Amine Degradation Research Articles

Phase separation behavior and thermal degradation analysis of DETA/DEA/DMAC biphasic absorbent

Thermal stability is crucial for maintaining the efficient performance and low regeneration energy of biphasic absorbents, while the synergistic degradation reactions and condition fluctuations could significantly influence the thermal degradation process of biphasic solutions. In this research, a typical amide-based biphasic absorbent diethylenetriamine(DETA)/diethanolamine(DEA)/N, N-dimethylacetamide(DMAC) with low regeneration energy, was applied in a thermal degradation investigation. The thermal stability of active amine in DETA/DEA/DMAC was superior to 30 wt% MEA, 7 M DETA solution, and other biphasic absorbents, with a 19.9 % lower amine degradation ratio compared to 7 M DETA. The primary thermal degradation products in DETA/DEA/DMAC with and without CO2 were analyzed using Cation Ion Chromatography (IC) and 13C Nuclear Magnetic Resonance (NMR). A series of synergistic reactions between DETA and DMAC, with DMAC being an inducer, was revealed in thermal degradation of DETA/DEA/DMAC, leading to accelerated DETA degradation and DEA formation. Various operational conditions including CO2 loading and degradation temperature were considered to build a systemic impact mechanism on thermal degradation for biphasic absorbents. Before phase separation, CO2 absorption and increasing temperature significantly exacerbated DETA degradation. However, phase separation behavior was found to effectively prevent the synergistic degradation reactions in the solution, leading to a 27.4 % reduction in the DETA degradation ratio of the aqueous phase after phase separation. Moreover, it achieved a 24.1 % reduction of the DETA degradation ratio caused by rising temperature in the solution after phase separation. Therefore, it is essential to ensure the completion of phase separation for biphasic solvents before entering the stripper in applications. After thermal degradation, the regeneration rate and cyclic capacity of DETA/DEA/DMAC were strengthened, which was 84.9 % and 63.3 % higher than that of 30 wt% MEA, respectively.

Microbial Dynamics and Pathogen Control During Fermentation of Distiller Grains: Effects of Fermentation Time on Feed Safety.

Determining the effects of fermentation duration on the microbial ecosystem, potential pathogenic risks, and metabolite generation during the fermentation of distilled grains is essential for safeguarding the safety and enhancing the nutritional profile of animal feed. This study investigates the effect of varying fermentation times (9, 30, and 60 days) on microbial diversity, pathogenic risk, and metabolite profiles in distiller grains using 16S rDNA sequencing and LC-MS-based metabolomics. The results showed that early fermentation (9-30 days) enhanced the abundance of beneficial bacteria, such as Lactobacillus reuteri and Lactobacillus pontis (p < 0.05), while pathogenic bacteria, like Serratia marcescens and Citrobacter freundii, were significantly reduced (p < 0.05). Metabolomic analysis revealed an increase in unsaturated fatty acids and the degradation of biogenic amines during early fermentation. However, prolonged fermentation (60 days) led to a resurgence of pathogenic bacteria and reduced the synthesis of essential metabolites. These findings suggest that fermentation duration must be optimized to balance microbial safety and nutrient quality, with 30 days being the optimal period to reduce pathogenic risks and enhance feed quality.

Degradation of the AMP/PZ-based solvent CESAR1 and effects of solvent management in two longtime pilot plant tests

Two 24/7 longtime testing campaigns at the CO2 capture pilot plant at Niederaussem with an accumulated testing time of more than 40,000 h with the CESAR1 solvent, an aqueous solution of 26.7 wt% 2-amino-2-methylpropan-1-ol (AMP) and 12.9 wt% piperazine (PZ), provide a unique data base for the development of solvent management technologies and the evaluation of hypotheses on amine degradation. In the first campaign with a testing time of 34,000 h without replacement of the solvent inventory, three solvent management strategies with different effect mechanisms were investigated: adsorptive removal of trace elements from the solvent by two kinds of active carbon, removal of ionic contaminants by ion exchange using cation and anion exchange resins, and removal of NO2 from the flue gas by treatment with a thiosulfate/sulfite solution. After replacement of the solvent inventory the second campaign was conducted, in which none of the solvent management technologies mentioned have been applied for 10,000 h. The results of the two campaigns allow a direct comparison of the solvent degradation behavior. It is shown that active carbon does not significantly affect the accumulation rate of degradation products in CESAR1, and that an inappropriate kind of active carbon can cause foaming. Anionic degradation products, metal complexes, trace components and cationic contaminants can be effectively removed from the aged solvent by ion exchange. However, after their removal, accelerated formation of oxidative degradation products by a factor of up to 3 higher than before the anion exchange was observed. Removal of NO2 from the flue gas did not affect the NH3 emissions from the CO2 absorber, but it led to the highest observed increase rate of the accumulation of acidic degradation products for aged CESAR1. The results show that exaggerated efforts for solvent management are contra-productive and that a reassessment of the effect mechanisms of solvent management technologies is necessary.

