Abundance Of Gammaproteobacteria Research Articles

Mineral and Microbial Properties Drive the Formation of Mineral-Associated Organic Matter and Its Response to Increased Temperature.

A comprehensive understanding of the formation of mineral-associated organic matter (MAOM) is a prerequisite for the sustainable management of soil carbon (C) and the development of effective long-term strategies for C sequestration in soils. Nevertheless, the precise manner by which microbial and mineral properties drive MAOM formation efficiency and its subsequent response to elevated temperature at the regional scale remains unclear. Here, we employed isotopically labelled laboratory incubations (at 15°C and 25°C) with soil samples from a ~3000 km transect across the Tibetan Plateau to elucidate the mechanisms underlying MAOM formation and its temperature response. The results indicated that both mineral protection and microbial properties were critical predictors of MAOM formation across the geographic gradient. The efficiency of MAOM formation was found to increase with the content of iron (Fe) oxides and their reactivity [i.e., the ratio of poorly crystalline Fe oxides to total Fe oxides (Feo:Fed)] but to decrease with the relative abundance of Gammaproteobacteria and Actinobacteria across the plateau. Moreover, a notable decline in MAOM formation efficiency was observed under elevated temperatures, which was concomitant with a reduction in the content and reactivity of Fe oxides, as well as the microbial assimilation of the labelled substrate. The attenuation of mineral-organic associations was identified as the primary factor contributing to the warming-induced reduction in MAOM formation. These findings highlight the necessity of incorporating organo-mineral associations and microbial properties into Earth System Models to accurately project soil C dynamics under changing climate.

Vermicomposting reduces the antimicrobial resistance in livestock waste

Vermicomposting, a process in which housefly larvae are used to decompose organic waste, has attracted attention as a method for managing antimicrobial-resistant bacteria (ARB) in livestock manure. Vermicomposting effectively reduces antimicrobial resistance genes (ARGs) and residual antimicrobials. However, the evaluation of live bacteria, including ARB, remains scarce. Additionally, conventional DNA extraction methods include DNA from dead bacteria, impeding the accurate evaluation of ARG-associated risk in compost and the microbiome. This study assesses the effectiveness of vermicomposting pig manure against antimicrobial resistance (AMR) by evaluating the ARB, ARGs (focusing on DNA from live bacteria), and microbiome associated with vermicomposting processes. Vermicomposting significantly reduces the abundance of bacteria, including ARB, and decreases the ARG (tetA, tetB, blaTEM, and blaCTX−M) copy number in live bacteria. Bacterial community analysis revealed an increase in the abundance of Gammaproteobacteria. Moreover, the vermicomposted samples effectively cultivated myriad plants. Overall, vermicomposting effectively reduces the ARB and ARGs in pig manure, with potential benefits for plant growth and sustainable waste management. Hence, it can be widely applied to treat livestock manure and other organic wastes to combat AMR.

Biochar combined with organic fertilizer improved soil quality, promoted the growth of Cunninghamia lanceolata (Lamb.) Hook and changed the microbial community

ABSTRACT Cunninghamia lanceolata (Lamb.) Hook plantations play an important role in mitigating greenhouse gas emissions. This experiment explored the effects of seed shell biochar and meal organic fertilizer derived from Camellia oleifera Abel on the growth characteristics of Cunninghamia lanceolata, as well as the effects on soil fertility and microbial community. The results demonstrated that the use of tea seed shell biochar or meal organic fertilizer improved plant height, biomass, chlorophyll content, and N, P, and K content of Cunninghamia lanceolata. They increased the pH of acid-red soil and improved soil fertility, including organic matter, total nitrogen, nitrate nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium. However, they decreased ammonium nitrogen. They increased the alpha diversity of the bacteria, but had no significant effect on the alpha diversity of the fungi. They also enhanced the relative abundances of Gammaproteobacteria, Alphaproteobacteria, Leotiomycetes, and Sordariomycetes, but reduced the relative abundances of Acidobacteriae and Agaricomycetes. To sum up, the use of tea seed shell biochar and meal organic fertilizer could promote the growth and nutrient absorption of Cunninghamia lanceolata, while modifying soil fertility and improving the structure of microbial communities.

