-
Environmental Science and Pollution... Oct 2023Chloroethenes are globally prevalent groundwater contaminants. Since 2014, TCE has been shown to be degradable in an aerobic metabolic process where it is used as sole...
Chloroethenes are globally prevalent groundwater contaminants. Since 2014, TCE has been shown to be degradable in an aerobic metabolic process where it is used as sole energy source and growth substrate by a mixed bacteria culture (SF culture). In 2019, the SF culture was shown to be successfully used in bioaugmentation approaches under field-relevant conditions. In this study, a combined bio-/electro-approach to stimulate the TCE degradation by the SF culture was investigated in laboratory experiments. Column experiments were set up to compare a bioaugmentation approach with an electrochemical biostimulated bioaugmentation approach. Low strength direct current increased the amount of degraded TCE to about 150 % of the control. Through lowering the inflow concentration of oxygen, the effect of the electro-biostimulation in a low oxygen setting confirmed the potential of the bio-electro process for treatment of oxygen-deprived, TCE-contaminated sites.
Topics: Biodegradation, Environmental; Water Pollutants, Chemical; Aerobiosis; Groundwater; Oxygen
PubMed: 37735338
DOI: 10.1007/s11356-023-29839-1 -
Journal of Dairy Science Feb 2024Experiments were conducted over a 3-yr period to evaluate the effects of bacterial inoculants on the fermentation profile and aerobic stability of whole-plant corn...
Experiments were conducted over a 3-yr period to evaluate the effects of bacterial inoculants on the fermentation profile and aerobic stability of whole-plant corn silage (WPC), snaplage (SNA), and high-moisture corn (HMC). Whole-plant corn was inoculated with Lentilactobacillus buchneri PJB1 in combination with Lactiplantibacillus plantarum MTD1 or with Lpb. plantarum alone (experiments 1 and 2). Snaplage (experiment 3) and HMC (experiments 4 and 5) were inoculated with Len. buchneri in combination with Lpb. plantarum or with Len. buchneri alone. After inoculation, the feedstuffs were ensiled in 7.57-L silos and stored at 21 ± 2°C for 30 or 90 d. In experiment 5, silage was subjected to air stress for 2 h every 2 wk through 42 d and then for 2 h/wk until 90 d and had samples analyzed for their bacterial community composition by metagenomics. Overall, in all experiments, silages inoculated with Len. buchneri alone or in combination with Lpb. plantarum had more acetic acid and 1,2-propanediol and fewer yeasts than uninoculated silages. After 30 d of ensiling, inoculation with Len. buchneri alone or in combination with Lpb. plantarum did not affect the aerobic stability of SNA, but it slightly increased the stability of WPC and markedly improved the stability of HMC. After 90 d of ensiling, inoculation with Len. buchneri alone or in combination with Lpb. plantarum markedly improved the aerobic stability of WPC, SNA, and HMC. In experiment 5, inoculation increased the relative abundance (RA) of Lactobacillaceae and reduced the RA of Enterobacteriaceae and Leuconostocaceae in HMC at 30 and 90 d and the RA of Clostridiaceae in non-air-stressed HMC at 90 d. Air-stressed HMC inoculated with Len. buchneri had less lactic acid, more acetic acid and 1,2-propanediol, and markedly greater aerobic stability than uninoculated air-stressed HMC at 90 d. In conclusion, inoculation with Len. buchneri PJB1 alone or in combination with Lpb. plantarum MTD1 increased the production of acetic acid and 1,2-propanediol, inhibited yeasts development, and improved the aerobic stability of WPC, SNA, and HMC. In HMC, inoculation markedly improved aerobic stability as soon as after 30 d of ensiling, and after 90 d, inoculation improved stability even under air stress conditions.
Topics: Animals; Silage; Zea mays; Propylene Glycol; Aerobiosis; Lactobacillus plantarum; Yeasts; Acetic Acid; Fermentation; Lactobacillus
PubMed: 37730174
DOI: 10.3168/jds.2023-23672 -
Nature Aug 2023The human gut microbiota has gained interest as an environmental factor that may contribute to health or disease. The development of next-generation probiotics is a...
