产生物胺乳酸菌的筛查与检测

目的对上海市场上食品和药品中分离出的20株乳杆菌,13株链球菌,3株乳球菌和3株肠球菌的产生物胺能力进行检测,以揭示其潜在的安全性问题。方法检测的生物胺共包括6种：分别为酪胺、精胺、尸胺、组胺、腐胺和色胺。利用添加了前体氨基酸的氨基酸脱羧酶筛选培养基对各菌株的产胺能力进行初筛,通过培养基中指示剂的颜色变化判定产胺能力。结果在检测的39株菌中,8株菌具有产酪胺的能力,7株菌具有产精胺的能力,1株菌具有产组胺的能力,1株菌具有产腐胺的能力。尤其是精胺和酪胺的产量较为引人关注。结论生物胺的危害水平取决于个体解毒的能力,但在筛选食品药品用菌株时应运用规范的方法来检测其产生物胺的能力,以保障相应食品药品的安全问题。     

长江口棘头梅童鱼幼鱼栖息地的初步评估

为了评估鱼类对长江口栖息地的选择偏好,选取长江口春季的优势种棘头梅童鱼幼鱼为模式物种,从19个水文、水质因子及生物因素指标中,筛选出狭额绒螯蟹丰度、盐度、底质类型和水深4个因子作为棘头梅童鱼栖息地指示因子,建立栖息地适合曲线,并计算了栖息地适宜度指数(HSI).结果表明:长江口北支水域棘头梅童鱼幼鱼HSI普遍较高,基本在0.5以上,而南支水域普遍较低,基本上在0.2以下,表明长江口北支为棘头梅童鱼幼鱼的主要索饵场,同时发现,其幼鱼的最适生长水域为盐度大于14、底质平均粒径在29μm以下、水深2~5 m的水域,与HSI的空间分布一致.生物因子可较好地表征棘头梅童鱼幼鱼对水文、水质等因素的响应;化学需氧量、铵氮、总磷和挥发性酚与棘头梅童鱼幼鱼丰度不具有显著相关性,亚硝酸盐氮、硝酸盐氮和总氮与其丰度具有显著正相关性,说明调查水域内水质的富营养化尚未对棘头梅童鱼栖息地造成破坏;而铜离子和镉离子浓度与其丰度具有极显著的负相关性,表明重金属污染已经对棘头梅童鱼幼鱼的生长和分布造成了一定的危害,推测重金属污染对长江口水域的鱼类栖息地分布具有限制性影响.     

长江口近岸水域棘头梅童鱼资源现状的评估

为了评估长江口近岸水域棘头梅童鱼的资源状况,利用2012—2013年底拖网调查数据,基于体长频率分布的方法研究了长江口近岸棘头梅童鱼的生长和种群参数.采用FiSATⅡ软件中的ELEFAN模块计算了长江口棘头梅童鱼的Von Bertalanffy生长参数,结合Pauly经验公式估算其自然死亡系数,并建立Beverton-Holt动态综合模型预测其资源变化趋势.结果表明: 2012—2013年共采集到棘头梅童鱼样本4201尾,体长范围18~155 mm,其生长系数(K)和极限体长(L_∞)分别为1.1和162.75 mm,种群总死亡系数(Z)、自然死亡系数(M)和捕捞死亡系数(F)分别为4.040、1.683和2.357.当前长江口近岸水域棘头梅童鱼的资源开发率(E)为0.583,大于F_opt (0.5),年平均资源数量为1.33亿尾,对应的资源量为576.02 t.目前长江口水域棘头梅童鱼资源已处于过度捕捞状态.
     