Application of flow airlift fluidized bed (CAFB) - Aerobic denitrification bioreactor using polycaprolactone (PADR) as organic carbon source and biofilm carrier for synthetic marine aquaculture wastewater treatment

Aerobic denitrification, a novel method for complete nitrate removal process, relies on a constant carbon supply, and carbon availability can be a limiting factor for the process. Three biodegradable polymers - polybutylene succinate (PBS), polycaprolactone (PCL), and polylactic acid (PLA) were used as carbon source of aerobic denitrifying bacteria, Halomonas venusta for treating recirculating aquaculture wastewater in batch tests, respectively. The group utilizing PCL displayed the greatest efficiency in nitrate removal. Afterwards, a continuous flow airlift fluidized bed (CAFB) - aerobic denitrification bioreactor using PCL(PADR) as bio-carriers and carbon source was started up. The effect of shifting temperature on the nitrate removal and microbial community of CAFB-PADR was investigated under different hydraulic retention times (HRT). The results showed that no significant difference was detected in denitrification activity at 25 and 30 °C condition, where the denitrification rate was 1.1–1.8 times higher than that at 15 °C. However, the nitrogen removal efficiency was above 50 % and there was barely accumulation of nitrite at 15 °C, indicating the good nitrate removal performance in CAFB-PADR at all three temperature conditions. Microbial composition analyses revealed that as the temperature decreased, the relative abundance of Gammaproteobacteria increased, while those of Alphaproteobacteria and Bacteroidia diminished decreased. The existence of denitrifying function genera (Marinobacter, Pseudomonas, Halomonas and Hydrogenophaga) ensured the rapid removal of nitrogen in the biofilter. When the temperature dropped to 15 °C, Pseudomonas progressively took the position of Marinobacter, both of which had denitrification and degradation activities. The relative abundance of the denitrifying bacteria Halomonas that we inoculated has been less than 1 % since phase II. Overall, the PCL-supported CAFB-PADR demonstrated in this study shows potential for removing high concentrations of nitrate from recirculating marine aquaculture wastewater.

Fetal echogenic bowel may be related to intestinal microbiota: A prospective cohort study.

The purpose of the current study was to determine the difference in intestinal microbiota after delivery between healthy fetuses and fetuses with hyperechogenic bowel during the second trimester and the relationship between fetal echogenic bowel and microbiota. Fourteen healthy fetuses (control group), 13 fetuses with echogenic bowel (EB group), and seven fetuses with echogenic bowel and other abnormalities (C-EB group) were selected. The first meconium after delivery was collected for 16S rRNA sequencing. A total of 1 222 131 high-quality sequences were generated after sequencing optimization of all samples. Each sample contained an average of 35 945 high-quality sequences and 2036 operational taxonomic units (OTUs). There was no significant difference in the Shannon, Simpson index among the three groups. At the genus level, the abundance of Escherichia coli/Shigella in the EB and C-EB groups was significantly lower than the control group, while the abundance of Staphylococcus, Methylobactrium, and Curvibacter in the EB group was significantly higher than the other groups. There was a difference in abundance of Gammaproteobacteria, Fusobacteria, Enterobacteriaceae, and E. coli in the EB and C-EB groups. The formation of echogenic bowel may be related to the microbiota.

Associations between gut microbiota and incident fractures in the FINRISK cohort

The gut microbiota (GM) can regulate bone mass, but its association with incident fractures is unknown. We used Cox regression models to determine whether the GM composition is associated with incident fractures in the large FINRISK 2002 cohort (n = 7043, 1092 incident fracture cases, median follow-up time 18 years) with information on GM composition and functionality from shotgun metagenome sequencing. Higher alpha diversity was associated with decreased fracture risk (hazard ratio [HR] 0.92 per standard deviation increase in Shannon index, 95% confidence interval 0.87–0.96). For beta diversity, the first principal component was associated with fracture risk (Aitchison distance, HR 0.90, 0.85–0.96). In predefined phyla analyses, we observed that the relative abundance of Proteobacteria was associated with increased fracture risk (HR 1.14, 1.07–1.20), while the relative abundance of Tenericutes was associated with decreased fracture risk (HR 0.90, 0.85–0.96). Explorative sub-analyses within the Proteobacteria phylum showed that higher relative abundance of Gammaproteobacteria was associated with increased fracture risk. Functionality analyses showed that pathways related to amino acid metabolism and lipopolysaccharide biosynthesis associated with fracture risk. The relative abundance of Proteobacteria correlated with pathways for amino acid metabolism, while the relative abundance of Tenericutes correlated with pathways for butyrate synthesis. In conclusion, the overall GM composition was associated with incident fractures. The relative abundance of Proteobacteria, especially Gammaproteobacteria, was associated with increased fracture risk, while the relative abundance of Tenericutes was associated with decreased fracture risk. Functionality analyses demonstrated that pathways known to regulate bone health may underlie these associations.

