Association of Polyamine Intake, Other Dietary Components, and Fecal Content of N-acetyl Putrescine and Cadaverine with Patients' Colorectal Lesions.

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide. Early detection and the modification of risk factors, such as diet, can reduce its incidence. Among food components, polyamines are important for maintaining gastrointestinal health and are metabolites of gut microbiota. Their disruption is linked to CRC, making polyamines a potential marker of the disease. This study analyzed the relationship between dietary components, including polyamines, and the presence of polyamines in feces to determine whether their presence could contribute to predicting the occurrence of colorectal lesions in patients. In total, 59 participants of both sexes (aged 50 to 70 years) who had undergone colonoscopy screening for CRC (18 without and 41 with colorectal lesions) participated in the study. A nutritional survey and determination of fecal polyamine content were performed. Specific dietary components and putrescine levels were higher in patients with colorectal lesions. The diet ratio of putrescine-spermidine and the fecal content of N-acetyl putrescine and cadaverine were elevated in patients with precancerous lesions and adenocarcinomas, showing a potential predictive value for the presence of colorectal lesions. These findings suggest that N-acetyl putrescine and cadaverine could be complementary markers for the diagnosis of suspected colorectal lesions.

Pillar[n]arene-Based Fluorescence Turn-On Chemosensors for the Detection of Spermine, Spermidine, and Cadaverine in Saline Media and Biofluids.

Polyamines are essential analytes due to their critical role in various biological processes and human health in general. Due to their role as regulators for cell growth and proliferation (putrescine and spermine), as neuroprotectors, gero-, and cardiovascular protectors (spermidine), and as bacterial growth indicators (cadaverine), rapid, simple, and cost-effective methods for polyamine detection in biofluids are in demand. The present study focuses on the development and investigation of self-assembled and fluorescent host⋅dye chemo-sensors based on sulfonated pillar[5]arene for the specific detection of polyamines. Binding studies, as well as stability and functionality assessments of the turn-on chemosensors for selective polyamine detection in saline and biologically relevant media, are shown. Furthermore, the practical applicability of the developed chemo-sensors is demonstrated in biofluids such as human urine and saliva.

[Metabolic engineering of Escherichia coli for the production of cadaverine].

Cadaverine is a fundamental C5 building block in the production of polyamides. Due to the limited regeneration efficiency of intracellular pyridoxal 5'-phosphate (PLP), the current fermentation-based production of cadaverine exhibits low efficiency. In this study, we developed an Escherichia coli strain L01 by introducing lysine decarboxylase (lysine decarboxylase, LDC, a key enzyme in the synthesis of cadaverine) into a lysine-producing strain E. coli LY-4, achieving a cadaverine tier of 1.07 g/L in shake flask fermentation. Subsequently, a dual metabolic pathway enhancement strategy was proposed to synergistically strengthen both endogenous and exogenous PLP synthesis modules, thereby improving intracellular PLP synthesis. The optimized strain L11 achieved a cadaverine titer of 9.23 g/L in shake flask fermentation. Finally, the fermentation process for cadaverine production by strain L11 was optimized in a 5 L fermenter. After 48 h of fed-batch fermentation, the engineered strain L11 achieved the cadaverine titer, yield, and productivity of 54.43 g/L, 0.22 g/g, and 1.13 g/(L·h), respectively. This study provides a theoretical and technical foundation for establishing microbial cell factories for bioamine production.

Histamine H4 receptor and TRPV1 mediate itch induced by cadaverine, a metabolite of the microbiome.

