低温贮藏过程中鱿鱼细菌组成的变化及优势腐败菌鉴定

将鱿鱼在0、5、10、15℃有氧贮藏过程中的细菌菌相进行定性和定量分析。研究表明,鱿鱼贮藏初期其细菌组成较复杂,其中91.48%是革兰氏阴性菌,革兰氏阳性菌仅占4.26%,优势菌为气单胞菌(Aeromonas spp.)、浅黄金色单胞菌(Chryseomonas luteola)和假单胞菌(Stenotrophomonas spp.),比例分别为27.66%、23.40%和17.02%。此外,还检测出一定量的洛菲氏不动杆菌(Pantoea agglomerans)、成团泛菌(Acinetobacter lwoffii)。0、5、10、15℃贮藏过程中,细菌菌相逐渐变得单一,假单胞菌上升趋势明显,达到高品质期终点分别为360、239、96、47 h,货架期终点分别为525、286、147、86 h。0、5、10、15℃贮藏较好品质期时,TVBN均值为(17.15±0.29)mg/100g,菌落总数为(5.89±0.40)Lg CFU/g,假单胞菌比例分别为84.09%、72.09%、65.52%和76.36%,平均比例为75.92%;货架期终点时TVBN均值为(30.05±0.92)mg/100 g,菌落总数为(8.33±0.30)Lg CFU/g,假单胞菌比例达到93.24%、90.53%、88.57%和81.95%,平均比例为87.63%。由此得出鱿鱼0~15℃贮藏过程中的优势腐败菌是假单胞菌。     

糖尿病患者肠道中4 种重要菌群的定量分析

目的：了解正常人群与Ⅱ型糖尿病人,以及Ⅱ型糖尿病人在是否有家族遗传、是否用药治疗和是否伴随肥胖等情况下肠道中拟杆菌、双歧杆菌、柔嫩梭菌和乳杆菌的含量与变化,为预防和治疗Ⅱ型糖尿病开辟新途径。方法：收集上述各类人群粪便样品（每组10 人）,分别提取样品中微生物的总DNA,运用荧光定量聚合酶链式反应（polymerase chain reaction,PCR）扩增4 种重要菌群的特异性片段,计算含量,分析上述菌群的变化差异。结果：正常人群肠道中的拟杆菌和双歧杆菌含量均显著低于Ⅱ型糖尿病人群;柔嫩梭菌和乳杆菌含量均显著高于后者。在Ⅱ型糖尿病人群中,用药患者组和肥胖＋高血糖患者组的肠道中拟杆菌和双歧杆菌含量均显著低于未用药患者组和单纯高血糖患者组,而柔嫩梭菌和乳杆菌含量均显著高于后者。有无Ⅱ型糖尿病遗传史对患者肠道内4 种菌群的含量均无显著影响。结论：4 种重要菌群与Ⅱ型糖尿病的发生和发展有密切关系;用药治疗后的患者肠道中4 种重要菌群含量比其他各组更接近正常人群;肥胖易加重Ⅱ型糖尿病病情;而有无Ⅱ型糖尿病家族遗传对这4 种菌群的含量几乎没有影响。     

云南剑川县山羊乳饼化学组成与微生物学分析

对云南剑川不同地区13个家庭的山羊乳饼化学成分和微生物学组成进行分析。分析指标包括脂肪、游离脂肪酸、总蛋白质、水溶性氮、非蛋白氮、游离氨基氮、干物质、灰分、总钙、游离钙、总磷、游离磷、pH值和乳酸度；微生物组成包括乳酸菌数和酵母菌数。结果表明，山羊乳饼中含有较高的蛋白质、脂肪、钙和磷；同时乳酸菌数高于酵母菌数。     

Quality attributes of farmed eel (Anguilla anguilla) stored under air, vacuum and modified atmosphere packaging at 0 degrees C

