Rapid Enrichment and Isolation of Polyphosphate-Accumulating Organisms Through 4'6-Diamidino-2-Phenylindole (DAPI) Staining With Fluorescence-Activated Cell Sorting (FACS)

The HOPS and vCLAMP protein Vam6 connects polyphosphate with mitochondrial function and oxidative stress resistance in Cryptococcus neoformans

Cryptococcus neoformans is considered one of the most dangerous fungal threats to human health, and the World Health Organization recently ranked it in the critical priority group for perceived public health importance. Proliferation of C. neoformans within mammalian hosts is supported by its ability to overcome nutritional limitations and endure stress conditions induced by the host immune response. Previously, we reported that the Vam6/Vps39/TRAP1-domain protein Vam6 was crucial for vacuolar morphology, iron acquisition, and virulence. However, the molecular mechanisms underlying the pleiotropic phenotypes resulting from loss of Vam6 remain poorly understood. In this study, we determined that Vam6 has roles in the HOPS complex for endomembrane trafficking to the vacuole and in the vCLAMP membrane contact site between the vacuole and mitochondria. Importantly, both of these roles regulate polyphosphate (polyP) metabolism, as demonstrated by a defect in trafficking of the VTC complex subunit Vtc2 for polyphosphate synthesis and by an influence on mitochondrial functions. In the latter case, Vam6 was required for polyP accumulation in response to electron transport chain inhibition and for overcoming oxidative stress. Overall, this work establishes connections between endomembrane trafficking, mitochondrial functions, and polyP homeostasis in C. neoformans.IMPORTANCEA detailed understanding of stress resistance by fungal pathogens of humans may provide new opportunities to improve antifungal therapy and combat life-threatening diseases. Here, we used a vam6 deletion mutant to investigate the role of the homotypic fusion and vacuole protein sorting (HOPS) complex in mitochondrial functions and polyphosphate homeostasis in Cryptococcus neoformans, an important fungal pathogen of immunocompromised people including those suffering from HIV/AIDS. Specifically, we made use of mutants defective in late endocytic trafficking steps to establish connections to oxidative stress and membrane trafficking with mitochondria. In particular, we found that mutants lacking the Vam6 protein had altered mitochondrial function, and that the mutants were perturbed for additional mitochondria and vacuole-related phenotypes (e.g., membrane composition, polyphosphate accumulation, and drug sensitivity). Overall, our study establishes connections between endomembrane trafficking components, mitochondrial functions, and polyphosphate homeostasis in an important fungal pathogen of humans.

Advancements in phosphorus species profiling and bioavailability assessment with implications for phosphorus sustainability

Phosphorus (P) is an essential nutrient that governs ecosystem productivity, drives global biogeochemical cycles, and plays a central role in water-energy-food nexus. The increasing scarcity of P reserves and their environmental losses necessitate precise detection to monitor P in all contexts for effective and sustainable resource management. This review highlights recent advances in analytical techniques for P speciation and bioavailability across environmental matrices, including both bulk and single-cell methods. Furthermore, recent emerging insights into microbial P cycling were discussed, particularly the role of polyphosphate and polyphosphate-accumulating organisms in dynamic P transformations. By emphasizing the sustainability implications of P, we stress the importance of precise and quantitative detection methods to inform sustainable P management and mitigate the global P crisis.

Ruthenium polypyridine complexes containing prenyl groups as antibacterial agents against Staphylococcus aureus through a membrane-disruption mechanism