长江口棘头梅童鱼食物组成和摄食习性的季节变

棘头梅童鱼是长江口水域的常见小型经济鱼类,具有一定的捕捞价值.为了解长江口棘头梅童鱼食物组成和摄食习性的季节变化,本研究利用胃含物分析法对2013年11月—2014年8月在长江口水域捕获的棘头梅童鱼样本进行了分析.结果表明：长江口棘头梅童鱼全年摄食的饵料生物有8目30种,其中虾类(游泳亚目)是主要饵料生物,相对重要性指数百分比(IRI%)为38.5,优势指数(Ip)为79.1;其次为糠虾目和磷虾目.全年饵料生物中的主要优势种类为葛氏长臂虾、安氏白虾、脊尾白虾、长额刺糠虾、短额刺糠虾、光背节鞭水虱和中华哲水蚤等.饵料生物优势种存在季节差异,春季和夏季的主要优势种均为葛氏长臂虾、安氏白虾和短额刺糠虾,秋季主要优势种为长额刺糠虾、短额刺糠虾和脊尾白虾,冬季主要优势种为葛氏长臂虾、中华哲水蚤和中华假磷虾.长江口棘头梅童鱼全年空胃率为10.4%,冬季最高,秋季最低;全年平均胃饱满系数为0.6%,冬季最低,春季最高,摄食习性存在季节变化.     

发酵乳杆菌多铜氧化酶的异源表达及酶学性质

生物胺是一种存在于发酵食品中的含氮小分子有机化合物,过量摄入可能引起过敏或其他不良反应。利用酶法降解是减少发酵食品中生物胺含量从而保障食品安全的有效方法之一。文中成功克隆了来源于发酵乳杆菌的多铜氧化酶基因,在大肠杆菌中表达的酶活水平为484 U/L。通过镍柱亲和层析方法获得了此多铜氧化酶的纯酶。该多铜氧化酶的最适反应温度为50℃,最适反应pH为3.5,其K_m为1.3 mmol/L,V_(max)为7.67×10~(-2) mmol/(L·min)。对酶的应用特性研究表明,来源于发酵乳杆菌的多铜氧化酶对18%(W/F)NaCl有一定的耐受性,并可降解包括色胺、苯乙胺、腐胺、尸胺、组胺、酪胺和亚精胺在内的7种生物胺。其中它对组胺和酪胺的降解能力最高,分别为51.6%和40.9%。此外,该酶对酱油中的生物胺也有普遍降解作用,使用较低酶量(500 U/L)时,对酱油中总胺的降解率达到10.6%。多铜氧化酶具备降解发酵食品中生物胺的潜力,为进一步实现这类食品酶的实际应用奠定基础。     

2017—2020年珠江口棘头梅童鱼的种群特征

为了掌握珠江口重要经济鱼类棘头梅童鱼的种群特征,根据2017—2020年春(3—4月)、秋(9—10月)两季在珠江口海域开展的底拖网调查及采集到的棘头梅童鱼样本,对其生物学特征和资源密度分布特征进行了初步分析。结果表明: 珠江口棘头梅童鱼体长、体重变化范围分别为22～168 mm、0.23～103.11 g,其中雌性个体的体长、体重均大于雄性个体,未见明显的小型化现象;性成熟体长集中在90～140 mm,未见性成熟提早现象。总体长体重关系式中的异速生长因子b值为2.9057,且年际变化小,而条件因子a值(3.029×10^-5)小于1988年该海域的调查结果,说明珠江口棘头梅童鱼整体生长发育良好,但栖息地环境质量(饵料供应、生长环境)下降。研究海域梅童鱼的开发率E为0.67,处于过度捕捞状态;梅童鱼资源密度平均值为77.73 kg·km^-2, 中西侧资源密度大于东侧,在纬度方向上总体分布均匀;根据4个资源密度高值区初步推测其产卵场在南沙港附近。2017—2020年的年平均资源密度比1980—1982年下降了93.5%,为持续利用该资源,建议条件成熟时可于春季在产卵场设立保护区,以保护补充群体与产卵群体。     

一串红胚胎发育过程中多胺含量的变化

选取发育正常和败育一串红(Saliva splendens)5个不同时期的胚胎,分别提取、测定多胺(精胺、亚精胺、腐胺与尸胺)的含量变化.通过比较一串红胚胎发育不同阶段多胺物质的变化规律,探讨多胺在一串红胚胎发育中的生理作用.结果表明,一串红的胚胎败育和胚珠中较低的多胺含量及其在发育进程中较大的降幅有关;在盛花期,胚胎发育的关键时期,正常胚珠中哑精胺的含量有一个明显的峰值,而败育的胚珠中则无,这表明亚精胺含量变化在胚胎发育中起关键调节作用.     

