Colonization,penetration and transformation of manganese oxide nodules by Aspergillus niger

In this study, the ability of the geoactive fungus Aspergillus niger to colonize and transform manganese nodules from the Clarion-Clipperton Zone in both solid and liquid media was investigated. Aspergillus niger was able to colonize and penetrate manganese nodules embedded in solid medium and effect extensive transformation of the mineral in both fragmented and powder forms, precipitating manganese and calcium oxalates. Transformation of manganese nodule powder also occurred in a liquid medium in which A. niger was able to remove the fine particles from suspension which were accumulated within the central region of the resulting mycelial pellets and transformed into manganese oxalate dihydrate (lindbergite) and calcium oxalate dihydrate (weddellite). These findings contribute to an understanding of environmental processes involving insoluble manganese oxides, with practical relevance to chemoorganotrophic mineral bioprocessing applications, and, to the best of our knowledge, represent the first demonstration of fundamental direct and indirect interactions between geoactive fungi and manganese nodules.     

Removal of malachite green from aqueous solution by immobilized Pseudomonas sp. DY1 with Aspergillus oryzae

Triphenylmethane dyes are considered to be one of the most recalcitrant pollutants in the environment. Malachite Green (MG) was successfully removed from aqueous solution by Pseudomonas sp. DY1 immobilization with Aspergillus oryzae. Inhibition test in the presence of sodium azide and nystatin indicated that A. oryzae was a natural immobilization reagent, and removal of MG by the immobilized cell pellets was attributed to the biodegradation by Pseudomonas sp. DY1. Optimum conditions of immobilization for maximum biodegradation were obtained using Taguchi design at 37 °C, inoculation size of Pseudomonas sp. DY1 (dry cell mass) 0.01 g, of A. oryzae (spore number) 1.0 × 10⁹, initial pH 6.5. Decolorization and biodegradation of MG by immobilized pellets under optimum conditions were 99.5% and 93.3%, respectively. Immobilized pellets exhibited more than 96% decolorization after 16 days in batch condition, indicating it had stable and high biodegradation capabilities when immobilized for long-term operation.     

Description and genome analysis of Luteimonas viscosa sp. nov., a novel bacterium isolated from soil of a sunflower field

Strain XBU10^T was isolated from a soil sample of a sunflower plot in Inner Mongolia, China. The isolate was a Gram-stain-negative, aerobic, non-motile, rod-shaped bacterium, and its colonies were bright yellow in colour. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain XBU10^T belonged to the genus Luteimonas of the family Lysobacteraceae and was most closely related to Luteimonas panaciterrae Gsoil 068^T (97.8%), Luteimonas marina FR1330^T (97.6%), Luteimonas aquatica RIB1-20^T (97.4%) and Luteimonas huabeiensis HB2^T (97.2%). Growth occurred at 4–40 °C (optimum, 28–30 °C), with 0–5.0% (w/v) NaCl (optimum, 0.5%) and at pH 6.0–10.0 (optimum, pH 7.0???8.0). The chemotaxonomic characteristics of strain XBU10^T, which had Q-8 as its predominant quinone and iso-C_17:1 ω9c, iso-C_15:0, iso-C_17:0 and iso-C_16:0 as its major fatty acids, were consistent with classification in the genus Luteimonas. The polar lipid profile of strain XBU10^T comprised phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminophospholipids and three unidentified polar lipids. The genome of strain XBU10^T was 4.17 Mbp with a G?+?C content of 69.9%. Its genome sequence showed genes encoding alkaline phosphatase and catalase. Protein-coding genes related to carbohydrate-active enzymes were also observed. Average nucleotide identity (ANI) values between XBU10^T and other species of the genus Luteimonas were found to be low (ANIm?<?88.0%, ANIb?<?85.0% and OrthoANIu?<?85.0%). Furthermore, digital DNA-DNA hybridization (dDDH) and average amino acid identity (AAI) values between strain XBU10^T and the closely related species ranged from 20.3 to 28.9% and from 64.2 to 82.3%, respectively. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain XBU10^T represents a novel species within the genus Luteimonas, for which the name Luteimonas viscosa sp. nov. is proposed. The type strain is XBU10^T (=?CGMCC 1.12158^T?=?KCTC 23878^T).