Four new ruthenium polypyridyl complexes with prenyl groups, [Ru(bpy)2 (MHIP)](PF6 )2 (Ru(II)-1), [Ru(dtb)2 (MHIP)](PF6 )2 (Ru(II)-2), [Ru(dmb)2 (MHIP)](PF6 )2 (Ru(II)-3), and [Ru(dmob)2 (MHIP)](PF6 )2 (Ru(II)-4) (bpy = 2,2'-bipyridine, dtb = 4,4'-di-tert-butyl-2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, dmob = 4,4'-dimethoxy-2,2'-bipyridine, and MHIP = 2-(2,6-dimethylhepta-1,5-dien-1-yl)-1H-imidazo[4,f][1,10]phenanthroline), were synthesized and characterized. Their antibacterial activities against Staphylococcus aureus were assessed, and the minimum inhibition concentration (MIC) value of Ru(II)-2 against S. aureus was only 0.5 µg/mL, showing the best antibacterial activity among them. S. aureus could be quickly killed by Ru(II)-2 in 30 min and Ru(II)-2 displayed an obvious inhibitive effect on the formation of a biofilm, which was essential to avoid the development of drug-resistance. Meanwhile, Ru(II)-2 exhibited a stable MIC value against antibiotic-resistant bacteria. The antibacterial mechanism of Ru(II)-2 was probably related to depolarization of the cell membrane, and a change of permeability was associated with the formation of reactive oxygen species, leading to leakage of nucleic acid and bacterial death. Furthermore, Ru(II)-2 hardly showed toxicity to mammalian cells and the Galleria mellonella worm. Finally, murine infection studies also illustrated that Ru(II)-2 was highly effective against S. aureus in vivo.

Administration of the probiotic Lactiplantibacillus paraplantarum is effective in controlling hyperphosphatemia in 5/6 nephrectomy rat model

AIMS

Several studies have linked gut microbes to human diseases. Most of the mechanisms by which lactic acid bacteria have beneficial effects on the human body are related to immune modulation. Controlled studies of the ability of lactic acid bacteria to absorb phosphorus directly from the intestine and thereby control serum phosphorus level in in vivo uremic animal models are limited.

MATERIALS AND METHODS

We screened lactic acid bacteria living in Korean fermented foods to identify those that absorb the most phosphorus and noted Lactiplantibacillus paraplantarum KCCM 11826P. The mechanism through which better intracellular absorption of phosphorus occurs in this strain was studied using genomic DNA sequencing. After the strain was administered to 5/6 nephrectomized rats for 6 weeks, it was observed whether hyperphosphatemia had improved.

KEY FINDINGS

The L. paraplantarum KCCM 11826P strain has a polyP gene cluster; thus, it absorbs phosphorus better than other bacteria and can suppress strains that produce indole. Supplementing the diets of 5/6 nephrectomized rats with this L. paraplantarum strain significantly decreased serum phosphate level (by 22 %) and reduced blood indoxyl sulphate concentration (by 40 %) compared with vehicle treatment.

SIGNIFICANCE

These results suggest that Lactiplantibacillus preparations can be used for multiple purposes, such as the removal of phosphorus and uremic toxins from patients with chronic kidney disease (CKD). This study also demonstrates the novel concept of a probiotic phosphate binder.

A Novel Perturbed Spiral Sheathless Chip for Particle Separation Based on Traveling Surface Acoustic Waves (TSAW)

The combination of the new perturbed spiral channel and a slanted gold interfingered transducer (IDT) is designed to achieve precise dynamic separation of target particles (20 μm). The offset micropillar array solves the defect that the high-width flow (avoiding the occurrence of channel blockage) channel cannot realize the focusing of small particles (5 μm, 10 μm). The relationship between the maximum design gap of the micropillar (Smax) and the particle radius (a) is given: Smax = 4a, which not only ensures that small particles will not pass through the micropillar gap, but also is compatible with the appropriate flow rates. A non-offset micropillar array was used to remove 20 μm particles in the corner area. The innovation of a spiral channel structure greatly improves the separation efficiency and purity of the separation chip. The separation chip designed by us achieves deflection separation of 20 μm particles at 24.95-41.58 MHz (κ = 1.09-1.81), at a flow rate of 1.2 mL per hour. When f = 33.7 MHz (κ = 1.47), the transverse migration distance of 20 μm particles is the smallest, and the separation purity and efficiency are as high as 92% and 100%, respectively.

Status and advances in technologies for phosphorus species detection and characterization in natural environment- A comprehensive review

Poor recovery of phosphorus (P) across natural environment (water, soil, sediment, and biological sources) is causing rapid depletion of phosphate rocks and continuous accumulation of P in natural waters, resulting in deteriorated water quality and aquatic lives. Accurate detection and characterization of various P species using suitable analytical methods provide a comprehensive understanding of the biogeochemical cycle of P and thus help its proper management in the environment. This paper aims to provide a comprehensive review of the analytical methods used for P speciation in natural environment by dividing them into five broad categories (i.e., chemical, biological, molecular, staining microscopy, and sensors) and highlighting the suitability (i.e., targeted species, sample matrix), detection limit, advantages-limitations, and reference studies of all methods under each category. This can be useful in designing studies involving P detection and characterization across environmental matrices by providing insights about a wide range of analytical methods based on the end user application needs of individual studies.