罗伊氏乳杆菌对组胺引起黄颡鱼肝肠损伤修复效果评价

以黄颡鱼(Pelteobagrus fulvidraco)(14.23±0.65) g为实验对象, 分别饲喂3组等氮饲料(C组: 组胺含量147 mg/kg; H组: 479 mg/kg和H+B组: 496 mg/kg+1×105 CFU/g罗伊氏乳杆菌Lactobacillus reuteri), 进行56d的养殖实验, 研究组胺及罗伊氏乳杆菌对黄颡鱼的影响。结果显示, H+B组血清谷丙转氨酶(ALT)及谷草转氨酶(AST)活力显著低于H组(P<0.05), 而与C组无差异(P>0.05); H+B组肝脏谷胱甘肽S转移酶(GSH-ST)活力及丙二醛(MDA)含量显著低于H组(P<0.05), 与C组无差异(P>0.05); 肝脏HE染色显示, H组肝脏中有较多炎症细胞浸润, 而H+B组肝脏细胞结构完整, 无明显损伤; 肠道HE染色显示, H组肠道皱襞数量明显减少、长度显著变短, 有水肿发生, 而H+B组肠道皱襞数量、长度与对照组无差异, 水肿程度不明显。结果表明: 组胺会引起黄颡鱼肝脏、肠道损伤, 而罗伊氏乳杆菌对组胺引发的肝肠损伤有保护功效。     

中药渣发酵物对围产期母猪粪便菌群和代谢产物的影响

为了探讨中药渣发酵物作为母猪饲料原料的可行性,试验选取2~6胎次妊娠90 d母猪32头,随机分成两组,每组16头,限位栏饲养。对照组饲喂基础饲粮,试验组在基础饲粮中添加0.5%的中药渣发酵物。分别于产后第1、14和21 d采集母猪新鲜粪便样品,采用荧光定量PCR方法测定粪便中菌群数量,同时采用气相色谱和高效液相色谱方法测定粪便中代谢产物含量。结果表明:与对照组相比,试验组母猪产后第1 d粪便中双歧杆菌数量以及丁酸、异丁酸、酪胺和亚精胺含量显著升高(P0.05);产后第14 d粪便中精胺含量显著降低,乙酸、丙酸、异丁酸、异戊酸、总短链脂肪酸、酪胺和亚精胺含量显著升高(P0.05);产后第21 d各测定指标均无显著变化。上述结果表明,围产期饲粮添加中药渣发酵物可增加母猪后肠有益菌数量、功能性短链脂肪酸和生物胺含量,这有利于改善围产期母猪肠道健康。     

饲料中添加谷胱甘肽对黄颡鱼幼鱼组织谷胱甘肽含量、免疫及抗氧化性能的影响

研究旨在探讨饲料中添加还原型谷胱甘肽(Glutathione, GSH)对黄颡鱼幼鱼(Pelteobagrus fulvidraco)组织谷胱甘肽含量、免疫及抗氧化性能的影响。选用初始体重为(1.32±0.01) g的黄颡鱼800尾, 随机分为5组, 每组4个重复, 每个重复40 尾鱼, 分别投喂基础饲料和添加100、300、500和700 mg/kg GSH的试验饲料, 饲养56d后采样分析, 并采用氯化铵进行96h氨氮应激试验。结果表明: 除100 mg/kg组外, 饲料中添加GSH显著提高黄颡鱼肝脏、血清GSH含量(P<0.05), 当GSH添加量≥300 mg/kg时, 肝脏和血清GSH含量均呈现稳定状态。随着饲料中谷胱甘肽水平的增加, 血清免疫和肝脏抗氧化指标均呈现先升高后降低的趋势, 其中300和500 mg/kg组溶菌酶与碱性磷酸酶活性、300 mg/kg组免疫球蛋白M与补体4含量、500 mg/kg组酸性磷酸酶活性与对照组相比显著升高(P<0.05)。与对照组和700 mg/kg组相比, 300 mg/kg组肝脏超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化酶活性和总抗氧化能力与血清超氧化物歧化酶、谷胱甘肽过氧化酶活性均显著高升高(P<0.05); 且300 mg/kg组血清丙二醛含量显著降低(P<0.05)。氨氮应激96h时, 与对照组相比, 300 mg/kg组肝脏和血清超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化酶活性力均显著升高(P<0.05), 且300 mg/kg组血清丙二醛含量显著降低(P<0.05)。由此可见, 饲料中添加谷胱甘肽能提高黄颡鱼幼鱼组织谷胱甘肽含量、免疫及抗氧化性能, 其中以300—500 mg/kg为宜。     

