Novel Archaeal Histamine Oxidase from Natronobeatus ordinarius: Insights into Histamine Degradation for Enhancing Food Safety.

Histamine, found abundantly in salt-fermented foods, poses a risk of food poisoning. Natronobeatus ordinarius, a halophilic archaeon isolated from a salt lake, displayed a strong histamine degradation ability. Its histamine oxidase (HOD) gene was identified (hodNbs). This is the first report of an archaeal HOD. The HODNbs protein was determined to be a tetramer with a molecular weight of 307 kDa. HODNbs displayed optimum activity at 60-65 °C, 1.5-2.0 M NaCl, and pH 6.5. Notably, within the broad NaCl range between 0.5 and 2.5 M, HODNbs retained above 50% of its maximum activity. HODNbs exhibited good thermal stability, pH stability, and salinity tolerance. HODNbs was able to degrade various biogenic amines. The Vmax of HODNbs for histamine was 0.29 µmol/min/mg, and the Km was 0.56 mM. HODNbs exhibited high efficiency in histamine removal from fish sauce, namely, 100 µg of HODNbs degraded 5.63 mg of histamine (37.9%) in 10 g of fish sauce within 24 h at 50 °C. This study showed that HODNbs with excellent enzymatic properties has promising application potentials to degrade histamine in high-salt foods.

Physiological specialization of the brain in bumble bee castes: Roles of dopamine in mating-related behaviors in female bumble bees.

We aimed to investigate the roles of dopamine in regulating caste-specific behaviors in bumble bees and mating-related behaviors in bumble bee gynes. We examined caste differences in behaviors, biogenic amine levels, and expression levels of genes encoding dopamine receptors in the brains of bumble bees, and analyzed the effects of dopamine-related drugs on bumble bee behavior. Locomotor and flight activities were significantly higher in 8-day-old gynes and light avoidance was significantly lower in 4-8-day-old gynes than in same-aged workers. Brain levels of dopamine and octopamine were significantly higher in 8-day-old gynes than in same-aged workers, but tyramine and serotonin levels did not differ between the castes. Relative expression levels of the dopamine receptor gene BigDop1 were significantly lower in 8-day-old gynes than in same-aged workers, but expression levels of other dopamine receptor genes did not differ between castes. Dopamine significantly enhanced locomotor and flight activities in 7-9-day-old workers, whereas the dopamine receptor antagonist flupentixol inhibited flight activity and mating acceptance in same-aged gynes. These results suggest that dopamine plays important roles in gyne-specific behavior in bumble bees and has a common dopaminergic function in female eusocial bees.

High-Resolution Comparative and Quantitative Proteomics of Biogenic-Amine-Producing Bacteria and Virulence Factors Present in Seafood.

The presence of biogenic amines (histamine, tyramine, putrescine, and cadaverine) in seafood is a significant concern for food safety. This review describes for the first time a shotgun quantitative proteomics strategy to evaluate and compare foodborne strains of bacteria that produce biogenic amines in seafoods. This approach recognized 35,621 peptide spectrum matches, belonging to 20,792 peptides, and 4621 proteins. It allowed the determination of functional pathways and the classification of the strains into hierarchical clusters. The study identified a protein-protein interaction network involving 1160 nodes/10,318 edges. Proteins were related to energy pathways, spermidine biosynthesis, and putrescine metabolism. Label-free quantitative proteomics allowed the identification of differentially regulated proteins in specific strains such as putrescine aminotransferase, arginine decarboxylase, and l-histidine-binding protein. Additionally, 123 peptides were characterized as virulence factors and 299 peptide biomarkers were selected to identify bacterial species in fish products. This study presents the most extensive proteomic repository and progress in the science of food biogenic bacteria and could be applied in the food industry for the detection of bacterial contamination that produces histamine and other biogenic amines during food processing/storage.

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.

Effects of the physical structure and surface charge of activated carbon on the reduction of biogenic amines in anchovy fish sauce.

