Changes In Microbial Composition Research Articles

More persistent weather causes a pronounced soil microbial legacy but does not impact subsequent plant communities

A soil history of exposure to extreme weather may impact future plant growth and microbial community assembly. Currently, little is known about whether and how previous precipitation regime (PR)-induced changes in soil microbial communities influence plant and soil microbial community responses to a subsequent PR. We exposed grassland mesocosms to either an ambient PR (1 day wet-dry alternation) or a persistent PR (30 days consecutive wet-dry alternation) for one year. This conditioned soil was then inoculated as a 10 % fraction into 90 % sterilized “native” soil, after which new plant communities were established and subjected to either the ambient or persistent PR for 60 days. We assessed whether past persistent weather-induced changes in soil microbial community composition affect soil microbial and plant community responses to subsequent weather persistence. The historical regimes caused enduring effects on fungal communities and only temporary effects on bacterial communities, but did not trigger soil microbial legacy effects on plant productivity when exposed to either current PR. This study provides experimental evidence for soil legacy of climate persistence on grassland ecosystems in response to subsequent climate persistence, helping to understand and predict the influences of future climate change on soil biota.

Exploring the nitrogen fixing strategy of bacterial communities in nitrogen cycling by adding calcium superphosphate at various periods during composting

Chicken manure, as an organic solid waste with a high nitrogen content, generates large amounts of ammonia during composting, which leads to pollution of the surrounding environment, and causes a reduction in the quality of the compost product. Nitrogen is transformed through the nitrogen cycle and bacterial communities are the main contributors to the transformation of the nitrogen cycle. The microbial composition changes dramatically at different stages during composting. Therefore, calcium superphosphate (SSP) was added to compost as a nitrogen-fixing agent to elucidate the strategy and function of the bacterial community involved in the nitrogen cycle. The results showed that the addition of SSP at the initial, high temperature and cooling stages increased the inorganic nitrogen (NH4+-N, NO3−-N) content by 51.99 %, 202.72 % and 173.37 % compared to CK, respectively. In addition, nitrogen cycle functional genes (gdh, nifH, pmoA-amoA, hao, nxrA, nirK, napA, nosZ, narG) abundance were determined by real-time qPCR. The nitrogen cycle genetic results showed that SSP addition at high temperature phase resulted in a 62.43 % down-regulation of ammonification genes, while nitrogen fixation and nitrification genes were enhanced. Random forests revealed a shift in the participation strategy of bacterial communities (e.g., Mycobacterium, Izemoplasmatales, Paracoccus, Ruminococcus) within the nitrogen cycle, leading to altered importance rankings despite involvement in different nitrogen cycle pathways. Moreover, Regression analysis and structural equation modelling revealed that SSP addition at high temperature stage stimulated the bacterial community engaged in nitrogen fixation and nitrification, resulting in increased nitrogen accumulation as NO3−-N during composting. This paper offers the potential to yield novel scientific insights into the impact of microbially mediated nitrogen transformation processes and reduce gaseous pollution.

Uncovering changes in microbiome profiles across commercial and backyard poultry farming systems.

