Ammonia Tolerance Research Articles

Various effects of feeding level on ammonia tolerance in Carassius auratus under different ammonia exposure stress and the underlying mechanisms

Elevated ammonia levels in aquaculture systems could reduce fish growth and survival rates and produce a range of physiological problems. Ammonia toxicity in aquatic environments was regulated by various factors. Feeding was usually reported to help in the detoxification of fish, thereby increasing their capacity to tolerate ammonia nitrogen. However, the impact of different feeding amounts on fish in relation to ammonia exposure stress remains to be determined. To determine how feeding levels affected fish's responses to different ammonia nitrogen concentrations, two acute toxicity experiments were conducted with Carassius auratus gibelio, the major strain of gibel carp in aquaculture systems in China. In Test I, fed Carassius auratus gibelio (3 % body weight) showed a higher survival rate under a specific ammonia exposure stress. 96-h LC50 of NH3-N to 3 %F gibel carp was 1.1 times greater than that for NF (no feeding). In Test II, all fed groups (2 %F and 4 %F) under low and high ammonia stress exhibited improved ammonia detoxification, evidenced by higher liver GSase, GDH, and glutamine concentrations compared with the NF treatment. Muscle glycogen levels in feeding treatments were higher than those in NF, indicating that fed fish have more energy for ammonia detoxification. While compared with low ammonia treatment (2.70 mg L−1 TAN; NH3 0.06 mg L−1), fish exposed to high ammonia levels (26.03 mg L−1 TAN; NH3 0.57 mg L−1) demonstrated a decrease in food consumption, severe histopathological alterations in their liver, gill, and kidney, and decreased GSase, GDH, and glutamine production in the liver and brain. The results partly supported our hypothesis and suggested that increasing feeding enhances gibel carp's tolerance to ammonia nitrogen. The highest detoxification metabolism was observed under low ammonia stress. While excessive ammonia exposure could inhibit feeding and damage the detoxification organs of fish, and thus reduce the detoxification metabolism of gibel carp.

MiR-199-5p mediates the regulation of autophagy by targeting mTOR signaling and involvement in ammonia detoxification under ammonia stress in yellow catfish (Pelteobagrus fulvidraco)

Ammonia is a widely distributed hazardous aquatic pollutant that poses a threat to the development of aquatic organisms. A two-stage study was carried out to the response of yellow catfish to ammonia stress.At stage 1, yellow catfish were subjected to 0 mg/L total ammonia nitrogen (T-AN, CON group) and 125 mg/L T-AN (AM group) for 96 h, respectively. At stage 2, yellow catfish in AM group were transferred to water containing 0 mg/L T-AN for a 48-h recovery experiment (AMR group). Ammonia exposure significantly increases serum ammonia (SA), total cholesterol (T-CHO), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels, while decreases glucose (Glu) level. Only SA, GLU, TCHO, and AST returned to normal levels in AMR group, while extensive hepatocyte necrosis and vacuolization persisted. The results showed that the liver possesses a certain degree of ammonia-lowering capacity, yet ammonia-induced liver damage is irreversible. Ammonia stress-induced 486 down-regulated and 18 up-regulated microRNAs (miRNAs). Functional enrichment analysis of the top 10 miRNAs highlighted significant effects of ammonia on the “mTOR signaling pathway” and “autophagy-animals”. Furthermore, the significant negative correlation between the expression levels of miR-199-5p and mTOR suggests that mTOR as a potential target gene of miR-199-5p. The levels of LC3B, autophagosomes (AP), and autolysosomes (AL) in the AM group decreased significantly after 24 h of ammonia stress but returned to baseline after 96 h. Additionally, increased numbers of AP and AL were observed in the AMR group, suggesting that hepatic autophagy is initially suppressed under ammonia stress, followed by spontaneous recovery. This study also found that the expression levels of urea and glutamine synthesis-related genes (cps 1; arg; otc; ass; asl, and gs) significantly increased in the AM and AMR groups. Additionally, the contents of urea and glutamine in the liver was significantly elevated in the AM group. This indicates a simultaneous occurrence of urea and glutamine synthesis with the activation of autophagy during ammonia detoxification. The miR-199-5p/mTOR axis may regulate liver autophagy, potentially contributing to ammonia detoxification. The study has provided novel targets for enhancing ammonia tolerance in fish through nutritional regulation.