This study aimed to efficiently reduce a large number of biogenic amines in salt-fermented fish sauce while minimizing sensory reduction using various activated carbons. Aromatic amines, such as tryptamine and phenethylamine, were reduced by 86.1-100 % after treating with activated carbon. Histamine with a heterocyclic structure decreased by 13-42 %. No significant effects were observed on the levels of aliphatic amines, putrescine, cadaverine, spermine, and spermidine. The major taste component, amino acid nitrogen, was reduced to within 3 %, and brown color removal was reduced depending on the type of activated carbon used. Acid-modified AC-A and AC-B had rough surfaces, high total acidity, low point of zero charge (pHpzc), and rich surface functional groups. Owing to its smooth surface, low total acidity, high pHpzc, and few surface functional groups, AC-C exhibited a higher histamine elimination and less color reduction despite its lower surface area compared to other activated carbons.

Formation of Histamine, phenylethylamine and γ-Aminobutyric acid during sprouting and fermenting of selected wholegrains.

Sprouting and fermentation are known to cause hydrolysis of proteins into amino acids in grains, which in turn can be converted into some neuroactive compounds by some specific enzymes.One of these compounds is γ-aminobutyric acid, which is directly related to stress management. This study invesitgatesthe effects of sprouting and fermentation processes performed under different conditions on the formation of γ-aminobutyric acid.. Concomitant phenylethylamine and histamine formations were also investigated from the food safety point of view. The combined application of sprouting and fermentation increased the concentrations of histamine and phenylethylamine to a maximum of 44 ± 5 ​​ and 3.9 ± 0.002 mg/kg, respectively. Nevertheless, these values ​​did not reach the level that would cause undesirable effects. γ-Aminobutyric acid concentrations were found to reach levels comparable to γ-Aminobutyric acid -rich foods (maximum 674 ± 31 mg/kg) both with separate and combined application of sprouting and fermentation.

How specific molecules can lead to overeating.

A molecular pathway involving compounds found in processed foods and biogenic amines increases food intake and aging in the roundworm C. elegans.

Amine-recognizing domain in diverse receptors from bacteria and archaea evolved from the universal amino acid sensor.

Bacteria possess various receptors that sense different signals and transmit information to enable an optimal adaptation to the environment. A major limitation in microbiology is the lack of information on the signal molecules that activate receptors. Signals recognized by sensor domains are poorly reflected in overall sequence identity, and therefore, the identification of signals from the amino acid sequence of the sensor alone presents a challenge. Biogenic amines are of great physiological importance for microorganisms and humans. They serve as substrates for aerobic and anaerobic growth and play a role of neurotransmitters and osmoprotectants. Here, we report the identification of a sequence motif that is specific for amine-sensing sensor domains that belong to the Cache superfamily of the most abundant extracellular sensors in prokaryotes. We identified approximately 13,000 sensor histidine kinases, chemoreceptors, receptors involved in second messenger homeostasis and Ser/Thr phosphatases from 8,000 bacterial and archaeal species that contain the amine-recognizing motif. The screening of compound libraries and microcalorimetric titrations of selected sensor domains confirmed their ability to specifically bind biogenic amines. Mutants in the amine-binding motif or domains that contain a single mismatch in the binding motif had either no or a largely reduced affinity for amines. We demonstrate that the amine-recognizing domain originated from the universal amino acid-sensing Cache domain, thus providing insight into receptor evolution. Our approach enables precise "wet"-lab experiments to define the function of regulatory systems and therefore holds a strong promise to enable the identification of signals stimulating numerous receptors.

Shotgun Proteomics Analysis, Functional Networks, and Peptide Biomarkers for Seafood-Originating Biogenic-Amine-Producing Bacteria.

Biogenic amine-producing bacteria are responsible for the production of basic nitrogenous compounds (histamine, cadaverine, tyramine, and putrescine) following the spoilage of food due to microorganisms. In this study, we adopted a shotgun proteomics strategy to characterize 15 foodborne strains of biogenic-amine-producing bacteria. A total of 10,673 peptide spectrum matches belonging to 4081 peptides and corresponding to 1811 proteins were identified. Relevant functional pathways were determined, and strains were differentiated into hierarchical clusters. An expected protein-protein interaction network was created (260 nodes/1973 interactions). Most of the determined proteins were associated with networks/pathways of energy, putrescine metabolism, and host-virus interaction. Additionally, 556 peptides were identified as virulence factors. Moreover, 77 species-specific peptide biomarkers corresponding to 64 different proteins were proposed to identify 10 bacterial species. This represents a major proteomic dataset of biogenic-amine-producing strains. These results may also be suitable for new treatments for food intoxication and for tracking microbial sources in foodstuffs.