An isolated salt-tolerant Tetragenococcus halophilus 2MH-3 improved the volatile flavor of low-salt fermented fish sauce by regulating the microbial community

The application of low-salt fish sauce is limited by its tendency to spoil easily and inadequate flavor generation. Herein, a salt-tolerant Tetragenococcus halophilus 2MH-3 strain with strong abilities of enzyme production and biogenic amine degradation was utilized as a starter for the production of low-salt fish sauce. Bacterial community analysis revealed discrepancies in microbiota between low-salt fish sauces fermented with (Th group) or without 2MH-3 (LF group). Staphylococcus was the primary genus in the Th group at 1 M fermentation (47.42 %), followed by Psychrobacter (10.82 %), while Tetragenococcus swiftly ascended to the dominant status with a relative abundance of 5.88 % after 3 M fermentation. Conversely, the abundance of Tetragenococcus throughout the LF fermentation period was no significant change. In Th group, 118 volatile components were detected with 21 high-concentration flavor compounds being the primary flavor components (OAV ≥ 1), which were basically produced by Alkaliphilus, Psychrobacter, Tetragenococcus, Bacteroides and Staphylococcus based on the co-occurrence heatmaps after PLS-DA evaluation. Furthermore, the co-occurrence network map demonstrated that the decrease in key biogenic amines such as histamine, putrescine, cadaverine and tyramine, the increase in bacterial diversity, as well as the increase in 21 core volatile flavor compounds (OVA ≥ 1.0), were mainly caused by the addition of T. halophilus 2MH-3 in the low-salt fish sauce. Therefore, T. halophilus 2MH-3 could be utilized as an underlying microbial starter in the industrialization of fish sauce.

Insights into Genomic Characteristics and Biogenic Amine Degradation Potential and Mechanisms: A Strain of Pediococcus acidilactici Sourced from Doubanjiang.

The control of excess biogenic amines (BAs) is crucial for the sustainable development of fermented foods. This study aimed to screen endogenous functional strains in Doubanjiang with the capacity to degrade BAs and to elucidate their application potential. Pediococcus acidilactici L-9 (PA), which was confirmed as a safe strain by phenotypic and genotypic analyses, exhibited an efficient degradation ability on BAs, particularly regarding tyramine. Notably, the degradation of tyramine was maintained at 24.03-50.60% at different temperatures (20-40 °C), pH values (4.0-9.0), and NaCl concentrations (3-18%, w/v). Additionally, genomic data revealed the presence of the laccase-coding gene, which was demonstrated to play a pivotal role in BA degradation by heterologous expression. Further, molecular docking results indicated that the degradation of BA by laccase is closely linked to the electron transfer pathway formed by the substrate and key amino acid residues. Finally, the degradation of tyramine by PA remained within the range of 8.19-64.19% under the simulated system with 6-12% salinity. This study provided valuable insights into the safety of PA and its potential degradation capacity on BAs, particularly in mitigating tyramine accumulation, which could improve the quality of Doubanjiang and other fermented foods.