Effects of three short-chain fatty acids on growth, intestinal microbiota composition, and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

The objective of this research was to examine how the growth, ammonia tolerance, and intestinal microbiota composition of juvenile yellow catfish are affected by dietary supplementation of isobutyric acid (IBA), isovaleric acid (IVA), and 2-methylbutyric acid (2-MBA). During the 8-week trial, four groups were fed the basal diet (Control), and the basal diet supplementation with 0.25% IBA, IVA and 2-MBA, respectively. The research shows that the yellow catfish in the IBA and 2-MBA groups had a higher weight gain rate and specific growth rate than the control group, but feed conversion ratio has the opposite trend. Dietary supplementation of IBA and 2-MBA can significantly improve digestive enzymes activities (α-amylase, lipase, and trypsin) in intestinal tract and blood health (serum albumin increased, alanine transaminase and aspartate transaminase decreased). The up-regulation of IGF-1, Myod, and MyoG gene mRNA expression levels occurred significantly in the muscle tissue of the IBA, IVA, and 2-MBA groups, but IL 1 and IL8 genes in intestinal tract were significantly down-regulated. Supplementation of IBA, IVA and 2-MBA significantly increased the relative abundance of Candidatus Arthromitus, while decreased the relative abundance of Achromobacter, most notably in IBA group. After 96-h ammonia stress, cumulative mortality in IBA group was the lowest. Supplementing the diet of yellow catfish with IBA or 2-MBA can enhance their growth, digestive enzyme activity, and blood health status. Additionally, IBA can improve ammonia tolerance, which may be related to the increase abundance of Candidatus Arthromitus in intestine.

Effects of dietary D-mannose supplementation on growth performance, intestinal digestive capacity, gut microbiota, and ammonia tolerance of largemouth bass Micropterus salmoides

To investigate the effects of D-mannose on the growth performance, intestinal digestion capacity, intestinal microbiota composition, and ammonia tolerance of largemouth bass, experiments were conducted using largemouth bass fry with an average body weight of 7.41±0.05 g. Three experimental groups were designed, with 3 replicates per group and 30 fish per replicate. The fish were fed with feed containing different concentrations of D-mannose (0.00%, 1.00%, and 2.00% - Control, 1% mannose, 2% mannose) and were given full satiation twice a day for 56 days. The results indicated that the addition of 2% D-mannose in the feed enhanced the growth performance of the largemouth bass while reducing the feed conversion ratio. The addition of D-mannose in the feed increased the activity of digestive enzymes in the intestines (lipase, α-amylase, pepsin, alkaline phosphatase, Na+/K+ATPase, gamma-glutamyl transpeptidase, and creatine kinase). It also led to an increase in intestinal villi height and intestinal wall thickness; Adding D-mannose reduced the abundance of Staphylococcus and Achromobacter in the gut microbiota, while increasing the abundance of Aurantimicrobium. After being subjected to ammonia stress for 96 hours, the addition of D-mannose in the feed resulted in a decrease in mortality rate and neuronal nitric oxide synthase activity, while simultaneously enhancing the activity of liver argininosuccinate synthetase, argininosuccinate lyase, arginase, ornithine transcarboxylase, and inducible nitric oxide synthase. Adding D-mannose to the feed promotes the growth of largemouth bass, enhances their digestive capacity, and has a positive impact on their intestinal microbiota composition. Furthermore, it has been demonstrated that it can enhance the tolerance of largemouth bass to ammonia.

Regulation of urea cycle by reversible high-stoichiometry lysine succinylation.

The post-translational modification lysine succinylation is implicated in the regulation of various metabolic pathways. However, its biological relevance remains uncertain due to methodological difficulties in determining high-impact succinylation sites. Here, using stable isotope labelling and data-independent acquisition mass spectrometry, we quantified lysine succinylation stoichiometries in mouse livers. Despite the low overall stoichiometry of lysine succinylation, several high-stoichiometry sites were identified, especially upon deletion of the desuccinylase SIRT5. In particular, multiple high-stoichiometry lysine sites identified in argininosuccinate synthase (ASS1), a key enzyme in the urea cycle, are regulated by SIRT5. Mutation of the high-stoichiometry lysine in ASS1 to succinyl-mimetic glutamic acid significantly decreased its enzymatic activity. Metabolomics profiling confirms that SIRT5 deficiency decreases urea cycle activity in liver. Importantly, SIRT5 deficiency compromises ammonia tolerance, which can be reversed by the overexpression of wild-type, but not succinyl-mimetic, ASS1. Therefore, lysine succinylation is functionally important in ammonia metabolism.

