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Journal of Applied Microbiology Jan 2022The experiment aimed to compare the effects of citric acid residue (CAR) to that of three commonly used short-chain fatty acids on the fermentation quality, aerobic...
The experiment aimed to compare the effects of citric acid residue (CAR) to that of three commonly used short-chain fatty acids on the fermentation quality, aerobic stability and structural carbohydrate degradation of lucerne ensiled with lactic acid bacteria (LAB) inoculants. Fresh lucerne was ensiled with distilled water (control), LAB inoculant (L), CAR + LAB inoculant (CL), formic acid + LAB inoculant (FL), acetic acid + LAB inoculant (AL) and propanoic acid + LAB inoculant (PL) for 50 days. Chemical composition and microbial populations were determined after ensiling. The residual silages ensiled for 50 days were evaluated for aerobic stability. Compared with control, CL, FL, AL and PL treatments significantly (p < 0.05) decreased pH, ammonia nitrogen (NH -N) and butyric acid contents and increased lactic acid, acetic acid and propionic acid contents. Among them, CL silages had the lowest pH, dry matter and water-soluble carbohydrate (WSC) content, whereas the population of LAB and the lactic acid contents were highest. Besides, CL outperformed in enhancing fibre degradation, CL silages significantly decreased (p < 0.05) neutral detergent fibre, acid detergent fibre, hemicellulose and cellulose contents compared with control and had the highest Flieg's point. All treated-silages improved the aerobic stability compared with control, of which L improved 32 h, whereas CL, FL, AL and PL improved 46, 20, 46, >64 h, respectively. Applying a combination of CAR and LAB inoculant improved the fermentation quality and structural carbohydrate degradation of lucerne silage and had a similar effect on aerobic stability compared with other three short-chain fatty acids. The CAR had a comparable effect on enhancing the fermentation quality compared with three short-chain fatty acids. Thus, the combination of CAR and LAB inoculant might be used as an ideal additive for lucerne silage making with low WSC and high moisture content.
Topics: Acetic Acid; Aerobiosis; Agricultural Inoculants; Citric Acid; Fermentation; Lactic Acid; Lactobacillus; Medicago sativa; Silage
PubMed: 34309978
DOI: 10.1111/jam.15236 -
Environmental Science and Pollution... Oct 2022Pseudomonas sp. Y-5, a strain with simultaneous nitrification and denitrification (SND) capacity, was isolated from the Wuhan Municipal Sewage Treatment Plant. This...
Pseudomonas sp. Y-5, a strain with simultaneous nitrification and denitrification (SND) capacity, was isolated from the Wuhan Municipal Sewage Treatment Plant. This strain could rapidly remove high concentrations of inorganic nitrogen. Specifically, Pseudomonas sp. Y-5 removed 103 mg/L of NH-N in 24 h without nitrate or nitrite accumulation when NH-N was its sole nitrogen source. The NH-N removal efficiency (RE) was 97.26%, and the average removal rate (RR) was 4.30 mg/L/h. Strain Y-5 also removed NO-N and NO-N even in aerobic conditions, with average RRs of 4.39 and 4.23 mg/L/h, respectively, and REs of up to 99.34% and 95.81% within 24 h. When cultured in SND medium (SNDM-1), strain Y-5 achieved an NH-N RE of up to 97.80% and a total nitrogen (TN) RE of 93.01%, whereas NO-N was fully depleted in 48 h. Interestingly, high nitrite concentrations did not inhibit the nitrification capacity of Y-5 when grown in SNDM-2, the RE of NH-N and TN reached 96.29% and 94.26%, respectively, and nitrite was consumed completely. Strain Y-5 also adapted well to high concentrations of ammonia (~401.68 mg NH-N/L) or organic nitrogen (~315.12 mg TN/L). Our results suggested that Pseudomonas sp. Y-5 achieved efficient simultaneous nitrification and denitrification, thus demonstrating its potential applicability in the treatment of nitrogen-polluted wastewater.