Cadaverine is an endogenous metabolite produced by the gut microbiome with various activity in physiological and pathological conditions. However, whether cadaverine regulates pain or itch remains unclear. In this study, we first found that cadaverine may bind to histamine 4 receptor (H4R) with higher docking energy score using molecular docking simulations, suggesting cadaverine may act as an endogenous ligand for H4R. We subsequently found intradermal injection of cadaverine into the nape or cheek of mice induces a dose-dependent scratching response in mice, which was suppressed by a selective H4R antagonist JNJ-7777120, transient receptor potential vanilloid 1 (TRPV1) antagonist capsazepine and PLC inhibitor U73122, but not H1R antagonist or TRPA1 antagonist or TRPV4 antagonist. Consistently, cadaverine-induced itch was abolished in Trpv1-/- but not Trpa1-/- mice. Pharmacological analysis indicated that mast cells and opioid receptors were also involved in cadaverine-induced itch in mice. scRNA-Seq data analysis showed that H4R and TRPV1 are mainly co-expressed on NP2, NP3 and PEP1 DRG neurons. Calcium imaging analysis showed that cadaverine perfusion enhanced calcium influx in the dissociated dorsal root ganglion (DRG) neurons, which was suppressed by JNJ-7777120 and capsazepine, as well as in the DRG neurons from Trpv1-/- mice. Patch-clamp recordings found that cadaverine perfusion significantly increased the excitability of small diameter DRG neurons, and JNJ-7777120 abolished this effect, indicating involvement of H4R. Together, these results provide evidences that cadaverine is a novel endogenous pruritogens, which activates H4R/TRPV1 signaling pathways in the primary sensory neurons.

A smartphone-adaptable fluorescent probe for visual monitoring of fish freshness and its application in fluorescent dyes.

Due to increasing food safety issues, developing intelligent, on-site, and visual methods for detecting fish freshness has attracted significant attention. Here, we have prepared a benzo[h]chromene derivative BCN that can visually detect 12 biogenic amines (BAs) with high sensitivity. The mechanism for recognizing cadaverine (Cad) is that the probe reacts with Cad to produce a Schiff base derivative, which alters the charge distribution within the molecule, resulting in significant colorimetric and fluorescence changes. The sensing label BCN/FPS was prepared by loading the probe BCN on filter paper, and a visual detection platform was constructed by combining it with a smartphone. By monitoring the correspondence between label color and TVB-N content, a working curve of (R + B)/(R + B + G) with TVB-N content was obtained, enabling visual evaluation of salmon freshness using only a mobile phone. In addition, based on the good solubility and processability of BCN, its application in fluorescent dyes including impregnating dyes, printing inks, coatings, and flexible films has been explored, which opens up new directions for the application of BCN. Therefore, BCN has the potential for real-time monitoring of meat freshness and preparation of fluorescent materials.

The effects of Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 on preventing the accumulation of biogenic amines and promoting the production of volatile organic compounds during sour meat fermentation.

Lactic acid bacteria (LAB) are frequently used in meat fermentation, and mixed stater cultures are reported to perform better than single ones. Lactiplantibacillus plantarum 3-19 and Pediococcus pentosaceus 18-1 were chosen from 28 sour-meat-origin strains to examine the effects of single and combined inoculation on sour meat quality. Natural fermentation was used as a control to investigate changes in pH, water activity (aw), amino acid nitrogen (AN), texture, microbial diversity, and volatile organic compounds (VOCs) during fermentation. The pH and aw of each inoculation group were significantly decreased, and AN content was significantly increased. The inoculation of P. pentosaceus 18-1 significantly reduced putrescine, cadaverine, and tryptamine content (p < 0.05), while the inoculation of Lpb. plantarum 3-19 significantly reduced cadaverine amounts (p < 0.05). At the fermentation endpoint, the total biogenic amines content in the C group was 992.96 ± 14.07, which was 1.65, 2.57, and 3.07 times higher than that in the Lp, Pe, and M groups, respectively. The mixed inoculation group combined the advantages of both strains and decreased total biogenic amines most significantly. At the end of fermentation, the VOCs in C, Lp, Pe, and M groups were 10.11, 11.56, 12.45, and 13.39 times higher than those at the beginning of fermentation. Inoculation promoted the production of key VOCs (OAV > 2000) such as heptanal, octanal, and (E)-2-nonanal. The mixed inoculation group had the highest variety and content of VOCs and the highest content of the above key VOCs, significantly enhancing its fruity, floral, ester, and other aromas. Sensory evaluation indicated that the M group had the best overall acceptability. Finally, it was suggested that a combination of Lpb. plantarum 3-19 and P. pentosaceus 18-1 is a novel and efficient starter culture for processing sour meat since they lower the amounts of biogenic amines in the meat and promote the production of VOCs.