Revealing the full biosphere structure and versatile metabolic functions in the deepest ocean sediment of the Challenger Deep

BACKGROUND

The full biosphere structure and functional exploration of the microbial communities of the Challenger Deep of the Mariana Trench, the deepest known hadal zone on Earth, lag far behind that of other marine realms.

RESULTS

We adopt a deep metagenomics approach to investigate the microbiome in the sediment of Challenger Deep, Mariana Trench. We construct 178 metagenome-assembled genomes (MAGs) representing 26 phyla, 16 of which are reported from hadal sediment for the first time. Based on the MAGs, we find the microbial community functions are marked by enrichment and prevalence of mixotrophy and facultative anaerobic metabolism. The microeukaryotic community is found to be dominated by six fungal groups that are characterized for the first time in hadal sediment to possess the assimilatory and dissimilatory nitrate/sulfate reduction, and hydrogen sulfide oxidation pathways. By metaviromic analysis, we reveal novel hadal Caudovirales clades, distinctive virus-host interactions, and specialized auxiliary metabolic genes for modulating hosts' nitrogen/sulfur metabolism. The hadal microbiome is further investigated by large-scale cultivation that cataloged 1070 bacterial and 19 fungal isolates from the Challenger Deep sediment, many of which are found to be new species specialized in the hadal habitat.

CONCLUSION

Our hadal MAGs and isolates increase the diversity of the Challenger Deep sediment microbial genomes and isolates present in the public. The deep metagenomics approach fills the knowledge gaps in structure and diversity of the hadal microbiome, and provides novel insight into the ecology and metabolism of eukaryotic and viral components in the deepest biosphere on earth.

Enhanced bacterial disinfection by CuI–BiOI/rGO hydrogel under visible light irradiation

Compared with traditional layered graphene, graphene hydrogels have been used to construct highly efficient visible light-excited photocatalysts due to their particular three-dimensional network structure and efficient electron transport capacity. In this work, CuI–BiOI/rGO hydrogel with excellent photocatalytic antibacterial activity was prepared and its activity against Escherichia coli and Staphylococcus aureus was evaluated. The result indicates that CuI–BiOI/rGO hydrogel exhibits superior sterilization performance and higher stability than CuI–BiOI and BiOI/rGO, and could completely kill Escherichia coli and Staphylococcus aureus within 40 min. However, only a small amount of Escherichia coli and Staphylococcus aureus can be inactivated by CuI–BiOI and BiOI/rGO hydrogels. Graphene hydrogel plays a significant part in enhancing the disinfection activity of CuI–BiOI/rGO hydrogel. Furthermore, the synergistic effect between CuI of p-type semiconductors, as a hole transport layer, and graphene hydrogel greatly increases the separation and transfer efficiency of photogenerated electron holes excited by BiOI, and further improves the disinfection activity of CuI–BiOI/rGO hydrogel.

Compared with traditional layered graphene, graphene hydrogels have been used to construct highly efficient visible light-excited photocatalysts due to their particular three-dimensional network structure and efficient electron transport capacity.

Polyanions in Coagulation and Thrombosis: Focus on Polyphosphate and Neutrophils Extracellular Traps

Neutrophil extracellular traps (NETs) and polyphosphates (polyP) have been recognized as procoagulant polyanions. This review summarizes the activities and regulation of the two procoagulant mediators and compares their functions. NETs are composed of DNA which like polyP is built of phosphate units linked by high-energy phosphoanhydride bonds. Both NETs and polyP form insoluble particulate surfaces composed of a DNA/histone meshwork or Ca²⁺-rich nanoparticles, respectively. These polyanionic molecules modulate coagulation involving an array of mechanisms and trigger thrombosis via activation of the factor XII-driven procoagulant and proinflammatory contact pathway. Here, we outline the current knowledge on NETs and polyP with respect to their procoagulant and prothrombotic nature, strategies for interference of their activities in circulation, as well as the crosstalk between these two molecules. A better understanding of the underlying, cellular mechanisms will shed light on the therapeutic potential of targeting NETs and polyP in coagulation and thrombosis.