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Environmental Science and Pollution... Jun 2024Azotobacter chroococcum and Bacillus subtilis were selected as fermentation strains, and biogas residue after anaerobic digestion of kitchen waste and residual sludge...
Azotobacter chroococcum and Bacillus subtilis were selected as fermentation strains, and biogas residue after anaerobic digestion of kitchen waste and residual sludge was used as fermentation substrate. A single factor optimization test was used to optimize the solid-state fermentation parameters of biogas residue with the number of viable bacteria and the number of spores as indexes. The results showed that the optimum inoculation conditions involved the following: 55% initial moisture content, 15% initial inoculation amount, 30 ℃, and 1:1 initial inoculation ratio for 13 days. Pot experiment showed that the prepared three kinds of bacterial fertilizers could not only effectively promote the growth of white clover, improve the composition of soil nutrients, but also change the structure of soil bacterial community, which is of great significance to the health of soil ecosystem in white clover.
PubMed: 38918298
DOI: 10.1007/s11356-024-33924-4 -
Bioresource Technology Jun 2024A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in...
A bioelectrochemical upflow anaerobic sludge blanket (BE-UASB) was constructed and compared with the traditional UASB to investigate the role of bioelectrocatalysis in modulating methanogenesis and sulfidogensis involved within anaerobic treatment of high-sulfate methanolic wastewater (COD/SO ratio ≤ 2). Methane production rate for BE-UASB was 1.4 times higher than that of the single UASB, while SO removal stabilized at 16.7%. Bioelectrocatalysis selectively enriched key functional anaerobes and stimulated the secretion of extracellular polymeric substances, especially humic acids favoring electron transfer, thereby accelerating the electroactive biofilms development of electrodes. Methanomethylovorans was the dominant genus (35%) to directly convert methanol to CH. Methanobacterium as CO electroreduction methane-producing archaea appeared only on electrodes. Acetobacterium exhibited anode-dependence, which provided acetate for sulfate-reducing bacteria (norank Syntrophobacteraceae and Desulfomicrobium) through synergistic coexistence. This study confirmed that BE-UASB regulated the microbial ecology to achieve efficient removal and energy recovery of high-sulfate methanolic wastewater.
PubMed: 38917910
DOI: 10.1016/j.biortech.2024.131026 -
Journal of Agricultural and Food... Jun 2024The synthetic community of lactic acid bacteria (LAB) is commonly utilized in the food industry for manipulating product properties. However, the intermediate...
The synthetic community of lactic acid bacteria (LAB) is commonly utilized in the food industry for manipulating product properties. However, the intermediate interactions and ecological stability resulting from metabolic differences among various LAB types remain poorly understood. We aimed to analyze the metabolic behavior of single and combined lactic acid bacteria in China rice wine based on microbial succession. Three-stage succession patterns with obligate heterofermentative LAB dominating prefermentation and homofermentative LAB prevailing in main fermentation were observed. Facultative heterofermentative LAB exhibited significant growth. Pairwise coculture interactions revealed 63.5% positive, 34.4% negative, and 2.1% neutral interactions, forming nontransitive and transitive competition modes. Nontransitive competitive combinations demonstrated stability over ∼200 generations through amino acid (mainly aspartic acid, glutamine, and serine) cross-feeding and lactic acid detoxification, which also showed potential for controlling biogenic amines and developing LAB starter cultures. Our findings offer insights into the mechanistic underpinnings of LAB interaction networks.
PubMed: 38913831
DOI: 10.1021/acs.jafc.4c02461 -
Frontiers in Cellular and Infection... 2024We assessed the anti-chlamydial activity of fresh vaginal secretions, deciphering the microbial and metabolic components able to counteract viability.
INTRODUCTION
We assessed the anti-chlamydial activity of fresh vaginal secretions, deciphering the microbial and metabolic components able to counteract viability.
METHODS
Forty vaginal samples were collected from a group of reproductive-aged women and their anti-chlamydial activity was evaluated by inhibition experiments. Each sample underwent 16S rRNA metabarcoding sequencing to determine the bacterial composition, as well as H-NMR spectroscopy to detect and quantify the presence of vaginal metabolites.