Metagenomic analysis towards understanding the effects of ammonia on chain elongation process for medium chain fatty acids production

The production of medium chain fatty acids (MCFAs) through chain elongation (CE) from organic wastes/wastewater has attracted much attention, while the effects of a common inhibitor-ammonia has not been elucidated. The mechanism of ammonia affecting CE was studied by metagenomic. The lag phase duration of caproate production was increased, and the maximum caproate production rate was decreased by 43.4 % at 4 g-N/L, as compared to 0 g-N/L. And hydrochar (HC) alleviated the inhibition of ammonia at 4 g-N/L. Metagenomic analysis indicated that ammonia induced UBA4085 sp.FDU78 as the dominant microorganism, and metabolic reconstruction revealed its potential CE ability. Furthermore, ammonia inhibited the reverse β oxidation pathway and Acetyl-CoA production pathway. The tolerance of UBA4085 sp.FDU78 to ammonia was associated with the uptake of inorganic ions, energy conservation, and synthesis of osmoprotectants. The present study provided a deep-insight on the ammonia tolerance mechanism on the CE process.

Effects of dietary sodium acetate on growth, intestinal microbiota composition, and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

Short-chain fatty acids (SCFAs), such as acetates, play a role in modifying metabolic disorders and regulating the homeostasis of the organism. In this study, the impact of dietary sodium acetate (SA) on growth, intestinal microbiota composition, and ammonia tolerance of yellow catfish. During a 56-day study, four groups of yellow catfish weighing an average of 2.72 ± 0.11 g were provided with diets containing varying proportions of SA. The diets included 0%, 0.1%, 0.2%, and 0.4% SA. Each batch consisted of three replicates, with each replicate containing 40 fish. The results indicated that dietary supplemented with 0.2% SA had significantly higher weight gain and specific growth rates than those in 0% and 0.1% groups. The feed efficiency ratio in 0% groups was significantly the highest. Dietary SA can significantly increase the activities of intestinal lipase, amylase, and pepsin, and the contents of liver total protein, immunoglobulin M, and 50% hemolytic complement, while decreasing the contents of liver triglyceride, glucose, high-density lipoprotein cholesterol, aspartate aminotransferase, alanine aminotransferase, tumor necrosis factor-α, interleukin-1, and interleukin-8, and the activities of liver superoxide dismutase, and catalase. In addition, dietary SA significantly increased the relative abundance of beneficial bacteria (Achromobacter) and production of butyrate, meanwhile decreasing the harmful bacterial (Rhodobacter) abundance. After the challenge, cumulative mortality in fish fed 0% SA diets was higher than in fish fed 0.1–0.5% SA diets after 96 h ammonia stress. Correlation analysis showed that the SA induced the enhancement of the metabolic efficiency of carbohydrates, amino acids, and lipids were also associated with the increased relative abundance of Achromobacter. In general, SA can function as a beneficial additive for enhancing growth, intestinal health, and ammonia tolerance in yellow catfish.

Sodium butyrate improves the growth performance, intestinal immunity, and ammonia tolerance of yellow catfish Pelteobagrus fulvidraco by increasing the relative abundance of Candidatus_Arthromitus