Effect of NOX and SOX Contaminants on Corrosion Behaviors of 304L and 316L Stainless Steels in Monoethanolamine Aqueous Amine Solutions

This work is devoted to evaluating the corrosion behaviors of SS 304L and SS 316L in monoethanolamine solutions (MEA) containing SOX and NOX pollutants, examining both lean and CO2-loaded conditions at 25 °C and 40 °C. Electrochemical techniques (potentiodynamic and cyclic polarization) were used along with Scanning Electron Microscopy, Confocal Microscopy and weight loss measurements. The results reveal that the introduction of SOX and NOX pollutants increased the corrosion rate, whereas CO2 loading primarily reduced the corrosion resistance in the lean MEA solution, while its impact on solutions with SOX and NOX was less pronounced. This suggests that SOX and NOX play primary roles in the metal’s dissolution. Also, SS 316L demonstrated superior corrosion resistance compared to 304L in nearly all of the cases examined. Elevated temperatures were also found to intensify the corrosion rate, indicating a correlation between the corrosion rate and temperature. A microscopic observation and EDX analysis revealed that corrosion products are characterized by high concentrations of iron (Fe) and oxygen (O) as well as carbon (C). There is also an indication of the possible formation of amine complexes, suggesting a potential for amine degradation. No pitting corrosion was observed in SS 304L and SS 316L across any tested solution. Finally, the immersion results expose a tendency for passivity in all amine solutions and at both temperatures after several days of exposure. Moreover, they confirm the very low corrosion rate calculated from potentiodynamic curves due to minimal weight loss after 24 days of immersion.

Comprehensive Analysis of Gut Microbiota Composition and Functional Metabolism in Children with Autism Spectrum Disorder and Neurotypical Children: Implications for Sex-Based Differences and Metabolic Dysregulation.

This study aimed to investigate the gut microbiota composition in children with autism spectrum disorder (ASD) compared to neurotypical (NT) children, with a focus on identifying potential differences in gut bacteria between these groups. The microbiota was analyzed through the massive sequencing of region V3-V4 of the 16S RNA gene, utilizing DNA extracted from stool samples of participants. Our findings revealed no significant differences in the dominant bacterial phyla (Firmicutes, Bacteroidota, Actinobacteria, Proteobacteria, Verrucomicrobiota) between the ASD and NT groups. However, at the genus level, notable disparities were observed in the abundance of Blautia, Prevotella, Clostridium XI, and Clostridium XVIII, all of which have been previously associated with ASD. Furthermore, a sex-based analysis unveiled additional discrepancies in gut microbiota composition. Specifically, three genera (Megamonas, Oscilibacter, Acidaminococcus) exhibited variations between male and female groups in both ASD and NT cohorts. Particularly noteworthy was the exclusive presence of Megamonas in females with ASD. Analysis of predicted metabolic pathways suggested an enrichment of pathways related to amine and polyamine degradation, as well as amino acid degradation in the ASD group. Conversely, pathways implicated in carbohydrate biosynthesis, degradation, and fermentation were found to be underrepresented. Despite the limitations of our study, including a relatively small sample size (30 ASD and 31 NT children) and the utilization of predicted metabolic pathways derived from 16S RNA gene analysis rather than metagenome sequencing, our findings contribute to the growing body of evidence suggesting a potential association between gut microbiota composition and ASD. Future research endeavors should focus on validating these findings with larger sample sizes and exploring the functional significance of these microbial differences in ASD. Additionally, there is a critical need for further investigations to elucidate sex differences in gut microbiota composition and their potential implications for ASD pathology and treatment.

Corrosion performance of carbon steel and 304 stainless steel in activated methyldiethanolamine solution using autoclave tests

This study evaluated the corrosion performance of carbon steel (CS) and 304 stainless steel (304 SS) under high temperature and pressure (inside an autoclave) in a CO2-saturated solution of activated methyldiethanolamine (aMDEA). The aim was to determine the effect of temperature, presence of chloride ions, degradation of the aMDEA and amount of dissolved oxygen on the corrosion resistance of these materials. The results indicated that raising the temperature between 50 and 120°C led to a higher corrosion rate of both CS and 304 SS. However, the corrosion rate of 304 SS decreased and remained stable at higher temperatures as the corrosion reaction became mass-controlled. Oxygen loading results in the passivation of both CS and 304 SS. The amine degradation products were found to accelerate the corrosion rate of CS at 50°C due to a chelation effect of iron ions, and also increase the corrosion rate of 304 SS at 120°C by causing the passive film rupture. The SCC test on U-shaped 304 SS samples showed transversal microcracks with a depth of more than 25 µm after 2 months of immersion in an autoclave containing CO2-saturated aMDEA at 120°C, which confirmed the SCC risk of 304 SS.

Dietary Protein Quality Affects the Interplay between Gut Microbiota and Host Performance in Nile Tilapia.