The microbiome profiles of poultry production systems significantly impact bird health, welfare, and the environment. This study investigated the influence of broiler-rearing systems on the microbiome composition of commercial and backyard chicken farms and their environment over time. Understanding these effects is vital for optimizing animal growth, enhancing welfare, and addressing human and environmental health implications. We collected and analyzed various samples from commercial and backyard farms, revealing significant differences in microbial diversity measurements between the two systems. Backyard farms exhibited higher alpha diversity measurements in soil and water samples, while commercial farms showed higher values for litter and feeder samples. The differences in microbial diversity were also reflected in the relative abundance of various microbial taxa. In backyard farms, Proteobacteria levels increased over time, while Firmicutes levels decreased. Campilobacterota, including the major poultry foodborne pathogen Campylobacter, increased over time in commercial farm environments. Furthermore, Bacteroides, associated with improved growth performance in chickens, were more abundant in backyard farms. Conversely, pathogenic Acinetobacter was significantly higher in backyard chicken fecal and feeder swab samples. The presence of Brevibacterium and Brachybacterium, associated with low-performing broiler flocks, was significantly higher in commercial farm samples. The observed differences in microbial composition and diversity suggest that farm management practices and environmental conditions significantly affect poultry health and welfare and have potential implications for human and environmental health. Understanding these relationships can inform targeted interventions to optimize poultry production, improve animal welfare, and mitigate foodborne pathogens and antimicrobial resistance risks. IMPORTANCE The microbiome of poultry production systems has garnered significant attention due to its implications on bird health, welfare, and overall performance. The present study investigates the impact of different broiler-rearing systems, namely, commercial (conventional) and backyard (non-conventional), on the microbiome profiles of chickens and their environment over time. Understanding the influence of these systems on microbiome composition is a critical aspect of the One-Health concept, which emphasizes the interconnectedness of animal, human, and environmental health. Our findings demonstrate that the type of broiler production system significantly affects both the birds and their environment, with distinct microbial communities associated with each system. This study reveals the presence of specific microbial taxa that differ in abundance between commercial and backyard poultry farms, providing valuable insights into the management practices that may alter the microbiome in these settings. Furthermore, the dynamic changes in microbial composition over time observed in our study highlight the complex interplay between the poultry gut microbiome, environmental factors, and production systems. By identifying the key microbial players and their fluctuations in commercial and backyard broiler production systems, this research offers a foundation for developing targeted strategies to optimize bird health and welfare while minimizing the potential risks to human and environmental health. The results contribute to a growing body of knowledge in the field of poultry microbiome research and have the potential to guide future improvements in poultry production practices that promote a sustainable and healthy balance between the birds, their environment, and the microbial communities they host.

Impact of Varying Mass Concentrations of Ammonia Nitrogen on Biogas Production and System Stability of Anaerobic Fermentation

High ammonium release from chicken manure poses a significant limitation to aerobic digestion, impeding microbial processes and inhibiting biogas production. In this study, we conducted anaerobic digestion of a mixture consisting of chicken manure and corn straw as the fermented raw material. The inoculum used was obtained from the residue of previously fermented chicken manure. To assess the inhibitory effect, we varied the ammonia levels within the range of 750–4250 mg/L by introducing ammonium chloride. The efficiency of aerobic digestion was monitored through the measurement of volatile fatty acids (VFA), chemical oxygen demand (COD), total inorganic carbon (TOC), and methane yield. Our results indicated that elevated levels of ammonia nitrogen had a suppressive impact on methane release, and this decrease followed a linear relationship with the increasing ammonia nitrogen load. Moreover, the addition of ammonia led to a slower release, with the maximum daily ammonia concentration observed at 15 days compared to the 6th day at lower ammonia levels. Furthermore, on the 40th day of aerobic digestion, the cumulative methane production at 4250 mg/L was inhibited by 41% compared to the 750 mg/L condition. The patterns of VFA, inorganic carbon, and COD reduction were consistent across all ammonia levels, with VFA and TOC levels being highest at the highest ammonia concentration and lowest at the lowest ammonia concentration. The accumulation of VFA resulted in a decrease in pH and a decline in methanogenic activity. Additionally, high ammonia levels altered the relative abundance of methanogens. Acetoclastic methanogens (Methanosaeta) exhibited a decrease in abundance, while hydrogenotrophic methanogens (Methanosaeta, Methanoculleus) and methylotrophic methanogens (Candidatus Methanoplasma) demonstrated an increase in abundance. Overall, our findings highlight the inhibitory effects of high ammonia concentrations on biogas production, providing insights into the changes in microbial composition and activity during anaerobic fermentation.

Interactions between Mediterranean Diet Supplemented with Dairy Foods and the Gut Microbiota Influence Cardiovascular Health in an Australian Population.