     

Inhibition of NF‐κB is required for oleanolic acid to downregulate PD‐L1 by promoting DNA demethylation in gastric cancer cells

Gastric cancer is one of the most common causes of cancer‐related death worldwide. Immunotherapy via programmed cell death protein 1 (PD‐1)/programmed cell death‐ligand 1 (PD‐L1) blockade has shown benefits for gastric cancer. Epigenetic DNA methylation critically regulates cancer immune checkpoints. We investigated how the natural compound oleanolic acid (OA) affected PD‐L1 expression in gastric cancer cells. Interleukin‐1β (IL‐1β) at 20 ng/mL was used to stimulate human gastric cancer MKN‐45 cells. IL‐1β significantly increased PD‐L1 expression, which was abolished by OA. Next, OA‐treated MKN‐45 cells were co‐cultured with activated and PD‐1‐overexpressing Jurkat T cells. OA restored IL‐2 levels in the co‐culture system and increased T cell killing toward MKN‐45 cells. Overexpression of PD‐L1 eliminated OA‐enhanced T cell killing capacity; however, PD‐1 blocking antibody abrogated the cytotoxicity of T cells. Moreover, OA abolished IL‐1β‐increased DNA demethylase activity in MKN‐45 cells. DNA methyltransferase inhibitor 5‐azacytidine rescued OA‐reduced PD‐L1 expression; whereas DNA demethylation inhibitor gemcitabine inhibited PD‐L1 expression, and, in combination with OA, provided more potent inhibitory effects. Furthermore, OA selectively reduced the expression of DNA demethylase TET3 in IL‐1β‐treated MKN‐45 cells, and overexpression of TET3 restored OA‐reduced PD‐L1 expression. Finally, OA disrupted nuclear factor κB (NF‐κB) signaling IL‐1β‐treated MKN‐45 cells, and overexpression of NF‐κB restored OA downregulation of TET3 and PD‐L1. The cytotoxicity of T cells toward MKN‐45 cells was also weakened by NF‐κB overexpression. Altogether, OA blocked the IL‐1β/NF‐κB/TET3 axis in gastric cancer cells, leading to DNA hypomethylation and downregulation of PD‐L1. Our discoveries suggested OA as an epigenetic modulator for immunotherapy or an adjuvant therapy against gastric cancer.     

Global analysis of the perturbation effects of metal-based nanoparticles on soil nitrogen cycling

Although studies have investigated the effects of metal-based nanoparticles (MNPs) on soil biogeochemical processes, the results obtained thus far are highly variable. Moreover, we do not yet understand how the impact of MNPs is affected by experimental design and environmental conditions. Herein, we conducted a global analysis to synthesize the effects of MNPs on 17 variables associated with soil nitrogen (N) cycling from 62 studies. Our results showed that MNPs generally exerted inhibitory effects on N-cycling process rates, N-related enzyme activities, and microbial variables. The response of soil N cycling varied with MNP type, and exposure dose was the most decisive factor for the variations in the responses of N-cycling process rates and enzyme activities. Notably, Ag/Ag₂S and CuO had dose-dependent inhibitory effects on ammonia oxidation rates, while CuO and Zn/ZnO showed hormetic effects on nitrification and denitrification rates, respectively. Other experimental design factors (e.g., MNP size and exposure duration) also regulated the effect of MNPs on soil N cycling, and specific MNPs, such as Ag/Ag₂S, exerted stronger effects during long-term (>28 days) exposure. Environmental conditions, including soil pH, organic carbon, texture, and presence/absence of plants, significantly influenced MNP toxicity. For instance, the effects of Ag/Ag₂S on the ammonia oxidation rate and the activity of leucine aminopeptidase were more potent in acid (pH <6), organic matter-limited (organic carbon content ≤10 g kg⁻¹), and coarser soils. Overall, these results provide new insights into the general mechanisms by which MNPs alter soil N processes in different environments and underscore the urgent need to perform multivariate and long-term in situ trials in simulated natural environments.     

