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This study aimed to investigate the effects of tea polyphenol (TP), epigallocatechin gallate (EGCG), and their palmitic acid-modified derivatives palmitoyl-TP (pTP) and palmitoyl-EGCG (pEGCG) on the accumulation of N-nitrosamine and biogenic amines (BAs), residual nitrites, and lipid oxidation in Chinese sausages. The microorganisms, color, and texture properties of sausages were evaluated. TP, EGCG, pTP, or pEGCG significantly inhibited the accumulation of N-nitrosodimethylamine (NDMA) and BAs, residual nitrites, and lipid oxidation, but enhanced the redness, hardness, and chewiness of sausages. The concentration of NDMA in sausages was reduced by 58.11%, 63.51%, 36.49%, and 44.59%, respectively, after treatment with TP, EGCG, pTP, and pEGCG. Both EGCG and pEGCG exhibited excellent inhibitory effects on the predominant BAs, including putrescine, tyramine, cadaverine, histamine, and 2-phenylethylamine. Palmitoyl-EGCG was found to be the strongest inhibitor of lipid oxidation. Besides, the four antioxidants weakly affected the population of total aerobic bacteria and lactic acid bacteria but totally suppressed the growth of undesirable Enterobacteriaceae. The principal component and correlation analyses proved that BAs, nitrites, lipid oxidation, and microbiota were responsible for the formation of NDMA. The results indicated that palmitic acid-modified TPs and similar derivatives might serve as potential preservatives to improve the safety and quality of fermented meat products.

Biogenic amines (BAs) are organic compounds with low molecular weight and can be used as indicators of the quality and safety of canned aquatic products during processing and storage. However, excess of these amines can cause foodborne poisoning. Therefore, the determination, analysis, and prevention of BAs are of great importance. This article focuses on the sources, formation, and pretreatment methods, as well as analytical techniques, change tendency, and control techniques of BAs, with the aim of promoting more appropriate analysis of canned aquatic products to provide a reference for the food industries. [ABSTRACT FROM AUTHOR]

Essential foods as part of a daily meal may include numerous kinds of biogenic amines (BAs) at various concentrations. BAs have a variety of toxicological effects on human health and have been linked to multiple outbreaks of foodborne disease. BAs also are known to cause cancer based on their ability to react with nitrite salts, resulting in the production of carcinogenic organic compounds (nitrosamines). Ingestion of large quantities of BAs in food causes toxicological effects and health disorders, including psychoactive, vasoactive, and hypertensive effects and respiratory, gastrointestinal, cardiovascular, and neurological disorders. The toxicity of BAs is linked closely to the BAs histamine and tyramine. Other amines, such as phenylethylamine, putrescine, and cadaverine, are important because they can increase the negative effects of histamine. The key method for reducing BA concentrations and thus foodborne illness is management of the bacterial load in foods. Basic good handling and hygiene practices should be used to control the formation of histamine and other BAs and reduce the toxicity histamine and tyramine. A better understanding of BAs is essential to enhance food safety and quality. This review also includes a discussion of the public health implications of BAs in foods. [ABSTRACT FROM AUTHOR]

The effects of salt treatment (2% [w/w] low salt and 6% [w/w] high salt) and storage time (0 to 12 days) on two biogenic amines (histamine and tyramine), total volatile base nitrogen (TVB-N), pH, and volatile compounds of the North Pacific squid during storage at 4°C were evaluated. The freshness of squid muscle was evaluated by monitoring the changes in these indicators during storage. Results showed that histamine and tyramine contents increased with storage time (4.29 to 22.47 mg/kg for histamine and 28.10 to 135.78 mg/kg for tyramine) and that, in samples treated with salt, formation of these amines can be effectively inhibited (P < 0.05) compared with untreated samples. The overall pH level initially decreased and then increased during storage (ranging from 6.49 to 7.13), and the pH level of the two salt treatment groups was a little lower than that of the control group. The TVB-N value increased with time and was effectively inhibited by salt (P < 0.05). The number and content of the volatile components in squid varied during the entire storage time. The main volatile components detected in North Pacific squid were aliphatic hydrocarbons, alcohols, aldehydes, ketones, acids, esters, aromatic hydrocarbons, phenols, nitrogenous compounds, sulfo compounds, and esters. Several compounds, such as trimethylamine, butyric acid, and sulfureted hydrogen, can be used to determine the quality of aquatic products, and salt treatment can inhibit their formation. The TVB-N value was significantly correlated with pH level and with the concentrations of histamine, tyramine, and several volatile compounds in all samples (P < 0.05). In summary, salt concentration had a positive effect on extending the shelf life of North Pacific squid, and multiple indicators should be used to determine the quality of squid. Salt treatment at 2 and 6% can effectively reduce the decomposition of squid. Salt treatment decreased the total number and concentration of total volatile compounds. There are good correlations among pH, TVB-N, and biogenic amines. [ABSTRACT FROM AUTHOR]

Fermented foods can cause human illness because of the unhealthy effect of biogenic amines (BAs) that accumulate by decarboxylation of free amino acids. Salami-type fermented sausages can contain BAs, but which bacteria and environmental factors contribute to BA production is not clear. Sixty-two sausages purchased from Swiss markets were evaluated for decarboxylating bacterial strains and concentrations of the BAs cadaverine, histamine, putrescine, and tyramine. Based on the size and number of employees of the meat processing plants, sausages were separated into two groups: artisanal and industrial. Concentrations of all four BAs were higher in industrial sausages than in artisanal sausages. Tyramine was the major BA detected in 46 of 62 sausages, at a maximum concentration of 785.22 mg/kg. Enterococci and coagulase-negative staphylococci (mainly the meat starter culture Staphylococcus xylosus) were the main tyramine producers. Putrescine was found in 20 of 62 samples, at a maximum concentration of 707.77 mg/kg. Concentrations of these two BAs were significantly correlated (P = 0.0407). Cadaverine and histamine were detected in nine and eight samples, respectively, and both were found in significantly higher concentrations (P = 0.019 and 0.036, respectively) in industrial sausages. Based on the tyramine concentration, five groups of fermented sausages were identified: group 1, very high concentrations (>700 mg/kg); group 2, high concentrations (400 to 700 mg/kg); group 3, moderate concentrations (200 to 400 mg/kg); group 4, low concentrations (< 200 mg/kg); group 5, concentrations below the detection limit (0.05 mg/kg). Product samples with tyramine concentrations >200 mg/kg were considered of lower quality because consumption of such samples could be unhealthy for sensitive consumers. BAs concentrations were higher in industrial than in artisanal salami-type sausages. Putrescine was always detected when high concentrations of tyramine were present. The meat starter culture S. xylosus may contain the tyramine decarboxylase gene. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the effects of long-term storage at various temperatures (4, 25, and 358C) on flavor and microbiological and physicochemical qualities of traditional Chinese low-salt fermented fish (Suanyu). Food spoilage and pathogenic bacteria (coliforms, Pseudomonas, and Salmonella) were inhibited during the 90 days of storage at all temperatures. Lactic acid bacteria, yeast, and total viable bacteria counts of samples stored at 358C were reduced sharply, whereas other parameters were stable. Compared with refrigerated storage (48C), higher storage temperatures (25 and 358C) accelerated moisture migration, lipid oxidation, and proteolytic degradation. Storage time had a greater effect than storage temperature on the increase of volatile compounds in Suanyu. Refrigerated storage was better than higher storage temperatures (25 and 358C) for maintaining the odor quality of Suanyu during the storage period. Total biogenic amine concentrations in all samples were -200 mg/kg. Suanyu can be consumed safely during 90 days of storage based on the levels of spoilage and pathogenic bacteria and concentrations of biogenic amines, but refrigerated storage effectively slows down the microbial and physicochemical changes, resulting in better organoleptic quality. The results of this study will be useful for processors controlling the safety and quality of fermented fish during transport and storage. [ABSTRACT FROM AUTHOR]