Dietary protein quality plays a key role in maintaining intestinal mucosal integrity, but also modulates the growth of luminal microorganisms. This work assessed the effect of dietary protein sources on the performance, gut morphology, and microbiome in Nile tilapia. Four isonitrogenous and isolipidic diets comprising equivalent amounts of the protein supply derived from either PLANT, ANIMAL, INSECT, or BACTERIAL (bacterial biomass) sources were fed to triplicate groups of fish (IBW: 12 g) for 46 days. Fish fed the ANIMAL and BACTERIAL diets showed significantly higher weight gains than those fed the PLANT and INSECT diets (p < 0.05). Relative abundance at the phylum level showed that Bacteroidetes, Fusobacteria, and Proteobacteria were the more abundant phyla in tilapia's intestine, while Cetobacterium was the most representative genus in all treatments. Interesting patterns were observed in the correlation between amino acid intake and genus and species abundance. Metabolism prediction analysis showed that BACTERIAL amine and polyamine degradation pathways are modulated depending on diets. In conclusion, different protein sources modulate the relationship between bacteria functional pathways and amino acid intake.

Screening and evaluating microorganisms with broad-spectrum biogenic amine-degrading ability from naturally fermented dry sausage collected from Northeast China

This study aimed to screen autochthonous strains with broad-spectrum biogenic amine (BA) degradation ability from traditional dry sausages and to evaluate their BA-degrading ability in dry sausages. A total of 120 strains were isolated from dry sausages collected from various regions in Northeast China, and 35 of 120 isolates were identified as non-BA producing strains by the in vitro agar method. The random amplified polymorphic DNA polymerase chain reaction technique genotyped these 35 isolates into 18 biotypes. Moreover, high performance liquid chromatography (HPLC) quantification showed that six strains (Latilactobacillus sakei MDJ6; Lactiplantibacillus plantarum SH7; Weissella hellenica DQ9; Staphylococcus saprophyticus JX18 and SYS8; and Macrococcus caseolyticus SYS11) of the 18 biotypes exhibited broad-spectrum BA-degrading ability, all of which had various levels of amine oxidase activity with monoamine oxidase and diamine oxidase activities ranged of 6.60–619.04 and 26.32–352.81 U/mg protein, respectively. These six strains were subsequently inoculated into dry sausages and the results showed that they exhibited varying degrees of BA-degrading ability, of which strain Lat. sakei MDJ6 allowed to have less BA production on dry sausage with a final concentration of 61.33 mg/kg.

Experimental and computational study of the thermal degradation of primary amines used in CO2 capture

CO2 loaded amine polymerizes during solvent regeneration at temperatures above 100 °C, resulting in the deterioration of solvent performance. Herein, five primary amines were heated to 120, 135 and 150 °C with CO2 loading of 0.4C/N to study thermal degradation. It was found that 2-amine-1-butanol showed the greatest amine loss of 38.5 % after heating to 135 °C for 672 hrs while 2-amino-2-methyl-1-propanol was most stable with amine loss of 17.4 % under the same conditions. The degradation products were identified and the reaction pathway was studied through density functional theory (DFT) calculation. Furthermore, the transition state for ring closure and opening reactions was analyzed. The ring closure reaction to form oxazolidinones had a higher energy barrier, showing that it was the limiting step. This is further supported by the good agreement with experimental results. The structure–activity relationship showed the strong steric hindrance effect and the methyl group at β-carbon improved the amine stability.

The relationship between oxidative degradation and ammonia emission of carbon capture amines based on their chemical structures

Abstract This work investigates the effect of chemical structural positioning of different functional groups in 29 amines covering primary, secondary and tertiary alkanolamines as well as multi-alkylamines and cyclic amines on both amine degradation and ammonia (NH3) emissions during post-combustion amine-based carbon dioxide capture. The results helped to elucidate possible relationships between degradation and emissions as related to the chemical structure of the amine. The results showed that longer alkyl chain lengths in multi-alkylamines caused a more drastic decrease in both degradation and NH3 emissions followed by secondary alkanolamines. The decrease in those activities for primary and tertiary alkanolamines as well as cyclic amines was low and more so for NH3 emissions. In contrast, the increase in hydroxyl groups in secondary alkanolamines caused a drastic increase in degradation and NH3 emissions. On the other hand, having more hydroxyl groups in sterically hindered primary and tertiary alkanolamines caused a more drastic decrease in degradation and a smaller decrease in NH3 emissions due to the steric hindrance within their structure. An increase in the number of amino groups in an amine caused an increase in both degradation and NH3 emission rates because these provided the reactive sites for the formation of free radicals. This effect was not as large in alkyl-cyclic amines as in multi-alkylamines due to the ability of the former to resist oxidative degradation. Furthermore, branched alkyl groups between amino and hydroxyl groups more drastically increased both the degradation and NH3 emission activities than branched alkyl groups located at the nitrogen atom.