Cholestasis-Associated Pulmonary Inflammation, Oxidative Stress, and Tissue Fibrosis: The Protective Role of the Biogenic Amine Agmatine.

INTRODUCTION: Cholestasis is the stoppage of bile flow, leading to the accumulation of potentially cytotoxic bile components in the liver. These cytotoxic molecules affect many organs. Cholestasis-induced lung injury is a severe complication that could lead to tissue fibrosis and respiratory distress. Substantial evidence indicates the role of oxidative stress and inflammatory response in the pathogenesis of cholestasis-associated pulmonary damage. Agmatine (AGM; 1-amino-4-guanidinobutane) is a biogenic amine endogenously synthesized in the human body. This amine provides potent anti-inflammatory and antioxidant properties. METHODS: In the current study, a series (six C57BL/6J male mice/group) of bile duct-ligated (BDL) animals were monitored at scheduled intervals (7, 14, and 28 days after the BDL operation) to ensure inflammatory response in their lung tissue (by analyzing their bronchoalveolar lavage fluid [BALF]). It was found that the level of inflammatory cells, pro-inflammatory cytokines, and IgG in the BALF reached their maximum level on day 28 after the BDL surgery. Therefore, other research groups were selected as follows: 1) Sham-operated (2.5 mL/kg normal saline, i.p., for 28 consecutive days), 2) BDL, 3) BDL + AGM (1 mg/kg/day, i.p., for 28 consecutive days), and 4) BDL + AGM (10 mg/kg/day, i.p., for 28 consecutive days). Then, the BALF was monitored at scheduled time intervals (7, 14, and 28 days post-BDL). RESULTS: It was found that pro-inflammatory cytokines (TNF-α, IL-6, and IL-1ß), bile acids, bilirubin, and inflammatory cells (monocytes, neutrophils, and lymphocytes) were significantly increased in the BALF of BDL mice. Moreover, biomarkers of oxidative stress were significantly increased in the pulmonary tissue of cholestatic animals. Lung tissue histopathological changes, tissue collagen deposition, and increased TGF-ß were also detected. It was found that AGM significantly ameliorated cholestasis-induced lung injury. CONCLUSION: The effects of AGM on inflammatory indicators, oxidative stress biomarkers, and tissue fibrosis seem to play a pivotal role in its protective properties.

Structural basis of amine odorant perception by a mammal olfactory receptor.

Odorants are detected as smell in the nasal epithelium of mammals by two G-protein-coupled receptor families, the odorant receptors and the trace amine-associated receptors1,2 (TAARs). TAARs emerged following the divergence of jawed and jawless fish, and comprise a large monophyletic family of receptors that recognize volatile amine odorants to elicit both intraspecific and interspecific innate behaviours such as attraction and aversion3-5. Here we report cryo-electron microscopy structures of mouse TAAR9 (mTAAR9) and mTAAR9-Gs or mTAAR9-Golf trimers in complex with ß-phenylethylamine, N,N-dimethylcyclohexylamine or spermidine. The mTAAR9 structures contain a deep and tight ligand-binding pocket decorated with a conserved D3.32W6.48Y7.43 motif, which is essential for amine odorant recognition. In the mTAAR9 structure, a unique disulfide bond connecting the N terminus to ECL2 is required for agonist-induced receptor activation. We identify key structural motifs of TAAR family members for detecting monoamines and polyamines and the shared sequence of different TAAR members that are responsible for recognition of the same odour chemical. We elucidate the molecular basis of mTAAR9 coupling to Gs and Golf by structural characterization and mutational analysis. Collectively, our results provide a structural basis for odorant detection, receptor activation and Golf coupling of an amine olfactory receptor.

The Small RNA NcS25 Regulates Biological Amine-Transporting Outer Membrane Porin BCAL3473 in Burkholderia cenocepacia.