Hyposalinity elicits physiological responses and alters intestinal microbiota in Korean rockfish Sebastes schlegelii.

Global warming significantly impacts aquatic ecosystems, with changes in the salt environment negatively affecting the physiological responses of fish. We investigated the impact of hyposalinity on the physiological responses and intestinal microbiota of Sebastes schlegelii under the context of increased freshwater influx due to climate change. We focused on the osmoregulatory capacity, oxidative stress responses, and alterations in the intestinal microbiome of S. schlegelii under low-salinity conditions. Our findings revealed compromised osmoregulatory capacity in S. schlegelii under low-salinity conditions, accompanied by the activation of oxidative stress responses, indicating physiological adaptations to cope with environmental stress. Specifically, changes in Na+/K+-ATPase (NKA) activity in gill tissues were associated with decreased osmoregulatory capacity. Furthermore, the analysis of the intestinal microbiome led to significant changes in microbial diversity. Exposure to low-salinity environments led to dysbiosis, with notable decreases in the relative abundance of Gammaproteobacteria at the class level and specific genera such as Enterovibrio, and Photobacterium. Conversely, Bacilli classes, along with genera like Mycoplasma, exhibited increased proportions in fish exposed to low-salinity conditions. These findings underscore the potential impact of environmental salinity changes on the adaptive capacity of fish species, particularly in the context of aquaculture. Moreover, they highlight the importance of considering both physiological and microbial responses in understanding the resilience of aquatic organisms to environmental stress. Additionally, they highlight the importance of intestinal microbiota analyses in understanding the immune system and disease management in fish.

Organic matter decay and bacterial community succession in mangroves under simulated climate change scenarios.

Mangroves are coastal environments that provide resources for adjacent ecosystems due to their high productivity, organic matter decomposition, and carbon cycling by microbial communities in sediments. Since the industrial revolution, the increase of Greenhouse Gases (GHG) released due to fossil fuel burning led to many environmental abnormalities such as an increase in average temperature and ocean acidification. Based on the hypothesis that climate change modifies the microbial diversity associated with decaying organic matter in mangrove sediments, this study aimed to evaluate the microbial diversity under simulated climate change conditions during the litter decomposition process and the emission of GHG. Thus, microcosms containing organic matter from the three main plant species found in mangroves throughout the State of São Paulo, Brazil (Rhizophora mangle, Laguncularia racemosa, and Avicennia schaueriana) were incubated simulating climate changes (increase in temperature and pH). The decay rate was higher in the first seven days of incubation, but the differences between the simulated treatments were minor. GHG fluxes were higher in the first ten days and higher in samples under increased temperature. The variation in time resulted in substantial impacts on α-diversity and community composition, initially with a greater abundance of Gammaproteobacteria for all plant species despite the climate conditions variations. The PCoA analysis reveals the chronological sequence in β-diversity, indicating the increase of Deltaproteobacteria at the end of the process. The GHG emission varied in function of the organic matter source with an increase due to the elevated temperature, concurrent with the rise in the Deltaproteobacteria population. Thus, these results indicate that under the expected climate change scenario for the end of the century, the decomposition rate and GHG emissions will be potentially higher, leading to a harmful feedback loop of GHG production. This process can happen independently of an impact on the bacterial community structure due to these changes.

Iron-carbon microelectrolysis coordinated advanced N and P removal from municipal tailwater: Unexpected N conversion and microbial characteristic