The human gut microbiota has gained interest as an environmental factor that may contribute to health or disease. The development of next-generation probiotics is a promising strategy to modulate the gut microbiota and improve human health; however, several key candidate next-generation probiotics are strictly anaerobic and may require synergy with other bacteria for optimal growth. Faecalibacterium prausnitzii is a highly prevalent and abundant human gut bacterium associated with human health, but it has not yet been developed into probiotic formulations. Here we describe the co-isolation of F. prausnitzii and Desulfovibrio piger, a sulfate-reducing bacterium, and their cross-feeding for growth and butyrate production. To produce a next-generation probiotic formulation, we adapted F. prausnitzii to tolerate oxygen exposure, and, in proof-of-concept studies, we demonstrate that the symbiotic product is tolerated by mice and humans (ClinicalTrials.gov identifier: NCT03728868 ) and is detected in the human gut in a subset of study participants. Our study describes a technology for the production of next-generation probiotics based on the adaptation of strictly anaerobic bacteria to tolerate oxygen exposures without a reduction in potential beneficial properties. Our technology may be used for the development of other strictly anaerobic strains as next-generation probiotics.
Topics: Animals; Humans; Mice; Butyrates; Gastrointestinal Microbiome; Oxygen; Probiotics; Aerobiosis; Faecalibacterium prausnitzii; Symbiosis; Biotechnology
PubMed: 37532933
DOI: 10.1038/s41586-023-06378-w -
Frontiers in Cellular and Infection... 2023spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited...
spp. are considered the most frequent cause of acute gastroenteritis worldwide. However, outside high-income countries, its burden is poorly understood. Limited published data suggest that prevalence in low- and middle-income countries is high, but their reservoirs and age distribution are different. Culturing is expensive due to laboratory equipment and supplies needed to grow the bacterium (e.g., selective culture media, microaerophilic atmosphere, and a 42°C incubator). These requirements limit the diagnostic capacity of clinical laboratories in many resource-poor regions, leading to significant underdiagnosis and underreporting of isolation of the pathogen. CAMPYAIR, a newly developed selective differential medium, permits isolation without the need for microaerophilic incubation. The medium is supplemented with antibiotics to allow isolation in complex matrices such as human feces. The present study aims to evaluate the ability of the medium to recover from routine clinical samples. A total of 191 human stool samples were used to compare the ability of CAMPYAIR (aerobic incubation) and a commercial medium (CASA, microaerophilic incubation) to recover . All isolates were then identified by MALDI-TOF MS. CAMPYAIR showed sensitivity and specificity values of 87.5% (95% CI 47.4%-99.7%) and 100% (95% CI 98%-100%), respectively. The positive predictive value of CAMPYAIR was 100% and its negative predictive value was 99.5% (95% CI 96.7%-99.9%); Kappa Cohen coefficient was 0.93 (95% CI 0.79-1.0). The high diagnostic performance and low technical requirements of the CAMPYAIR medium could permit culture in countries with limited resources.
Topics: Culture Media; Aerobiosis; Campylobacter; Campylobacter Infections; Feces; Predictive Value of Tests; Microbiological Techniques
PubMed: 37384222
DOI: 10.3389/fcimb.2023.1153693 -
Food Microbiology Sep 2023The use of yeast respiratory metabolism has been proposed as a promising approach to solve the problem of increasing ethanol content in wine, which is largely due to...
The use of yeast respiratory metabolism has been proposed as a promising approach to solve the problem of increasing ethanol content in wine, which is largely due to climate change. The use of S. cerevisiae for this purpose is mostly hampered by acetic acid overproduction generated under the necessary aerobic conditions. However, it was previously shown that a reg1 mutant, alleviated for carbon catabolite repression (CCR), showed low acetic acid production under aerobic conditions. In this work directed evolution of three wine yeast strains was performed to recover CCR-alleviated strains, expecting they will also be improved concerning volatile acidity. This was done by subculturing strains on galactose, in the presence of 2-deoxyglucose for around 140 generations. As expected, all evolved yeast populations released less acetic acid than their parental strains in grape juice, under aerobic conditions. Single clones were isolated from the evolved populations, either directly or after one cycle of aerobic fermentation. Only some clones from one of three original strains showed lower acetic acid production than their parental strain. Most clones isolated from EC1118 showed slower growth. However, even the most promising clones failed to reduce acetic acid production under aerobic conditions in bioreactors. Therefore, despite the concept of selecting low acetic acid producers by using 2-deoxyglucose as selective agent was found to be correct, especially at the population level, the recovery of strains with potential industrial utility by this experimental approach remains a challenge.
Topics: Acetic Acid; Deoxyglucose; Fermentation; Saccharomyces cerevisiae; Vitis; Wine; Galactose; Food Microbiology; Directed Molecular Evolution; Aerobiosis; Anaerobiosis
PubMed: 37290870
DOI: 10.1016/j.fm.2023.104282 -
Role of the ubiquinone-synthesizing UbiUVT pathway in adaptation to changing respiratory conditions.MBio Aug 2023Isoprenoid quinones are essential for cellular physiology. They act as electron and proton shuttles in respiratory chains and various biological processes. and many...
