内蒙古西部区酸粥中酵母菌的分离鉴定及优势菌分析

从内蒙古地区采集28份酸粥样品,从中分离出40株酵母菌,并对其进行了分子生物学鉴定和生物多样性分析。26S rDNA D1/D2区域 (600bp左右)碱基序列分析结果表明,酸粥中的酵母菌有Issatchenkia orientalis、Saccharomyces cerevisiae、Geotrichum sp.、Candida pararugosa、 Candida parapsilosis、Trichosporon asahii、Trichosporon coremiiforme、Clavispora lusitaniae和Candida tropicalis。经过分析,Issatchenkia orientalis(75%,Frequency percentage)为酸粥中的优势菌。     

Prevention of Yeast Spoilage in Feed and Food by the Yeast Mycocin HMK

The yeast Williopsis mrakii produces a mycocin or yeast killer toxin designated HMK; this toxin exhibits high thermal stability, high pH stability, and a broad spectrum of activity against other yeasts. We describe construction of a synthetic gene for mycocin HMK and heterologous expression of this toxin in Aspergillus niger. Mycocin HMK was fused to a glucoamylase protein carrier, which resulted in secretion of biologically active mycocin into the culture media. A partial purification protocol was developed, and a comparison with native W. mrakii mycocin showed that the heterologously expressed mycocin had similar physiological properties and an almost identical spectrum of biological activity against a number of yeasts isolated from silage and yoghurt. Two food and feed production systems prone to yeast spoilage were used as models to assess the ability of mycocin HMK to act as a biocontrol agent. The onset of aerobic spoilage in mature maize silage was delayed by application of A. niger mycocin HMK on opening because the toxin inhibited growth of the indigenous spoilage yeasts. This helped maintain both higher lactic acid levels and a lower pH. In yoghurt spiked with dairy spoilage yeasts, A. niger mycocin HMK was active at all of the storage temperatures tested at which yeast growth occurred, and there was no resurgence of resistant yeasts. The higher the yeast growth rate, the more effective the killing action of the mycocin. Thus, mycocin HMK has potential applications in controlling both silage spoilage and yoghurt spoilage caused by yeasts.     

Potential Rates of Fermentation in Digesta from the Gastrointestinal Tract of Pigs: Effect of Feeding Fermented Liquid Feed

Microbial catabolic capacity in digesta from the gastrointestinal tract of pigs fed either dry feed or fermented liquid feed (FLF) was determined with the PhenePlate multisubstrate system. The in vitro technique was modified to analyze the kinetics of substrate catabolism mediated by the standing stock of enzymes (potential rates of fermentation), allowing a quantitative evaluation of the dietary effect on the catabolic capacity of the microbiota. In total, the potential rates of fermentation were significantly reduced in digesta from the large intestine (cecum, P < 0.1; colon, P < 0.01; and rectum, P < 0.0001) of pigs fed FLF compared to pigs fed dry feed. No effect of diet was observed in the stomach (P = 0.71) or the distal part of the small intestine (P = 0.97). The highest rates of fermentation and the most significant effect of diet were observed for readily fermentable carbohydrates like maltose, sucrose, and lactose. Feeding FLF to pigs also led to a reduction in the large intestine of the total counts of anaerobic bacteria in general and lactic acid bacteria specifically, as well as of microbial activity, as determined by the concentration of ATP and short-chain fatty acids. The low-molecular-weight carbohydrates were fermented mainly to lactic acid in the FLF before being fed to the animals. This may have limited microbial nutrient availability in the digesta reaching the large intestine of pigs fed FLF and may have caused the observed reduction in activity and density of the cecal and colonic microbial population. On the other hand, feeding FLF to pigs reduced the viable counts of coliform bacteria (indicator of Escherichia coli and Salmonella spp.) most profoundly in the stomach and the distal part of the small intestine, probably due to the bactericidal effect of lactic acid and low pH. The results presented clearly demonstrate that feeding FLF to pigs had a great impact on the indigenous microbiota, as reflected in bacterial numbers, short-chain fatty acid concentration, and substrate utilization. However, completely different mechanisms may be involved in the proximal and the distal parts of the gastrointestinal tract. The present study illustrates the utility of the PhenePlate system for quantifying the catabolic capacity of the indigenous gastrointestinal tract microbiota.     

