黄瓜连作土壤酚酸类物质积累对土壤微生物和酶活性的影响

伴随连作年限的增加,日光温室黄瓜连作土壤中酚酸类物质(对羟基苯甲酸、阿魏酸、苯甲酸)明显积累,连作5～9年的土壤酚酸类物质含量显著高于连作1～3年的土壤.伴随外源酚酸类物质处理浓度的增加,黄瓜根区土壤中细菌、放线菌和微生物总量以及N生理群均呈先升后降趋势,在80 μg·g^-1处理浓度下细菌、放线菌数量最多,处理浓度在120μg·g^-1以下土壤真菌数量(包括尖孢镰刀菌、疫霉)急剧增长;多酚氧化酶、过氧化氢酶、蔗糖酶、脲酶和蛋白酶活性也同样呈先升后降趋势,但其峰值对应的浓度不同.     

Effect of intestinal microfloras from vegetarians and meat eaters on the genotoxicity of 2-amino-3-methylimidazo[4,5-f]quinoline, a carcinogenic heterocyclic amine

Aim of this study was to investigate the impact of intestinal microfloras from vegetarians and non-vegetarians on the DNA-damaging activity of 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ), a carcinogenic heterocyclic amine that is found in fried meats. Floras from four vegetarians (Seventh Day Adventists) and from four individuals who consumed high amounts of meats were collected and inoculated into germfree F344 rats. The rats were kept on isocaloric diets that either contained animal derived protein and fat (meat consumers group) or proteins and fat of plant origin (vegetarian groups). IQ (90 mg/kg bw) was administered orally, after 4 h the extent of DNA-damage in colon and liver cells was determined in single cell gel electrophoresis assays. In all groups, the IQ induced DNA-migration was in the liver substantially higher than in the colon. In animals harbouring floras of vegetarians, the extent of damage was in both organs significantly (69.2% in the liver, P<0.016 and 64.7%, P<0.042 in the colon, respectively) lower than in the meat consumer groups. Our findings show that diet related differences in the microfloras have a strong impact on the genotoxic effects of IQ and suggest that heterocyclic amines are less genotoxic and carcinogenic in individuals that consume mainly plant derived foods.     

Consumption of milk from transgenic goats expressing human lysozyme in the mammary gland results in the modulation of intestinal microflora

Lysozyme is a key antimicrobial component of human milk that has several health-promoting functions including the development of a healthy intestinal tract. However, levels of lysozyme in the milk of dairy animals are negligible. We have generated transgenic dairy goats that express human lysozyme (HLZ) in their milk in an attempt to deliver the benefits of human milk in a continual fashion. To test the feasibility of this transgenic approach to achieve a biological impact at the level of the intestine, feeding trials were conducted in two animal models. Pasteurized milk from HLZ transgenic animals was fed to both kid goats (ruminant model) and young pigs (human model), and the numbers of total coliforms and Escherichia coli present in the small intestine were determined. Data from this proof-of-principle study demonstrate that milk from transgenic animals was capable of modulating the bacterial population of the gut in both animal models. Pigs that consumed pasteurized milk from HLZ transgenic goats had fewer numbers of coliforms and E. coli in their intestine than did those receiving milk from non-transgenic control animals. The opposite effect was seen in goats. Milk from these transgenic animals not only represent one of the first transgenic food products with the potential of benefiting human health, but are also a unique model to study the development and role of intestinal microflora on health, well-being and resistance to disease.     

Actinomycetes isolated from beehives in Thailand

Actinomycetes are one of the main microbial groups that produce bioactive compounds used as antibiotics. Although bacteria, mold and yeast have frequently been found in bees, the presence of actinomycetes in bee hives had not been previously identified or reported. The aim of our research was to focus on the diversity of actinomycetes in bee hives in Thailand. Bees, brood cells and hive materials were collected from apiaries and natural sources. Thirty-two isolates of actinomycetes were isolated and identified using morphological, physiological, chemical and molecular characterization. Most of the isolates belonged to the genus Streptomyces. Some less frequent isolates were classified in the genera Nonomuraea, Nocardiopsis and Actinomadura.     