The impact of a Mediterranean diet on the intestinal microbiome has been linked to its health benefits. We aim to evaluate the effects of a Mediterranean diet supplemented with dairy foods on the gut microbiome in Australians at risk of cardiovascular disease. In a randomised controlled cross-over study, 34 adults with a systolic blood pressure ≥120 mmHg and with risk factors for cardiovascular disease were randomly allocated to a Mediterranean diet with 3-4 daily serves of dairy foods (Australian recommended daily intake (RDI) of 1000-1300 mg per day (MedDairy)) or a low-fat (LFD) control diet. Between each 8-week diet, participants underwent an 8-week washout period. Microbiota characteristics of stool samples collected at the start and end of each diet period were determined by 16S rRNA amplicon sequencing. MedDairy-associated effects on bacterial relative abundance were correlated with clinical, anthropometric, and cognitive outcomes. No change in the overall faecal microbial structure or composition was observed with either diet (p > 0.05). The MedDairy diet was associated with changes in the relative abundance of several bacterial taxa, including an increase in Butyricicoccus and a decrease in Colinsella and Veillonella (p < 0.05). Increases in Butyricicoccus relative abundance over 8 weeks were inversely correlated with lower systolic blood pressure (r = -0.38, p = 0.026) and positively correlated with changes in fasting glucose levels (r = 0.39, p = 0.019), specifically for the MedDairy group. No significant associations were observed between the altered taxa and anthropometric or cognitive measures (p > 0.05). Compared to a low-fat control diet, the MedDairy diet resulted in changes in the abundance of specific gut bacteria, which were associated with clinical outcomes in adults at risk of CVD.

Fate of micropollutants in a lab-scale urban wastewater system: Impact of iron-rich drinking water treatment sludge

Iron rich drinking water treatment sludge (Fe-DWTS) could be a potential alternative for Fe salts in controlling sulfide in the sewer network. This study investigated the impact of in-sewer dosed Fe-DWTS on the fate of 26 different intrinsic organic micropollutants in wastewater by using a lab-scale integrated system consisting of sewer reactors and a sequential batch reactor (SBR) to simulate urban wastewater collection and treatment. The batch results revealed that seven among these 26 compounds had higher removal in the Fe-DWTS dosed sewer reactor compared to the control sewer reactor. In contrast, the removal of 7 out of the 26 investigated compounds were reduced, along with the biofilm methanogenic activity due to the long-term Fe-DWTS dosing. Cycle experiments in the SBR showed that the removal of acesulfame was enhanced and the formation of carbamazepine, desvenlafaxine, tramadol and hydrochlorothiazide were reduced, compared to their behaviour in the control SBR. However, the long-term experiments showed no adverse or beneficial effect of in-sewer dosed Fe-DWTS on the removal of most micropollutants in the SBR. Codeine, trimethoprim and gabapentin were exceptions with slightly higher concentrations in the experimental SBR effluent, possibly due to change in microbial composition.

Spatial and temporal changes of charosphere hotspots with or without nitrogen additions

The charosphere is a thin soil one surrounding the biochar with highly active biochemical functions. Yet, little is known about the spatial and temporal distribution of charosphere hotspots. In this study, repacked soil cores were incubated with a central layer of biochar (pristine or acid-modified) with or without nitrogen (N) additions for 30 days and sliced at the millimeter scale for analyzing soil pH, mineral N, bacterial and fungal communities as well as the putative functions. We aimed to determine gradient distributions (in millimeter scale) of charosphere affected by biochar under different N additions. Our results showed narrower gradient changes (3 mm) of microbial community composition and wider shifts (6 mm) in pH and inorganic N contents in charosphere. The pristine biochar increased the soil pH up to 1.5 units in the charosphere, and subsequently boosted the relative abundance of Proteobacteria, Acidobacteria, and Zygomycota. With N addition, both the biochar site and charosphere were observed with decreased complexity of microbial networks, which might imply the limited microbial functionality of charosphere. These results will advance the understanding and prediction of biochar’s environmental impacts in soil.Graphical abstract

Temperature and organic carbon quality control the anaerobic carbon mineralization in peat profiles via modulating microbes: A case study of Changbai Mountain