Topics: Aerobiosis; Ammonia; Denitrification; Heterotrophic Processes; Nitrates; Nitrification; Nitrites; Nitrogen; Nitrogen Dioxide; Pseudomonas; Sewage; Wastewater
PubMed: 35562612
DOI: 10.1007/s11356-022-20708-x -
International Journal of Molecular... Nov 2021Melatonin is synthesized in the pineal gland at night. Since melatonin is produced in the mitochondria of all other cells in a non-circadian manner, the amount... (Review)
Review
Melatonin is synthesized in the pineal gland at night. Since melatonin is produced in the mitochondria of all other cells in a non-circadian manner, the amount synthesized by the pineal gland is less than 5% of the total. Melatonin produced in mitochondria influences glucose metabolism in all cells. Many pathological cells adopt aerobic glycolysis (Warburg effect) in which pyruvate is excluded from the mitochondria and remains in the cytosol where it is metabolized to lactate. The entrance of pyruvate into the mitochondria of healthy cells allows it to be irreversibly decarboxylated by pyruvate dehydrogenase (PDH) to acetyl coenzyme A (acetyl-CoA). The exclusion of pyruvate from the mitochondria in pathological cells prevents the generation of acetyl-CoA from pyruvate. This is relevant to mitochondrial melatonin production, as acetyl-CoA is a required co-substrate/co-factor for melatonin synthesis. When PDH is inhibited during aerobic glycolysis or during intracellular hypoxia, the deficiency of acetyl-CoA likely prevents mitochondrial melatonin synthesis. When cells experiencing aerobic glycolysis or hypoxia with a diminished level of acetyl-CoA are supplemented with melatonin or receive it from another endogenous source (pineal-derived), pathological cells convert to a more normal phenotype and support the transport of pyruvate into the mitochondria, thereby re-establishing a healthier mitochondrial metabolic physiology.
Topics: Aerobiosis; Cell Communication; Glucose; Glycolysis; Humans; Melatonin; Mitochondria; Neoplasms; Warburg Effect, Oncologic
PubMed: 34830375
DOI: 10.3390/ijms222212494 -
Bioresource Technology Jan 2022To improve poor nitrate removal by microorganisms under strong alkaline conditions, a new type of aerobic nitrification-reducing bacteria was isolated in this study....
To improve poor nitrate removal by microorganisms under strong alkaline conditions, a new type of aerobic nitrification-reducing bacteria was isolated in this study. Using nitrogen balance and genome information, the capacity of Pseudomonas XS-18 to remove nitrate and the mechanism of alkali tolerance were analyzed. At pH 11.0, XS-18 could remove 12.17 mg N/(L·h) nitrate. At C/N ratios of 13.0 and 25 °C, nitrite and ammonia nitrogen were barely enriched. XS-18 could reduce nitrate through dissimilation and assimilation, and 21.74% and 77.39% of nitrate was converted into cellular components and organic nitrogen, respectively. Meanwhile, functional genes (nirBD, nasAB, gdhA, glnA, and gltBD) associated with nitrogen metabolism were determined. In addition, Na/H antiporters (MnhACDEFG, PhaACDEFG, NhaCD and TrkAH) and a cell surface protein (SlpA) from the XS-18 genome, as well as compatible solutes that help stabilize intracellular pH, were also characterized. XS-18 possessed significant potential in alkaline wastewater treatment.
Topics: Aerobiosis; Alkalies; Denitrification; Heterotrophic Processes; Nitrates; Nitrification; Nitrites; Nitrogen; Pseudomonas
PubMed: 34678448
DOI: 10.1016/j.biortech.2021.126175 -
Bioresource Technology May 2022This study aimed to figure out the main contributors to aerobic phosphorus (P) removal in the algal-bacterial aerobic granular sludge (AGS)-based wastewater treatment...