RESULTS
Samples characterized by a high anti-chlamydial activity were enriched in , especially and , while not-active samples exhibited a significant reduction of lactobacilli, along with higher relative abundances of and . showed an opposite behavior compared to , being more prevalent in not-active vaginal samples. Higher concentrations of several amino acids (i.e., isoleucine, leucine, and aspartate; positively correlated to the abundance of and ) lactate, and 4-aminobutyrate were the most significant metabolic fingerprints of highly active samples. Acetate and formate concentrations, on the other hand, were related to the abundances of a group of anaerobic opportunistic bacteria (including and ). Finally, glucose, correlated to and genera, emerged as a key molecule of the vaginal environment: indeed, the anti-chlamydial effect of vaginal fluids decreased as glucose concentrations increased.
DISCUSSION
These findings could pave the way for novel strategies in the prevention and treatment of chlamydial urogenital infections, such as lactobacilli probiotic formulations or lactobacilli-derived postbiotics.
Topics: Female; Humans; Vagina; RNA, Ribosomal, 16S; Lactobacillus; Chlamydia trachomatis; Adult; Streptococcus; Young Adult; Lactobacillus crispatus; Chlamydia Infections
PubMed: 38912205
DOI: 10.3389/fcimb.2024.1403782 -
Environmental Research Jun 2024In this study, g-CN/PANI was prepared by in situ oxidative polymerization. Graphite-phase carbon nitride (g-CN) with surface defects was deposited onto the surface of...
In this study, g-CN/PANI was prepared by in situ oxidative polymerization. Graphite-phase carbon nitride (g-CN) with surface defects was deposited onto the surface of conductive polyaniline (PANI) to form a p-n heterojunction. This construction aimed to create an efficient heterogeneous catalyst, increasing the surface defect level and active sites of the composite, and augmenting its capability to capture and transfer extracellular electrons under anaerobic conditions. This addresses the challenge of low efficiency in direct interspecies electron transfer between bacteria and archaea during anaerobic digestion for methane production. The results showed that the prepared g-CN/PANI increased the CH yield and CH production rate by 82% and 96%, respectively. Notably, the conductivity and XPS test results showed that the ratio of g-CN to PANI was 0.15, and the composite exhibited favorable conductivity, with a uniform distribution of pyrrolic nitrogen, pyridinic nitrogen, and graphitic nitrogen, each accounting for approximately 30%. Furthermore, g-CN/PANI effectively enhanced the metabolic efficiency of intermediate products such as acetate and butyrate. Analysis of the microbial community structure revealed that g-CN/PANI led to a significant increase in the abundance of hydrogenotrophic methanogen Methanolinea (from 48% to 64%) and enriched Clostridium (a rise of 1%) with direct interspecies electron transfer capability. Microbial community function analysis demonstrated that the addition of g-CN/PANI boosted the activities of key enzymes involved in anaerobic digestion, including phosphate transacetylase (PTA), phospho-butyryl transferase (PTB), and NAD-independent lactate dehydrogenase (NNLD), by 47%, 135%, and 153%, respectively. This acceleration in enzymatic activity promoted the metabolism of acetyl-CoA, butyryl-CoA, and pyruvate. Additionally, the function of ABC transporters was enhanced, thereby improving the efficiency of material and energy exchange among microorganisms.
PubMed: 38909948
DOI: 10.1016/j.envres.2024.119480 -
Environmental Research Jun 2024Microaerobic sludge bed systems could align with low-energy, reasonable carbon-nitrogen (C/N) ratio, and synchronous removal objectives during wastewater treatment....
Advancing the treatment of low carbon-to-nitrogen ratio municipal wastewater using a novel microaerobic sludge bed approach: Insights into enhanced performance and functional microbial community.