The shelf life of fresh eel in various packaging conditions of atmospheric air, vacuum and modified atmosphere packaging (MAP) (40% CO(2), 30% N(2) and 30% O(2)) at 0 degrees C was investigated. All raw eel samples received acceptable sensory scores during the first 11+/-1 days of storage in atmospheric air, 11+/-1 days of storage in vacuum and finally 18+/-1 days of storage in MAP conditions. Using the microbial quality indicators the shelf life of eel packed in air, vacuum and MAP was estimated to be more than 18, 28 and 34 days, respectively. The main spoilage microorganisms under MAP conditions were lactic acid producing bacteria followed by Shewanella spp., pseudomonads, Enterobacteriaceae and yeasts. Chemical data revealed that pH, ammonia, glucose and lactate examinations might not be useful for monitoring eel quality differences.     

骆驼乳对慢性酒精性肝损伤小鼠肠道菌群的影响

目的:探究骆驼乳对慢性酒精性肝损伤小鼠肠道菌群多样性及结构的影响。将雄性C57BL/6NCr小鼠随机分为4组:对照组(Con,n=6)、模型组(Et,n=6)、骆驼乳剂量组(EtCM,n=6)和牛乳剂量组(EtNM,n=6);实验期为8周,前4周饲喂Lieber-DeCarli液体饲料(含对照),后4周在饲喂Lieber-DeCarli液体饲料的基础上,灌胃相应的乳或生理盐水。灌胃结束后,按照5 g/kg剂量一次性灌胃31.5%酒精溶液,建立NIAAA模型。检测血清LPS含量,并在无菌条件下取小鼠结肠粪便,进行16S rRNA测序,分析肠道菌群α多样性、β多样性及基于门、属水平的物种结构。血清指标结果显示,EtCM组和EtNM组小鼠血清LPS显著降低(P<0.01)。16S r RNA测序结果表明,骆驼乳和牛乳能显著提高ALD小鼠结肠肠道菌群的丰度和均匀度,更好地调整肠道菌群结构,其中骆驼乳较牛乳显示出更好的α多样性。在门水平上,骆驼乳和牛乳显著提高拟杆菌门的丰度,降低厚壁菌门的丰度。在属水平上,骆驼乳和牛乳显著提高副拟杆菌属、拟杆菌属、阿克曼菌属的丰度,降低瘤胃菌科下的未知属Ruminococcaceae_UCG-013丰度。其中,骆驼乳的有益菌丰度较牛乳高出9%。结论:骆驼乳通过改变ALD小鼠肠道菌群环境,来调节肠道菌群结构,可作为调节肠道菌群的功能性乳制品,可预防慢性ALD引起的肠道屏障功能障碍。     

基于16S rRNA技术分析当归超微粉对小鼠肠道菌群多样性的影响

研究不同剂量当归超微粉对小鼠肠道菌群多样性、肠道生理结构的作用。将C57BL/6小鼠分为当归超微粉高剂量组(2.0g/kg)、中剂量组(1.0 g/kg)、低剂量组(0.5 g/kg)、传统饮片组(2.0 g/kg)、传统粉末组(2.0 g/kg)和空白组,灌胃给药15 d,记录体重,在灌喂第15 d时无菌取结肠内容物,扩增肠道菌群16S rRNA基因的V3+V4区,采用高通量测序分析β多样性和α多样性、分析门水平和属水平的物种组成,HE染色法观察胃肠道病理变化。结果显示,C57BL/6小鼠体重正常生长,当归超微粉饮片高剂量组的对小鼠肠道微生物的疣微菌门(Verrucomicrobia)含量显著增加(p<0.05),放线菌门(Actinobacteria)含量减少(p<0.01)。另外,当归超微粉饮片中剂量组拟杆菌门(Bacteroidetes)含量降低最为显著,厚壁菌门(Firmicutes)增加最为显著;在属水平中剂量Faecalibaculum增加最明显(p<0.05),故超微粉的中剂量为最佳实验剂量。各处理组小鼠胃肠道无病理变化。本实验可为当归以超微粉的使用方式,对人体保健或治疗使用的科学用量和安全性,提供理论依据。另外,可为以肠道菌群相关的有效性提供技术支持。     