This study aimed to figure out the main contributors to aerobic phosphorus (P) removal in the algal-bacterial aerobic granular sludge (AGS)-based wastewater treatment system. Kinetics study showed that aerobic P removal was controlled by macropore (contributing to 64-75% P removal) and micropore diffusion, and the different light intensity (0, 4.0, 12.3, and 24.4 klux) didn't exert significant (p > 0.05) influence on P removal. On the other hand, the increasing light intensity did promote microalgae metabolism, leading to the elevated wastewater pH (8.0-9.8). The resultant pH increase had a strongly negative relationship (R = 0.9723) with P uptake by polyphosphate-accumulating organisms, while promoted chemical Ca-P precipitation at a molar Ca/P ratio of 1.05. Results from this work could provide an in-depth understanding of microalgae-bacteria symbiotic interaction, which is helpful to better design and operate the algal-bacterial AGS systems.
Topics: Aerobiosis; Bacteria; Bioreactors; Microalgae; Nitrogen; Phosphorus; Sewage; Waste Disposal, Fluid; Wastewater
PubMed: 35378284
DOI: 10.1016/j.biortech.2022.127104 -
The Science of the Total Environment Jan 2021Plug flow reactors (PFRs) made of multiple completely stirred tank reactors (CSTRs) in series were used to cultivate aerobic granules in real domestic wastewater....
Plug flow reactors (PFRs) made of multiple completely stirred tank reactors (CSTRs) in series were used to cultivate aerobic granules in real domestic wastewater. Theoretically, changing the number of CSTR chambers in series will change the nature of plug flow, and thus alter the pattern of the feast/famine condition and impact the aerobic granulation progress. Therefore, PFRs were operated in 4-, 6-, and 8-chamber mode under the same gravity selection pressure (a critical settling velocity of 9.75 m h) and hydraulic retention time (6.5 h) until steady states were reached to evaluate the effect of the feast/famine condition on continuous flow aerobic granulation. The sludge particle size, circularity, settleability, specific gravity, zone settling velocity, and extracellular polymeric substance contents were analyzed to evaluate the role that a feast/famine regime plays in aerobic granulation. It was found that aerobic granulation failed whenever the feast/famine ratio was greater than 0.5. The results support a conclusion that the feast/famine condition is likely a prerequisite for continuous flow aerobic granulation.
Topics: Aerobiosis; Bioreactors; Extracellular Polymeric Substance Matrix; Sewage; Waste Disposal, Fluid
PubMed: 32853933
DOI: 10.1016/j.scitotenv.2020.141467 -
Environmental Research Nov 2022One of the biggest challenges of applying heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria to treat high salt organic wastewater lies in the...
One of the biggest challenges of applying heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria to treat high salt organic wastewater lies in the inhibitory effect exerted by salinity. To study the inhibition effect and underlying mechanism induced by different ion types and ion composition, the individual and combined effects of NaCl, KCl and NaSO on HN-AD bacteria Acinetobacter sp. TAC-1 were systematically investigated by batch experiments. Results indicated that the ammonia nitrogen removal yield and TAC-1 activity decreased with increased salt concentration. NaCl, KCl and NaSO exerted different degrees of inhibition on TAC-1, with half concentration inhibition constant values of 0.205, 0.238 and 0.110 M, respectively. A synergistic effect on TAC-1 was found with the combinations of NaCl + KCl, NaCl + NaSO and NaCl + KCl + NaSO. The whole RNA resequencing suggested that transcripts of denitrification genes (nirB and nasA) were significantly downregulated with increased NaSO concentration. Simultaneously, NaSO stress disrupted cell respiration, DNA replication, transcription, translation, and induced oxidative stress. Finally, we proposed a conceptual model to summarize the inhibition mechanisms and possible response strategies of TAC-1 bacteria under NaSO stress.
Topics: Aerobiosis; Bacteria; Denitrification; Nitrification; Nitrites; Nitrogen; Salinity; Sodium Chloride; Wastewater
PubMed: 35810810
DOI: 10.1016/j.envres.2022.113834 -
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 -
The Science of the Total Environment May 2022Aerobic denitrification has been proved to be profoundly affected by temperature and antibiotics, but little is known about how aerobic denitrifiers respond to...
