inflammatory effects. We investigated the therapeutic efficacy of LM49 in an experimental rat model of APN. The model was established by injecting 0.5 mL Escherichia coli (ATCC 25922, 108 CFU/mL) into the urinary bladders of Sprague Dawley rats. This model showed increased kidney viscera indices and renal bacterial growth scores, as well as pathological changes in kidneys. We also performed a broth microdilution antimicrobial susceptibility test of the E. coli strain. Both norfloxacin and LM49 treatment reduced kidney viscera indices and decreased microbial counts in urine cultures and kidney homogenates in APN rats. However, in vitro experiments showed that LM49 did not directly inhibit bacteria. Rather, LM49 treatment inhibited inflammatory cell infiltration or abscess and improved tissue lesions in the renal medullary junction, renal pelvis, and calyx, and high-dose LM49 treatment inhibited the production of inflammatory interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) in serum. CD4+ T cells were higher in the LM49 groups treated with high, medium, and low doses than in the model group, whereas only high-dose LM49 treatment increased the number of CD8+ T cells, as compared with that in the model group. However, LM49 treatment did not influence hematological parameters. Our results show that LM49 therapeutic effects in an APN animal model may be achieved by regulating immune responses and inhibiting inflammatory mediators, suggesting it as a candidate APN treatment.