Combined assessment of lysine and N-acetyl cadaverine levels assist as a potential biomarker of the smoker periodontitis.

Periodontitis is an inflammatory condition of supporting structures of teeth leading to attachment and bone loss. Cigarette smoking is the single most important and modifiable risk factor with 5 to 20-fold susceptibility for periodontal diseases. Reverse smoking is a peculiar habit of smoking where the lit end is kept inside the mouth, which is predominant in the northern coastal districts of Andhra Pradesh. Polyamines are biologically active amines involved in tissue regeneration and modulation of inflammation. The study aimed to evaluate polyamines and check their utility as a marker in detection of periodontitis among different groups. Total polyamine levels showed significant increase in reverse smokers with periodontitis when compared to the other groups. Qualitative analysis by thin layer chromatography showed three polyamine bands with varying intensity among the different groups. Mass spectrometric and NMR analyses of the three bands identified them as N1, N8-diacetyl spermidine, N-acetyl cadaverine and lysine. Most significantly elevated levels of lysine was observed in the smoker and reverse smoker periodontitis groups when compared to healthy and non-smoker periodontitis groups. The significantly elevated levels of N-acetyl cadaverine could be responsible for the more destruction of periodontium in the reverse smoker group. Antioxidant potential decreased significantly in different smoker periodontitis groups. The present study suggests that the quantitative analysis of salivary polyamines, lysine and N-acetyl cadaverine can aid as an easy noninvasive diagnostic method for assessing the periodontal status, especially in smokers.

Fine-Tuning Pyridoxal 5'-Phosphate Synthesis in Escherichia coli for Cadaverine Production in Minimal Culture Media.

Cadaverine is a critical C5 monomer for the production of polyamides. Pyridoxal 5'-phosphate (PLP), as a crucial cofactor for the key enzyme lysine decarboxylase in the cadaverine biosynthesis pathway, has seen a persistent shortage, leading to limitations in cadaverine production. To address this issue, a dual-pathway strategy was implemented, synergistically enhancing both endogenous and heterologous PLP synthesis modules and resulting in improved PLP synthesis. Subsequently, a growth-stage-dependent molecular switch was introduced to balance the precursor competition between PLP synthesis and cell growth. Additionally, a PLP sensor-based negative feedback circuit was constructed by integrating a newly identified PLP-responsive promoter PygjH and an arabinose-regulated system, dynamically regulating the expression of the PLP synthetic genes and preventing excessive intracellular PLP accumulation. The optimal strain, L18, cultivated in the minimal medium AM1, demonstrated cadaverine production with a titer, yield, and productivity of 64.03 g/L, 0.23 g/g glucose, and 1.33 g/L/h, respectively. This represents the highest titer reported to date in engineered Escherichia coli by fed-batch fermentation in a minimal medium.

A study on phytogenotoxicity induced by biogenic amines: cadaverine and putrescine.

Among the compounds present in necro-leachate, a liquid released during the process of decomposition of the human body, are the biogenic amines cadaverine and putrescine. Although some studies on necro-leachate have indicated a potential ecotoxicological and public health risk associated with it, the research on this type of contamination is still rather limited. This study presents information about the phytotoxic and cytogenotoxic potential of cadaverine and putrescine, evaluated separately and within a mixture. Phytotoxicity was evaluated through a germination test, the initial growth of seedlings with Lactuca sativa, and cytogenotoxicity through chromosomal aberration and micronucleus tests with Allium cepa. The L. sativa results showed a phytotoxic effect for the evaluated amines, by reducing root (> 90%) and hypocotyl (> 80%) elongation. The co-exposure of cadaverine and putrescine potentiated cytogenotoxic activity by aneugenic action in the meristematic cells of A. cepa. From this result, it is possible to infer the eco-toxicogenic potential of cadaverine and putrescine. This study not only highlights the importance of the phytotoxic and cytogenotoxic effects of these amines but also emphasizes the urgent need for further investigation into contamination originating from cemetery environments. By evaluating the risks associated with necro-leachate, this research is aimed at informing global efforts to protect ecological and public health.