Isoprenoid quinones are essential for cellular physiology. They act as electron and proton shuttles in respiratory chains and various biological processes. and many α-, β-, and γ-proteobacteria possess two types of isoprenoid quinones: ubiquinone (UQ) is mainly used under aerobiosis, while demethylmenaquinones (DMK) are mostly used under anaerobiosis. Yet, we recently established the existence of an anaerobic O-independent UQ biosynthesis pathway controlled by , , and genes. Here, we characterize the regulation of genes in . We show that the three genes are transcribed as two divergent operons that are both under the control of the O-sensing Fnr transcriptional regulator. Phenotypic analyses using a mutant devoid of DMK revealed that UbiUV-dependent UQ synthesis is essential for nitrate respiration and uracil biosynthesis under anaerobiosis, while it contributes, though modestly, to bacterial multiplication in the mouse gut. Moreover, we showed by genetic study and O labeling that UbiUV contributes to the hydroxylation of ubiquinone precursors through a unique O-independent process. Last, we report the crucial role of in allowing to shift efficiently from anaerobic to aerobic conditions. Overall, this study uncovers a new facet of the strategy used by to adjust its metabolism on changing O levels and respiratory conditions. This work links respiratory mechanisms to phenotypic adaptation, a major driver in the capacity of to multiply in gut microbiota and of facultative anaerobic pathogens to multiply in their host. IMPORTANCE Enterobacteria multiplication in the gastrointestinal tract is linked to microaerobic respiration and associated with various inflammatory bowel diseases. Our study focuses on the biosynthesis of ubiquinone, a key player in respiratory chains, under anaerobiosis. The importance of this study stems from the fact that UQ usage was for long considered to be restricted to aerobic conditions. Here we investigated the molecular mechanism allowing UQ synthesis in the absence of O and searched for the anaerobic processes that UQ is fueling in such conditions. We found that UQ biosynthesis involves anaerobic hydroxylases, that is, enzymes able to insert an O atom in the absence of O. We also found that anaerobically synthesized UQ can be used for respiration on nitrate and the synthesis of pyrimidine. Our findings are likely to be applicable to most facultative anaerobes, which count many pathogens (, , and ) and will help in unraveling microbiota dynamics.
Topics: Animals; Mice; Escherichia coli; Ubiquinone; Nitrates; Quinones; Terpenes
PubMed: 37283518
DOI: 10.1128/mbio.03298-22 -
Nature May 2023While early multicellular lineages necessarily started out as relatively simple groups of cells, little is known about how they became Darwinian entities capable of...
While early multicellular lineages necessarily started out as relatively simple groups of cells, little is known about how they became Darwinian entities capable of sustained multicellular evolution. Here we investigate this with a multicellularity long-term evolution experiment, selecting for larger group size in the snowflake yeast (Saccharomyces cerevisiae) model system. Given the historical importance of oxygen limitation, our ongoing experiment consists of three metabolic treatments-anaerobic, obligately aerobic and mixotrophic yeast. After 600 rounds of selection, snowflake yeast in the anaerobic treatment group evolved to be macroscopic, becoming around 2 × 10 times larger (approximately mm scale) and about 10-fold more biophysically tough, while retaining a clonal multicellular life cycle. This occurred through biophysical adaptation-evolution of increasingly elongate cells that initially reduced the strain of cellular packing and then facilitated branch entanglements that enabled groups of cells to stay together even after many cellular bonds fracture. By contrast, snowflake yeast competing for low oxygen remained microscopic, evolving to be only around sixfold larger, underscoring the critical role of oxygen levels in the evolution of multicellular size. Together, this research provides unique insights into an ongoing evolutionary transition in individuality, showing how simple groups of cells overcome fundamental biophysical limitations through gradual, yet sustained, multicellular evolution.
Topics: Acclimatization; Biological Evolution; Models, Biological; Saccharomyces cerevisiae; Anaerobiosis; Aerobiosis; Oxygen; Cell Shape; Cell Aggregation
PubMed: 37165189
DOI: 10.1038/s41586-023-06052-1 -
Communications Biology Apr 2023AMPK plays significant roles in the modulation of metabolic reprogramming and viral infection. However, the detailed mechanism by which AMPK affects viral infection is...