Regulation of porin expression in bacteria is complex and often involves small-RNA regulators. Several small-RNA regulators have been described for Burkholderia cenocepacia, and this study aimed to characterize the biological role of the conserved small RNA NcS25 and its cognate target, outer membrane protein BCAL3473. The B. cenocepacia genome carries a large number of genes encoding porins with yet-uncharacterized functions. Expression of the porin BCAL3473 is strongly repressed by NcS25 and activated by other factors, such as a LysR-type regulator and nitrogen-depleted growth conditions. The porin is involved in transport of arginine, tyrosine, tyramine, and putrescine across the outer membrane. Porin BCAL3473, with NcS25 as a major regulator, plays an important role in the nitrogen metabolism of B. cenocepacia. IMPORTANCE Burkholderia cenocepacia is a Gram-negative bacterium which causes infections in immunocompromised individuals and in people with cystic fibrosis. A low outer membrane permeability is one of the factors giving it a high level of innate resistance to antibiotics. Porins provide selective permeability for nutrients, and antibiotics can also traverse the outer membrane by this means. Knowing the properties and specificities of porin channels is therefore important for understanding resistance mechanisms and for developing new antibiotics and could help in overcoming permeability issues in antibiotic treatment.

Caste-specific storage of dopamine-related substances in the brains of four Polistes paper wasp species.

How the role of dopamine differs according to the evolution of eusociality and how it is required in the flexible society of Polistes paper wasps need further clarification. In the present study, we compared the storage and usage of dopamine-related substances in brains between the castes of paper wasps. The head widths, lipid stores in the abdomen, and levels of biogenic amines in the brains were measured in newly emerged females before male emergence (workers) and after male emergence (gynes) in four Polistes species. The head widths and the lipid stores were significantly larger in gynes than workers in P. snelleni, P. rothneyi, and P. jokahamae, whereas they did not differ between castes in P. chinensis. The levels of dopamine precursors in the brains were significantly higher in gynes than workers in P. snelleni, P. chinensis, and P. rothneyi, whereas those of dopamine and its metabolites did not differ between castes in these species. In P. jokahamae, the levels of dopamine precursors and dopamine in the brains did not differ between castes, but those of a dopamine metabolite were significantly higher in gynes than workers. Thus, the caste differences in the levels of dopamine-related substances did not always match body sizes and nutritional reserves. Foundresses in P. rothneyi had significantly lower levels of dopamine precursors and higher levels of dopamine and its metabolite than newly emerged gynes. These results suggested that in several Polistes species, dopamine precursors were stored in the brain without dopamine biosynthesis at emergence, and then converted into dopamine in foundresses during colony founding. These neuroendocrinal states in Polistes species largely differed from those in eusocial bees.

Impact of axenic and mixed starter cultures on metabolomic and sensory profiles of ripened Italian salami.

In this work, the synergistic/antagonistic impact of glucose and mixed starter cultures, namely Latilactobacillus sakei, Pediococcus pentosaceus, and Staphylococcus xylosus, was evaluated in Italian salami in terms of metabolomics and sensory profiles. As expected, Salami manufactured with 0.5 % glucose exhibited a substantial pH drop, showing values close to 5 at 12 days of ripening. Metabolomics revealed 1841 metabolites, mainly belonging to amino acids, peptides, glycerolipids, and nucleic acids, showing a greater hierarchical role of glucose addition when compared with inoculated microbial starters. Distinct metabolomic fingerprints could be observed across treatments, mainly concerning glutamyl peptides like gamma-glutamyl-glutamate (related to the kokumi taste), biogenic amines (spermine), and lipid oxidation products (i.e., the oxylipin 13S-hydroperoxylinolenic acid). Such differences may drive the differences in sensory profiles recorded among treatments. These findings indicate the need to select ad-hoc starter cultures to improve the safety, quality, and sensory traits of salami.

Study on spoilage potential and its molecular basis of Shewanella putrefaciens in response to cold conditions by Label-free quantitative proteomic analysis.