Cadaverine and putrescine exposure influence carbon and nitrogen cycling genes in water and sediment of the Yellow River.

The response patterns of microbial functional genes involved in biogeochemical cycles to cadaver decay is a central topic of recent environmental sciences. However, the response mechanisms and pathways of the functional genes associated with the carbon (C) and nitrogen (N) cycling to cadaveric substances such as cadaverine and putrescine remain unclear. This study explored the variation of functional genes associated with C fixation, C degradation and N cycling and their influencing factors under cadaverine, putrescine and mixed treatments. Our results showed only putrescine significantly increased the alpha diversity of C fixation genes, while reducing the alpha diversity of N cycling genes in sediment. For the C cycling, the mixed treatment significantly decreased the total abundance of reductive acetyl-CoA pathway genes (i.e., acsB and acsE) and lig gene linked to lignin degradation in water, while only significantly increasing the hydroxypropionate-hydroxybutylate cycle (i.e., accA) gene abundance in sediment. For the N cycling, mixed treatment significantly decreased the abundance of the nitrification (i.e., amoB), denitrification (i.e., nirS3) genes in water and the assimilation pathway gene (i.e., gdhA) in sediment. Environmental factors (i.e., total carbon and total nitrogen) were all negatively associated with the genes of C and N cycling. Therefore, cadaverine and putrescine exposure may inhibit the pathway in C fixation and N cycling, while promoting C degradation. These findings can offer some new insight for the management of amine pollution caused by animal cadavers.

Combining directed evolution with high cell permeability for high-level cadaverine production in engineered Escherichia coli.

The biosynthesis of cadaverine from lysine is an environmentally promising technology, that could contribute to a more sustainable approach to manufacturing bio-nylon 5X. However, the titer of biosynthesized cadaverine has still not reached a sufficient level for industrial production. A powerful green cell factory was developed to enhance cadaverine production by regulating lipopolysaccharide (LPS) genes and improving membrane permeability. Firstly, 10 LPS mutant strains were constructed and the effect on the growth was investigated. Then, the lysine decarboxylase (CadA) was overexpressed in 10 LPS mutant strains of Escherichia coli MG1655 and the ability to produce cadaverine was compared. Using 20.0 g L-1 of L-lysine hydrochloride (L-lysine-HCl) as the substrate for the biotransformation reaction, Cad02 and Cad06 strains exhibited high production levels of cadaverine, with 8.95 g L-1 and 7.55 g L-1 respectively while the control strain Cad00 only 4.92 g L-1 . Directed evolution of CadA was also used to improve its stability under alkaline conditions. The cadaverine production of the Cad02-M mutant stain increased by 1.86 times at pH 8.0. Finally, the production process was scaled up using recombinant whole cells as catalysts, achieving a high titer of 211 g L-1 cadaverine (96.8%) by fed-batch bioconversion. This study demonstrates the potential role of LPS in enhancing the efficiency of mass transfer between substrate and enzymes in vivo by increasing cell permeability. The results indicate that the argumentation of cell permeability could not only significantly enhance the biotransformation efficiency of cadaverine, but also provide a universally applicable, straightforward, environment-friendly, and cost-effective method for the biosynthesis of other high-value chemicals.

Engineering RuBisCO-based shunt for improved cadaverine production in Escherichia coli.

The process of biological fermentation is often accompanied by the release of CO2, resulting in low yield and environmental pollution. Refixing CO2 to the product synthesis pathway is an attractive approach to improve the product yield. Cadaverine is an important diamine used for the synthesis of bio-based polyurethane or polyamide. Here, aiming to increase its final production, a RuBisCO-based shunt consisting of the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and phosphoribulate kinase (PRK) was expressed in cadaverine-producing E. coli. This shunt was calculated capable of increasing the maximum theoretical cadaverine yield based on flux model analysis. When a functional RuBisCO-based shunt was established and optimized in E. coli, the cadaverine production and yield of the final engineered strain reached the highest level, which were 84.1 g/L and 0.37 g/g Glucose, respectively. Thus, the design of in situ CO2 fixation provides a green and efficient industrial production process.

