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Journal of Agricultural and Food... Sep 2022In this study, the complex volatilome of maize silage samples conserved for 229 d, inoculated with () and (), is explored by means of advanced fingerprinting...
In this study, the complex volatilome of maize silage samples conserved for 229 d, inoculated with () and (), is explored by means of advanced fingerprinting methodologies based on comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry. The combined untargeted and targeted (UT) fingerprinting strategy covers 452 features, 269 of which were putatively identified and assigned within their characteristic classes. The high amounts of short-chain free fatty acids and alcohols were produced by fermentation and led to a large number of esters. The impact of fermentation was not clearly distinguishable from the control samples; however, had a strong and distinctive signature that was dominated by propionic acid and 1-propanol characteristic volatiles. The approach provides a better understanding of silage stabilization mechanisms against the degradative action of yeasts and molds during the exposure of silage to air.
Topics: 1-Propanol; Aerobiosis; Fatty Acids, Nonesterified; Lactobacillus; Lacticaseibacillus paracasei; Propionates; Silage; Zea mays
PubMed: 36103255
DOI: 10.1021/acs.jafc.2c03652 -
Fungal Genetics and Biology : FG & B Nov 2020Oxygen is fundamental to the life of aerobic organisms and is not always available to Paracoccidioides cells. During the life cycle stages, reduced oxygen levels...
Oxygen is fundamental to the life of aerobic organisms and is not always available to Paracoccidioides cells. During the life cycle stages, reduced oxygen levels directly affect general metabolic processes and oxygen adaptation mechanisms may play a fundamental role on fungal ability to survive under such condition. Heme proteins can bind to oxygen and participate in important biological processes. Several fungi, including Paracoccidioides, express a heme-binding globin (fungoglobin - FglA) presumable to regulate fungal adaptation to hypoxia. However, the characterization of fungoglobin in Paracoccidioides spp. has not yet been performed. In this study, we predicted the structure of fungoglobin and determined its level of expression during hypoxic-mimetic conditions. Genomic screening revealed that the fungoglobin gene is conserved in all species of the Paracoccidioides genus. Molecular modeling showed biochemical and biophysical characteristics that support the hypothesis that FglA binds to the heme group and oxygen as well. The fungoglobin transcript and proteins are expressed at higher levels at the early treatment time, remaining elevated while oxygen is limited. A P. brasiliensis fglA knockdown strain depicted reduced growth in hypoxia indicating that this protein can be essential for growth at low oxygen. Biochemical analysis confirmed the binding of fungoglobin to heme. Initial analyzes were carried out to establish the relationship between FlglA and iron metabolism. The FglA transcript was up regulated in pulmonary infection, suggesting its potential role in the disease establishment. We believe that this study can contribute to the understanding of fungal biology and open new perspectives for scientific investigations.
Topics: Aerobiosis; Cell Hypoxia; Fungal Proteins; Gene Expression Regulation, Fungal; Heme; Hemeproteins; Oxygen; Paracoccidioides
PubMed: 32822859
DOI: 10.1016/j.fgb.2020.103446 -
International Journal of Environmental... Nov 2022Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. AGS formation belongs to microbial self-aggregation. Investigation of the formation and...
Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. AGS formation belongs to microbial self-aggregation. Investigation of the formation and stability of AGS is widely paid attention to, in particular the structure stability of large size granules. Two types of AGS were developed in two sequencing batch reactors fed by two different wastewaters, respectively. Through confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM), the structure and composition of granules were analyzed. Filamentous bacteria were observed in granules from synthetic wastewater reactor, while filamentous bacteria and stalked ciliates ( sp.) were simultaneously found in granules from domestic wastewater reactor. The analytic results show that filamentous bacteria and stalked ciliates acting as skeletons play important roles in the formation and stability of granules. With the bonding of extracellular polymeric substances (EPS), the filamentous bacteria and stalked ciliates could build bridges and frames to promote the aggregation of bacteria; these microorganisms could create a space grid structure around the surface layer of granules to enhance the strength of granules, and the remnants of the stalks could serve as supports to fix the steadiness of granules.