The study aimed to analyze the effect of dietary sodium butyrate (SB) on intestinal digestive enzyme activity, liver physiological status, immune parameter, intestinal microbiota structure and composition, and ammonia tolerance in yellow catfish. Over the course of an 8-week experiment, four separate groups including 480 healthy male yellow catfish (1.52 ± 0.66 g) were fed diets containing varying concentrations of SB: 0, 0.05, 0.1, and 0.2%. Following this, an acute ammonia stress experiment that lasted for 96-h was conducted. The study showed that dietary supplementation of SB can improve growth performance and feed utilization (weight gain rate increased from 163.66 to 226.1%; specific growth rate increased from 1.73 to 2.11%/d; feed conversion rate decreased from 2.02 to 1.34), and increase intestinal digestive enzyme activity (lipase increased from 22.66 to 41.46 U/mg prot; amylase increased from 0.38 to 0.46 U/mg prot; pepsin increased from 10.13 to 12.83 U/mg prot). Plasma total protein (from 510.79 to 523.02 μg/mL), 50% hemolytic complement (from 35.46 to 40.46 U/mL), and immunoglobulin M (from 0.45 to 0.48 g/L) increased as dietary SB levels. On the contrary, plasma glucose (from 6.2 to 3.39 mmol/mL), high-density lipoprotein cholesterol (from 0.38 to 0.25 mmol/mL), aspartate aminotransferase (from 55.66 to 37.36 U/L), alanine aminotransferase (from 358.82 to 283.25 U/L), superoxide dismutase (from 163.84 to 147.13 U/mL), catalase (from 152.89 to 135.07 U/mL), tumor necrosis factor-α (from 67.58 to 62.13 pg/mL), interleukin-1 (from 40.07 to 30.96 pg/mL), and interleukin-8 (from 57.16 to 52.16 pg/mL) decreased with dietary SB levels. In addition, dietary supplementation of 0.2% SB significantly increased the relative abundance of Candidatus_Arthromitus in intestine by approximately 22-fold. To sum up, the utilization of SB has potential to enhance fish growth performance, elevate its physiological status, and improve its ability to tolerate acute ammonia toxicity. This is achievable by increasing the prevalence of Candidatus_Arthromitus in the intestine.

Thermodynamic restrictions determine ammonia tolerance of functional floras during anaerobic digestion

Ammonia inhibition is a major challenge in anaerobic digestion processes, affecting the activity and performance of functional floras, including syntrophic butyrate oxidation (FSBO), syntrophic propionate oxidation (FSPO), acetoclastic methanogenesis (FAMs), and hydrogenotrophic methanogenesis (FHMs). FHMs was more tolerant to ammonia, with a half maximal inhibitory concentration (IC50) of 18.80 g/L, followed by FSBO (IC50 = 14.26 g/L) and FSPO (IC50 = 10.47 g/L), and FAMs was the most sensitive to ammonia with the lowest IC50 (1.74 g/L). The order of ammonia tolerance (IC50) was found to be correlated with the Gibbs free energy of metabolic reactions in each functional flora. The results suggested the functional flora with higher energy availability (exergonic capacity) exhibited enhanced ammonia resistance ability. These findings provide insights into the thermodynamic restrictions and ammonia tolerance mechanisms of functional floras, which can guide the optimization and operation of anaerobic digestion systems for efficient methane production.

Expression and Functional Analysis of AMT1 Gene Responding to High Ammonia Stress in Razor Clam (Sinonovacula constricta).

Ammonium transporter 1 (AMT1), a member of ammonia (NH3/NH4+) transport proteins, has been found to have ammonia transport activity in plants and microorganisms. However, the functional characteristics and molecular mechanisms of AMT1 in mollusks remain unclear. The razor clam (Sinonovacula constricta) is a suitable model species to explore the molecular mechanism of ammonia excretion because of the high concentration of ambient ammonia it is exposed to in the clam-fish-shrimp polyculture system. Here, the expression of AMT1 in S. constricta (Sc-AMT1) in response to high ammonia (12.85 mmol/L NH4Cl) stress was identified by real-time quantitative PCR (qRT-PCR), Western blotting, RNA interference, and immunofluorescence analysis. Additionally, the association between the SNP_g.15211125A > T linked with Sc-AMT1 and ammonia tolerance was validated by kompetitive allele-specific PCR (KASP). A significant upregulated expression of Sc-AMT1 was observed during ammonia exposure, and Sc-AMT1 was found to be localized in the flat cells of gill. Moreover, the interference with Sc-AMT1 significantly upregulated the hemolymph ammonia levels, accompanied by the increased mRNA expression of Rhesus glycoprotein (Rh). Taken together, our findings imply that AMT1 may be a primary contributor to ammonia excretion in S. constricta, which is the basis of their ability to inhabit benthic water with high ammonia levels.

Ammonia tolerance of filamentous algae Oedogonium, Spirogyra, Tribonema and Cladophora, and its implications on wastewater treatment processes