Distinct spatiotemporal succession of bacterial generalists and specialists in the lacustrine plastisphere

The assembly processes of generalists and specialists and their driving mechanisms during spatiotemporal succession is a central issue in microbial ecology but a poorly researched subject in the plastisphere. We investigated the composition variation, spatiotemporal succession, and assembly processes of bacterial generalists and specialists in the plastisphere, including non-biodegradable (NBMPs) and biodegradable microplastics (BMPs). Although the composition of generalists and specialists on NBMPs differed from that of BMPs, colonization time mainly mediated the composition variation. The relative abundance of generalists and the relative contribution of species replacement were initially increased and then decreased with colonization time, while the specialists initially decreased and then increased. Besides, the richness differences also affected the composition variation of generalists and specialists in the plastisphere, and the generalists were more susceptible to richness differences than corresponding specialists. Furthermore, the assembly of generalists in the plastisphere was dominated by deterministic processes, while stochastic processes dominated the assembly of specialists. The network stability test showed that the community stability of generalists on NBMPs and BMPs was lower than corresponding specialists. Our results suggested that different ecological assembly processes shaped the spatiotemporal succession of bacterial generalists and specialists in the plastisphere, but were less influenced by polymer types.     

The critical role of T cells in glucocorticoid-induced osteoporosis

Glucocorticoids (GC) are widely used clinically, despite the presence of significant side effects, including glucocorticoid-induced osteoporosis (GIOP). While GC are believed to act directly on osteoblasts and osteoclasts to promote osteoporosis, the detailed underlying molecular mechanism of GC-induced osteoporosis is still not fully elucidated. Here, we show that lymphocytes play a pivotal role in regulating GC-induced osteoporosis. We show that GIOP could not be induced in SCID mice that lack T cells, but it could be re-established by adoptive transfer of splenic T cells from wild-type mice. As expected, T cells in the periphery are greatly reduced by GC; instead, they accumulate in the bone marrow where they are protected from GC-induced apoptosis. These bone marrow T cells in GC-treated mice express high steady-state levels of NF-κB receptor activator ligand (RANKL), which promotes the formation and maturation of osteoclasts and induces osteoporosis. Taken together, these findings reveal a critical role for T cells in GIOP.Subject terms: Mechanisms of disease, Osteoimmunology     

Abundance and diversity of eukaryotic rather than bacterial community relate closely to the trophic level of urban lakes

Scientific understanding of biotic effects on the water trophic level is lacking for urban lakes during algal bloom development stage. Based on the Illumina MiSeq sequencing, quantitative polymerase chain reaction (PCR), and multiple statistical analyses, we estimated distribution patterns and ecological roles of planktonic bacteria and eukaryotes in urban lakes during algal bloom development stage (i.e., April, May, and June). Cyanobacteria and Chlorophyta mainly dominated algal blooms. Bacteria exhibited significantly higher absolute abundance and community diversity than eukaryotes, whereas abundance and diversity of eukaryotic rather than bacterial community relate closely to the water trophic level. Multinutrient cycling (MNC) index was significantly correlated with eukaryotic diversity rather than bacterial diversity. Stronger species replacement, broader environmental breadth, and stronger phylogenetic signal were found for eukaryotic community than for bacterial community. In contrast, bacterial community displayed stronger community stability and environmental constraint than eukaryotic community. Stochastic and differentiating processes contributed more to community assemblies of bacteria and eukaryotes. Our results emphasized that a strong linkage between planktonic diversity and MNC ensured a close relationship between planktonic diversity and the water trophic level of urban lakes. Our findings could be useful to guide the formulation and implementation of environmental lake protection measures.