Transcriptomics and proteomics revealed the psychrotolerant and antibiotic-resistant mechanisms of strain Pseudomonas psychrophila RNC-1 capable of assimilatory nitrate reduction and aerobic denitrification.
Aerobic denitrification has been proved to be profoundly affected by temperature and antibiotics, but little is known about how aerobic denitrifiers respond to temperature and antibiotic stress. In this study, the nitrate reduction performance and the intracellular metabolism by a psychrotolerant aerobic denitrifying bacteria, named Pseudomonas psychrophila RNC-1, were systematically investigated at different temperatures (10 °C, 20 °C, 30 °C) and different sulfamethoxazole (SMX) concentrations (0 mg/L, 0.1 mg/L, 0.5 mg/L, 1.0 mg/L, and 5.0 mg/L). The results showed that strain RNC-1 performed satisfactory nitrate removal at 10 °C and 20 °C, but its growth was significantly inhibited at 30 °C. Nitrate removal by strain RNC-1 was slightly promoted in the presence of 0.5 mg/L SMX, whereas it was significantly suppressed with 5.0 mg/L SMX. Nitrogen balance analysis indicated that assimilatory nitrate reduction and dissimilatory aerobic denitrification jointly dominated in the nitrate removal process of strain RNC-1, in which the inhibition effected on assimilation process was much higher than that on the aerobic denitrification process under SMX exposure. Further transcriptomics and proteomics analysis revealed that the psychrotolerant mechanism of strain RNC-1 could be attributed to the up-regulation of RNA translation, energy metabolism, ABC transporters and the over-expression of cold shock proteins, while the down-regulation of oxidative phosphorylation pathway was the primary reason for the deteriorative cell growth at 30 °C. The promotion of nitrate reduction with 0.5 mg/L SMX was related to the up-regulation of amino acid metabolism pathways, while the down-regulation of folate cycle, glycolysis/gluconeogenesis and bacterial chemotaxis pathways were responsible for the inhibition effect at 5.0 mg/L SMX. This work provides a mechanistic understanding of the metabolic adaption of strain RNC-1 under different stress, which is of significance for its application in nitrogen contaminated wastewater treatment processes.
Topics: Aerobiosis; Anti-Bacterial Agents; Denitrification; Nitrates; Nitrogen; Proteomics; Pseudomonas; Transcriptome
PubMed: 35051480
DOI: 10.1016/j.scitotenv.2022.153169 -
Journal of Environmental Management May 2022The structure of bacterial community was greatly varied from different seed sludge sources, which affected the sludge characteristics. To explore the role of different...
The structure of bacterial community was greatly varied from different seed sludge sources, which affected the sludge characteristics. To explore the role of different functional bacteria in AGS granulation and pollutant degradation, three different resources of seed sludge obtained from pharmaceutical wastewater (R1), livestock (R2), and municipal sludge (R3) were employed in this study. Results showed that the initial bacterial community had important significance for AGS formation and pollutants removal. Seed sludge taken from R3 granulated faster than those from R1 and R2. A large number of mature granules were formed after 20 days of operation in R3. In addition, the final mixed liquor suspended solids (MLSS) reached 6853 mg L, with 48 mL g sludge volume index (SVI) in R3, indicating that it had better settling performance and granulation. In the stable stage of R3, the removal rates of COD, NH-N, and TN reached 99.2%, 98.5%, and 97.6%, respectively. The α-diversity analysis showed that the bacterial community of seed sludge greatly determined the microbial composition of AGS. Firmicutes, Gracilibacteria, and Spirochaetes were abundant in R3, which maintained the structures and functions of aerobic granules. This study might provide approaches and insights for AGS culture from different sludge sources.
Topics: Aerobiosis; Bacteria; Bioreactors; Sewage; Waste Disposal, Fluid
PubMed: 35158114
DOI: 10.1016/j.jenvman.2022.114706