Peatlands account for a significant fraction of the global carbon stock. However, the complex interplay of abiotic and biotic factors governing anaerobic carbon mineralization in response to warming remains unclear. In this study, peat sediments were collected from a typical northern peatland-Changbai Mountain to investigate the behavior and mechanism of anaerobic carbon mineralization in response to depth (0–200 cm) and temperature (5 °C, 15 °C and 20 °C), by integrating geochemical and microbial analysis. Several indices including humification indexes (HI), aromaticity, and water extractable organic carbon (WEOC) components were applied to evaluate carbon quality, while 16S rRNA sequencing was used to measure microbial composition. Regardless of temperature, degradations of carbon quality and associated reduction in microbial abundance as well as diversity resulted in a decrease in anaerobic carbon mineralization (both CO2 and CH4) towards greater depth. Warming either from 5 °C to 15 °C or 20 °C significantly increased anaerobic carbon mineralization in all depth profiles by improving carbon availability. Enhanced carbon availabilities were mediated by the change in microbial composition (p < 0.01) and an increase in metabolic activities, which was particularly evident in the enhanced β-glucosidase activity and microbial collaborations. A remarkable increase of over 10-fold in the relative abundance of the Geothrix genus was observed under warming. Overall, warming resulted in an enhanced contribution of CH4 emission and a higher ratio of hydrogenotrophic methanogenesis, as evidenced by carbon isotope fractionation factors. In addition, deep peat soils (>100 cm) with recalcitrant carbon demonstrated greater temperature sensitivity (Q10: ∼2.0) than shallow peat soils (Q10:∼1.2) when temperature increased from 15 °C to 20 °C. The findings of this study have significantly deepened our understanding for mechanisms of carbon quality and microbe-driven anaerobic carbon mineralization in peatlands under global warming.

Microbial and immune faecal determinants in infants hospitalized with COVID-19 reflect bifidobacterial dysbiosis and immature intestinal immunity

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly worldwide, seriously endangering human health. Although SARS‐CoV‐2 had a lower impact on paediatric population, children with COVID-19 have been reported as suffering from gastrointestinal (GI) symptoms at a higher rate than adults. The aim of this work was to evaluate faeces as a source of potential biomarkers of severity in the paediatric population, with an emphasis on intestinal microbiota and faecal immune mediators, trying to identify possible dysbiosis and immune intestinal dysfunction associated with the risk of hospitalization. This study involved 19 patients with COVID-19 under 24 months of age hospitalized during the pandemic at 6 different hospitals in Spain, and it included a comparable age-matched healthy control group (n = 18). Patients and controls were stratified according to their age in two groups: newborns or young infants (from 0 to 3 months old) and toddlers (infants from 6 to 24 months old). To characterize microbial intestinal communities, sequencing with Illumina technology of total 16S rDNA amplicons and internal transcribed spacer (ITS) amplicons of bifidobacteria were used. Faecal calprotectin (FC) and a range of human cytokines, chemokines, and growth factors were measured in faecal samples using ELISA and a multiplex system. Significant reduction in the abundance of sequences belonging to the phylum Actinobacteria was found in those infants with COVID-19, as well as in the Bifidobacteriaceae family. A different pattern of bifidobacteria was observed in patients, mainly represented by lower percentages of Bifidobacterium breve, as compared with controls. In the group of hospitalized young infants, FC was almost absent compared to age-matched healthy controls. A lower prevalence in faecal excretion of immune factors in these infected patients was also observed.Conclusion: Hospitalized infants with COVID-19 were depleted in some gut bacteria, such as bifidobacteria, in particular Bifidobacterium breve, which is crucial for the proper establishment of a functional intestinal microbiota, and important for the development of a competent immune system. Our results point to a possible immature immune system at intestine level in young infants infected by SARS-CoV2 requiring hospitalization.What is Known:• Although SARS‐CoV‐2 had a lower impact on paediatric population, children with COVID-19 have been reported as suffering from gastrointestinal symptoms at a higher rate than adults.• Changes in microbial composition have been described in COVID-19 adult patients, although studies in children are limited.What is New:• The first evidence that hospitalized infants with COVID-19 during the pandemic had a depletion in bifidobacteria, particularly in Bifidobacterium breve, beneficial gut bacteria in infancy that are crucial for the proper establishment of a competent immune system.• In young infants (under 3 months of age) hospitalized with SARS-CoV2 infection, the aberrant bifidobacterial profile appears to overlap with a poor intestinal immune development as seen by calprotectin and the trend of immunological factors excreted in faeces.