Comparison of a capillary electrophoresis method with high-performance liquid chromatography for the determination of biogenic amines in various food samples

A capillary electrophoresis (CE) and a high-performance liquid chromatography (HPLC) method to analyze biogenic amines in food were compared. An automated precolumn derivatization with o-phthaldialdehyde (OPA) allows for the determination of aliphatic amines and amino acids by HPLC. In contrast, for the measurement of histamine and tyramine by CE, no laborious sample pretreatment was necessary. The biogenic amines were separated by CE or HPLC in less than 9 or 20 min, respectively. The calibration curves were linear to at least 100 mg/kg (r=0.999) and 1,000 mg/kg for HPLC and CE, respectively, with detection limits for histamine of 0.5 mg/kg (fluorescence detector) or 1 mg/kg (diode array detector) with HPLC and 2 mg/kg with CE. The detection limits for tyramine were 1.5 mg/kg with HPLC and 6 mg/kg with CE and for further amines (e.g., putrescine, spermidine, cadaverine, agmatine) ranging from 1.0 to 8.5 mg/kg with HPLC. There was a good correlation between CE and HPLC (correlation coefficient for histamine: 0.994).     

Correlation between microbial flora, sensory changes and biogenic amines formation in fresh chicken meat stored aerobically or under modified atmosphere packaging at 4 °C: possible role of biogenic amines as spoilage indicators

This study evaluated the formation of biogenic amines (BAs) in breast chicken meat during storage under aerobic and modified atmospheric packaging (MAP) conditions at 4 °C, the correlation of microbial and sensory changes in chicken meat with formation of BAs and the possible role of BAs as indicators of poultry meat spoilage. Poultry breast fillets were stored aerobically or under MAP (30%, CO₂, 70% N₂) at 4 °C for up to 17 days. Quality evaluation was carried out using microbiological, chemical and sensory analyses. Total viable counts, Pseudomonads and Enterobacteriaceae, were in general higher for chicken samples packaged in air whereas lactic acid bacteria (LAB) and Enterobacteriaceae were among the dominant species for samples under MAP. Levels of putrescine and cadaverine increased linearly with storage time and were higher in aerobically stored chicken samples. Spermine and spermidine levels were also detected in both aerobically and MAP stored chicken meat. Levels of tyramine in both chicken samples stored aerobically and or under MAP were low (< 10 mg kg⁻¹) whereas the formation of histamine was only observed after day 11 of storage when Enterobacteriaceae had reached a population of ca. 10⁷ CFU g⁻¹. Based on sensory and microbiological analyses and also taking into account a biogenic amines index (BAI, sum of putrescine, cadaverine and tyramine), BAI values between 96 and 101 mg kg⁻¹ may be proposed as a quality index of MAP and aerobically-packaged fresh chicken meat. Spermine and spermidine decreased steadily throughout the entire storage period of chicken meat under aerobic and MAP packaging, and thus these two amines cannot be used as indicators of fresh chicken meat quality.     