The biochemical mechanisms that iron-carbon microelectrolysis (IC-ME) advanced and coordinated treating nitrogen (N) and phosphorus (P) from tailwater are not intensive. Depending on the optimal operating conditions of the iron carbon biofilter (ICBF), the interface P reaction, functional microbial community and characteristics were analyzed. Results demonstrated that iron (Fe) engaged in reaction with nitrate nitrogen (NO3−-N), facilitating the release of both nitrite nitrogen (NO2−-N) and ammonia nitrogen (NH4+-N) to 0.75 and 2.46 mg/L. Total nitrogen (TN) and total phosphorus (TP) were simultaneously removed lower than 10 and 0.3 mg/L under the optimum conditions i.e., gas water ratio of 15, empty bed contact time (EBCT) of 105 min, and backwashing cycle of 12 h. Microelectrolysis (ME) exhibited a robust capacity to degrade macromolecular pollutants, and P was predominantly eliminated via Fe3(PO4)2 and Fe4(PO4)3(OH)2 precipitation. Intriguingly, IC-ME did alter the microbial community composition, especially the Fe-containing microflora (Desulfuromonas, Azospira, Denitratisoma, Rhodobacter and Paludibaculum). The relatively high abundance of Gammaproteobacteria (29.67–38.3 %) promoted N transformation and the N cycle was mainly dominated by nitrogen respiration (1.95–3.39 %), nitrate reduction (2.06–3.45 %) and nitrate respiration (1.95–3.39 %). ME invigorated functional metabolism, thereby promoting organic carbon metabolism.

Fufang Zhenzhu Tiaozhi polysaccharides ameliorates high-fat diet-induced non-alcoholic steatohepatitis and intestinal flora disorders in mice

Non-alcoholic fatty liver disease (NAFLD) is increasingly recognized for its global prevalence and potential progression to more severe liver diseases such as non-alcoholic steatohepatitis (NASH). The primary treatment for NASH is modifying lifestyle through dietary or exercise interventions. The aim of the current study is to investigate the roles of Fufang Zhenzhu Tiaozhi polysaccharides (FTZPs) in mice with NASH. FTZPs were concurrently administered to high-fat diet (HFD)-induced 24-week NASH model mice. FTZPs treatment effectively improved liver lipid metabolism, reduced inflammation and fibrosis, improved the integrity of the intestinal mucosal barrier, and modulated the structure of the intestinal microbiota. FTZPs treatment significantly reduced the abundance of Gammaproteobacteria, Clostridium, and Coprococcus while as induced the abundance of Dehalobacteraceae and Dehalobacterium. Furthermore, sixteen differential metabolites were screened by metabolomics, and the change of asparagine was the most significant. In addition, the correlation analysis showed that there was a significant correlation between asparagine and the aforementioned differential bacteria. The present study demonstrated that FTZPs, as the fundamental pharmacological elements of FTZ (Fufang Zhenzhu Tiaozhi), protect against NASH by improving intestinal barrier damage and regulating intestinal flora with the increase in asparagine.

Analysis of the intestinal microbiota and profiles of blood amino acids and acylcarnitines in neonates with hyperbilirubinemia

ObjectiveThis study aimed to discuss the distinctive features of the intestinal microbiota in neonates with hyperbilirubinemia and to comprehensively analyse the composition of the intestinal microbiota as well as the levels of free amino acids and acylcarnitines in the peripheral blood of neonates experiencing hyperbilirubinemia.ResultsAt the phylum level, Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Chloroflexi were the five predominant microbial groups identified in both the hyperbilirubinemia and control groups. Alpha diversity analysis, encompassing seven indices, showed no statistically significant differences between the two groups. However, Beta diversity analysis revealed a significant difference in intestinal microbiota structure between the groups. Linear discriminant analysis effect size (LEfSe) indicated a significant reduction in the abundance of Gammaproteobacteria and Enterobacteriaceae within the hyperbilirubinemia group compared to that in the control group. The heatmap revealed that the control group exhibited increased abundances of Escherichia and Bifidobacterium, while the hyperbilirubinemia group exhibited increased levels of Enterococcus and Streptococcus. Regarding blood amino acids and acylcarnitines, there were greater concentrations of citrulline (Cit), arginine (Arg), ornithine (Orn), and valine (Val) in the hyperbilirubinemia group than in the control group. The hyperbilirubinemia group also exhibited significant increases in medium-chain fatty acids (C6, C8), long-chain fatty acids (C18), and free carnitine (C0).ConclusionBy comparing neonates with hyperbilirubinemia to those without, a significant disparity in the community structure of the intestinal microbiota was observed. The intestinal microbiota plays a crucial role in the bilirubin metabolism process. The intestinal microbiota of neonates with hyperbilirubinemia exhibited a certain degree of dysbiosis. The abundances of Bacteroides and Bifidobacterium were negatively correlated with the bilirubin concentration. Therefore, the fact that neonates with hyperbilirubinemia exhibit some variations in blood amino acid and acylcarnitine levels may provide, to a certain degree, a theoretical basis for clinical treatment and diagnosis.