Topics: Sewage; Wastewater; Waste Disposal, Fluid; Bioreactors; Aerobiosis; Bacteria
PubMed: 36497821
DOI: 10.3390/ijerph192315747 -
Astrobiology Oct 2019Observational evidence supports the presence of methane (CH) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether...
Observational evidence supports the presence of methane (CH) in the martian atmosphere on the order of parts per billion by volume (ppbv). Here, we assess whether aerobic methanotrophy is a potentially viable metabolism in the martian upper regolith, by calculating metabolic energy gain rates under assumed conditions of martian surface temperature, pressure, and atmospheric composition. Using kinetic parameters for 19 terrestrial aerobic methanotrophic strains, we show that even under the imposed low temperature and pressure extremes (180-280 K and 6-11 hPa), methane oxidation by oxygen (O) should in principle be able to generate the minimum energy production rate required to support endogenous metabolism (, cellular maintenance). Our results further indicate that the corresponding metabolic activity would be extremely low, with cell doubling times in excess of 4000 Earth years at the present-day ppbv-level CH mixing ratios in the atmosphere of Mars. Thus, while aerobic methanotrophic microorganisms similar to those found on Earth could theoretically maintain their vital functions, they are unlikely to constitute prolific members of hypothetical martian soil communities.
Topics: Aerobiosis; Euryarchaeota; Extraterrestrial Environment; Kinetics; Mars; Methane; Oxidation-Reduction; Temperature
PubMed: 31173512
DOI: 10.1089/ast.2018.1943 -
The ISME Journal Dec 2017Sulfide (HS, HS and S) oxidation to sulfite and thiosulfate by heterotrophic bacteria, using sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO), has...
Sulfide (HS, HS and S) oxidation to sulfite and thiosulfate by heterotrophic bacteria, using sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO), has recently been reported as a possible detoxification mechanism for sulfide at high levels. Bioinformatic analysis revealed that the sqr and pdo genes were common in sequenced bacterial genomes, implying the sulfide oxidation may have other physiological functions. SQRs have previously been classified into six types. Here we grouped PDOs into three types and showed that some heterotrophic bacteria produced and released HS from organic sulfur into the headspace during aerobic growth, and others, for example, Pseudomonas aeruginosa PAO1, with sqr and pdo did not release HS. When the sqr and pdo genes were deleted, the mutants also released HS. Both sulfide-oxidizing and non-oxidizing heterotrophic bacteria were readily isolated from various environmental samples. The sqr and pdo genes were also common in the published marine metagenomic and metatranscriptomic data, indicating that the genes are present and expressed. Thus, heterotrophic bacteria actively produce and consume sulfide when growing on organic compounds under aerobic conditions. Given their abundance on Earth, their contribution to the sulfur cycle should not be overlooked.
Topics: Aerobiosis; Bacteria; Bacterial Proteins; Heterotrophic Processes; Oxidation-Reduction; Quinone Reductases; Sulfides; Sulfur
PubMed: 28777380
DOI: 10.1038/ismej.2017.125 -
Scientific Reports Jun 2021Soil microorganisms and their activities are essential for maintaining soil health and fertility. Microorganisms can be negatively affected by application of herbicides....
Soil microorganisms and their activities are essential for maintaining soil health and fertility. Microorganisms can be negatively affected by application of herbicides. Although effects of herbicides on microorganisms are widely studied, there is a lack of information for chloroacetamide herbicide dimethachlor. Thus, dimethachlor and well known linuron were applied to silty-loam luvisol and their effects on microorganisms were evaluated during112 days long laboratory assay. Dimethachlor and linuron were applied in doses 1.0 kg ha and 0.8 kg ha corresponding to 3.33 mg kg and 2.66 mg kg respectively. Also 100-fold doses were used for magnification of impacts. Linuron in 100-fold dose caused minor increase of respiration, temporal increase of soil microbial biomass, decrease of soil dehydrogenase activity, and altered microbial community. Dimethachlor in 100-fold dose significantly increased respiration; microbial biomass and decreased soil enzymatic activities. Microbial composition changed significantly, Proteobacteria abundance, particularly Pseudomonas and Achromobacter genera increased from 7 to 28th day. In-silico prediction of microbial gene expression by PICRUSt2 software revealed increased expression of genes related to xenobiotic degradation pathways. Evaluated characteristics of microbial community and activity were not affected by herbicides in recommended doses and the responsible use of both herbicides will not harm soil microbial community.