Food supplements are a category of products perceived safe and therefore commonly used by different categories of consumers without any particular attention or precaution. However, health risks associated with the consumption of supplements containing undeclared substances cannot be excluded. A variety of analytical methods are used to control supplement quality composition, but usually, these procedures are complex and time-consuming. Here, we report the results of a simple and fast liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, to detect and quantify simultaneously different categories of active molecules, such as biogenic ammines and natural alkaloids that at high doses can produce negative health effect in consumers. Three categories of products intended for body weight loss, energy boosting, and erectile dysfunction treatment, purchased through e-commerce sites and from local supermarkets, were analyzed (n = 91). The caffeine, synephrine, agmatine sulfate, yohimbine, phenethylamine, and icariin were correctly separated and identified with good precision (RSD < 20%) and recovery (89-109%). The identification and quantification of the analytes in real samples highlighted that the 26% of the samples were not compliant with labeling, confirming that frauds are very common also in the natural supplements market. This LC-MS/MS method could be easily used to test natural supplements in order to check the correct labeling and to protect consumers from potential health risks and food frauds., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

A high concentration of biogenic amines have been reported to be hazardous for human health. This article is an analytical report on one lot to identify the changes of biogenic amines in each period of soy sauce brewing and clarify the key control point for biogenic amine production. The content of putrescine, cadaverine, spermidine, spermine, tryptamine, phenylethylamine, histamine, serotonin, tyramine, and agmatine was detected in the koji-making and fermenting process. The content of putrescine increased from 27.11 ± 1.05 to 185.86 ± 1.18 mg/kg in the koji-making process, indicating that putrescine is the main biogenic amine produced by microbes in this period. The content of tryptamine increased to the highest value of 581.77 ± 36.38 mg/L on day 24 of the fermenting process and then decreased rapidly to 81.98 ± 0.20 mg/L at the end (day 122). In addition, histamine and tyramine reached the highest values (486.91 ± 24.67 and 180.84 ± 2.32 mg/L, respectively) after 52 days of fermentation, followed by a decrease to 287.24 ± 15.00 and 144.67 ± 3.61 mg/L, respectively, at the end of the fermenting process. The samples were further characterized by the analysis of other indices, including the content of water, salt, soluble saltless solids, crude fat, total acid, amino acid nitrogen, total nitrogen, and ammonium salt. The content of soluble saltless solids decreased from 9.28 ± 0.16 to 5.30 ± 1.40 g/100 g during the first 38 days of fermentation, followed by an increase to 14.68 ± 1.12 g/100 g during the last 84 days. The content of total acid, crude fat, amino acid nitrogen, total nitrogen, and ammonium salt all increased rapidly in the early stage of the fermenting process and then slowed down. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the microbiological safety and quality and biogenic amine concentrations of ready-to-eat meat products at retail in and around the capital of the Republic of Kosovo. A total of 128 ready-to-eat meat products from 49 retail shops were sampled in November 2017 and March 2018. Pathogenic Escherichia coli and Salmonella were not detected in enrichment cultures from 25-g samples. Levels of lecithinase-positive Staphylococcus aureus were consistently <2 log CFU/g. Listeria monocytogenes was detected in 4 of 88 cooked-cured products (25-g samples). Cooked-cured meats had significantly higher water activity (aw) and pH (P < 0.001) than did dried or fermented meats. All samples of dried or fermented meats had either low pH and aw or had a shelf life <5 days. Thus, by definition these products would be classified as not able to support growth of L. monocytogenes according to European Union food safety microbiological criteria. Among the cooked-cured products, total bacteria counts and lactic acid bacteria counts were >2-log higher in sliced than in nonsliced items. In the dried or fermented samples, E. coli and Enterobacteriaceae (at ≥1 and ≥2 log CFU/g, respectively) and L. monocytogenes (25 g) were detected in the 11 samples that had been wrapped in cling plastic when handed over to the consumer but not in the 29 vacuum-packed samples. The maximum histamine concentration was 263.9 mg/kg. Putrescine concentrations of health concern (based on 100-g portions and 60 kg of body weight) were found in 1 of 88 cooked-cured and 8 of 40 dried or fermented samples. Median concentrations of cadaverine, histamine, putrescine, and tyramine were higher in dried or fermented than in cooked-cured samples. Results suggest that in the Republic of Kosovo non–vacuum-packed dried or fermented meats are more prone to contamination under retail conditions and these meats become contaminated during transport, handling, and retail sale. [ABSTRACT FROM AUTHOR]

