Algicidal activity synchronized with nitrogen removal by actinomycetes: Algicidal mechanism, stress response of algal cells, denitrification performance, and indigenous bacterial community co-occurrence.

The harmful algal blooms (HABs) can damage the ecological equilibrium of aquatic ecosystems and threaten human health. The bio-degradation of algal by algicidal bacteria is an environmentally friendly and economical approach to control HABs. This study applied an aerobic denitrification synchronization algicidal strain Streptomyces sp. LJH-12-1 (L1) to control HABs. The cell-free filtrate of the strain L1 showed a great algolytic effect on bloom-forming cyanobacterium, Microcystis aeruginosa (M. aeruginosa). The optimal algicidal property of strain L1 was indirect light-dependent algicidal with an algicidal rate of 85.0%. The functional metabolism, light-trapping, light-transfer efficiency, the content of pigments, and inhibition of photosynthesis of M. aeruginosa decreased after the addition of the supernatant of the strain L1 due to oxidative stress. Moreover, 96.05% nitrate removal rate synchronized with algicidal activity was achieved with the strain L1. The relative abundance of N cycling functional genes significantly increased during the strain L1 effect on M. aeruginosa. The algicidal efficiency of the strain L1 in the raw water was 76.70% with nitrate removal efficiency of 81.4%. Overall, this study provides a novel route to apply bacterial strain with the property of denitrification coupled with algicidal activity in treating micro-polluted water bodies.

Aerobic Denitrification Promoting by Actinomycetes Coculture: Investigating Performance, Carbon Source Metabolic Characteristic, and Raw Water Restoration.

The coculture theory that promotes denitrification relies on effectively utilizing the resources of low-efficiency denitrification microbes. Here, the strains Streptomyces sp. PYX97 and Streptomyces sp. TSJ96 were isolated and showed lower denitrification capacity when cultured individually. However, the coculture of strains PYX97 and TSJ96 enhanced nitrogen removal (removed 96.40% of total nitrogen) and organic carbon reduction (removed 92.13% of dissolved organic carbon) under aerobic conditions. Nitrogen balance analysis indicated that coculturing enhanced the efficiency of nitrate converted into gaseous nitrogen reaching 70.42%. Meanwhile, the coculturing promoted the cell metabolism capacity and carbon source metabolic activity. The coculture strains PYX97 and TSJ96 thrived in conditions of C/N = 10, alkalescence, and 150 rpm shaking speed. The coculturing reduced total nitrogen and CODMn in the raw water treatment by 83.32 and 84.21%, respectively. During this treatment, the cell metabolic activity and cell density increased in the coculture strains PYX97 and TSJ96 reactor. Moreover, the coculture strains could utilize aromatic protein and soluble microbial products during aerobic denitrification processes in raw water treatment. This study suggests that coculturing inefficient actinomycete strains could be a promising approach for treating polluted water bodies.

Molecular Features of Resected Melanoma Brain Metastases, Clinical Outcomes, and Responses to Immunotherapy.

Importance: Central nervous system (CNS)-penetrant systemic therapies have significantly advanced care for patients with melanoma brain metastases. However, improved understanding of the molecular landscape and microenvironment of these lesions is needed to both optimize patient selection and advance treatment approaches. Objective: To evaluate how bulk and single-cell genomic features of melanoma brain metastases are associated with clinical outcome and treatment response. Design, Setting, and Participants: This cohort study analyzed bulk DNA sequencing and single nuclear RNA-sequencing data from resected melanoma brain metastases and included 94 consecutive patients with a histopathologically confirmed diagnosis of melanoma brain metastasis who underwent surgical resection at a single National Comprehensive Cancer Network cancer center in San Francisco, California, from January 1, 2009, to December 31, 2022. Exposure: A Clinical Laboratory Improvement Amendments-certified targeted sequencing assay was used to analyze tumor resection specimens, with a focus on BRAF V600E alteration. For frozen pathologic specimens from CNS treatment-naive patients undergoing surgical resection, commercial single nuclear RNA sequencing approaches were used. Main Outcomes and Measures: The primary outcome was overall survival (OS). Secondary outcomes included CNS progression-free survival (PFS), microenvironmental composition with decreased T-cell and macrophage populations, and responses to immunotherapy. Results: To correlate molecular status with clinical outcome, Kaplan-Meier survival analysis of 94 consecutive patients (median age, 64 years [range, 24-82 years]; 70 men [74%]) with targeted BRAF alteration testing showed worse median intracranial PFS (BRAF variant: 3.6 months [IQR, 0.1-30.6 months]; BRAF wildtype: 11.0 months [IQR, 0.8-81.5 months]; P < .001) and OS (BRAF variant: 9.8 months [IQR, 2.5-69.4 months]; BRAF wildtype: 23.2 months [IQR, 1.1-102.5 months]; P = .005; log-rank test) in BRAF V600E variant tumors. Multivariable Cox proportional hazards regression analysis revealed that BRAF V600E status was an independent variable significantly associated with both PFS (hazard ratio [HR], 2.65; 95% CI, 1.54-4.57; P < .001) and OS (HR, 1.96; 95% CI, 1.08-3.55; P = .03). For the 45 patients with resected melanoma brain metastases undergoing targeted DNA sequencing, molecular classification recapitulated The Cancer Genome Atlas groups (NRAS variant, BRAF variant, NF1 variant, and triple wildtype) with no subtype enrichment within the brain metastasis cohort. On a molecular level, BRAF V600E variant lesions were found to have a significantly decreased tumor mutation burden. Moreover, single nuclear RNA sequencing of treatment-naive BRAF V600E variant (n = 3) brain metastases compared with BRAF wildtype (n = 3) brain metastases revealed increased immune cell populations in BRAF wildtype tumors (mean [SD], 11% [4.1%] vs 3% [1.6%] CD45-positive cells; P = .04). Survival analysis of postoperative immunotherapy responses by BRAF status revealed that BRAF wildtype lesions were associated with a response to checkpoint inhibition (median OS: with immunotherapy, undefined; without immunotherapy, 13.0 months [range, 1.1-61.7 months]; P = .001; log-rank test) while BRAF variant lesions (median OS: with immunotherapy, 9.8 months [range, 2.9-39.8 months]; without immunotherapy, 9.5 months [range, 2.5-67.2 months]; P = .81; log-rank test) were not. Conclusions and Relevance: This molecular analysis of patients with resected melanoma brain metastases found that BRAF V600E alteration is an important translational biomarker associated with worse clinical outcomes, differential microenvironmental composition, and benefit from immunotherapy. Patients with BRAF V600E variant melanoma brain metastases may thus benefit from alternative CNS-penetrant systemic regimens.