Nutritional and Toxicological Assessment of White-Rot Fermented Animal Feed

The fungal fermented wheat straws as animal feeds have been evaluated for its toxicological and nutritional status in male rats (Holtzman strain). Digestibility of dry matter and other nutrients as well as fiber fractions were found significantly higher (P < 0.05) in straw fermented with either Ganoderma sp. rckk02 (T3) or Crinipellis sp. RCK-1 (T4) than unfermented straw (T1) or straw fermented with Pycnoporus cinnabarinus (T2). The aflatoxin B1, B2, G1 and G2 were either absent or present in permissive levels in T3 and T4 diets and exhibited normal stress enzyme activity in case of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) enzymes whereas, rats fed on T2 diet showed elevated levels of stress enzymes (ALT, AST and LDH activity), 100% high morbidity and 8.3% mortality. This study suggests that Ganoderma sp. rckk02 and Crinipellis sp. RCK-1 are efficient in improving the nutritive value of poor quality straw and do not posses any threat for their subsequent use as ruminant feed.     

微生物发酵饲料在绿色养殖中应用的研究进展

微生物发酵饲料，目前是饲料工业和养殖业的关注热点之一，也是绿色安全养殖的重要条件。我国早在20世纪90年代开始研究。近年来，微生物发酵饲料在畜牧业生产中得到迅速发展，其生产和应用形式更加多样化。在水产畜牧养殖时，将日基础饲粮部分替换成微生物发酵饲料或经复合微生物发酵后直接饲用，因含有活菌及相关代谢产物，能进一步改善动物对饲料的营养吸收、提高动物的生产性能、防病治病和改善养殖环境。未来将在饲料替代抗生素、饲养高品质动物、畜禽防病等方面发挥必不可少的作用。本文阐释了微生物发酵饲料概念，作用机理及其在畜牧业、水产养殖应用中的最新研究现状，为微生物发酵饲料产品及新技术的研发提供参考。     

酵母的分子生物学鉴定

酵母种类繁多,与人类的关系极其密切,但目前由于研究方法的不同,对于酵母的分类还存在着不同的分类体系。而准确快速的对酵母进行鉴定,既可以有效防止食品腐化变质,又可以增加经济效益,同时也为酵母的分类鉴定奠定一定的理论基础。对常用的核糖体DNA鉴定法、DNA指纹图谱鉴定、脉冲场电泳鉴定、实时PCR和基因芯片等分子生物学鉴定方法在酵母鉴定工作中的研究情况进行了比较。     

Predictive Occurrence Models for Bat Species in California

Abstract: The ability to accurately predict the potential occurrence of species of management concern is useful for wildlife managers, particularly for those whose management activities involve large areas where sampling is difficult due to logistical or financial constraints. During the summers of 2002 and 2003, we used mist nets to capture bats (Myotis yumanensis, M. californicus, M. evotis, M. thysanodes, Eptesicus fuscus, Lasionycteris noctivagans, Tadarida brasiliensis, Antrozous pallidus, Lasiurus borealis, and Lasiurus cinereus) in Whiskeytown National Recreation Area in north-central California, USA. We used landscape-scale variables, logistic regression, and Akaike's Information Criterion (AIC_c) to model species distributions and produce spatially discerning predictive occurrence maps. We developed a priori models that we used to determine which landscape-scale variables best discriminated between capture sites and non-capture sites. The odds of capturing a bat were 3.3 greater when total edge increased by 10,000 m, whereas for Yuma myotis (Myotis yumanensis), the odds of predicting presence were 0.2 greater when distance to lakes and ponds decreased by 2,000 m. Elevation was important in predicting the distribution of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus). Increasing elevation by 400 m decreased the odds of capturing a silver-haired bat by 0.1 and a big brown bat by 0.4. Classification accuracy for our models ranged from 80.9% for all bat species combined to 72.3% for Yuma myotis and silver-haired bats. Predictive occurrence models can be valuable to bat conservation efforts because they provide spatial data important for evaluating the effects of management activities on species distributions.     