We analyzed the volatile basic nitrogen content, pH, total viable cell count, and biogenic amine contents in chub mackerel (Scomber japonicus) stored at 5 and 25°C to examine changes in freshness. Among the various parameters, we found the volatile basic nitrogen content had the highest correlation with cadaverine content (r2 = 0.72 to 0.88). We also tried to measure cadaverine contents at different times during storage by using near-infrared (NIR) spectroscopy. However, because of the high water content in the fish, we could not obtain meaningful results. Next, we prepared samples for NIR spectroscopy by dilution with 0.1 N HCl, ultrafiltration (3 or 10 kDa) with a glass filter, and dehydration. The samples prepared with the 3-kDa filter had peaks in the NIR spectra between 1,379.3 and 1,388.9 nm, and those prepared with the 10-kDa filter had peaks in the spectra between 1,897.3 and 1,898.6 nm. The correlation coefficient (r2) between the NIR spectroscopy and high-performance liquid chromatography with cadaverine results was 0.98 to 0.99. We concluded that the biogenic amine content could be used to evaluate freshness in fish products, and that NIR measurements could be used to rapidly and accurately determine freshness. Correlation between the VBN content and other various parameters was studied to determine freshness. The VBN content had the highest correlation with cadaverine content (r2 = 0.72 to 0.88). Cadaverine in biogenic amine content and NIR measurements were used to test freshness in fish. [ABSTRACT FROM AUTHOR]

Quorum sensing (QS) is a cell density-dependent signaling system responsible for various physiological activities in bacteria. We initially investigated the relation between a QS system and biogenic amine (BA) production in Shewanella baltica, the specific spoilage organism of refrigerated large yellow croaker (Pseudosciaene crocea). In addition, the inhibition effects of anthocyanins from blueberry and purple sweet potato against QS signals and putrescine production were explored. Two kinds of diketopiperazines, cyclo-(L-Pro-L-Leu) and cyclo-(L-Pro-L-Pro), and two kinds of BAs, putrescine and cadaverine, were detected in the culture extract of S. baltica cultivated in sterile large yellow croaker juice, wherein putrescine presented significantly positive correlations with cyclo-(L-Pro-L-Leu) and cyclo-(L-Pro-L-Pro). In addition, anthocyanins at subminimum inhibitory concentration inhibited the production of diketopiperazines and putrescine in S. baltica 23, a strain with strong putrescine production. Furthermore, a transcriptional analysis showed that anthocyanins suppressed the expression of the odc gene in S. baltica, the gene responsible for the production of putrescine from decarboxylation of ornithine. These results established a correlation of the main BA putrescine with the QS system in S. baltica and revealed that anthocyanins could be developed as new QS inhibitors and seafood preservative candidates. [ABSTRACT FROM AUTHOR]

Because of the increased awareness of the health benefits of fish, fish consumption has increased each year in several countries, including Korea. However, fish consumption is associated with acute toxicity owing to the presence of biogenic amines in rapidly spoiling fish. Several food safety agencies have established standards for acceptable histamine concentrations in some restrictive fish and fishery products; however, such standards are not available for other species. We aimed to generate data from biogenic amine monitoring to evaluate the safety of fish commonly consumed in Korea. We monitored the biogenic amine concentrations in 609 fish samples from 19 commonly consumed species. Of these 609 samples, several had amine concentrations higher than the maximums allowed. An age-specific exposure assessment based on human biogenic amine exposure per serving revealed that persons 1 to 3 years of age had the highest exposure to total biogenic amines, although no significant differences were found between the age groups analyzed. The analysis also revealed that the exposure in some fish species, such as Japanese jack mackerel, Konoshiro gizzard shad, and brown sole, exceeded the standard limits established in some countries. These results suggest that more fish species should be included to establish standards for exposure to various biogenic amines. Parameters such as age-specific consumption and data for populations with maximum consumption should be considered because the current standards are limited to histamine and do not account for the differences in histamine sensitivity associated with these variables. Our results provide important data on limits for biogenic amines in various fish species that could be used to minimize potential health risks. [ABSTRACT FROM AUTHOR]

Photobacterium species are members of the bacterial communities typically associated with scombrotoxin-forming fish. Reclassification and discovery of new Photobacterium species has caused confusion as to which species are capable of biogenic amine production. We analyzed histamine, cadaverine, and putrescine production by 104 Photobacterium strains representing 23 species. The presence of the genes for histidine decarboxylase (hdc), lysine decarboxylase (ldc), and ornithine decarboxylase (odc) was determined by real-time or conventional PCR and whole genome sequencing. Significant histamine production (.> 200 ppm) was detected in five Photobacterium species: P. angustum, P. aquimaris, P. kishitanii, P. damselae, and P. phosphoreum. The hdc gene was detected in all of these histamine-producing species except P. phosphoreum. Cadaverine was produced by eight Photobacterium species: P. angustum, P. aquimaris, P. damselae, P. iliopiscarium, P. kishitanii, P. leiognathi, P. mandapamensis, and P. phosphoreum. Putrescine was produced by six Photobacterium species: P. angustum, P. aquimaris, P. kishitanii, P. leiognathi, P. mandapamensis, and Photobacterium sp. Cadaverine production correlated closely with the presence of the ldc gene, but putrescine production did not correlate closely with the presence of the odc gene. Characterization of the biogenic amine production by Photobacterium species will allow identification of these marine bacteria and help ensure that current guidelines account for mitigation of these bacteria. [ABSTRACT FROM AUTHOR]

Biogenic amines have been widely studied because of their potential toxicity in fermented foods. Several lactic acid bacteria have the potential to decarboxylate the amino acid tyrosine to tyramine. In this work, we identified two strains of Lactobacillus curvatus, Lbc1 and Lbc2, endowed with the ability to produce tyramine, a metabolic feature that limits their application in starter cultures for fermented meat. To overcome this limitation, we set out to eliminate tyramine production from L. curvatus strains by using classical strain improvement. About 4,000 mutant isolates of both strains were screened using a colorimetric method, and then potential tyrosine decarboxylase-negative mutants were selected. Firm identification of loss-of-function mutants was performed by analytical determination of tyrosine and tyramine in cultivation medium. Of the 8,000 mutants screened, only one mutant of Lbc1 and two mutants of Lbc2 had completely lost the potential to produce tyramine. Subsequently, one tyrosine decarboxylase-negative mutant of both Lbc1 and Lbc2 was characterized in more detail. DNA sequencing of the Lbc1 mutant tdcA gene disclosed two missense mutations in the promoter distal part of the coding sequence. These two mutations result in two amino acid changes in the encoded tyrosine decarboxylase, Pro87Thr and Ser130Leu, presumably inactivating the enzyme activity. The DNA sequence of the other characterized mutant, derived from strain Lbc2, showed that insertion of a 6-bp fragment at nucleotide position 1348 in the tdc gene is presumably the factor leading to loss of activity. With the successful elimination of the undesirable tyramine-producing phenotype without the use of recombinant DNA technology, these developed L. curvatus mutant strains can be safely used in the dairy industry or in the manufacture of various food products. [ABSTRACT FROM AUTHOR]