Biochemical Characterization of Three Heterologous Lactic Acid Bacteria Laccases from Pediococcus, Lactobacillus, and Lactococcus Genus and Their Potential to Degrade Biogenic Amines Using ABTS and Epicatechin as Mediators

In this study, we cloned and characterized three bacterial laccases from strains of the species Pediococcus parvulus, Lacticaseibacillus paracasei, and Lactococcus lactis isolated from wine and cheese and evaluated their biogenic amine degradation abilities in the presence/absence of artificial 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) or natural (epicatechin) mediator compounds. Although some recombinant bacterial laccases have been characterized and found to be biological tools for degrading biogenic amines with or without the use of mediators, no prior research has investigated the role of natural mediators, like phenolic substrates found in wine and certain vegetable foods, in the degradation of biogenic amines. The three recombinant bacterial laccases exhibited sigmoidal kinetics and had similar molecular mass but varied in k0.5, kcat, and specific activity toward ABTS. They are acidophilic and have an optimal temperature of 28 °C. However, they exhibit low thermal stability at temperatures higher than 37 °C. The three laccases were capable of degrading dopamine without the use of mediators, while the other amines were not degraded. The presence of ABTS enhanced the degradation of dopamine and tyramine, but the addition of epicatechin did not improve their degradation. This study presents a comparison of the laccases’ biogenic amine-degrading efficiency using different mediators. This is the first time such a comparison has been made.

Genomic profiling and characteristics of a C1 degrading heterotrophic fresh-water bacterium Paracoccus sp. strain DMF.

Paracoccus species are metabolically versatile gram-negative, aerobic facultative methylotrophic bacteria showing enormous promise for environmental and bioremediation studies. Here we report, the complete genome analysis of Paracoccus sp. strain DMF (P. DMF) that was isolated from a domestic wastewater treatment plant in Kanpur, India (26.4287°N, 80.3891°E) based on its ability to degrade a recalcitrant organic solvent N, N-dimethylformamide (DMF). The results reveal a genome size of 4,202,269 base pairs (bp) with a G + C content of 67.9%. The assembled genome comprises 4141 coding sequences (CDS), 46 RNA sequences, and 2 CRISPRs. Interestingly, catabolic operons related to the conventional marine-based methylated amines (MAs) degradation pathway were functionally annotated within the genome of an obligated aerobic heterotroph that is P. DMF. The genomic data-based characterization presented here for the novel heterotroph P. DMF aims to improve the understanding of the phenotypic gene products, enzymes, and pathways involved with greater emphasis on facultative methylotrophic motility-based latent pathogenicity.

Reduction of histamine, putrescine and cadaverine by the bacteria Lacticaseibacillus casei depending on selected factors in the real condition of the dairy product

One way to effectively reduce the number of biogenic amines (BAs) in food is through enzymatic reduction using bacteria, such as lactic acid bacteria. This study focuses on the ability of the bacterial strain Lacticaseibacillus casei CCDM 198 to reduce the number of three important BAs (histamine, putrescine and cadaverine) over time, depending on different conditions (temperature and pH) in vitro and for the real dairy product – skimmed milk. The obtained results show that the studied strain significantly (P < 0.05) affects the number of individual amines, and the content of all amines has a decreasing character compared to the initial relative content of BAs at time zero. Furthermore, a statistical dependence (P < 0.05) of the rate of amine degradation on the combination of investigated factors was demonstrated. The presence and the activity of multicopper oxidase enzyme was also detected in this bacterial strain. This is the first known publication demonstrating multicopper oxidase activity in Lacticaseibacillus casei CCDM 198. Moreover, the studied strain is able to reduce the tested BAs in skimmed milk and would be a good candidate for degrading these toxic compounds in other dairy products, such as cheese. These findings could significantly enhance the food safety of dairy products.