浓香型大曲原核微生物群落的PCR-SSCP解析

采用PCR-SSCP(单链构象多态性)技术对浓香型大曲发酵过程中原核微生物群落结构的变化情况进行了研究, 结果表明: (1)发酵各时期曲样的群落结构相似, 同时也具有多态性; (2)不同微生物群落具有协同和制约的复杂生态学效应; (3)各时期曲样微生物多样性指数均在1.69~2.01之间, 群落结构相对较稳定; (4)各曲样微生物群落相似性位于0.67~1.00之间, 邻近时期样品间的相似性程度较高。     

西瓜连作障碍及其预防

<正>我国西瓜种植面积居世界第一,2008年约173.34万公顷,总产量约6282.2万吨。西瓜本身忌连作,连作一年就会有病害发生,需要轮作8年后,才可再种植;连作障碍严重影响了西瓜的生产和市场的供应。     

急性胰腺炎患者舌苔微生物研究

目的观察急性胰腺炎（ＡＰ）患者舌苔微生物的变化,总结不同舌象、不同病情的ＡＰ患者舌苔微生物变化规律。方法将纳入的５２例ＡＰ患者按分级标准分为轻症（ＭＡＰ）组（ｎ＝３３）,重症（ＳＡＰ）组（ｎ＝１９）,分别于治疗前、第３天及第９天清晨观察并采集舌苔,作细菌培养、鉴定、定量,测溶菌酶（ＬＺＭ）含量。２５例健康薄白苔作为对照组。结果ＡＰ患者舌苔菌落总数减少。厚苔菌落总数及Ｇ－厌氧杆菌多于薄苔,口腔优势菌在厚苔变化表现为厌氧菌检出率增高而需氧菌下降。ＳＡＰ组肠道杆菌的检出率显著增加;病程早期除口腔链球菌、Ｇ＋厌氧杆菌减少外,ＳＡＰ组Ｇ－厌氧杆菌也减少;病程第９天时,ＭＡＰ组基本恢复正常,而ＳＡＰ组各种异常无改变。ＡＰ患者舌苔ＬＺＭ均显著升高。结论ＡＰ病程中口腔舌面出现微生态失调现象,严重程度与病情及舌苔的变化有关。ＡＰ厚苔菌落总数多于薄苔,主要为Ｇ－厌氧杆菌增加。厚苔厌氧菌增加,而需氧菌减少。     

The gas environment of germinating barley in various microbial states during malting

Steeped barley was germinated in laboratory scale solid-state fermentors at various oxygen partial pressures. Experiments were performed with sterile living barley and with barley colonized by the natural microflora. On line monitoring of CO₂ concentration in the off-gas of the reactors reflected the metabolic activity more accurately than heat production measurement. When colonized by micro-organisms, the respiratory activity of germinating barley increased with the oxygen level in the air. However, CO₂ profiles of sterile barley did not alter at different oxygen concentrations in the inlet air of the reactor. It is concluded that the germination phase of malting can be optimized by controlling the oxygen supply to the barley based on CO₂ production measurements and taking into account microbial aspects.     

菌群检测值的模式识别分析法判断肠道菌群失调的研究

本文对１０名患有腹泻或肠炎的患者和１０名健康者做了肠道五种优势菌群的检测，应用模式识别对两组菌群检测值进行分析。结果，图形上两组清楚地分为两处，有明显的分界线。表明，５种菌群数值在两组间具有明显差异。经评估，可知该方法平均诊断预报能力可达７５％以上。     

Microbial regulation of host hydrogen sulfide bioavailability and metabolism

Hydrogen sulfide (H₂S), generated through various endogenous enzymatic and nonenzymatic pathways, is emerging as a regulator of physiological and pathological events throughout the body. Bacteria in the gastrointestinal tract also produce significant amounts of H₂S that regulates microflora growth and virulence responses. However, the impact of the microbiota on host global H₂S bioavailability and metabolism remains unknown. To address this question, we examined H₂S bioavailability in its various forms (free, acid labile, or bound sulfane sulfur), cystathionine γ-lyase (CSE) activity, and cysteine levels in tissues from germ-free versus conventionally housed mice. Free H₂S levels were significantly reduced in plasma and gastrointestinal tissues of germ-free mice. Bound sulfane sulfur levels were decreased by 50–80% in germ-free mouse plasma and adipose and lung tissues. Tissue CSE activity was significantly reduced in many organs from germ-free mice, whereas tissue cysteine levels were significantly elevated compared to conventional mice. These data reveal that the microbiota profoundly regulates systemic bioavailability and metabolism of H₂S.