Remediation Effect and Mechanism of Biochar in Combination with Nitrogen Fertilizer on Cd-contaminated Paddy Soil

Cadmium (Cd) heavy metal pollution has posed serious threats to soil health and the safe production utilization of agricultural products. A pot experiment was conducted to study the effects of biochar (BC) and nitrogen fertilizer with three levels, namely 2.6 g·pot-1 (N1), 3.5 g·pot-1 (N2), 4.4 g·pot-1 (N3) biochar combined with nitrogen fertilizer (BCN1, BCN2, and BCN3), on soil Cd fractions, Cd enrichment, the transport of rice, and soil enzyme activity, as well as the changes in microbial community composition and complex interactions between microorganisms through high-throughput sequencing. The results showed that biochar combined with nitrogen fertilizer led to the transformation of Cd from the exchangeable state to the residue state, and the proportion of the exchangeable state was significantly reduced by 6.2%-14.7%; by contrast, the proportion of the residue state increased by 18.6%-26.4% relative to that in CK. In addition, singular treatments of nitrogen fertilizer enhanced the accumulation capacities of Cd in roots, which increased by 22%-33.5% compared with that in CK. By contrast, the BC and BCN treatments reduced Cd accumulation in roots and the transfer capacity from stems to rice husks and husk to rice. Furthermore, the BCN treatments promoted soil enzyme activities (urease, acid phosphatase, invertase, and catalase). MiSeq sequencing showed that BCN treatments increased the abundance of the main species of soil bacterial microbes (such as Acidobacteriales, Solibacterales, Pedosphaerales, and Nitrospirales). Moreover, co-occurrence network analysis showed that the complexity of the soil bacterial network was enhanced under the N, BC, and BCN treatments. Overall, biochar combined with nitrogen fertilizer reduced soil Cd availability, inhibited the capacity of Cd accumulation and the transport of rice, and improved the soil eco-environmental quality. Thus, using BCN could be a feasible practice for the remediation of Cd-polluted agricultural soil.

Succession of bacterial community structure in response to a one-time application of biochar in barley rhizosphere and bulk soils

Biochar is often used as an amendment to enhance soil fertility by directly increasing soil pH and nutrient availability. However, biochar may also improve soil fertility indirectly by altering the succession of bacterial communities that, in turn, may alter nutrient supply and availability. To determine how biochar affects soil bacterial richness and diversity, as well as how bacterial communities respond to biochar across space and time, we studied the rhizosphere and bulk soils of potted barley plants for 2 years. Adding biochar significantly increased bacterial community richness (Chao 1 richness index) by the end of the second year in the rhizosphere (P = 0.037), but in bulk soils, we observed an increase in richness in Year 1 that dissipated by Year 2. In contrast to richness, adding biochar only had a significant effect on bacterial community diversity (Shannon diversity index) in Year 1 seedling stage (P &amp;lt; 0.001), but the effect dissipated thereafter. We also found that adding biochar increased the relative abundances of Actinobacteria and Proteobacteria but decreased the relative abundances of Acidobacteria and Chloroflexi, suggesting these communities were sensitive to biochar inputs. The biochar-sensitive genera belonging to Actinobacteria and Proteobacteria made up 45%–58% of sensitive taxa in both rhizosphere and bulk soils. Of the Proteobacteria sensitive to adding biochar, Nitrosospira and Sphingomonas were most abundant in the rhizosphere relative to bulk soils. However, despite the initial increase of biochar sensitive responders in the rhizosphere, their numbers decreased after 2 years and had 179 fewer genera than bulk soils. Our findings suggest the effect of adding biochar was relatively short-lived and that the influence of the plant phenology was a stronger driver of bacterial community change than biochar inputs 2 years after its application. Altogether, the succession of soil bacterial community structure reflected changes in the soil environment induced by the combined effect of biochar, rhizospheric inputs, and plant phenology, suggesting that changes in microbial community composition observed after amending soils with biochar, may also contribute to changes in soil fertility.

Microbial composition and diversity of the tobacco leaf phyllosphere during plant development.

Phyllosphere-associated microorganisms affect host plant's nutrients availability, its growth and ecological functions. Tobacco leaves provide a wide-area habitat for microbial life. Previous studies have mainly focused on phyllosphere microbiota at one time point of tobacco growth process, but more is unknown about dynamic changes in phyllospheric microbial composition from earlier to the late stage of plant development. In the current study, we had determined the bacterial and fungal communities succession of tobacco growth stages (i.e., seedling, squaring, and maturing) by using both 16S rRNA sequencing for bacterial and ITS sequencing for fungi. Our results demonstrated that among tobacco growth stages, the phyllospheric bacterial communities went through more distinct succession than the fungal communities did. Proteobacteria and Actinobacteria exerted the most influence in tobacco development from seedling to squaring stages. At maturing stage, Proteobacteria and Actinobacteria dominance was gradually replaced by Firmicutes and Bacteroidetes. Network analysis revealed that Proteobacteria, as the core phyllospheric microbia, played essential role in stabilizing the whole bacterial network during tobacco development, and consequently rendered it to more profound ecological functions. During tobacco development, the contents of leaf sugar, nicotine, nitrogen and potassium were significantly correlated with either bacterial or fungal communities, and these abiotic factors accounted for 39.3 and 51.5% of the total variation, respectively. We overall evinced that the development of tobacco phyllosphere is accompanied by variant dynamics of phyllospheric microbial community.