Microaerobic sludge bed systems could align with low-energy, reasonable carbon-nitrogen (C/N) ratio, and synchronous removal objectives during wastewater treatment. However, its ability to treat municipal wastewater (MW) with varying low C/N ratio, low NH concentration, along with managing sludge bulking and loss are still unclear. Against this backdrop, this study investigated the performance of an Upflow Microaerobic Sludge Bed Reactor (UMSR) treating MW characterized by varying low C/N ratios and low NH concentrations. The study also thoroughly examined associated sludge bulking and loss, pollutant removal efficiencies, sludge settleability, microbial community structures, functional gene variations, and metabolic pathways. Findings revealed that the effluent NH-N concentration gradually decreased to 0 mg/L with a decrease in the C/N ratio, whereas the effluent COD was unaffected by the influent, maintaining a concentration below 50 mg/L. Notably, TN removal efficiency reached 90% when C/N ratio was 3. The decrease in the C/N ratio (C/N ratio was 1) increased microbial community diversity, with abundances of AOB, AnAOB, aerobic denitrifying bacteria, and anaerobic digestion bacteria reaching 8.34%, 0.96%, 5.07%, and 9.01%, respectively. Microorganisms' metabolic pathways significantly shifted, showing increased carbohydrate and cofactor/vitamin metabolism and decreased amino acid metabolism and xenobiotic biodegradation. This study not only provides a solution for the effluent of different pre-capture carbon processes but also demonstrates the UMSR's capability in managing low C/N ratio municipal wastewater and emphasizes the critical role of microbial community adjustments and functional gene variations in enhancing nitrogen removal efficiency.
PubMed: 38909945
DOI: 10.1016/j.envres.2024.119461 -
Bioresource Technology Jun 2024This paper examines the adaptive responses of microbial communities to gradual shifts in pH toward the mild alkaline range in anaerobic digestion (AD) systems. The...
This paper examines the adaptive responses of microbial communities to gradual shifts in pH toward the mild alkaline range in anaerobic digestion (AD) systems. The results indicate that a pH of 8.0 serves as a critical upper limit for stable AD operation, beyond which microbial efficiency declines, underscoring the importance of microbial resilience against elevated pH stress. Specifically, hydrolysis genera, e.g. Eubacterium and Anaerobacterium, and syntrophic bacteria were crucial for reactor stability. Fibrobacter had also been shown to play a key role in the accumulation of propionate, thus leading to its dominance in the volatile fatty acid profile throughout the experimental phases. Overall, this investigation revealed the potential adaptability of microbial communities in AD systems to mild alkaline pH shifts, emphasizing the hydrolysis bacteria and syntrophic bacteria as key factors for maintaining metabolic function in elevated pH conditions.
PubMed: 38909869
DOI: 10.1016/j.biortech.2024.131009 -
The Lancet. Microbe Jun 2024Microbiota alterations are common in patients hospitalised for severe infections, and preclinical models have shown that anaerobic butyrate-producing gut bacteria...
Association between butyrate-producing gut bacteria and the risk of infectious disease hospitalisation: results from two observational, population-based microbiome studies.
BACKGROUND
Microbiota alterations are common in patients hospitalised for severe infections, and preclinical models have shown that anaerobic butyrate-producing gut bacteria protect against systemic infections. However, the relationship between microbiota disruptions and increased susceptibility to severe infections in humans remains unclear. We investigated the relationship between gut microbiota and the risk of future infection-related hospitalisation in two large population-based cohorts.
METHODS
In this observational microbiome study, gut microbiota were characterised using 16S rRNA gene sequencing in independent population-based cohorts from the Netherlands (HELIUS study; derivation cohort) and Finland (FINRISK 2002 study; validation cohort). HELIUS was conducted in Amsterdam, Netherlands, and included adults (aged 18-70 years at inclusion) who were randomly sampled from the municipality register of Amsterdam. FINRISK 2002 was conducted in six regions in Finland and is a population survey that included a random sample of adults (aged 25-74 years). In both cohorts, participants completed questionnaires, underwent a physical examination, and provided a faecal sample at inclusion (Jan 3, 2013, to Nov 27, 2015, for HELIUS participants and Jan 21 to April 19, 2002, for FINRISK participants. For inclusion in our study, a faecal sample needed to be provided and successfully sequenced, and national registry data needed to be available. Primary predictor variables were microbiota composition, diversity, and relative abundance of butyrate-producing bacteria. Our primary outcome was hospitalisation or mortality due to any infectious disease during 5-7-year follow-up after faecal sample collection, based on national registry data. We examined associations between microbiota and infection risk using microbial ecology and Cox proportional hazards.