Amines in fresh beef of normal pH and the role of bacteria in changes in concentration observed during storage in vacuum packs at chill temperatures

E dwards , R.A., D ainty , R.H., H ibbard , C.M. & R amantanis , S.V. 1987. Amines in fresh beef of normal pH and the role of bacteria in changes in concentration observed during storage in vacuum packs at chill temperatures.
The amine content of fresh and vacuum-packaged beef of normal pH stored at 1°C was evaluated by high performance liquid chromatography of dansyl derivatives. Fresh samples contained five amines, viz. putrescine, cadaverine, histamine, sperm-ine and spermidine. Development of a natural spoilage flora during storage led to increases in concentration of putrescine and cadaverine and the production of a sixth amine, tyramine. Pure culture meat inoculation experiments showed tyramine formation to be restricted to lactobacilli and to strains of Lactobacillus divergens and Lact. carnis in particular; strains of leuconostocs, Enterobacteriaceae, Pseudomonas spp. and Brochothrix thermosphacta were negative. Production of tyramine at cell densities >log₁₀ 6/cm² indicated its potential as an objective measure of acceptability/spoilage.     

Amines in fresh beef of normal pH and the role of bacteria in changes in concentration observed during storage in vacuum packs at chill temperatures

The amine content of fresh and vacuum-packaged beef of normal pH stored at 1 degree C was evaluated by high performance liquid chromatography of dansyl derivatives. Fresh samples contained five amines, viz. putrescine, cadaverine, histamine, spermine and spermidine. Development of a natural spoilage flora during storage led to increases in concentration of putrescine and cadaverine and the production of a sixth amine, tyramine. Pure culture meat inoculation experiments showed tyramine formation to be restricted to lactobacilli and to strains of Lactobacillus divergens and Lact. carnis in particular; strains of leuconostocs, Enterobacteriaceae, Pseudomonas spp. and Brochothrix thermosphacta were negative. Production of tyramine at cell densities less than log10 6/cm2 indicated its potential as an objective measure of acceptability/spoilage.     

Biogenic amine production by lactic acid bacteria isolated from cider

AIMS: To study the occurrence of histidine, tyrosine and ornithine decarboxylase activity in lactic acid bacteria (LAB) isolated from natural ciders and to examine their potential to produce detrimental levels of biogenic amines. METHODS AND RESULTS: The presence of biogenic amines in a decarboxylase synthetic broth and in cider was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). Among the 54 LAB strains tested, six (five lactobacilli and one oenococci) were biogenic amine producers in both media. Histamine and tyramine were the amines formed by the LAB strains investigated. Lactobacillus diolivorans were the most intensive histamine producers. This species together with Lactobacillus collinoides and Oenococcus oeni also seemed to produce tyramine. No ability to form histamine, tyramine or putrescine by Pediococus parvulus was observed, although it is a known biogenic amine producer in wines and beers. CONCLUSIONS: This study demonstrated that LAB microbiota growing in ciders had the ability to produce biogenic amines, particularly histamine and tyramine, and suggests that this capability might be strain-dependent rather than being related to a particular bacterial species. SIGNIFICANCE AND IMPACT OF THE STUDY: Production of biogenic amines by food micro-organisms has continued to be the focus of intensive study because of their potential toxicity. The main goal was to identify the microbial species capable of producing these compounds in order to control their presence and metabolic activity in foods.     

The effect of treating method of game on the content of biogenic amines in wild duck (Anas platyrhynchos) meat during the course of storage

The aim of present study was to assess the correlation between the method of treating the carcasses of shot wild ducks (Anas platyrhynchos) and the formation of biogenic amines in the their muscles. The carcasses of wild ducks (n?=?180) were divided into three groups of 60 carcasses according to the method of treatment: eviscerated, drawn, and left untreated. Each group was further divided into three subgroups of 20 duck carcasses on the basis of the storage temperature (0, 7, and 15 °C) and stored for 21 days. Samples of breast and thigh muscles were taken at regular weekly intervals. Biogenic amines (cadaverine, putrescine, tyramine, histamine, phenylethylamine, and tryptamine) in samples of breast and thigh muscles were separated by reverse-phase liquid chromatography and detected by tandem mass spectrometry. The sum of biogenic amines was compared with a value of 5 mg/kg, indicating the critical content for fresh meat of high hygienic quality. The results of this study indicated that the sum of biogenic amines in wild duck meat exceeded this limit in an extremely short period of time after the commencement of storage (during the first week of storage). Higher content of biogenic amines were recorded in thigh muscle compared to breast muscle of drawn ducks and untreated ducks. According to our results, the generally recommended method for treating the carcasses of feathered game after hunting (evisceration) does not represent a method that would ensure a longer period of freshness or higher hygiene quality of the game than the other two possible methods of treatment from the biogenic amines point of view.     