A decade of microbial community dynamics on sinking particles during high carbon export events in the eastern Fram Strait

Marine sinking particles sequester atmospheric carbon dioxide to the deep ocean via the biological carbon pump. Understanding how environmental shifts drive changes in the microbial composition of particles, and how these affect the export of organic matter from the surface to the deep ocean, is critical, especially in the rapidly changing Arctic Ocean. Here, we applied next generation sequencing of the 18S and 16S rRNA genes to sediment trap samples from around 200 m water depth in the eastern Fram Strait, covering a time frame of more than one decade (2000-2012). The aim was to characterize their microbial composition during annual highest particulate organic carbon flux events. The bimodal annual spring and summer export fluxes were representative of the strong seasonality in the region. Furthermore, the study period was characterized by considerable interannual variation, marked especially by a warm water anomaly between 2005 and 2007. During this period changes in the hydrography and sea ice cover also led to measurable changes in the microbial composition of particles. The warm water period was marked by a decrease in diatoms affiliated with Chaetoceros, an increase of small phytoplankton and an increase in sequence abundance of the bacterial taxa Oceanospirillales, Alteromonadales and Rhodobacterales on the particles. The resulting changes in microbial composition and the associated microbial network structure suggest the emergence of a more developed retention system in the surface ocean. Our results provide the first long-term assessment of the microbial composition of sinking particles in the Arctic Ocean, and stress the importance of sea ice and hydrography for particle composition and subsequent flux of organic matter to deeper waters.

Influence of Gallic Acid-Containing Mouth Spray on Dental Health and Oral Microbiota of Healthy Dogs: A Pilot Study.

The pilot study aimed to investigate the effects of GAMS on oral microbiota in healthy dog subjects. Thirty-eight dogs were recruited and randomly allocated to the placebo (n = 19) and treatment groups (n = 19). The dogs were treated with mouth spray once daily for 42 days. The changes in the gingival index (GI), plaque index (PI), and calculus index (CI) were measured at baseline (day 0) and end of the study (42nd day). The changes in the oral microbial composition of representative dogs (placebo, n = 7; and treatment, n = 7) were also evaluated at baseline and end of the study. Oral microbial composition was assessed by sequencing. The sequences were annotated using the QIIME 2.0TM. The GI, PI, and CI indexes were reduced after the GAMS usage. The abundance of the commensal bacterial phylum Actinobacteria and Chloroflexi, genera Frederiksenia, and Bergeyella was improved after six weeks of GAMS usage. GAMS reduced the pathogenic bacterial species, including Neisseria sp., Desulfobulbus sp., Capnocytophaga canis, and Corynebacterium mustelae. Moreover, some pathogenic bacterial abundances were increased at the end of the study. All the microbial variations were observed within the group. The inter-group analysis revealed that the changes were unrelated to GAMS usage. Further studies need to be carried out using more experimental subjects to confirm the effectiveness of GAMS. More metagenomic data are required to evidence the GMAS impact on the oral microbiome of healthy dogs.

The Effect of Commonly Used Organic Acids on the Microbiota of Cured Deli-Style Turkey Breast