AMPK plays significant roles in the modulation of metabolic reprogramming and viral infection. However, the detailed mechanism by which AMPK affects viral infection is unclear. The present study aims to determine how AMPK influences white spot syndrome virus (WSSV) infection in shrimp (Marsupenaeus japonicus). Here, we find that AMPK expression and phosphorylation are significantly upregulated in WSSV-infected shrimp. WSSV replication decreases remarkably after knockdown of Ampkα and the shrimp survival rate of AMPK-inhibitor injection shrimp increases significantly, suggesting that AMPK is beneficial for WSSV proliferation. Mechanistically, WSSV infection increases intracellular Ca level, and activates CaMKK, which result in AMPK phosphorylation and partial nuclear translocation. AMPK directly activates mTORC2-AKT signaling pathway to phosphorylate key enzymes of glycolysis in the cytosol and promotes expression of Hif1α to mediate transcription of key glycolytic enzyme genes, both of which lead to increased glycolysis to provide energy for WSSV proliferation. Our findings reveal a novel mechanism by which WSSV exploits the host CaMKK-AMPK-mTORC2 pathway for its proliferation, and suggest that AMPK might be a target for WSSV control in shrimp aquaculture.
Topics: Aerobiosis; AMP-Activated Protein Kinases; Glycolysis; Mechanistic Target of Rapamycin Complex 2; Penaeidae; Phosphorylation; Signal Transduction; Virus Replication; White spot syndrome virus 1; Gene Knockdown Techniques
PubMed: 37012372
DOI: 10.1038/s42003-023-04735-z -
Water Research Apr 2023There is a growing interest to implement aerobic granular sludge (AGS) in existing conventional activated sludge (CAS) systems with a continuous flow-through...
There is a growing interest to implement aerobic granular sludge (AGS) in existing conventional activated sludge (CAS) systems with a continuous flow-through configuration. The mode of anaerobic contact of raw sewage with the sludge is an important aspect in the adaptation of CAS systems to accommodate AGS. It remains unclear how the distribution of substrate over the sludge by a conventional anaerobic selector compares to the distribution via bottom-feeding applied in sequencing batch reactors (SBRs). This study investigated the effect of the anaerobic contact mode on the substrate (and storage) distribution by operating two lab-scale SBRs; one with the traditional bottom-feeding through a settled sludge bed similar to full-scale AGS systems, and one where the synthetic wastewater was fed as a pulse at the start of the anaerobic phase while the reactor was mixed through sparging of nitrogen gas (mimicking a plug-flow anaerobic selector in continuous flow-through systems). The distribution of the substrate over the sludge particle population was quantified via PHA analysis, combined with the obtained granule size distribution. Bottom-feeding was found to primarily direct substrate towards the large granular size classes (i.e. large volume and close to the bottom), while completely mixed pulse-feeding gives a more equal distribution of substrate over all granule sizes (i.e. surface area dependant). The anaerobic contact mode directly controls the substrate distribution over the different granule sizes, irrespective of the solids retention time of a granule as an entity. Preferential feeding of the larger granules will enhance and stabilise the granulation compared to pulse-feeding, certainly under less advantageous conditions imposed by real sewage.
Topics: Sewage; Waste Disposal, Fluid; Anaerobiosis; Bioreactors; Wastewater; Aerobiosis
PubMed: 36870106
DOI: 10.1016/j.watres.2023.119803 -
Microorganisms Feb 2023Cytosolic pyruvate is an essential metabolite in lactic acid production during microbial fermentation. However, under aerobiosis, pyruvate is transported to the...
Cytosolic pyruvate is an essential metabolite in lactic acid production during microbial fermentation. However, under aerobiosis, pyruvate is transported to the mitochondrial matrix by the mitochondrial pyruvate carrier (MPC) and oxidized in cell respiration. Previous reports using or have shown that the production of pyruvate-derived chemicals is improved by deleting the gene. A previous lactate-producing strain engineered by our group was used as a host for the deletion of the gene. In addition, the expression of a bacterial hemoglobin gene under the alcohol dehydrogenase 2 promoter from , known to work as a hypoxia sensor, was used to evaluate whether aeration would supply enough oxygen to meet the metabolic needs during lactic acid production. However, unlike and , the deletion of Mpc1 had no significant impact on lactic acid production but negatively affected cell growth in strains. Furthermore, the relative quantification of the gene revealed that the expression of hemoglobin was detected even in aerobic cultivation, which indicates that the demand for oxygen in the bioreactor could result in functional hypoxia. Overall, the results add to our previously published ones and show that blocking cell respiration using hypoxia is more suitable than deleting Mpc for producing lactic acid in .
PubMed: 36838448
DOI: 10.3390/microorganisms11020483