Filamentous algae have high potential for wastewater treatment due to their direct uptake of nitrogen and ease of harvesting. Theoretically, filamentous algae are best applied upstream to directly remove total ammonia nitrogen (TAN = ammonia + ammonium) from wastewater, however their tolerance to toxic free NH3 remains unclear. This study investigated the ammonia tolerance of four filamentous algae species from the Oedogonium, Tribonema, Spirogyra and Cladophora genera. The algae were cultivated using buffers at pH values from 7.0 to 9.0 at 15 °C and 25 °C using either 60 mg-N/L nitrate or ammonium as the nitrogen source. Using nitrate, an increase in productivity as a function of pH was observed for all four species. Comparison of the results and the corresponding experimental conditions with previous studies suggested that the effect of algal productivity enhancement via CO2 addition lies heavily on carbon provision rather than direct pH control. In the presence of ammonium, Oedogonium, Tribonema and Spirogyra showed stable growth at low pH followed by a sharp decline in productivity above certain pH thresholds, while Cladophora showed a very low growth rate irrespective of pH. At 60 mg-N/L initial TAN, the critical pH range was found to be approximately 8.0–8.6, 7.5–8.3 and 7.5–8.0 for Tribonema, Oedogonium and Spirogyra respectively. The critical threshold calculated based on the initial amount of free NH3 was 1.5–3 mg-N/L for Tribonema and Oedogonium and approximately 1 mg-N/L for Spirogyra. Oedogonium was also cultivated under TAN at pH 7.5 and 15 °C over three weeks, showing stable growth and capability to utilise TAN under controlled conditions. Nevertheless, a 30 % nitrogen loss, presumably due to ammonia volatilisation, was also observed. Based on the results of this study, it was concluded that the use of filamentous algae for downstream wastewater treatment rather than direct TAN removal may be a more practical option.

Ammonia Tolerance of Atomically Dispersed Single Metal Site Catalysts: Mechanistic Understanding and High‐Performance Oxygen Reduction Electrocatalysis

AbstractThe anion‐exchange membrane direct ammonia fuel cell, as a carbon‐free fuel cell type, has recently received increasing attention albeit suffering from high cost of using the platinum‐group metal oxygen reduction reaction (ORR) catalysts. To pave the development of this promising power source, the atomically dispersed transition metal‐nitrogen‐carbon (M‐N‐C) materials with low cost and high ORR performance have allured to investigate their ammonia tolerance during the ORR. Herein, it is initially deconvoluted how compositional and structural elements of FeN4 sites modulate catalyst's performance. Furthermore, ORR catalytic activities of the M‐N‐C (M = Fe, Co or Mn) and Pt/C catalysts are investigated in ammonia‐containing electrolytes, showing that M‐N‐C catalysts have better ammonia tolerance than Pt/C. Among others, the Fe‐N‐C exhibits the best ammonia tolerance with only 4 mV negative shifts of half‐wave potential, 2.7% decrease of current, and negligibly irreversible activity loss. The superior ammonia tolerance of MN4 sites to Pt (111) surface is further confirmed by density functional theory calculations. The adsorption capacity of MN4 for O2 is higher than NH3 and the bonding force between MN4 and O2 is stronger than NH3, whereas opposite adsorption capacity and bonding force trends are observed on Pt (111) surface.

Impacts of ammonia stress on different Pacific whiteleg shrimp Litopenaeus vannamei families and the underlying adaptive mechanisms

Ammonia stress in aquaculture systems poses a great threat to the growth and survival of the Pacific whiteleg shrimp Litopenaeus vannamei. Although the ammonia stress tolerance capacity of L. vannamei has been found to vary significantly among different breeding families, the underneath mechanisms are still largely unknown. In this study, the ammonia tolerance capacity of different L. vannamei breeding families was compared. Results confirmed the significant differences in the ammonia adaptability among different families. To ascertain the underlying adaptive strategies, ATP status, ATP synthase activity, expression and activities of ammonia excretion and metabolism-related enzymes, and apoptosis in shrimp gills were analyzed. Furthermore, transcriptomic analyses were also performed to elucidate the molecular mechanisms. Our results indicated that ammonia-tolerant L. vannamei may possess (1) enhanced ability to excrete ammonia, (2) better capacity to convert ammonia into less toxic products, and (3) sufficient energy reserves for ammonia-compensating processes.

Dietary N-carbamylglutamate supplementation improves ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco.