Biogenic amines are formed in various fermented foods by microbial amino acid decarboxylation activities, and ingestion of these amines may cause human illness. However, the effect of digestion on the biogenic amines in fermented sausages has not been studied. This study was conducted to determine the effect of in vitro human digestion with the enterobacteria Escherichia coli and Lactobacillus casei on concentrations of the biogenic amine tyramine in six types of fermented sausages. Tyramine concentration was not significantly changed until simulated digestion in the small intestine. However, tyramine concentration for all sausage samples was increased after simulated digestion in the large intestine. Addition of E. coli and L. casei dramatically increased the tyramine concentrations (P< 0.05). This result indicates that enterobacteria increase biogenic amine concentrations during human digestion. [ABSTRACT FROM AUTHOR]

The microbiological and chemical changes in Taihu white prawn (Exopalaemon modestus) during ice storage were evaluated. For the microbiological changes, total viable counts were obtained. PCR coupled with denatured gradient gel electrophoresis was then performed to investigate the changes in microflora. For the chemical changes, total volatile basic nitrogen was determined and biogenic amines were detected. The initial total viable count was 6.2 log CFU/g, which increased to 7.1 log CFU/g after storage at 0°C for 10 days. Pseudomonas sp., Shewanella, Flavobacterium, and Staphylococcus were the dominant bacteria in fresh white prawn, whereas lactic acid bacteria, Pseudomonas sp., Shewanella, and Flavobacterium were dominant in the spoiled products. The initial total volatile basic nitrogen was 7.2 mg/100 g, a value that significantly increased to 30.5 mg/100 g at the end of storage. Putrescine was the dominant biogenic amine, and its content reached 95.5 mg/kg at the end of storage. PCR coupled with denatured gradient gel electrophoresis showed that Chryseobacterium sp., Acidovorax sp., Pelomonas sp., Kinneretia asaccharophila, and uncultured Curvibacter sp. were the dominant strains during storage, whereas Lactococcus garvieae became dominant at the end of storage. This study facilitated the development of preservation techniques that target these predominant spoilage bacteria. [ABSTRACT FROM AUTHOR]

Precooking of tuna is a potential critical control point (CCP) in the commercial manufacturing of canned tuna. To assess the efficacy of precooking as a CCP, an understanding of the thermal properties of histamine-producing bacteria (HPB) and their histidine decarboxylase (HDC) enzymes is required. The thermal properties of many HPB have been determined, but the thermal resistances of the HDC enzymes are unknown. The purpose of this study was to determine the D- and z-values of selected HDC enzymes to evaluate the CCP of precooking during the canning process and provide scientific data to support U.S. Food and Drug Administration guidelines. HDC (hdc) genes from three strains each of Morganella morganii,Enterobacter aerogenes,Raoultella planticola, and Photobacterium damselae were cloned, expressed, and purified using the Champion pET Directional TOPO Expression System, pET100 cloning vector, and HisPur Cobalt resin. The heat resistances of all enzymes were compared at 50°C, and the D- and z-values from one strain of each HPB were determined at 50 to 60°C. To evaluate the heat inactivation of HDC enzymes during canned tuna processing, tuna tissue was inoculated with HDCs and heated to 60°C in a water bath set at 65 and 100°C. The D-values for the HDC enzymes from M. morganii,E. aerogenes,R. planticola, and P. damselae ranged from 1.6 to 4.1, 1.6 to 6.3, 1.9 to 4.3, and 1.6 to 2.9 min, respectively, at 50 to 60°C. The z-values for M. morganii,E. aerogenes,R. planticola, and P. damselae were 19.2, 18.0, 22.0, and 13.3°C, respectively. The HDCs from all HPB except E. aerogenes showed no significant activity after being heated to 60°C. The data generated in this study will help refine current guidelines for the thermal destruction of the HDC enzymes. [ABSTRACT FROM AUTHOR]

To estimate biogenic amines and changes in quality of rainbow trout (Oncorhynchus mykiss) fillets at different temperatures, we determined the sensory attributes, total volatile basic nitrogen (TVB-N), total viable counts (TVC), and biogenic amines (BAs) of samples that were untreated (CK) or dry cured with 1.8% salt (T). There was no significant difference between CK and T samples in terms of TVB-N, TVC, and BAs. TVB-N and TVC increased significantly (P < 0.05) with storage time at 3, 9, and 15°C. Putrescine (PUT) and cadaverine (CAD) increased significantly (P < 0.05) at −3, 3, 9, and 15°C during storage. Histamine formed more easily when storage temperatures were higher. The kinetic models of sensory scores for TVB-N, TVC, PUT, CAD, and the sum of PUT and CAD (PUT+CAD) in T samples versus storage time and temperature were developed based on the Arrhenius equation. High regression coefficients (R2 > 0.9) indicated the acceptability of the kinetic model for predicting changes in the quality of the rainbow trout fillets. Relative errors between predicted and experimental values of TVB-N, TVC, and PUT+CAD were all within 10% except for TVB-N on day 6. The prediction model based on TVB-N, TVC, and PUT+CAD can be applied to evaluate changes in quality of rainbow trout fillets from −3 to 15°C (270 to 288 K). [ABSTRACT FROM AUTHOR]