Electrostatic Repulsion Hydrophilic Interaction Liquid Chromatography (ERLIC) for the Quantitative Analysis of Polyamines.

Highly polar low molecular weight organic molecules are still very challenging to analyze by liquid chromatography. Yet, with the steadily increasing application of metabolomics and similar approaches in chemical analysis, separating polar compounds might be even more important. However, almost all established liquid chromatography techniques (i.e., normal and reversed phase, hydrophilic interaction liquid chromatography (HILIC), ion chromatography) struggle with either carry-over, low sensitivity, or a lack of retention. For improving these shortcomings, electrostatic repulsion hydrophilic interaction chromatography (ERLIC) might be an alternative. By combining a HILIC mobile phase, that is highly organic with a low water content, and an ion exchange column, a distinct layer system develops. When the analyte's charge is of the same direction as the stationary phase, retention and elution are determined by two antagonistic forces: electrostatic repulsion and hydrophilicity. One prominent group of challenging polar analytes are the polyamines cadaverine, putrescine, spermidine, and spermine. Carrying charges from +2 to +4 at physiological pH, these compounds are essential cell constituents and found in all living organisms. However, they are still notoriously challenging to analyze via the established liquid chromatography methods. In the present work, an ERLIC tandem mass spectrometry method has been exemplarily developed, optimized, and validated for the quantitative determination of cadaverine, putrescine, spermidine, and spermine. This method enables symmetrical peak shapes and good separation of analytes with different charges while simultaneously selectively detecting the co-eluting diamines by MS/MS. Furthermore, high linearity (R > 0.998) and sensitivity (LODs ≤ 2 ng/mL) have been proven. Thus, ERLIC may be interesting for both targeted and untargeted analysis approaches of highly charged low molecular weight organic molecules.

Implications of two-component systems EnvZ/OmpR and BaeS/BaeR in in vitro temocillin resistance in Escherichia coli.

BACKGROUND: BaeS/BaeR is a two-component system of Escherichia coli that controls the expression of porins and efflux pumps. Its role in beta-lactam resistance is limited. OBJECTIVES: To study the role of baeS/baeR two-component system in temocillin resistance in E. coli. METHODS: E. coli strain BW25113 and single-gene deletion mutants related to two-component systems were collected from the KEIO collection. Double-gen deletion mutants were generated. Temocillin-resistant mutant frequencies were determined at 32 mg/L. E. coli BW25113 mutants were selected by selective pressure from serial passages. Biological costs were analysed by growth curves. Genomes of the generated mutants were sequenced. The expression level of the mdtA, mdtB, mdtC, acrD and tolC in the ΔbaeS mutant was determined by RT-PCR (with/without temocillin exposure). RESULTS: The frequency of temocillin mutants ranged from 2.12 × 10-8 to 4.51 × 10-8 in single-porin mutants. No mutants were recovered from E. coli BW25113 (>10-9). Selection of temocillin-resistant variants by serial passage yielded mutants up to 128 mg/L. Mutations were found in the baeS gene. Temocillin MICs ranged from 4 to 32 mg/L (highest MICs for ΔbaeS and ΔompR). The efflux pumps mdtA, mdtB, mdtC and acrD pumps were overexpressed 3-10-fold in the presence of temocillin in ΔbaeS compared to control. CONCLUSIONS: Mutations in the sensor histidine kinase, baeS, may be involved in temocillin resistance through the expression of the efflux pumps mdtABC and acrD. In addition, the low mutation rate may be a good predictor of temocillin activity.

Orchestrating Precision within the Tumor Microenvironment by Biomimetic Nanoprodrugs for Effective Tumor Therapy.