Introduction: Ammonia has been of concern for its high toxicity to animals. N-carbamylglutamate (NCG) can reduce blood ammonia levels in mammals, but studies on ammonia tolerance in fish are insufficient. Methods: Juvenile yellow catfish were fed two levels of NCG (0.00% and 0.05%) for 84days under three ammonia levels (0.00, 0.08, and 0.16mg/L NH3). Results and Discussion: The results showed that survival rate (SUR), final body weight (FBW), weight gain (WG), and serum total protein (TP), triglycerides (TG), glucose (Glu), ornithine (Orn), citrulline (Cit) contents, and liver superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), arginase (ARG), ornithine transcarbamylase (OTC) activities decreased with the increase of ammonia levels, on the contrary, feed conversion ratio (FCR), hepatosomatic index (HSI), and serum ammonia, urea, alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamine (Gln), arginine (Arg) contents, and liver malondialdehyde (MDA), tumor necrosis factor (TNF), interleukin (IL) 1, IL 8 contents, and mRNA expressions of cu/zn sod, cat, gpx, gr, tnf ɑ, il 1, and il 8 were significantly increased. Dietary 0.05% NCG supplementation had higher SUR, FBW, WG, feed intake (FI), whole-body protein, and serum TP, total cholesterol (TC), Glu, citrulline (Cit) contents, and liver SOD, GPx, argininosuccinate synthetase (ASS), argininosuccinate lyase (ASL), inducible nitric oxide synthase (iNOS) activities compared to 0.00% NCG group, but had lower serum ammonia, urea, ALT, AST, Gln, Arg contents, and liver MDA, TNF, IL 1, IL 8 contents, and neuronal nitric oxide synthase activity. At the end of bacterial challenge, cumulative mortality (CM) increased with ammonia levels increased, but serum antibody titer (AT), lysozyme (LYZ) activity, 50% hemolytic complement, immunoglobulin (Ig) contents, respiratory burst (RB), phagocytic indices decreased with ammonia levels increased. CM in 0.05% NCG group was lower than that in 0.00% NCG group, but serum AT, LYZ activity, Ig content, RB in 0.05% NCG group were significantly higher. The correlation analysis found that iNOS was positively correlated with ASS activity. This study indicates that dietary NCG supplementation can improve the ammonia tolerance of yellow catfish, and ASS may also be the target of NCG to activate the urea cycle.

Comparison of dietary arginine or/and inulin supplementation on growth, digestive ability and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

Most fish have limited use of arginine, and increasing arginine availability by adding other nutrients is an effective method. Inulin is thought to have potential synergistic effects with arginine. Four experiment groups were carried out to test the hypothesis that inulin can increase arginine availability of yellow catfish, including control, arginine, inulin and arginine mixed with inulin groups. The results showed that dietary arginine supplementation improved growth (weight gain and whole-body protein increased; IGF 1, MyoD, MyoG and Myf5 genes up-regulated), digestive ability (intestine protease and lipase increased), blood health (total protein and high-density lipoprotein cholesterol increased) and ammonia tolerance (cumulative mortality reduced; serum lysozyme, 50% hemolytic complement, respiratory burst and phagocytic indices increased) of yellow catfish, and reduced intestine inflammation (tumor necrosis factor and interleukin 1 decreased). Meanwhile, the addition of inulin to arginine-rich diets was further enhanced growth, digestive ability, intestine internal environment (butyric acid and total volatile fatty acids increased), blood health and ammonia tolerance (argininosuccinate synthetase, argininosuccinate lyase, arginase and ornithine transcarboxylase increased) of yellow catfish, and further relieved intestine inflammation. This study indicates that inulin can promote the utilization of dietary arginine; the potential synergistic effects between arginine and inulin were found in growth, digestive ability and ammonia tolerance of yellow catfish.

Ammonia tolerance and microbial community in thermophilic co-digestion of sewage sludge initiated with lignocellulosic biomass

Rice straw is a useful lignocellulosic biomass for controlling ammonia inhibition in the thermophilic anaerobic digestion of sewage sludge. However, it is challenging to procure rice straw throughout the year because of its seasonal production. This study investigated methane production in a laboratory-scale digester by gradually decreasing rice straw addition to solid thermophilic sewage sludge digestion. The decrease in rice straw did not accumulate volatile fatty acids and stabilized methane production. Even with increased sludge concentration without rice straw, methane production continued under high ammonia conditions. Ammonia tolerance of the digested sludge of the experimental digester was higher than that of conventionally digested sludge. The cellulose-degrading bacteria Clostridia and high ammonia-resistant archaea Methanosarcina were dominant in the experimentally digested sludge. The community was maintained for over 200 days after discontinuing the rice straw supply. These findings suggest that anaerobic digestion initiation with rice straw is appropriate to facilitate ammonia-tolerant communities.