Promoted aerobic denitrification through denitrifying fungal communities: Co-occurrence patterns and treatment of low C/N micro-polluted water.

Despite the growing interest in using mixed-culture aerobic denitrifying fungal flora (mixed-CADFF) for water remediation, there is limited research on their nitrogen removal performance in low C/N polluted water bodies. To address this knowledge gap, we isolated three mixed-CADFFs from overlying water in urban lakes to evaluate their removal performance. The total nitrogen (TN) removal efficiencies were 93.60 %, 94.64 %, and 95.18 %, while the dissolved organic carbon removal efficiencies were 96.64 %, 95.12 %, and 96.70 % for mixed-CADFF LN3, LN7, and LN15, respectively in the denitrification medium under aerobic conditions at 48 h cultivation. The three mixed-CADFFs could utilize diverse types of low molecular weight carbon sources to drive the aerobic denitrification processes efficiently. The optimal C/N ratio for the mixed-CADFFs were C/N = 10, and then C/N = 15, 7, 5, and 2. The high-throughput sequencing analysis of three mixed-CADFFs indicated that Eurotiomycetes, Cystobasidiomycetes, and Sordariomycetes were the dominant class in the communities at class level. The network analysis showed that the rare fungal species, such as Scedosporium dehoogii Saitozyma, and Candida intermedia presented positively co-occurred with the TN removal and organic matter reduction capacity. Immobilization mixed-CADFFs treatment raw water experiments indicated that three mixed-CADFFs could reduce nearly 62.73 % of TN in the low C/N micro-polluted raw water treatment. Moreover, the cell density and cell metabolism indexes were also increased during the raw water treatment. This study will provides new insight into resource utilization of the mixed-culture aerobic denitrifying fungal community in field of environment restoration.

Aerobic Denitrification Enhanced by Immobilized Slow-Released Iron/Activated Carbon Aquagel Treatment of Low C/N Micropolluted Water: Denitrification Performance, Denitrifying Bacterial Community Co-occurrence, and Implications.

The key limiting factors in the treatment of low C/N micropolluted water bodies are deficient essential electron donors for nitrogen removal processes. An iron/activated carbon aquagel (IACA) was synthesized as a slowly released inorganic electron donor to enhance aerobic denitrification performance in low C/N micropolluted water treatment. The denitrification efficiency in IACA reactors was enhanced by more than 56.72% and the highest of 94.12% was accomplished compared with those of the control reactors. Moreover, the CODMn removal efficiency improved by more than 34.32% in IACA reactors. The Illumina MiSeq sequencing consequence explained that the denitrifying bacteria with facultative denitrification, iron oxidation, and iron reduction function were located in the dominant species niches in the IACA reactors (e.g., Pseudomonas, Leptothrix, and Comamonas). The diversity and richness of the denitrifying bacterial communities were enhanced in the IACA reactors. Network analysis indicated that aerobic denitrifying bacterial consortia in IACA reactors presented a more complicated co-occurrence structure. The IACA reactors presented the potential for long-term denitrification operation. This study affords a pathway to utilize IACA, promoting aerobic denitrification during low C/N micropolluted water body treatment.