The purpose of this study was to investigate changes in the microbial community structure consisting of spoilage lactic acid bacteria (LAB) when sodium lactate (SL) and SL + sodium diacetate (SD) are included in RTE meat product formulations at concentrations commonly used for controlling Listeria monocytogenes. Sliced cooked, vacuum-packaged turkey breast samples containing no SD or SL (control [C]), 0.125% SD, and the combination of 2.5% SL + 0.125%SD (SLSD) were inoculated with a target of 3 log colony-forming units (CFU)/g of 5 different LAB species (Lactobacillus sakei, Leuconostoc mesenteroides [bacon and deli-shaved ham isolates], Lactococcus lactis, and Enterococcus faecium) and stored at 4°C for 35 d. Microbial community changes were analyzed utilizing 16S ribosomal RNA (rRNA) gene sequencing for the V4 region from the samples collected at days 0, 7, 14, 21, and 35. No significant difference (P&amp;gt;0.05) was observed between the richness of microbial community for all treatments. According to Bray-Curtis dissimilarity matrix and permutational analysis of variance, a significant difference in β-diversity was observed only between C and SLSD (P&amp;lt;0.05) because of the antimicrobial effect of the addition of SL that slowed down changes in microbial community composition until day 14. L. sakei remained a dominant strain throughout 35 d of storage regardless of treatment, whereas L. mesenteroides existed with a very low abundance. Two of the five strains were not seen after day 7. No significant effect (P&amp;gt;0.05) was observed for the SD treatment compared with C in the microbiota. According to the results from this study, only SLSD affected the microbial community structure at the beginning of the storage. This study demonstrated that the incorporation of SL in the formulation slowed down the microbial spoilage and the changes in the microbiota of RTE meat products.

Pleiotropic activities of succinate: The interplay between gut microbiota and cardiovascular diseases.

Cardiovascular diseases (CVDs) continue to be a significant contributor to global mortality, imposing a substantial burden and emphasizing the urgent need for disease control to save lives and prevent disability. With advancements in technology and scientific research, novel mechanisms underlying CVDs have been uncovered, leading to the exploration of promising treatment targets aimed at reducing the global burden of the disease. One of the most intriguing findings is the relationship between CVDs and gut microbiota, challenging the traditional understanding of CVDs mechanisms and introducing the concept of the gut-heart axis. The gut microbiota, through changes in microbial compositions and functions, plays a crucial role in influencing local and systemic effects on host physiology and disease development, with its metabolites acting as key regulators. In previous studies, we have emphasized the importance of specific metabolites such as betaine, putrescine, trimethylamine oxide, and N,N,N-trimethyl-5-aminovaleric acid in the potential treatment of CVDs. Particularly noteworthy is the gut microbiota-associated metabolite succinate, which has garnered significant attention due to its involvement in various pathophysiological pathways closely related to CVDs pathogenesis, including immunoinflammatory responses, oxidative stress, and energy metabolism. Furthermore, we have identified succinate as a potential biomarker, highlighting its therapeutic feasibility in managing aortic dissection and aneurysm. This review aims to comprehensively outline the characteristics of succinate, including its biosynthetic process, summarize the current evidence linking it to CVDs causation, and emphasize the host-microbial crosstalk involved in modulating CVDs. The insights presented here offer a novel paradigm for future management and control of CVDs.

Synthesis and evaluation of metal-impregnated carbon cloth supplementation to improve anaerobic digestion performance from municipal sludge

This study investigated the effect of metal-impregnated carbon cloth (CC) supplementation on thermophilic anaerobic digestion (AD) improvement by utilizing municipal sludge as a biomass input. Four types of metal-impregnated CC nanocomposites (Fe/CC, Ni/CC, Ni/Fe/CC, NiPcS/Fe/CC) were synthesized from activated CC (A-CC) using hydrothermal synthesis and compared with untreated CC (U-CC) to evaluate their functional significance for enhanced AD. The main factors inspected were electrical conductivity (EC) and Brunauer–Emmett–Teller (BET) surface area. A-CC had the highest surface area of 386.15 m2/g, followed by Fe/CC, NiPcS/Fe/CC, Ni/CC and Ni/Fe/CC with 140.96, 52.27, 43.52 and 36.07 m2/g, respectively. The A-CC and Fe/CC reactors produced 3.45 and 2.70 times more methane than Control (without CC) in the first 9 days. In contrast, the methane production for U-CC, Ni/CC, Ni/Fe/CC and NiPcS/Fe/CC was only 0.87, 1.26, 1.01 and 1.29 times, respectively, compared to Control. At a higher BET surface (>350 m2/g), the surface area becomes a more dominant factor, and the increase of EC value (>2.9*104 1/Ω.m) does not have an impact on methane enhancement. Microbial community analysis revealed that A-CC had the highest abundances of Syntrophomonas, Coprothermobacter and methanogenic populations, including Methanothermobacter and Methanosarcina, within 3 days compared to Control and metal-impregnated CC. There were minimal changes in microbial community composition in metal-impregnated CC compared to the U-CC. The result implies that the efficacy of CC supplementation for AD upgrading largely depends on the higher surface area compared to metal impregnation or conductivity.