Fulvic acid and fermentation agent optimize in situ composting by reducing antibiotic resistance genes abundances and altering succession of bacterial communities

The use of biostimulants to enhance microbial activity has been extensively reported. However, their regulatory properties on the ecological security of in situ composting have not yet been fully elucidated. Here, the effects of two biostimulants (fermentation agent [FM] and fulvic acid [FA]) on in situ composting were investigated under field conditions. The abundances of antibiotic resistance genes (ARGs), as well as those of the microbial communities and the activities of enzymes, were comprehensively investigated. The addition of biostimulants significantly reduced the abundances of streptomycin and sulfonamide resistance genes by 79%–97% and decreased the abundance of Gammaproteobacteria. This was particularly true for species that are members of the Enterobacteriaceae and contain many ARGs. The addition of biostimulants promoted the succession of bacterial communities toward enhancing the solubility of phosphorus, promoting the degradation of aromatic compounds, and reducing the emissions of NOx gas. The application of FA and FM resulted in distinct bacterial network structures, and many negative correlations were associated with ARGs in the temperature subnetwork in the FM treatment. This study provides an effective strategy for the in situ treatment of agricultural waste and underscores the significance of biostimulants in improving the biological safety of medium-temperature in-situ composting.

Soil quality and microbial communities in subtropical slope lands under different agricultural management practices.

Land degradation is a major threat to ecosystem. Long-term conventional farming practices can lead to severe soil degradation and a decline in crop productivity, which are challenging for both local and global communities. This study was conducted to clarify the responses on soil physicochemical properties and microbial communities to changes in farming practices. Slope land orchards under three agricultural management practices-conventional farming (CF), organic farming (OF), and ecofriendly farming (EFF)-were included in this study. We found that soil carbon stock increased by 3.6 and 5.1 times in surface soils (0-30 cm) under EFF and OF treatments, respectively. EFF and OF significantly increased the contents of total nitrogen by 0.33-0.46 g/kg, ammonia-N by 3.0-7.3 g/kg, and microbial biomass carbon by 0.56-1.04 g/kg but reduced those of pH by 0.6 units at least, and available phosphorous by 104-114 mg/kg. The application of phosphorous-containing herbicides and chemical fertilizers might increase the contents of phosphorous and nitrate in CF soil. High abundances of Acidobacteria and Actinobacteria were observed in EFF and OF soils, likely because of phosphorous deficiency in these soils. The abundance of fungi in OF soil indicated that plants' demand for available soil phosphorous induced the fungus-mediated mineralization of organic phosphorous. High abundances of Gammaproteobacteria, Planctomycetes, Firmicutes, and Nitrospirae were observed in CF soil, possibly because of the regular use of herbicides containing phosphorous and chemical fertilizers containing high total nitrogen contents.

Unleashing the power of acetylacetone: Effective control of harmful cyanobacterial blooms with ecological safety

Harmful algal blooms resulting from eutrophication pose a severe threat to human health. Acetylacetone (AA) has emerged as a potential chemical for combatting cyanobacterial blooms, but its real-world application remains limited. In this study, we conducted a 42-day evaluation of AA's effectiveness in controlling blooms in river water, with a focus on the interplay between ecological community structure, organism functional traits, and water quality. At a concentration of 0.2 mM, AA effectively suppressed the growth of Cyanobacteria (88 %), Bacteroidia (49 %), and Alphaproteobacteria (52 %), while promoting the abundance of Gammaproteobacteria (5.0 times) and Actinobacteria (7.2 times) that are associated with the degradation of organic matter. Notably, after dosing of AA, the OD680 (0.07 ± 0.02) and turbidity (8.6 ± 2.1) remained at a satisfactory level. AA induced significant disruptions in two photosynthesis and two biosynthesis pathways (P < 0.05), while simultaneously enriching eight pathways of xenobiotics biodegradation and metabolism. This enrichment facilitated the reduction of organic pollutants and supported improved water quality. Importantly, AA treatment decreased the abundance of two macrolide-related antibiotic resistance genes (ARGs), ereA and vatE, while slightly increased the abundance of two aminoglycoside-related ARGs, aacA and strB. Overall, our findings establish AA as an efficient and durable algicide with favorable ecological safety. Moreover, this work contributes to the development of effective strategies for maintaining and restoring the health and resilience of aquatic ecosystems impacted by harmful algal blooms.

Meta-Analysis of Organic Fertilization Effects on Soil Bacterial Diversity and Community Composition in Agroecosystems.