To elucidate how Shewanella putrefaciens survives and produces spoilage products in response to cold conditions, the metabolic and protease activity of S. putrefaciens DSM6067 cultured at three different temperatures (30 °C, 10 °C, and 4 °C) was studied by determining the bacterial growth, total volatile basic nitrogen (TVB-N), biogenic amines, extracellular protease activity, as well as the differential expressed proteins via Label-free quantitative proteomics analysis. The lag phase of the strain cultured at 10 °C and 4 °C was about 20 h and 120 h longer than at 30 °C, respectively. The TVB-N increased to 89.23 mg N/100 g within 28 h at 30 °C, and it needed at least 72 h and 224 h at 10 °C and 4 °C, respectively. Cold temperatures (10 °C and 4 °C) also inhibited the yield factors and the extracellular protease activity per cell at the lag phase. However, the protease activity per cell and the yield factors of the sample cultivated at 10 °C and 4 °C well recovered, especially at the mid and latter stages of the log phase. The further quantitative proteomic analysis displayed a complex biological network to tackle cold stress: cold stress responses, nutrient uptake, and energy conservation strategy. It was observed that the protease and peptidase were upregulated, so as to the degradation pathways of serine, arginine, and aspartate, which might lead to the accumulation of spoilage products. This study highlighted the spoilage potential of S. putrefaciens still should be concerned even at low temperatures.

Starter culture-related changes in free amino acids, biogenic amines profile, and antioxidant properties of fermented red beetroot grown in Poland.

Fermentation of two red beet cultivars (Wodan and Alto) with single-strain starter cultures consisting of selected strains of lactic acid bacteria (LAB) of plant origin (Weissella cibaria KKP2058, Levilactobacillus brevis ZF165) and a multi-strain culture (containing W. cibaria KKP2058, L. brevis ZF165, Lactiplantibacillus plantarum KKP1822, Limosilactobacillus fermentum KKP1820, and Leuconostoc mesenteroides JEIIF) was performed to evaluate their impact on betalains, free amino acids, formation of biogenic amines, and antioxidative properties of the juice formed. Next-generation sequencing data analysis used to identify the microbial community revealed that the starter cultures promoted the dominance of the genus Lactobacillus, and decreased the proportion of spoilage bacteria compared to spontaneously fermented juices. Generally, the fermentation process significantly influenced the amount of the analyzed compounds, leading in most cases to their reduction. The observed changes in the studied parameters depended on the starter culture used, indicating different metabolic activities of the LAB strains towards bioactive compounds. The use of multi-strain starter cultures allowed to largely prevent the reduction of betacyanins and histamine formation.

Reduction of biogenic amines formation by foodborne pathogens using postbiotics in lysine-decarboxylase broth.

Postbiotics is a novel term proposed to describe as a set of bioactive compounds obtained from beneficial microorganisms. In this work, postbiotics from four lactic acid bacteria (LAB) including Leuconostoc mesenteroides subsp. cremoris, Pediococcus acidilactici, Lactococcus lactis subsp. lactis and Streptococcus thermophilus were prepared in MRS broth. The antimicrobial properties and organic acids content of postbiotics were also investigated. Postbiotics were used to tentatively reduce the production of biogenic amines by foodborne pathogens (i.e., Salmonella paratyphi A and Escherichia coli) on lysine decarboxylase broth (LDB). Experimental data showed that acetic, propionic, and butyric acids were in the range of 387.51-709.21 mg/L, 0.00-1.28 mg/L, and 0.00-20.98 mg/L, respectively. The inhibition zone of postbiotics on E. coli and S. paratyphi A were 11.67, and 12.33 mm, respectively. Two different levels of postbiotics (25%, and 50%) were used in LDB to measure the diamines (cadaverine and putrescine), polyamines (agmatine, spermidine, and spermine, ammonia), and other biogenic amine formation by pathogens. E. coli produced cadaverine and putrescine with concentrations of 1072.21 and 1114.18 mg/L, respectively. The postbiotics reduced cadaverine formation by 67% in E. coli, and cadaverine production was mostly suppressed by postbiotics from P. acidilactici in E. coli (97%) and L. lactis subsp. lactis in S. paratyphi A (90%). Putrescine production by E. coli was reduced by 94% with postbiotics of P. acidilactici at a concentration of 25%, whereas putrescine production by S. paratyphi A has been decreased by 61% in the presence of postbiotics from L. lactis subsp. Lactis with a 25% concentration. The results revealed that an increase in postbiotics concentration (from 25% to 50%) in LDB may lead to synergistic effects, resulting from the production of biogenic amines by microbial pathogens. It was importantly concluded that postbiotics of LAB may degrade biogenic amines or prevent their formation by foodborne pathogens.