Chronic Heat Stress Affects Bile Acid Profile and Gut Microbiota in Broilers.

Heat stress (HS) can inhibit the growth performance of broilers and cause substantial economic losses. Alterations in bile acid (BA) pools have been reported to be correlated with chronic HS, yet the specific mechanism and whether it is related to gut microbiota remains unclear. In this study, 40 Rugao Yellow chickens were randomly selected and distributed into two groups (20 broilers in each group) when reaching 56-day age: a chronic heat stress group (HS, 36 ± 1 °C for 8 h per day in the first 7 days and 36 ± 1 °C for 24 h in the last 7 days) and a control group (CN, 24 ± 1 °C for 24 h within 14 days). Compared with the CN group, total BAs' serum content decreased, while cholic acid (CA), chenodeoxycholic acid (CDCA), and taurolithocholic acid (TLCA) increased significantly in HS broilers. Moreover, 12α-hydroxylase (CYP8B1) and bile salt export protein (BSEP) were upregulated in the liver, and the expression of fibroblast growth factor 19 (FGF19) decreased in the ileum of HS broilers. There were also significant changes in gut microbial composition, and the enrichment of Peptoniphilus was positively correlated with the increased serum level of TLCA. These results indicate that chronic HS disrupts the homeostasis of BA metabolism in broilers, which is associated with alterations in gut microbiota.

The pathogenesis of gut microbiota in hepatic encephalopathy by the gut-liver-brain axis.

Hepatic encephalopathy (HE) is a neurological disease occurring in patients with hepatic insufficiency and/or portal-systemic blood shunting based on cirrhosis. The pathogenesis is not completely clear till now, but it is believed that hyperammonemia is the core of HE. Hyperammonemia caused by increased sources of ammonia and decreased metabolism further causes mental problems through the gut-liver-brain axis. The vagal pathway also plays a bidirectional role in the axis. Intestinal microorganisms play an important role in the pathogenesis of HE through the gut-liver-brain axis. With the progression of cirrhosis to HE, intestinal microbial composition changes gradually. It shows the decrease of potential beneficial taxa and the overgrowth of potential pathogenic taxa. Changes in gut microbiota may lead to a variety of effects, such as reduced production of short-chain fatty acids (SCFAs), reduced production of bile acids, increased intestinal barrier permeability, and bacterial translocation. The treatment aim of HE is to decrease intestinal ammonia production and intestinal absorption of ammonia. Prebiotics, probiotics, antibiotics, and fecal microbiota transplantation (FMT) can be used to manipulate the gut microbiome to improve hyperammonemia and endotoxemia. Especially the application of FMT, it has become a new treated approach to target microbial composition and function. Therefore, restoring intestinal microbial homeostasis can improve the cognitive impairment of HE, which is a potential treatment method.

Long-term elevated precipitation induces grassland soil carbon loss via microbe-plant-soil interplay.

Global climate models predict that the frequency and intensity of precipitation events will increase in many regions across the world. However, the biosphere-climate feedback to elevated precipitation (eP) remains elusive. Here, we report a study on one of the longest field experiments assessing the effects of eP, alone or in combination with other climate change drivers such as elevated CO2 (eCO2 ), warming and nitrogen deposition. Soil total carbon (C) decreased after a decade of eP treatment, while plant root production decreased after 2 years. To explain this asynchrony, we found that the relative abundances of fungal genes associated with chitin and protein degradation increased and were positively correlated with bacteriophage genes, suggesting a potential viral shunt in C degradation. In addition, eP increased the relative abundances of microbial stress tolerance genes, which are essential for coping with environmental stressors. Microbial responses to eP were phylogenetically conserved. The effects of eP on soil total C, root production, and microbes were interactively affected by eCO2 . Collectively, we demonstrate that long-term eP induces soil C loss, owing to changes in microbial community composition, functional traits, root production, and soil moisture. Our study unveils an important, previously unknown biosphere-climate feedback in Mediterranean-type water-limited ecosystems, namely how eP induces soil C loss via microbe-plant-soil interplay.