Technological properties and biogenic amine production were analyzed in 56 bacteriocinogenic lactococci and enterococci strains isolated from raw goat's milk. Fifteen lactococci strains were able to reduce milk pH to 5.3 or lower after 6 h, while enterococci strains were initially slow in producing acids. Lactococcus lactis subsp. lactis GLc06 and three strains of Enterococcus faecalis (GEn20, GEn22, and GEn23) presented high proteolytic activity. L. lactis subsp. lactis GLc06 and E. faecalis GEn22 also showed a high percentage of autolysis after only 4 h, reaching 71.11 and 97.67%, respectively, after 24 h. No strain was able to secrete exopolysaccharides, and L. lactis subsp. lactis GLc22 and 25 of the Enterococcus strains were able to produce diacetyl. L. lactis subsp. lactis GLc05 and 23 of the Enterococcus strains presented a high tolerance to NaCl at 10% (wt/vol). Regarding biogenic amine production, 12 strains (5 lactococci and 7 enterococci) were capable of forming tyramine and 4 strains (1 lactococcus and 3 enterococci) were capable of forming 2-phenylethylamine, but in very low amounts. GLc06 presented great acidifying, proteolytic, and autolytic activities, and GLc05 was capable of growing at high NaCl concentrations (10%, wt/vol), possessing medium autolytic and proteolytic activities. Some enterococci strains produced diacetyl and high autolytic and extracellular proteolytic activities and also presented resistance to high NaCl concentrations. The interesting technological properties presented by some bacteriocinogenic strains can justify their use by the dairy industry, with the aim of ensuring both safety due to bacteriocin production and technological transformations in fermented products. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of tea polyphenol (TP), epigallocatechin gallate (EGCG), and their palmitic acid-modified derivatives palmitoyl-TP (pTP) and palmitoyl-EGCG (pEGCG) on the accumulation of N-nitrosamine and biogenic amines (BAs), residual nitrites, and lipid oxidation in Chinese sausages. The microorganisms, color, and texture properties of sausages were evaluated. TP, EGCG, pTP, or pEGCG significantly inhibited the accumulation of N-nitrosodimethylamine (NDMA) and BAs, residual nitrites, and lipid oxidation, but enhanced the redness, hardness, and chewiness of sausages. The concentration of NDMA in sausages was reduced by 58.11%, 63.51%, 36.49%, and 44.59%, respectively, after treatment with TP, EGCG, pTP, and pEGCG. Both EGCG and pEGCG exhibited excellent inhibitory effects on the predominant BAs, including putrescine, tyramine, cadaverine, histamine, and 2-phenylethylamine. Palmitoyl-EGCG was found to be the strongest inhibitor of lipid oxidation. Besides, the four antioxidants weakly affected the population of total aerobic bacteria and lactic acid bacteria but totally suppressed the growth of undesirable Enterobacteriaceae. The principal component and correlation analyses proved that BAs, nitrites, lipid oxidation, and microbiota were responsible for the formation of NDMA. The results indicated that palmitic acid-modified TPs and similar derivatives might serve as potential preservatives to improve the safety and quality of fermented meat products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Limited knowledge is currently available on the influence of fish thawing and subsequent storage conditions on bacterial growth kinetics, succession, and diversity alongside the production of biogenic amines. This study aimed to address these factors during the thawing and subsequent storage of mackerel. Thawing was either done fast in 18°C water for 2 h or slowly at 30°C overnight. Subsequent storage was at 30°C (ambient) for 36 h and 2 to 5°C (refrigerated) for 12 days. The cultivation methods used were total viable counts, hydrogen sulfide-producing bacteria, and Pseudomonas. Maximum growth rate, population density, and lag time were fitted on the counts using the Baranyi model. The bacterial diversity and succession were based on sequencing of 16S rRNA amplicons, and biogenic amines were quantified on high-pressure liquid chromatography-UV. The results show that lag time of hydrogen sulfide-producing bacteria was significantly affected by both thawing methods, and further, the interaction between thawing and storage significantly affected the maximum growth rate of these bacteria. However, the maximum growth rate of Pseudomonas was higher during refrigerated storage compared with storage at ambient temperature. Total viable counts showed longer lag time and reduced growth rate under refrigerated storage. Higher bacterial diversity was correlated to slow thawing and storage at ambient temperature compared with slow thawing and refrigerated storage. Overall, Acinetobacter and Psychrobacter genera were the dominant bacterial populations. The amine levels were low and could not be differentiated along the thawing and storage approaches, despite a clear increase in bacterial load, succession, and diversity. This corresponded well with the low abundance of biogenic amine-producing bacteria, with the exception of the genus Proteus, which was 8.6% in fast-thawed mackerel during storage at ambient temperature. This suggests that the decarboxylation potential is dependent on both microbial load and microbial community structure. [ABSTRACT FROM AUTHOR]

Lactobacillus plantarum D-103 isolated from a miso product that possesses amine-degrading activity was used as a starter culture in miso fermentation (25°C for 120 days) in this study. The salt content in control samples (without starter culture) and inoculated samples (inoculated with L. plantarum D-103) remained constant at 10.4% of the original salt concentration throughout fermentation, whereas the pH value decreased from 6.2 to 4.6 during fermentation. The inoculated samples had significantly lower (P < 0.05) levels of total volatile basic nitrogen than control samples after 40 days of fermentation. After 120 days of fermentation, the histamine and overall biogenic amine contents in inoculated samples were reduced by 58 and 27%, respectively, compared with control samples. To our knowledge, this is the first report to demonstrate that application of a starter culture with amine-degrading activity in miso products was effective in reducing the accumulation of biogenic amines. [ABSTRACT FROM AUTHOR]

To estimate the effect of a low concentration of sugar on the changes in quality of lightly salted grass carp (Ctenopharyngodon idellus) during storage under vacuum packaging at 4°C, we determined the sensory score, total viable counts, biochemical quality, and physical quality of fish fillets. Fish samples were left untreated, dry cured with 1.3% salt, or dry cured with 1.3% salt plus 1.0% sugar. Compared with untreated samples, curing treatments reduced chemical changes reflected in pH, inosine monophosphate, hypoxanthine riboside, hypoxanthine, and total volatile base nitrogen; decreased the formation of phenylethylamine, putrescine, cadaverine, and histamine; and increased the overall sensory quality of fillets (P < 0.05). Compared to dry cured with 1.3% salt samples, sugar treatment significantly inhibited (P < 0.05) the increase in pH and total volatile base nitrogen value, but it promoted microbial growth and the formation of phenylethylamine and tyramine at later stages of storage. By considering each indicator, the addition of sugar, which can improve the taste of fillets, has no significant effect on the shelf life of vacuum-packaged grass carp fillets. [ABSTRACT FROM AUTHOR]

Biogenic amines, ATP-related compounds, sensory attributes, total volatile basic nitrogen, microbial flora (total viable bacteria, Pseudomonas, Aeromonas, and H2S-producing bacteria), and free amino acids were determined in common carp (Cyprinus carpio var. Jian) stored at 20 and 0°C. Pseudomonas and H2S-producing bacteria became the dominant bacteria in carp stored at 20 and 0°C, whereas Aeromonas rapidly increased only in carp stored at 0°C. Inosine monophosphate, which is responsible for flavor and freshness, increased to a maximum of 2.37 μmol/g after 12 h at 20°C and to 4.72 μmol/g after 3 days at 0°C. Putrescine and cadaverine were the dominant amines in carp and their concentrations were significantly correlated (P < 0.05) with total volatile basic nitrogen and sensory scores in all samples during the storage. Significant correlations also were observed between histamine and total volatile basic nitrogen and sensory scores only in samples stored at 20°C. Arginine decreased while putrescine increased in all samples. A significant decrease (P < 0.05) in histidine was observed after 24 h of storage, which coincided with an increase in histamine after 36 h in samples stored at 20°C. Hypoxanthine concentrations were significantly correlated with the microbial species (P < 0.01) and sensory scores (P < 0.05) and seems to be a reliable marker for quality of carp fillets stored at 20 and 0°C. [ABSTRACT FROM AUTHOR]