酵母饲料的营养价值及应用研究

本文报道了以热带假丝酵母ＺＡＵ－１为生产菌株,应用固体发酵技术生产的酵母饲料的营养价值,并通过对比饲养试验评价应用效果。试验结果表明,粗蛋白提高１１．９７％,粗脂肪提高２．４４倍;赖氨酸、蛋氨酸和苏氨酸分别提高８０．００％、３４．０７％和６９．４２％;维生素Ｂ２提高１１．４１倍,Ｂ５和Ｂ６分别提高１９．５７％和６８．８４％;维生素Ｅ提高６３．４３倍,还含有维生素Ａ和Ｄ３用多种微量元素。饲养试验结果     

Molecular Identification of Species from the Penicillium roqueforti Group Associated with Spoiled Animal Feed

The Penicillium roqueforti group has recently been split into three species, P. roqueforti, Penicillium carneum, and Penicillium paneum, on the basis of differences in ribosomal DNA sequences and secondary metabolite profiles. We reevaluated the taxonomic identity of 52 livestock feed isolates from Sweden, previously identified by morphology as P. roqueforti, by comparing the sequences of the ribosomal internal transcribed spacer region. Identities were confirmed with random amplified polymorphic DNA analysis and secondary metabolite profiles. Of these isolates, 48 were P. roqueforti, 2 were P. paneum, and 2 were Penicillium expansum. No P. carneum isolates were found. The three species produce different mycotoxins, but no obvious relationship between mold and animal disease was detected, based on medical records. P. roqueforti appears to dominate in silage, but the ecological and toxicological importance of P. carneum and P. paneum as feed spoilage fungi is not clear. This is the first report of P. expansum in silage.     

Occurrence of Fusaproliferin and Beauvericin in Fusarium-Contaminated Livestock Feed in Iowa

Fusarium fungal contaminants and related mycotoxins were investigated in eight maize feed samples submitted to the Iowa State University Veterinary Diagnostic Laboratory. Fusarium moniliforme, F. proliferatum, and F. subglutinans were isolated from seven, eight, and five samples, respectively. These strains belonged to mating populations A, D, and E of the teleomorph Gibberella fujikuroi. Fusaproliferin was detected at concentrations of 0.1 to 30 μg/g in four samples, and beauvericin was detected (0.1 to 3.0 μg/g) in five samples. Fumonisins were detected in all eight samples (1.1 to 14 μg/g). Ten of 11 strains of F. proliferatum and all 12 strains of F. subglutinans isolated from the samples produced fusaproliferin in culture on whole maize kernels (4 to 350 and 100 to 1,000 μg/g, respectively). Nine F. proliferatum strains also produced beauvericin in culture (85 to 350 μg/g), but none of the F. subglutinans strains produced beauvericin. Fumonisin B₁ was produced by all nine F. moniliforme strains (50 to 2,000 μg/g) and by 10 of the F. proliferatum strains (1,000 to 2,000 μg/g). This is the first report of the natural occurrence of fusaproliferin outside Italy and of the natural occurrence of beauvericin in North America.     

酵母菌和食用真菌混合固态发酵配合蛋白饲料的应用研究

双菌混合发酵是现代发酵技术发展趋势之一,高温酵母菌和担子茵混合固态发酵尝试了一种生产配合饲料的新技术,高温酵母菌生长速度快,适应性强,蛋白含量高;担子菌分解纤维素和半纤维素能力强,利用它们各自特点,经双菌协同混合发酵,不但提高了淀粉渣的蛋白质含量,而且也降低了纤维素和半纤维素含量,从而使无法直接利用的淀粉渣转化为优质配合蛋白饲料。      