Integrated meta-omics approaches reveal Saccharopolyspora as the core functional genus in huangjiu fermentations

Identification of the core functional microorganisms in food fermentations is necessary to understand the ecological and functional processes for making those foods. Wheat qu, which provides liquefaction and saccharifying power, and affects the flavor quality, is a key ingredient in ancient alcoholic huangjiu fermentation, while core microbiota of them still remains indistinct. In this study, metagenomics, metabolomics, microbial isolation and co-fermentation were used to investigate huangjiu. Although Aspergillus is usually regarded as core microorganism in wheat qu to initiate huangjiu fermentations, our metagenomic analysis showed that bacteria Saccharopolyspora are predominant in wheat qu and responsible for breakdown of starch and cellulose. Metabolic network and correlation analysis showed that Saccharopolyspora rectivirgula, Saccharopolyspora erythraea, and Saccharopolyspora hirsuta made the greatest contributions to huangjiu’s metabolites, consisting of alcohols (phenylethanol, isoamylol and isobutanol), esters, amino acids (Pro, Arg, Glu and Ala) and organic acids (lactate, tartrate, acetate and citrate). S. hirsuta J2 isolated from wheat qu had the highest amylase, glucoamylase and protease activities. Co-fermentations of S. hirsuta J2 with S. cerevisiae HJ resulted in a higher fermentation rate and alcohol content, and huangjiu flavors were more similar to that of traditional huangjiu compared to co-fermentations of Aspergillus or Lactiplantibacillus with S. cerevisiae HJ. Genome of S. hirsuta J2 contained genes encoding biogenic amine degradation enzymes. By S. hirsuta J2 inoculation, biogenic amine content was reduced by 45%, 43% and 62% in huangjiu, sausage and soy sauce, respectively. These findings show the utility of Saccharopolyspora as a key functional organism in fermented food products.

Insights into microbial communities and metabolic profiles in the traditional production of the two representative Hongqu rice wines fermented with Gutian Qu and Wuyi Qu based on single-molecule real-time sequencing

Hongqu rice wine, a famous traditional fermented alcoholic beverage, is brewed with traditional Hongqu (mainly including Gutian Qu and Wuyi Qu). This study aimed to compare the microbial communities and metabolic profiles in the traditional brewing of Hongqu rice wines fermented with Gutian Qu and Wuyi Qu. Compared with Hongqu rice wine fermented with Wuyi Qu (WY), Hongqu rice wine fermented with Gutian Qu (GT) exhibited higher levels of biogenic amines. The composition of volatile flavor components of Hongqu rice wine brewed by different fermentation starters (Gutian Qu and Wuyi Qu) was obviously different. Among them, ethyl acetate, isobutanol, 3-methylbutan-1-ol, ethyl decanoate, ethyl palmitate, ethyl oleate, nonanoic acid, 4-ethylguaiacol, 5-pentyldihydro-2(3H)-furanone, ethyl acetate, n-decanoic acid etc. were identified as the characteristic aroma-active compounds between GT and WY. Microbiome analysis based on high-throughput sequencing of full-length 16S rDNA/ITS-5.8S rDNA amplicons revealed that Lactococcus, Leuconostoc, Pseudomonas, Serratia, Enterobacter, Weissella, Saccharomyces, Monascus and Candida were the predominant microbial genera during the traditional production of GT, while Lactococcus, Lactobacillus, Leuconostoc, Enterobacter, Kozakia, Weissella, Klebsiella, Cronobacter, Saccharomyces, Millerozyma, Monascus, Talaromyces and Meyerozyma were the predominant microbial genera in the traditional fermentation of WY. Correlation analysis revealed that Lactobacillus showed significant positive correlations with most of the characteristic volatile flavor components and biogenic amines. Furthermore, bioinformatical analysis based on PICRUSt revealed that microbial enzymes related to biogenic amines synthesis were more abundant in GT than those in WY, and the enzymes responsible for the degradation of biogenic amines were less abundant in GT than those in WY. Collectively, this study provides important scientific data for enhancing the flavor quality of Hongqu rice wine, and lays a solid foundation for the healthy and sustainable development of Hongqu rice wine industry.

The enzymatic and neurochemical outcomes of a mutation in Mexican cavefish MAO reveal teleost-specific aspects of brain monoamine homeostasis.