Biogenic amine and fatty acid contents were determined in vacuum-packed fillets of common carp (Cyprinus carpio). Samples were pressure treated at 300 and 500 MPa and were stored at 3.5 and 12°C for up to 28 days (control, 0 MPa) and 70 days (pressure-treated). The content of eight biogenic amines (putrescine, cadaverine, spermidine, spermine, histamine, tyramine, tryptamine, and phenylethylamine) were determined. Putrescine and cadaverine were influenced by all factors (temperature, pressurization level, and time of storage). Tyramine content was the most sensitive indicator of the improper status of sample; levels exceeding 10 mg/kg indicated both the loss of meat freshness and temperature abuse, in spite of persisting good sensory indices. Neither storage temperature nor pressurization level had a statistically important effect on the contents of fatty acids. Only polyunsaturated fatty acids decreased slightly if the storage time exceeded 42 days. [ABSTRACT FROM AUTHOR]

The effects of different salt concentrations on the quality changes of grass carp (Ctenopharyngodon idella) fillets were evaluated in terms of biogenic amines, adenosine triphosphate and its related compounds, sensory attributes, total volatile basic nitrogen (TVB-N), and total viable counts during 4 and 20°C storage. Grass carp fillets were brined in solutions of 2% NaCl (Tl) and 10% NaCl (T2), and unsalted carp fillets were used as controls (CK). Tl and T2 showed higher sensory scores than CK. According to the TVB-N values, CK, Tl, and T2 could maintain the freshness of carp for approximately 9, 12, and 27 days, respectively, when stored at 4°C. The higher salt concentration had better inhibitory effect on the accumulation of some biogenic amines, such as tryptamine (TRM), 2-phenylethylamine (PHE), putrescine (PUT), and cadaverine (CAD). TVB-N of untreated grass carp fillets showed a significant (P < 0.05) correlation with TRM, PHE, PUT, and CAD during storage. PUT and CAD showed a significant (/> < 0.05) correlation with TVB-N for T2 at 20°C and Tl at 4°C. [ABSTRACT FROM AUTHOR]

The formation of eight biogenic amines (BAs), total volatile base nitrogen (TVB-N), aerobic plate counts (APC), and sensory evaluation in crucian carp (Carassius auratus) during storage in ice and at 4°C were investigated. The sum of contents of all eight biogenic amines (SBA) in crucian carp increased from 49.82 to 197.09 mg/kg on day 36 when stored in ice and from 49.82 to 219.35 mg/kg on day 24 when stored at 4°C. TVB-N content increased with storage time; good relationships between TVB-N content and SBA were observed during storage in ice and at 4°C (R² = 0.95 and 0.93, respectively). APC of all samples significantly (P < 0.05) increased with storage time in the first 12 days and toward the end of the storage period, there were only minor changes; good relationships between APC and SBA were observed during storage in ice and at 4°C (R² = 0.96 and 0.58, respectively). According to sensory evaluation results, the crucian carp became unacceptable on days 24 and 16 during storage in ice and at 4°C, respectively. Putrescine and tyramine contents could be good quality evaluation indices for crucian carp during storage. [ABSTRACT FROM AUTHOR]

Twenty-five tuna sausage products were purchased from retail markets in Taiwan. The rates of occurrence of biogenic amines, histamine-forming bacteria, and adulteration by pork and poultry were determined. The average content of various biogenic amines in all tested samples was less than 2.0 mg/100 g (<0.05 to 1.85 mg/100 g). Thirteen histamine-producing bacterial strains isolated from tested samples produced 12.1 to 1,261 ppm of histamine in Trypticase soy broth supplemented with 1.0% L-histidine. Among them, Raoultella ornithinolytica (one strain), Enterobacter aerogenes (one strain), and Staphylococcus pasteuri (two strains) were identified as prolific histamine formers. PCR assay revealed that the adulteration rates were 80% (20 of 25) and 4% (1 of 25) for pork and poultry, respectively, in tuna sausage. The fish species in the tuna sausage samples were identified as Thunnus albacares for 22 samples (88%), Thunnus alalunga for 1 sample (4%), and Thunnus thynnus for 1 sample (4%), whereas the remaining sample was identified as Makaira nigricans (blue marlin). [ABSTRACT FROM AUTHOR]

This research was conducted to determine the biogenic amine (BA) and ethyl carbamate (EC) concentrations in commercial Primitivo wine samples and the influence of the use of malolactic starter culture on concentrations of these potentially hazardous compounds in this wine. One hundred sixty bottles of wine from eight producers in the Apulia region of southern Italy were purchased at retail and analyzed. The most common BAs were histamine, 2-phenylethylamine, tyramine, cadaverine, putrescine, spermine, and spermidine. Putrescine (derived from ornithine) was the most abundant BA in all commercial Primitivo wines (5.41 to 9.51 mg/liter), 2-phenylethylamine was detected in only two commercial wines (at less than 2.12 mg/liter), and histamine was found at concentrations of 1.49 to 16.34 mg/liter. The concentration of EC in commercial Primitivo wine was 6.81 to 15.62 ppb, which is not considered dangerous for human health. Malolactic fermentation (MLF) affected the concentrations of BAs and EC differently. For EC, no significant differences were detected between samples of wine produced by spontaneous fermentation and wine that was inoculated malolactic starter. Mean EC concentrations were 12 and 14 ppb in two batches tested (always 18 ppb or less), regardless of whether the malolactic starter was added. Although present at trace levels in wine before the MLF, histamine accumulated during the MLF process, regardless of whether the malolactic starter was added. However, the increase in histamine was higher in wines without the malolactic starter. The concentrations of putrescine and cadaverine increased after MLF, especially in the wine that spontaneously fermented. The use of a selected malolactic starter resulted in reductions in BA concentrations in wine produced by this guided MLF compared with wine produced by spontaneous MLF. [ABSTRACT FROM AUTHOR]