Melatonin Regulates the Daily Levels of Plasma Amino Acids, Acylcarnitines, Biogenic Amines, Sphingomyelins, and Hexoses in a Xenograft Model of Triple Negative Breast Cancer.

Metabolic dysregulation as a reflection of specific metabolite production and its utilization is a common feature of many human neoplasms. Melatonin, an indoleamine that is highly available during darkness, has a variety of metabolic functions in solid tumors. Because plasma metabolites undergo circadian changes, we investigated the role of melatonin on the profile of amino acids (AAs), biogenic amines, carnitines, sphingolipids, and hexoses present in the plasma of mice bearing xenograft triple negative breast cancer (MDA-MB-231 cells) over 24 h. Plasma concentrations of nine AAs were reduced by melatonin, especially during the light phase, with a profile closer to that of non-breast cancer (BC) animals. With respect to acylcarnitine levels, melatonin reduced 12 out of 24 molecules in BC-bearing animals compared to their controls, especially at 06:00 h and 15:00 h. Importantly, melatonin reduced the concentrations of asymmetric dimethylarginine, carnosine, histamine, kynurenine, methionine sulfoxide, putrescine, spermidine, spermine, and symmetric dimethylarginine, which are associated with the BC metabolite sets. Melatonin also led to reduced levels of sphingomyelins and hexoses, which showed distinct daily variations over 24 h. These results highlight the role of melatonin in controlling the levels of plasma metabolites in human BC xenografts, which may impact cancer bioenergetics, in addition to emphasizing the need for a more accurate examination of its metabolomic changes at different time points.

Histamine elimination by a coupling reaction of fungal amine oxidase and bacterial aldehyde oxidase†.

Histamine (HIST) and other biogenic amines found in fish and fishery products accumulated by the action of bacterial amino acid decarboxylase cannot be decomposed and eliminated by heating or other chemical methods. A simple method for HIST elimination is proposed by a coupling reaction of the fungal amine oxidase (FAO) and bacterial aldehyde oxidase (ALOX) of acetic acid bacteria. As a model reaction, FAO oxidized benzylamine to benzaldehyde, which in turn was oxidized spontaneously to benzoic acid with ALOX. Likely, in HIST elimination, FAO coupled well with ALOX to produce imidazole 4-acetic acid from HIST with an apparent yield of 100%. Imidazole 4-acetaldehyde was not detected in the reaction mixture. In the absence of ALOX, the coupling reaction was incomplete given a number of unidentified substances in the reaction mixture. The proposed coupling enzymatic method may be highly effective to eliminate toxic amines from fish and fishery products.

Bioinformatics analysis of amino acid decarboxylases related to four major biogenic amines in pickles.

Microbial amino acid decarboxylases (AADs) produce biogenic amines (BAs) in fermented food. However, a systematic comparison of the AADs' properties from different microorganisms in pickle fermentation remains unexplored. Here, we bioinformatically analyzed the amino acid sequences of AADs corresponding to four major BAs for common microorganisms in pickle fermentation. We showed that their sequences, besides tyrosine decarboxylase, differed among microorganisms. Overall, the AAD sequences varied lesser among bacterial species than between bacteria and fungi, with those in Lactobacillus sharing occasionally high similarity with other bacteria. Most AADs were predicted as stable cytosolic endoenzymes. Molecular docking showed that most commonly used spice components in pickle production, especially pepper, chili, and ginger, strongly bind to the AAD active sites, thus may inhibit the enzymes and reduce the BA accumulation. This study provides insights for deeply understanding the different microbial AAD properties in pickle fermentation and reducing BAs by appropriately using spices.