发酵肉制品中微生物对生物胺形成机理的影响研究

富含高蛋白质的食品中存在生物胺,发酵肉制品中蛋白质含量丰富可能存在高浓度的生物胺。微生物在不同发酵肉制品中的分布不尽相同,导致了在不同发酵肉制品中生物胺种类和数量上的差异。该文综述发酵肉制品中微生物对生物胺形成机理的研究进展,将发酵肉制品中的微生物群落构成与生物胺分析有机地结合起来,为利用发酵剂调控微生物菌群结构来降低生物胺潜在危害的应用提供科学依据。     

肠道菌群与婴幼儿食物过敏相关性的研究进展

随着婴幼儿食物过敏的发病率逐年上升,食物过敏逐渐成为了全球性公共卫生问题。大量研究表明人体内肠道菌群与食物过敏有着密切的关系,在受到外界因素的干扰后,肠道菌群多样性和数量发生改变,进而引发机体对某些正常抗原的免疫耐受度降低,导致过敏反应。本文介绍了食物过敏婴幼儿和健康婴幼儿肠道菌群的差别,对肠道菌群在食物过敏中的调节机制(影响肠道细胞功能和调节屏障保护特性、产生信号分子进行免疫调控以及促进和维护机体口服耐受)进行综述,并对肠道菌群调节婴幼儿食物过敏的策略进行展望。     

Development of the yeast flora of whole-crop maize during ensiling and during subsequent aerobiosis

The fresh maize plant was inhabited by non-fermenting basidiomycetous yeast species, viz. Candida ingeniosa, Cryptococcus laurentii, Sporobolomyces roseus, Sporidiobolus salmonicolor and Rhodotorula rubra. These species had vanished after 2 days of anaerobiosis in a laboratory-scale silo. After this time, ascomycetous species tolerant to acetic acid were isolated. Successively Candida holmii, C. milleri, C. krusei, C. lambica, C. famata, Geotrichum candidum and Hansenula anomala were encountered. Except for C. famata and G. candidum these yeasts vigorously ferment glucose. Total yeast counts were 10⁷ g^?1 during the first 2 weeks and gradually decreased to about 10⁵ g^?1 after 4 months. This shows that anaerobic silage provides an adverse environment for yeasts. Exposure of maize silage to air resulted in complete consumption of lactic and acetic acids within 5 days. This was due to growth of C. hoimii, C. lambica and C. milled. The physiologically similar yeast species C. holmii and C. milled were both abundant from the early stage of the fermentation and during aerobiosis. However, C. milled predominated in the first 2 weeks of anaerobiosis. The less frequently occurring yeast species C. famata, G. candidum and H. anomala assimilated lactic acid and ethanol as well as minor products of bacterial sugar fermentation such as acetoin and butan-2,3-diol but not diacetyl.     

Elimination of Listeria monocytogenes in soft and red smear cheeses by irradiation with low energy electrons

Soft and red smear cheeses are frequently contaminated by Listeria monocytogenes , sometimes at relatively high concentration (< 10⁵ CFUg^-1). This bacterium is radiosensitive (D₁₀ value of approximately 0.45 kGy) but irradiation of the whole cheese by X-rays induced off-flavours when the dose exceeded 1.0 kGy. Irradiation could be effective in eliminating L. monocytogenes only from lightly contaminated cheeses (> 10²CFU g^-1).
L. monocytogenes appears only in the rind (where the pH is greater than 6.3) and never grows in the core of the cheese. Under these conditions, a specific irradiation of the rind after ripening, with a low-energy electron beam at relatively high doses (up to 3.0 kGy), allows the total elimination of L. monocytogenes in heavily contaminated samples (10⁵-10⁶ CFU g^-1) without noticeable modifications of the organoleptic properties of the cheese.