FINDINGS
We profiled gut microbiota from 10 699 participants (4248 [39·7%] from the derivation cohort and 6451 [60·3%] from the validation cohort). 602 (5·6%) participants (152 [3·6%] from the derivation cohort; 450 [7·0%] from the validation cohort) were hospitalised or died due to infections during follow-up. Gut microbiota composition of these participants differed from those without hospitalisation for infections (derivation p=0·041; validation p=0·0002). Specifically, higher relative abundance of butyrate-producing bacteria was associated with a reduced risk of hospitalisation for infections (derivation cohort cause-specific hazard ratio 0·75 [95% CI 0·60-0·94] per 10% increase in butyrate producers, p=0·013; validation cohort 0·86 [0·77-0·96] per 10% increase, p=0·0077). These associations remained unchanged following adjustment for demographics, lifestyle, antibiotic exposure, and comorbidities.
INTERPRETATION
Gut microbiota composition, specifically colonisation with butyrate-producing bacteria, was associated with protection against hospitalisation for infectious diseases in the general population across two independent European cohorts. Further studies should investigate whether modulation of the microbiome can reduce the risk of severe infections.
FUNDING
Amsterdam UMC, Porticus, National Institutes of Health, Netherlands Organisation for Health Research and Development (ZonMw), and Leducq Foundation.
PubMed: 38909617
DOI: 10.1016/S2666-5247(24)00079-X -
Journal of Environmental Management Jun 2024Ofloxacin (OFL) is a commonly used antibiotic that can enter wastewater treatment plants and be adsorbed by the sludge, resulting in a high OFL concentration in sludge...
Ofloxacin (OFL) is a commonly used antibiotic that can enter wastewater treatment plants and be adsorbed by the sludge, resulting in a high OFL concentration in sludge and affecting the subsequent sludge anaerobic digestion process. However, the micro mechanisms involved in this process have not been thoroughly studied. Therefore, this study focuses on the effect of OFL on the sludge anaerobic digestion of sludge to provide such support. The experimental results showed that the maximal methane yield decreased from 277.7 to 164.7 mL/g VSS with the OFL concentration increased from 0 to 300 mg/L. Additionally, OFL hindered the intermediate biochemical processes of hydrolysis, acidogenesis, acetogenesis, and acetoclastic methanogenesis. However, it promoted hydrogenotrophic methanogenesis process, using H as substrate, with the concentration of 300 mg/L OFL was 5.54 fold methane production of that in the control. Further investigation revealed that the negative effect of OFL was likely due to the induction of reactive oxygen species, which led to a decrease in cell activity and interference with the activity of key enzymes. Microbiological analysis revealed that OFL reduced the relative abundance of hydrolysis and acidogenesis bacteria, and Methanosaeta archaea, while increasing the relative abundance of hydrogenotrophic methanogenesis microorganism from 36.54% to 51.48% as the OFL concentration increase from 0 to 300 mg/L.
PubMed: 38909576
DOI: 10.1016/j.jenvman.2024.121522 -
Bioresource Technology Jun 2024Anaerobic co-fermentation of swine manure (SM) and apple waste (AW) restricts by the slow hydrolysis of substrates with complex structures, which subsequently leads to...
Anaerobic co-fermentation of swine manure (SM) and apple waste (AW) restricts by the slow hydrolysis of substrates with complex structures, which subsequently leads to low lactic acid (LA) production. Therefore, a novel strategy based on enzymatic pretreatment for improving LA production from anaerobic co-fermentation of SM and AW was proposed in this study. The results indicated that the maximal LA concentration increased from 35.89 ± 1.84 to 42.70 ± 2.18 g/L with the increase of enzyme loading from 0 to 300 U/g VS. Mechanism exploration indicated that enzymatic pretreatment significantly promoted the release and hydrolysis of insoluble organic matter from fermentation substrate, thus providing an abundance of reaction intermediates that were directly available for LA production. Additionally, bacteria analysis revealed that the high concentration of LA was associated with the prevalence of Lactobacillus. This study offered an environmental-friendly strategy for promoting SM and AW hydrolysis and provided a viable approach for recovering valuable products.
PubMed: 38908762
DOI: 10.1016/j.biortech.2024.131012