Malignant tumors are still one of the most deadly diseases that threaten human life and health. However, developing new drugs is challenging due to lengthy trials, funding constraints, and regulatory approval procedures. Consequently, researchers have devoted themselves to transforming some clinically approved old drugs into antitumor drugs with certain active ingredients, which have become an attractive alternative. Disulfiram (DSF), an antialcohol medication, can rapidly metabolize in the physiological environment into diethyldithiocarbamate (DTC) which can readily react with Cu2+ ions in situ to form the highly toxic bis(N,N-diethyldithiocarbamate)-copper(II) (CuET) complex. In this study, DSF is loaded into mesoporous dopamine nanocarriers and surface-chelated with tannin and Cu2+ to construct M-MDTC nanoprodrugs under the camouflage of K7 tumor cell membranes. After intravenous injection, M-MDTC nanoprodrugs successfully reach the tumor sites with the help of mediated cell membranes. Under slightly acidic pH and photothermal stimulation conditions, DSF and Cu2+ are simultaneously released, forming a highly toxic CuET to kill tumor cells in situ. The generated CuET can also induce immunogenic cell death of tumor cells, increase the proportion of CD86+ CD80+ cells, and promote dendritic cell maturation. In vitro and in vivo studies of M-MDTC nanoprodrugs have shown excellent tumor-cell-killing ability and solid tumor suppression. This approach enables in situ amplification of chemotherapy in the tumor microenvironment, achieving an effective antitumor treatment.

Decarboxylase activity of the non-starter lactic acid bacterium Loigolactobacillus rennini gives crack defects in Gouda cheese through the production of γ-aminobutyric acid.

Ten Gouda cheese wheels with an age of 31 weeks from six different batch productions were affected by a crack defect and displayed an unpleasant off-flavor. To unravel the causes of these defects, the concentrations of free amino acids, other organic acids, volatile organic compounds, and biogenic amines were quantified in zones around the cracks and in zones without cracks, and compared with those of similar Gouda cheeses without crack defect. The Gouda cheeses with cracks had a significantly different metabolome. The production of the non-proteinogenic amino acid γ-aminobutyric acid (GABA) could be unraveled as the key mechanism leading to crack formation, although the production of the biogenic amines cadaverine and putrescine contributed as well. High-throughput amplicon sequencing of the full-length 16S rRNA gene based on whole-community DNA revealed the presence of Loigolactobacillus rennini and Tetragenococcus halophilus as most abundant non-starter lactic acid bacteria in the zones with cracks. Shotgun metagenomic sequencing allowed to obtain a metagenome-assembled genome of both Loil. rennini and T. halophilus. However, only Loil. rennini contained genes necessary for the production of GABA, cadaverine, and putrescine. Metagenetics further revealed the brine and the rennet used during cheese manufacturing as the most plausible inoculation sources of both Loil. rennini and T. halophilus.IMPORTANCECrack defects in Gouda cheeses are still poorly understood, although they can lead to major economic losses in cheese companies. In this study, the bacterial cause of a crack defect in Gouda cheeses was identified, and the pathways involved in the crack formation were unraveled. Moreover, possible contamination sources were identified. The brine bath might be a major source of bacteria with the potential to deteriorate cheese quality, which suggests that cheese producers should regularly investigate the quality and microbial composition of their brines. This study illustrated how a multiphasic approach can understand and mitigate problems in a cheese company.

Mixed-Linkage Donor-Acceptor Covalent Organic Framework as a Turn-On Fluorescent Sensor for Aliphatic Amines.

Amine determination is crucial to our daily life, including the prevention of pollution, the treatment of certain disorders, and the evaluation of food quality. Herein, a mixed-linkage donor-acceptor covalent organic framework (named DSE-COF) was first constructed by the polymerization between 2,4-dihydroxybenzene-1,3,5-tricarbaldehyde (DTA) and 4,4'-(benzo[c][1,2,5]selenadiazole-4,7-diyl)dianiline (SEZ). DSE-COF displayed superior turn-on fluorescent responses to primary, secondary, and tertiary aliphatic amines, such as cadaverine, isopropylamine, sec-butylamine, cyclohexylamine, hexamethylenediamine, di-n-butylamine, and triethylamine in absolute acetonitrile than other organic species. Further experiments and theoretical calculations demonstrated that the combination of intramolecular charge transfer (ICT) and photoinduced electron transfer (PET) effects between the DSE-COF and aliphatic amines resulted in enhanced fluorescence. Credibly, DSE-COF can quantitatively detect cadaverine content in actual pork samples with satisfactory results. In addition, DSE-COF-based test papers could rapidly monitor cadaverine from real pork samples, manifesting the potential application of COFs in food quality inspection.