Monoamine oxidases (MAO; MAO-A and MAO-B in mammals) are enzymes catalyzing the degradation of biogenic amines, including monoamine neurotransmitters. In humans, coding mutations in MAOs are extremely rare and deleterious. Here, we assessed the structural and biochemical consequences of a point mutation (P106L) in the single mao gene of the blind cavefish, Astyanax mexicanus. This mutation decreased mao enzymatic activity by ∼3-fold and affected the enzyme kinetics parameters, in line with potential structure-function alterations. HPLC measurements in brains of four A. mexicanus genetic lines (mutant and non-mutant cavefish, and mutant and non-mutant surface fish) showed major disturbances in serotonin, dopamine, noradrenaline and metabolite levels in mutants and demonstrated that the P106L mao mutation is responsible for monoaminergic disequilibrium in the P106L mao mutant cavefish brain. The outcomes of the mutation were different in the posterior brain (containing the raphe nucleus) and the anterior brain (containing fish-specific hypothalamic serotonergic clusters), revealing contrasting properties in neurotransmitter homeostasis in these different neuronal groups. We also discovered that the effects of the mutation were partially compensated by a decrease in activity of TPH, the serotonin biosynthesis rate-limiting enzyme. Finally, the neurochemical outcomes of the mao P106L mutation differed in many respects from a treatment with deprenyl, an irreversible MAO inhibitor, showing that genetic and pharmacological interference with MAO function are not the same. Our results shed light on our understanding of cavefish evolution, on the specificities of fish monoaminergic systems, and on MAO-dependent homeostasis of brain neurochemistry in general.

Genomic and biogenic amine-reducing characterization of Lactiplantibacillus planatraum JB1 isolated from fermented dry sausage

Biogenic amines are naturally present as hazardous, low-molecular organic basic compounds in various foods. Lactic acid bacteria show excellent potential to prevent biogenic amines accumulation. In this study, the amine-reducing mechanism of Lactiplantibacillus planatraum JB1, a strain isolated from fermented sausages, was explored according to its genome, and its ability to degrade biogenic amines was also evaluated in culture medium and dry sausage. The results showed that L. plantarum JB1 possessed a myriad of desirable properties, including tolerance to harsh environments and safety for assessment in vitro. Its genome contained genes encoding transport proteins and multicopper oxidase, which may be involved in biogenic amine degradation. In PBS and MRS medium, L. plantarum JB1 could degrade eight biogenic amines with high degradation rates for tyramine and putrescine. By inoculating sausages with L. plantarum JB1, the total content of biogenic amine was decreased by 32.84% after preparation and 32.07% after storage. Due to its good adaptability, security and amine-reducing capacity, L. plantarum JB1 could be considered a starter culture to ensure the safety of meat products.

Characteristics, Origins, and Atmospheric Processes of Amines in Fine Aerosol Particles in Winter in China

AbstractAmines affect particle formation, aerosol acidity, nitrogen cycle, and climate change. However, little is known about the temporal and spatial differences in the composition, source, and formation process of amines in fine particulate matter (PM2.5) in different regions of China. Seven amines (amine salts) were investigated in PM2.5 collected in the Yangtze River Delta (YRD, Shanghai and Nanjing), Pearl River Delta (PRD, Guangzhou), northern China (Xi'an and Haerbin), and background (Puding) areas in winter 2017–2018. Methylamine was the dominant amine species at the YRD, northern China, and background sites, while diethylamine dominated at the PRD site; moreover, the mass concentration and fraction of diethylamine were the lowest at the background site. These results could be attributed to changes in sources and atmospheric processes. Further, coal combustion and biomass burning were found to be important contributors of amines in northern cities in winter. The contribution of biomass and coal combustion to amines was weakened in other urban sites. In contrast, the amine abundance at the background site was largely controlled by biogenic sources. Acid‐base chemistry and displacement mechanism were tightly associated with the formation of amine salts at all sites. In particular, the atmospheric degradation of amines by hydroxyl radical (•OH) was significant at the Nanjing, Guangzhou, Xi'an, and Haerbin sites. The insignificant photochemical degradation of amines at the Shanghai and background sites can be explained by differentiated amine sources, meteorological conditions, and •OH levels. Overall, our findings deepen the understanding of the origins and atmospheric processes of amines.