Insight into the genetic basis of ammonia tolerance in razor clam Sinonovacula constricta by genome-wide association study

With the development of high-density integrated farming model, the razor clam Sinonovacula constricta faces severe pressures from environmental factors, especially ammonia nitrogen, which is the top factor threaten the growth and survival of aquatic animals. Hence, ammonia tolerance has been one of the most important economic traits for razor clam. To cultivate new strains with ammonia tolerance trait, it is necessary to dissect genetic basis comprehensively underlying ammonia tolerance of S. constricta. In this study, we performed a genome wide association study (GWAS) to identify the single nucleotide polymorphisms (SNPs) and genes associated with ammonia tolerance through whole genome resequencing of 231 individuals. As a result, 56 associated SNPs (-log10P = 5) which were embedded in or adjacent to 236 genes were identified among a total of 4,577,102 SNPs. Most of these genes were related to various processes of metabolism, homeostasis, response to stress and apoptosis, suggesting that the polygenic architecture in the trait of ammonia tolerance was complex in razor clam. Among these sites, 11 genome-wide significant associated SNPs (-log10P = 6.66) adjacent to five candidate genes, including beta-galactosidase (glb1), tetratricopeptide repeat protein 28 (ttc28), Na+/K+-ATPase alpha-1 (nka), tubulin beta (tubb) and elongation factor 1-alpha (eef1a). In particular, NKA has been demonstrated to be involved in NH4+ excretion to reduce ammonia accumulation in mollusca. Our results provide insight into genetic basis of ammonia tolerance, and the SNPs would be valuable markers for selective breeding of ammonia-tolerant strain in S. constricta.

Duckweeds for Phytoremediation of Polluted Water.

Tiny aquatic plants from the Lemnaceae family, commonly known as duckweeds, are often regarded as detrimental to the environment because of their ability to quickly populate and cover the surfaces of bodies of water. Due to their rapid vegetative propagation, duckweeds have one of the fastest growth rates among flowering plants and can accumulate large amounts of biomass in relatively short time periods. Due to the high yield of valuable biomass and ease of harvest, duckweeds can be used as feedstock for biofuels, animal feed, and other applications. Thanks to their efficient absorption of nitrogen- and phosphate-containing pollutants, duckweeds play an important role in the restorative ecology of water reservoirs. Moreover, compared to other species, duckweed species and ecotypes demonstrate exceptionally high adaptivity to a variety of environmental factors; indeed, duckweeds remove and convert many contaminants, such as nitrogen, into plant biomass. The global distribution of duckweeds and their tolerance of ammonia, heavy metals, other pollutants, and stresses are the major factors highlighting their potential for use in purifying agricultural, municipal, and some industrial wastewater. In summary, duckweeds are a powerful tool for bioremediation that can reduce anthropogenic pollution in aquatic ecosystems and prevent water eutrophication in a simple, inexpensive ecologically friendly way. Here we review the potential for using duckweeds in phytoremediation of several major water pollutants: mineral nitrogen and phosphorus, various organic chemicals, and heavy metals.

Thermodynamic restrictions determine ammonia tolerance of methanogenic pathways in Methanosarcina barkeri

Ammonia is a ubiquitous potential inhibitor of anaerobic digestion processes, mainly exhibiting inhibition towards methanogenic activity. However, knowledge as to how ammonia affects the methanogens is still limited. In this study, we cultured a multitrophic methanogen, Methanosarcina barkeri DSM 800, with acetate, H2/CO2, and methanol to evaluate the influence of ammonia on different methanogenic pathways. Aceticlastic methanogenesis was more sensitive to increased ammonia concentrations than hydrogenotrophic and methylotrophic methanogenesis. Theoretical maximum NH3 tolerances of M. barkeri fed with acetate, H2/CO2, and methanol were calculated to be 39.1 ± 9.0, 104.3 ± 7.4, and 85.7 ± 1.0 mg/L, respectively. The order of the ΔG range of M. barkeri under three methanogenic pathways reflected the order of ammonia tolerance of M. barkeri. Our results provide insights into the role of the thermodynamic potential of methanogenesis on the tolerance of ammonia stress; and shed light on the mechanism of ammonia inhibition on anaerobic digestion.

Influence of BFT and water exchange systems on growth, ammonia tolerance, and water footprint in Macrobrachium rosenbergii nursery in intensive systems

Influence of BFT and water exchange systems on growth, ammonia tolerance, and water footprint in Macrobrachium rosenbergii nursery in intensive systems