A novel biochemistry approach combined with MALDI-TOF MS to discriminate Escherichia coli and Shigella species.

Escherichia coli and Shigella spp. are closely related, making it crucial to accurately identify them for disease control and prevention. In this study, we utilized MALDI-TOF MS to identify characteristic peaks of decarboxylation products of lysine and ornithine to distinguish between E. coli and Shigella spp. Our findings indicate that the peak at m/z 103.12 ± 0.1 of the product cadaverine from lysine decarboxylase is unique to E. coli, while all Shigella species lack the m/z 103.12 ± 0.1 peak. However, S. sonnei and S. boydii serotype C13 exhibit a specific peak at m/z 89.10 ± 0.1, which is the product of putrescine from ornithine decarboxylase. We were able to correctly identify 97.06% (132 of 136) of E. coli and Shigella isolates and 100% (8 of 8) of S. sonnei isolates using this biochemical-based MALDI-TOF MS detection system. This technology is advantageous for its high-throughput, high quality, and ease of operation, and is of significant value for the diagnosis of E. coli and Shigella-related diseases.

Evaluation of the ecotoxicological effects of biogenic amines derived from cadaverous putrefaction on springtails Folsomia candida.

Necro-leachate, a liquid released during cadaveric decomposition, is considered the main culprit for impacts on cemetery environments. The biogenic amines cadaverine and putrescine make up part of the composition of necro-leachate and have a certain toxicity to different organisms. Springtails are among the most used bioindicators to assess the impacts of soil contaminants. As there are no data on the acute and chronic toxicity of springtails exposed to cadaverine and putrescine, the objective of this study was to evaluate the toxic potential of both amines, under the behavioral effect of avoidance and reproduction in the species Folsomia candida. Springtails were exposed to soils contaminated with different concentrations of cadaverine and putrescine, and different mixtures of these amines. To evaluate the avoidance and reproduction test, the individuals were exposed for periods of 48 h and 28 days, respectively. The results obtained in the avoidance test showed that springtails exhibited a preference for the treated soil in both isolated and mixed treatments. The chronic evaluation assays showed that the reproduction was affected, particularly in the treatments with combined amines, resulting in a reduction in the total number of juveniles. From the results, it is possible to infer that the methods applied in this research have provided information that will contribute to a better understanding of the toxicity of putrefactive biogenic amines, since there exist few ecotoxicological studies carried out with these amines, and especially with those from cemetery environments.

Specific Gene Expression in Pseudomonas Putida U Shows New Alternatives for Cadaverine and Putrescine Catabolism.

Pseudomonas putida strain U can be grown using, as sole carbon sources, the biogenic amines putrescine or cadaverine, as well as their catabolic intermediates, ɣ-aminobutyrate or δ-aminovalerate, respectively. Several paralogs for the genes that encode some of the activities involved in the catabolism of these compounds, such as a putrescine-pyruvate aminotransferase (spuC1 and spuC2 genes) and a ɣ-aminobutyrate aminotransferase (gabT1 and gabT2 genes) have been identified in this bacterium. When the expression pattern of these genes is analyzed by qPCR, it is drastically conditioned by supplying the carbon sources. Thus, spuC1 is upregulated by putrescine, whereas spuC2 seems to be exclusively induced by cadaverine. However, gabT1 increases its expression in response to different polyamines or aminated catabolic derivatives from them (i.e., ɣ-aminobutyrate or δ-aminovalerate), although gabT2 does not change its expression level concerning no-amine unrelated carbon sources (citrate). These results reveal differences between the mechanisms proposed for polyamine catabolism in P. aeruginosa and Escherichia coli concerning P. putida strain U, as well as allow a deeper understanding of the enzymatic systems used by this last strain during polyamine metabolism.