Topics: Acetamides; Aerobiosis; Biomass; Carbon Dioxide; Herbicides; Linuron; Metabolic Networks and Pathways; Microbiota; Phylogeny; Soil Microbiology
PubMed: 34140550
DOI: 10.1038/s41598-021-91755-6 -
Scientific Reports Apr 2021The effects of respiratory inhibitors, quinone analogues and artificial substrates on the membrane-bound electron transport system of the fastidious β-proteobacterium...
The effects of respiratory inhibitors, quinone analogues and artificial substrates on the membrane-bound electron transport system of the fastidious β-proteobacterium Eikenella corrodens grown under O-limited conditions were studied. NADH respiration in isolated membrane particles were partially inhibited by rotenone, dicoumarol, quinacrine, flavone, and capsaicin. A similar response was obtained when succinate oxidation was performed in the presence of thenoyltrifluoroacetone and N,N'-dicyclohexylcarbodiimide. NADH respiration was resistant to site II inhibitors and cyanide, indicating that a percentage of the electrons transported can reach O without the bc complex. Succinate respiration was sensitive to myxothiazol, antimycin A and 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Juglone, plumbagin and menadione had higher reactivity with NADH dehydrogenase. The membrane particles showed the highest oxidase activities with ascorbate-TCHQ (tetrachlorohydroquinone), TCHQ alone, and NADH-TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine), and minor activity levels with ascorbate-DCPIP (2,6-dichloro-phenolindophenol) and NADH-DCPIP. The substrates NADH-DCPIP, NADH-TMPD and TCHQ were electron donors to cyanide-sensitive cbb' cytochrome c oxidase. The presence of dissimilatory nitrate reductase in the aerobic respiratory system of E. corrodens ATCC 23834 was demonstrated by first time. Our results indicate that complexes I and II have resistance to their classic inhibitors, that the oxidation of NADH is stimulated by juglone, plumbagin and menadione, and that sensitivity to KCN is stimulated by the substrates TCHQ, NADH-DCPIP and NADH-TMPD.
Topics: Aerobiosis; Bacterial Proteins; Eikenella corrodens; Electron Transport; Electron Transport Complex I; NAD; Oxygen Consumption; Quinones; Uncoupling Agents
PubMed: 33903681
DOI: 10.1038/s41598-021-88388-0 -
BMC Evolutionary Biology Jan 2019Among the four bases, guanine is the most susceptible to damage from oxidative stress. Replication of DNA containing damaged guanines results in G to T mutations....
BACKGROUND
Among the four bases, guanine is the most susceptible to damage from oxidative stress. Replication of DNA containing damaged guanines results in G to T mutations. Therefore, the mutations resulting from oxidative DNA damage are generally expected to predominantly consist of G to T (and C to A when the damaged guanine is not in the reference strand) and result in decreased GC content. However, the opposite pattern was reported 16 years ago in a study of prokaryotic genomes. Although that result has been widely cited and confirmed by nine later studies with similar methods, the omission of the effect of shared ancestry requires a re-examination of the reliability of the results.
RESULTS
When aerobic and obligate aerobic prokaryotes were mixed together and anaerobic and obligate anaerobic prokaryotes were mixed together, phylogenetic controlled analyses did not detect significant difference in GC content between aerobic and anaerobic prokaryotes. This result is consistent with two generally neglected studied that had accounted for the phylogenetic relationship. However, when obligate aerobic prokaryotes were compared with aerobic prokaryotes, anaerobic prokaryotes, and obligate anaerobic prokaryotes separately using phylogenetic regression analysis, a significant positive association was observed between aerobiosis and GC content, no matter it was calculated from whole genome sequences or the 4-fold degenerate sites of protein-coding genes. Obligate aerobes have significantly higher GC content than aerobes, anaerobes, and obligate anaerobes.
CONCLUSIONS
The positive association between aerobiosis and GC content could be attributed to a mutational force resulting from incorporation of damaged deoxyguanosine during DNA replication rather than oxidation of the guanine nucleotides within DNA sequences. Our results indicate a grade in the aerobiosis-associated mutational force, strong in obligate aerobes, moderate in aerobes, weak in anaerobes and obligate anaerobes.