Application of organic fertilizers or their combination with chemical fertilizers is a feasible practice for improving soil fertility and reducing soil degradation in agroecosystems, and these regulations are mainly mediated though soil microbial communities. Despite bacteria ranking among the most abundant and diverse groups of soil microorganisms, the effects of long-term organic fertilization (OF) and chemical-organic fertilization (COF) on soil bacterial diversity and community composition remain unclear. In this study, we conducted a meta-analysis and demonstrated that OF had no significant effect on bacterial alpha diversity. Application of chemical fertilizer and crop residue significantly decreased bacterial Richness index. Both OF and COF significantly altered bacterial community structure, with these changes being predominately attributed to shifts in soil pH. For bacterial phyla, both OF and COF significantly increased the relative abundance of Proteobacteria and Bacteroidetes, suggesting that OF and COF may cause the enrichment of copiotrophic taxa. In addition, COF significantly increased the relative abundance of Gammaproteobacteria but decreased the relative abundance of Acidobacteria. Overall, our results suggest that organic and chemical-organic fertilization can effectively maintain bacterial diversity and enhance soil fertility in agroecosystems, and the alteration of soil bacterial community structure is closely intertwined with soil pH.

Fe‐modified biochar improved the stability of soil aggregates and organic carbon: Evidence from enzymatic activity and microbial composition

AbstractBiochar modifications are used to improve soil organic carbon (SOC) content, while its effects on soil structure stability and carbon (C) mineralization are less known especially in saline–alkaline soils. A 5 years field experiment was arranged with organic amendments addition in the Yellow River Delta, including (i) NPK, only 255, 56, and 190 kg ha−1 N, P, and K each year, (ii) RS, NPK + rice straw, (iii) BC, NPK + straw‐derived biochar, and (iv) FeBC, NPK + biochar modified with ferric chloride. Relative to NPK treatment, the mean weight diameter was significantly increased with organic amendments addition, which was the highest in FeBC treatment. Meanwhile, SOC content in the soil added with organic amendment was increased by 2%–18%. Compared with the RS and BC, FeBC addition increased the content of stable humin (HU), crystalline Fe oxides (Fed), and amorphous Fe oxides (Feo). There was a positive correlation between HU and Feo/Fed, indicating HU and Fe oxides might form organic mineral complexes to limit SOC biodegradation. While the mineralization rate of SOC in FeBC treatment was decreased by more than 30.4% than that in BC treatment. This might be due to the decrease of soil β‐glucosidase and cellobiohydrolase activities, as well as the abundance of Gammaproteobacteria and Actinobacteria. These results were the mechanism of soil enzyme activity and bacterial community regulating C stability. Therefore, Fe‐modified biochar is a better organic amendment to improve the stability of aggregates structure and SOC in saline–alkaline paddy soil.

Effects of ferrous sulfate modification on the fate of phosphorous in sewage sludge biochar and its releasing mechanisms in heavy metal contaminated soils.

Modifications of sludge biochar with metal-based materials can enhance its fertilizing efficiency and improve safety. To elucidate the effects of ferrous sulfate modification on the fate of phosphorus in sludge biochar and its effect on phosphorus fractionation in soil, we investigated the changes in fractionation and bioavailability of phosphorus in modified sludge biochar and studied the changes in soil characteristics, microbial diversity and response, bioavailability, plant uptake of phosphorus, and heavy metals in contaminated soils after treatment with ferrous sulfate modified sludge biochar. The results demonstrated that ferrous sulfate modifications were conducive to the formation of moderately labile phosphorus in sludge biochar, and the concentrations increased by a factor of 2.7 compared to control. The application of ferrous sulfate-modified sludge biochar to alkaline heavy metal-contaminated soils enhanced the bioavailable, labile, and moderately labile phosphorus contents by a factor of 2.9, 3.0, and 1.6, respectively, whereas it obviously reduced the leachability and bioavailability of heavy metals in soils, exhibited great potentials in the fertilization and remediation of actual heavy metal-contaminated soils in mining areas. The biochar-induced reduction in soil pH, enhancement of organic matter, surface oxygen-containing functional groups, the abundance of Gammaproteobacteria, and its phosphonate degradation activity were primarily responsible for the solubilization of phosphorus from modified biochar in heavy metal-contaminated soils.