Evolution of microbial populations and biogenic amine production in dry sausages produced in Southern Italy

AIMS: To evaluate the occurrence and evolution of biogenic amines during ripening of fermented sausages and their relationship with physico-chemical and microbiological properties of the product. METHODS AND RESULTS: Salsiccia and Soppressata were obtained from artisanal and industrial plants in Basilicata and pH, aW, microbial counts and biogenic amine content were measured. A high variability in amine content was observed. 2-Phenylethylamine and histamine were rarely found, while the tyramine, putrescine and cadaverine content increased during ripening. No correlation was found between individual biogenic amine content, microbial counts or physico-chemical parameters. CONCLUSION: Starter cultures did not necessarily prevent the production of biogenic amines whose total contents were usually higher in Soppressata, a product with a larger diameter and aW compared with Salsiccia. SIGNIFICANCE AND IMPACT OF THE STUDY: Literature findings on biogenic amine content and the evolution of microbial populations were confirmed. Normal ranges for amine content in Salsiccia and Soppressata are reported.     

Biogenic amine formation by poultry-associated spoilage and pathogenic bacteria

The production of biogenic amines by 50 poultry-associated bacterial strains (25 Pseudomonas , 13 Salmonella and 12 Listeria ) was investigated on amine agar plates containing lysine, histidine, ornithine, phenylalanine, tryptophan and tyrosine. Seventy-four per cent of all the strains produced cadaverine and putrescine, while phenylethylamine, histamine, tyramine and tryptamine were produced by 72, 56, 34 and 24% of strains, respectively. Different patterns of biogenic amine production amongst the three bacterial genera tested were apparent as well as amongst strains of the same genus. This study highlighted a high incidence of biogenic amine-producing bacterial strains associated with poultry.     

Tyramine functions as a toxin in honey bee larvae during Varroa-transmitted infection by Melissococcus pluton

From wounds of honey bee pupae, caused by the mite Varroa destructor, coccoid bacteria were isolated and identified as Melissococcus pluton. The bacterial isolate was grown anaerobically in sorbitol medium to produce a toxic compound that was purified on XAD columns, gelfiltration and preparative HPLC. The toxic agent was identified by GC-MS and FTICR-MS as tyramine. The toxicity of the isolated tyramine was tested by a novel mobility test using the protozoon Stylonychia lemnae. A concentration of 0.2 mg/ml led to immediate inhibition of mobility. In addition the toxicity was studied on honey bee larvae by feeding tyramine/water mixtures added to the larval jelly. The lethal dosis of tyramine on 4-5 days old bee larvae was determined as 0.3 mg/larvae when added as a volume of 20 microl to the larval food in brood cells. Several other biogenic amines, such as phenylethylamine, histamine, spermine, cadaverine, putrescine and trimethylamine, were tested as their hydrochloric salts for comparison and were found to be inhibitory in the Stylonychia mobility test at similar concentrations. A quantitative hemolysis test with human red blood cells revealed that tyramine and histamine showed the highest membranolytic activity, followed by the phenylethylamine, trimethylamine and spermine, while the linear diamines, cadaverine and putrescine, showed a significantly lower hemolysis when calculated on a molar amine basis. The results indicate that tyramine which is a characteristic amine produced by M. pluton in culture, is the causative agent of the observed toxic symptoms in bee larvae. Thus this disease, known as European foulbrood, is possibly an infection transmitted by the Varroa destructor mite.