Topics: Aerobiosis; Anaerobiosis; Base Composition; Humans; Least-Squares Analysis; Phylogeny; Prokaryotic Cells; Regression Analysis; Reproducibility of Results
PubMed: 30691392
DOI: 10.1186/s12862-019-1365-8 -
Water Research May 2021The aerobic granular sludge (AGS) process is an effective wastewater treatment technology for organic matter and nutrient removal that has been introduced in the market...
The aerobic granular sludge (AGS) process is an effective wastewater treatment technology for organic matter and nutrient removal that has been introduced in the market rapidly. Until now, limited information is available on AGS regarding the removal of bacterial and viral pathogenic organisms present in sewage. This study focussed on determining the relation between reactor operational conditions (plug flow feeding, turbulent aeration and settling) and physical and biological mechanisms on removing two faecal surrogates, Escherichia coli and MS2 bacteriophages. Two AGS laboratory-scale systems were separately fed with influent spiked with 1.0 × 10 CFU/100 mL of E. coli and 1.3 × 10 PFU/100 mL of MS2 bacteriophages and followed during the different operational phases. The reactors contained only granular sludge and no flocculent sludge. Both systems showed reductions in the liquid phase of 0.3 Log during anaerobic feeding caused by a dilution factor and attachment of the organisms on the granules. Higher removal efficiencies were achieved during aeration, approximately 1 Log for E. coli and 0.6 Log for the MS2 bacteriophages caused mainly by predation. The 18S sequencing analysis revealed high operational taxonomic units (OTUs) of free-living protozoa genera Rhogostoma and Telotrochidium concerning the whole eukaryotic community. Attached ciliates propagated after the addition of the E. coli, an active contribution of the genera Epistylis, Vorticella, and Pseudovorticella was found when the reactor reached stability. In contrast, no significant growth of predators occurred when spiking the system with MS2 bacteriophages, indicating a low contribution of protozoa on the phage removal. Settling did not contribute to the removal of the studied bacterial and viral surrogates.
Topics: Aerobiosis; Bioreactors; Escherichia coli; Sewage; Waste Disposal, Fluid; Water Purification
PubMed: 33714012
DOI: 10.1016/j.watres.2021.116992 -
Microbiological Research May 2023Corn straw is suitable for preservation as silage despite being neglected due to its varying chemical composition, yield, and pathogenic influence during ensiling. This...
Corn straw is suitable for preservation as silage despite being neglected due to its varying chemical composition, yield, and pathogenic influence during ensiling. This study examined the effects of beneficial organic acid-producing lactic acid bacteria (LAB), including Lactobacillus buchneri (Lb), L. plantarum (Lp), or their combination (LpLb), on fermentation profile, aerobic stability, and microbial community dynamics of corn straw harvested at late maturity stage after 7d, 14d, 30d, and 60d of ensiling. Higher levels of beneficial organic acids, LAB counts, and crude protein (CP), and lower levels of pH and ammonia nitrogen were detected in LpLb-treated silages after 60d. Lactobacillus, Candida, and Issatchenkia abundances were higher (P < 0.05) in Lb and LpLb-treated corn straw silages after 30d and 60d ensiling. Additionally, the positive correlation between Lactobacillus, Lactococcus and Pediococcus, and the negative correlation with Acinetobacter in LpLb-treated silages after 60d emphasizes a potent interaction mechanism initiated by organic acid and composite metabolite production to reduce pathogenic microorganisms' growth. Also, a significant correlation between Lb and LpLb-treated silages with CP and neutral detergent fiber after 60d further highlights the synergistic effect of incorporating L. buchneri and L. plantarum for improved nutritional components of mature silages. The combination of L. buchneri and L. plantarum improved aerobic stability, fermentation quality, and bacterial community and reduced fungal population after 60d of ensiling, which are properties of well-preserved corn straw.
Topics: Lactobacillus plantarum; Zea mays; Fermentation; Lactobacillus; Microbiota; Aerobiosis
PubMed: 36812838
DOI: 10.1016/j.micres.2023.127329