Effects of microplastics/nanoplastics on Vallisneria natans roots and sediment: Size effect, enzymology, and microbial communities

Microplastics/nanoplastics (MNPs) pollution in different environmental media and its adverse effects on organisms have received increasing attention from researchers. This paper compares the effects of natural concentrations of three different sizes (20 nm, 200 nm, and 2 μm) of MNPs on Vallisneria natans and sediments. MNPs with smaller sizes adhere more readily to V. natans roots, further promoting root elongation. In addition, the larger the particle size of MNPs, the higher the reactive oxygen species level in the roots, and the malondialdehyde level increased accordingly. In the sediment, 20 nm, and 200 nm MNPs increased the activity of related enzymes, including acid phosphatase, urease, and nitrate reductase. In addition, the dehydrogenase content in the treated sediments increased, and the content changes were positively correlated with the size of MNPs. Changes in microorganisms were only observed on the root surface. The addition of MNPs reduced the abundance of Proteobacteria and increased the abundance of Chloroflexi. In addition, at the class level of species composition on the root surface, the abundance of Gammaproteobacteria under the 20 nm, 200 nm, and 2 μm MNP treatments decreased by 21.19%, 16.14%, and 17.03%, respectively, compared with the control group, while the abundance of Anaerolineae increased by 44.63%, 26.31%, and 62.52%, respectively. These findings enhance the understanding of the size effects of MNPs on the roots of submerged plants and sediment.

Multiscalar Evaluation of the Water Distribution System and Diarrheal Disease Risk in Addis Ababa, Ethiopia.

Despite growing urbanization, our understanding of the impacts of water and sanitation on human health has largely come from studies in rural sectors. To this end, we collected data at both regional (water quality measures from water treatment systems) and community (cross-sectional surveys) scales to examine determinants of enteric pathogen infection and diarrheal disease among infants in Addis Ababa, Ethiopia. Regionally, the Legedadi water treatment plant had significantly lower heterotrophic plate counts, total coliform counts, and fecal coliform counts compared with the Gefersa water treatment plant. The number of pathogen types in infant stool also differed by plant. Decreases in chlorine levels and increases in the relative abundance of Gammaproteobacteria with distance from treatment plants suggest a compromised water distribution system. In communities, infants in households that obtained water from yard pipes or public taps had significantly lower odds of diarrhea compared to households that had water piped into their dwellings (OR = 0.35, 95% CI 0.16, 0.76, and OR = 0.39, 95% CI 0.15, 1.00, respectively). Similarly, infants in households that boiled or filtered water had significantly lower odds of diarrhea compared to households that did not treat water (OR = 0.40, 95% CI 0.19, 0.86 and OR = 0.23, 95% CI 0.06, 0.84, respectively). Integrating multiscalar data better informs the health impacts of water in urban settings.

Grazing and reclamation-induced microbiome alterations drive organic carbon stability within soil aggregates in alpine steppes

Grazing and reclamation are the major modulators of soil organic carbon (SOC) stability in alpine steppes. However, our understanding of changes in SOC caused by grazing and reclamation at the aggregate scale is limited, and the mediating role of microorganisms remains unclear. Here, based on a long-term observation transect, we selected three land-use types: a long-term enclosed natural steppe (NS), a grazed steppe (GS), and a steppe reclaimed as cropland (CL). We investigated the impacts of grazing and reclamation on soil aggregate distributions, SOC fractions and the microbial community, and microbial contributions to SOC stability. Overall, GS and CL significantly decreased the proportion of >2 mm aggregates (by 32.25–33.72%), and enhanced SOC stability within different aggregate sizes, with the highest SOC stability observed in 0.25–2 mm and <0.25 mm sizes. GS significantly decreased bacterial diversity and increased the relative abundance of Gammaproteobacteria, while CL significantly increased microbial diversity and the relative abundance of Alphaproteobacteria. Importantly, GS enhanced the complexity of the bacterial OTUs networks in >2 mm and <0.25 mm aggregates. GS and CL caused changes in the assembly processes of bacterial communities, shifting from being mainly controlled by variable selection to being mainly controlled by homogenizing dispersal. However, there were only minor differences observed in the microbial community assembly within different aggregate sizes under the same treatment. Random forest models and correlation analysis revealed that the bacterial community, especially the network patterns and community assembly, was a key determinant of SOC stability in soil aggregates. In conclusion, we emphasize the important contribution of soil bacterial network patterns and community assembly to SOC stability in the context of human activities, providing information that may be useful for developing alpine steppe management strategies to enhance soil carbon sequestration.