Biogenic amines in foods may pose a public health problem. Therefore, histamine, tyramine, putrescinc, cadaverine, spermine, and spermidine concentrations were measured in selected food items commonly consumed in Egypt. Foods examined were dairy products (blue cheese and Mesh cheese), meats (fermented and smoked cooked sausage), and fish (smoked and salted fermented fish [Feseekh], salted sardines, and anchovies). Egyptian fermented sausage had the highest concentration of total biogenic amines (2,482 mg/kg), followed by Mesh cheese (2,118 mg/kg) and blue cheese (2.084 mg/kg). The lowest concentration was found in smoked cooked sausage (111 mg/kg). Histamine was found at a high level (521 mg/kg) in Feseekh, and tyramine was highest (2,010 mg/kg) in blue cheese. These results indicate that some traditional Egyptian foods may pose a health risk due to the concentration of biogenic amines, especially histamine. [ABSTRACT FROM AUTHOR]

The incidence and concentrations associated with four important biogenic amines in leading commercial fermented beverages consumed in Botswana were determined using high-performance liquid chromatography. In 87 sorghum brew and 84 sour milk (madila, amasi) samples tested, putrescine was the most prevalent biogenic amine (63 and 61%, respectively), while histamine was the least prevalent (24 and 8%, respectively). Cadaverine was the most frequently detected biogenic amine in 79 of the commercial sour maize beverage (mageu/mahewu) samples tested (found in 70% of the samples), while tyramine was the least detected (occurring in 3% of the samples). In sorghum brew and sour milk, tyramine was found to be the most concentrated (mean concentration of 2.08 mg/100 ml and 3.2 mg/100 ml, respectively), and histamine was found to be the least concentrated (mean concentration of 0.94 mg/100 ml and 0.31 mg/100 ml, respectively). Overall, the biogenic amine concentrations of all three fermented products were within acceptable limits. However, one sorghum brew sample had a histamine content of 5.8 mg/ 100 ml, which was above the 5.0 mg/100 g allowable limit suggested by the U.S. Food and Drug Administration. [ABSTRACT FROM AUTHOR]

The effect of modification of different chemical and microbiological parameters and the production of biogenic amines (histamine, cadaverine, putrescine, and tyramine) was examined during ripening of various types of typical Italian dry sausages (salami). Water activity decreased from 0.97 to 0.87, and pH reached the lowest value between the 13th and the 20th day of the ripening period, and then increased. Putrescine (up to 122.7 mg/kg) and tyramine (up to 105.9 mg/kg) mean levels showed dominance in comparison with cadaverine (up to 26.1 mg/kg) and histamine (up to 6.2 mg/kg) mean values in all sausage types. The highest putrescine and tyramine concentrations were observed in salami with the largest diameters. This comparative study suggests a good correlation between microbial behavior and amine evolution, particularly tyramine and putrescine, in dry sausage production. [ABSTRACT FROM AUTHOR]

Poisoning due to ingestion of foods with elevated levels of biogenic amines (histamine, putrescine, cadaverine, and tyramine) is well documented. Histamine fish poisoning largely is due to growth of naturally occurring bacteria associated with scombroid fish species. A rapid and reliable method is needed to screen for the presence of histamine-forming bacteria in fish. This study included a comparison of three methods for the detection of histamine-producing bacteria. A total of 152 histamine-producing and non-histamine-producing bacteria from multiple sources were screened using a modified Niven's agar method, a potentiometric method, and a PCR-based assay targeting a 709-bp fragment of the histidine decarboxylase gene. Histamine production by bacterial isolates was confirmed by high-performance liquid chromatography (HPLC). Bacterial strains were categorized as producing high amounts of histamine, low amounts of histamine, or no histamine. Of the 152 strains tested, 128 (84%) were positive with the Niven's agar method, 73 (48%) were positive with the potentiometric technique, and 74 (49%) were positive with the PCR assay. Overall, a 38% false-positive rate was observed with the modified Niven's agar method, although this method detected both low-histamine and high-histamine strains. There was a high degree of concordance (>99%) between results of the potentiometric and PCR methods, but neither of these methods detected low-histamine bacteria. These observations support the need for a simple and straightforward yet sensitive method for detecting histamine-producing bacteria in seafood and environmental samples. [ABSTRACT FROM AUTHOR]

The effect of gutting on sensory, microbiological, and chemical properties of European hake (Merluccius merluccius var. mediterraneus) stored in ice was studied. Gutting of hake noticeably affected the development of gram-negative bacteria: counts of Enterobacteriaceae, Shewanella putrefaciens, and Pseudomonas throughout ice storage were higher in gutted than in ungutted samples. These differences in microbial loads were also reflected in the lower sensory scores of both raw and cooked hake, in the quicker trimethylamine accumulation, and in the higher contents of putrescine, cadaverine, tyramine, and histamine found in gutted hake. All of the fish quality indicators studied showed that gutting made hake more susceptible to spoilage during ice storage and decreased its shelf life by 4 days. [ABSTRACT FROM AUTHOR]

In this article, we examine the production of biogenic amines, histamine, putrescine, tyramine, and cadaverine by 90 strains of Oenococcus oeni isolated from different cellars of Castilla-La Mancha (Spain) during wine malolactic fermentation. Amino biogenic capacity of strains was qualitatively analyzed on agar. After that, production of amines on a synthetic medium and on wine, and presence in strains of histidine, ornithine, and tyrosine decarboxylase genes were determined. Only two strains were able to produce histamine or putrescine, both on synthetic medium and wine. The presence of the corresponding genes in these strains was also confirmed. These results suggest that O. oeni does not significantly contribute to the overall biogenic amine content of wines. The main contribution of this work is the isolation of a putrescine-producing O. oeni strain that harbors the ornithine gene, since this gene appears to be rarely present in the genome of O. oeni. [ABSTRACT FROM AUTHOR]

The aim of this study was to research decarboxylating bacterial strains and biogenic amine content in a typical Italian goat cheese (Robiola di Roccaverano). The study was performed on fresh and ripened samples of goat cheese manufactured from industrial and artisanal producers. Sixty-seven bacterial strains isolated showed decarboxylating activity, and Enterococcus faecalis was the most widespread decarboxylating species in all artisanal and industrial products. Pediococcus acidilactici and Enterococcus malodoratus were also identified as biogenic amine producers in Robiola di Roccaverano cheese. All the E. faecalis strains isolated in this study were able to decarboxylate tyrosine. Tyramine was the most abundant biogenic amine in cheese samples, while histamine was the most widespread. High amounts of these two biogenic amines were found in ripened samples (up to 2,067 mg/kg for tyramine and 1,786 mg/kg for histamine), whereas 2-phenylethylamine and tryptamine were present in almost all ripened cheeses at low concentrations. The detection of strains producing biogenic amines and the high concentrations of tyramine and histamine found in ripened Robiola di Roccaverano could represent a potential risk to the consumer. [ABSTRACT FROM AUTHOR]

In this study, the previously established PCR-single-strand conformation polymorphism (SSCP) system for detecting and identifying gram-negative histamine-producing bacteria was evaluated. This system can detect and identify histamine-producing bacteria directly from seafood by the use of sequence polymorphisms of the histidine decarboxylase gene (hdc). First, we isolated 81 histamine-producing strains of bacteria from fish samples and analyzed the hdc gene by the PCR-SSCP system. The 22 newly obtained SSCP banding patterns were added to our database, and the utility of our modified database was tested in a second experiment consisting of 18 strains of histamine-producing bacteria isolated from 25 fish samples. Approximately 80% of the histamine-producing strains corresponded to those in the new database. Use of the database for PCR-SSCP analysis, including the band patterns newly added in this study, for the hdc gene makes it possible to more accurately identify histamine producers. [ABSTRACT FROM AUTHOR]

Biogenic amines play an important physiological role in mammals, and high amounts of some exogenous amines in human diet may contribute to a wide variety of toxic effects. These amines are commonly found in many foodstuffs, particularly in fermented products such as cheese, meat products, beer, wine, and ciders. Here, the level of biogenic amines in some natural ciders was examined. Twenty-four samples of cider purchased from commercial sources were analyzed by reverse-phase high-performance liquid chromatography and fluorescence detection after precolumn derivatization with o-phthaldialdehyde. Amine levels were variable, ranging from not detected to 23 mg/liter. The average level of total biogenic amines in ciders was 5.94 ± 8.42 mg/liter. Putrescine, histamine, and tyramine were the prevailing amines being present in 50.0, 37.5, and 33.3% of the ciders studied; very small amounts of ethylamine and phenylethylarnine were observed in only one sample. Other cider parameters were analyzed to determine whether they affect the biogenic amine content in ciders, and the results were evaluated by applying cluster analysis and principal component analysis. Ciders that showed lower glycerol contents and higher amounts of 1,3-propanediol had much higher levels of histamine, tyramine, and putrescine, suggesting a high activity of lactic acid bacteria during cider making and thus the need for effective control of lactic acid bacteria. [ABSTRACT FROM AUTHOR]

This study describes an easy PCR method for the detection of foodborne bacteria that potentially produce histamine, tyramine, putrescine, and cadaverine. Synthetic oligonucleotide pairs for the specific detection of the gene coding for each group of bacterial histidine, tyrosine, ornithine, or lysine decarboxylases were designed. Under the conditions used in this study, the assay yielded fragments of 372 and 531 bp from histidine decarboxylase-encoding genes, a 825-bp fragment from tyrosine decarboxylases, fragments of 624 and 1,440 bp from ornithine decarboxylases, and 1,098- and 1,1 85-bp fragments from lysine decarboxylases. This is the first PCR method for detection of cadaverine-producing bacteria. The method was successfully applied to several biogenic amine-producing bacterial strains. [ABSTRACT FROM AUTHOR]

To protect public health from bovine spongiform encephalopathy, European Commission Regulation EC 1139/2003 on monitoring programs and specified risk material requires that as of 1 October 2003, each member state has in place a sampling plan with an appropriate laboratory test to detect central nervous system (CNS) tissue in bovine head meat harvested at slaughterhouses or cutting plants. With this study, we wanted to evaluate the accuracy and reliability of an enzyme immunoassay, the RIDASCREEN Risk Material 10/5, in targeting a CNS-specific marker, the glial fibrillary acidic protein. A receiver operating characteristics curve was plotted to identify the best cutoff of CNS concentration. Reliability was calculated by Cohen's kappa on data from two diagnostic sessions. Test performance showed high sensitivity and specificity (97.9 and 97.4%, respectively) for a cutoff value between positive and negative at a CNS concentration of 0.049%; reliability of test precision was also very good. When these criteria are applied, the RIDASCREEN Risk Material 10/5 test appears to be a reliable tool for monitoring CNS tissue contamination in meat. This diagnostic procedure should therefore be recommended for national application in monitoring programs. [ABSTRACT FROM AUTHOR]

The major causative agent of scombroid poisoning is histamine formed by bacterial decarboxylation of histidine. We reported previously that histamine was exclusively formed by the psychrotrophic halophdic bacteria Photobacterium phosphoreum in scombroid fish during storage at or below 10°C. Moreover, histamine-forming ability was affected by two histidine decarboxylases (HDCs): constitutive and inducible enzymes. In this study, the gene encoding P. phosphoreum HDC was cloned into Escherichia colt and sequenced. A sequence analysis of the DNA corresponding to the hdc gene revealed an open reading frame of 1,140 bp coding for a pyridoxal-5′-phosphate-dependent HI)(7 of 380 amino acid residues with a predicted molecular mass of 42.6 kDa. The HDC amino acid sequences formed a phylogenetic clade with strong bootstrap support and revealed high sequence similarities among the P. phosphoreum isolate and species of the family Enterobacteriaceae and a separate phylogenetic branch with the lowest sequence similarity between the isolate and the taxonomically closer Listonella anguillarum. The T7 promoter was used m overexpress the hdc gene in E. colt cells. The recombinant clone, E. coli BL21(DE3), displayed significant levels of HDC activity. The recombinant hdc gene was suggested to code the inducible HDC; therefore, the optimum reaction conditions of the recombinant HDC were similar to those of the inducible HDC in the P. phosphoreum isolate. In addition, a putative catabolite-repressor protein binding site. amino acid permease gene, and histidine-tRNA synthetase gene were found in flanking regions of the hdc gene. [ABSTRACT FROM AUTHOR]

Biogenic amines are frequently found in wine and other fermented food. We investigated the ability of 133 strains of lactic acid bacteria isolated from musts and wines of different origins to produce histamine, tyramine, and putrescine. We detected the genes responsible for encoding the corresponding amino acid decarboxylases through PCR assays using two primer sets for every gene: histidine decarboxylase (hdc), tyrosine decarboxylase (tdc), and ornithine decarboxylase (odc); these primers were taken from the literature or designed by us. Only one strain of Lactobacillus hilgardii was shown to possess the hdc gene, whereas four strains of Lactobacillus brevis had the tdc gene. None of the Oenococcus oeni strains, the main agents of malolactic fermentation, was a biogenic amine producer. All PCR amplicon band-positive results were confirmed by thin-layer chromatography and high-performance liquid chromatography analyses. [ABSTRACT FROM AUTHOR]