磨盘柿天然发酵制醋的真菌区系鉴定和毒素分析

北京地区天然发酵柿醋的真菌区系主要分布在发酵醪表层,１０ｃｍ以下直菌发生较少。主要发生的真菌有４种：Ａｓｐｅｒｇｉｌｌｕｓ ｐａｒａｓｉｔｉｃｕｓ发生频率为４．８％;Ｐｅｎｉｃｉｌｉｕｍ ｃａｎｅｓｅｎｓ发生频率为４２．８％;Ｐｅｎｉｃｉｌｉｕｍ ｅｘｐａｎｓｕｍ发生频率为３８．１％;Ｐ．ｃｒｕｓｔｏｓｕｍ发生频率为１４．２％。虽然发现有产毒菌株,但未检测到有黄典霉毒素。所以天然发酵柿醋是符合食品卫生标准的。     

Occurrence and Pathogenicity of Fusarium Species in Banana Fruits

Banana fruits were studied over a six-month period in order to determine the incidence of species of the Fusarium genus and assess their potential pathogenicity. The 72 samples studied were commercially available in Italy and Spain, where they were brought from Panama, Ecuador and Canary Islands. Among the species detected in the fruits, Fusarium semitectum var. majus Wollenw. was predominant, followed by F. moniliforme Sheld., F. solani (Mart.) Appel & WoUenw., F. oxysporum Schlecht., F. proliferatum (Matsushima) Nirenberg, F. graminearum Schw., F. camptoceras WoUenw. &C Reinking, F. subglutinans (WoUenw. & Reinking) Nelson et al., F. dimerum Penzig in Sacc, F. acuminatum EU. & Ev., and F. equiseti (Corda) Sacc. Fusarium proliferatum had never been reported to occur as contaminating fungi in banana fruits to date. Fusarium subglutinans, F. acuminatum and F. graminearum were found to be the most markedly pathogenic of all. The lack of noticeable differences in relation to the incidence of the different species isolated from the samples indicates that the mycoflora found is typical of this fruit and does not depend on its origin.     

天然茯苓和液体发酵茯苓粉末的研究

液体发酵茯苓为一种新型的发酵中药。本文在粉末显微特征、多糖、灰分和氨基酸含量等方面,对液体发酵茯苓粉末和天然茯苓粉末展开了研究。研究结果表明二者在显微特征和化学成分等方面均存在较大的差异,探讨了上述差异产生的原因。     

一株产虾青素酵母菌株的鉴定

从市售海水鱼内脏中分离得到一株产虾青素的酵母,编号为NZ- 01.采用传统形态学鉴定方法及rDNA序列分析法分别对从NZ- 01进行鉴定.形态学鉴定结果表明该菌为胶红酵母(Rhodotorula mucilaginosa),分别用特异性引物对rDNA 序列的18S rDNA D1/D2区、26S rDNA D1/D2区和ITS区进行扩增,PCR产物测序,将测序结果登录GenBank进行BLAST分析,结果均与形态学观察结果一致,NZ- 01为胶红酵母.     

解脂假丝酵母中神经酰胺的鉴别和定量分析

采用制备型薄层板分离解脂假丝酵母 (Yarrowialipolitica)中与神经酰胺标样近似的脂类成分 ,将其用于二级质谱分析 ,确认了其结构为脂肪酸碳链长度为 2 4的神经酰胺。结合高效液相色谱 蒸发光散射检测器 (HPLC ELSD)的检测方法 ,首次定量报道了解脂假丝酵母中神经酰胺的含量为 2 5‰。     

Isolation and Identification of a Sexual Hormone in Yeast

5-Fluorotryptophan (5FT), indolmycin (IM), 4-fluorotryptophan and 7-azatryptophan were found on screening to be tryptophan antagonists among various chemically synthesized and naturally occurring tryptophan analogues for the isolation of l-tryptophan (l-Trp) producing mutants of Bacillus subtilis K.

From among 5FT resistant mutants, potent l-Trp producers were obtained using an improved isolation medium. Growth of the isolated 5FT-resistant l-Trp producer, AJ 11709, was inhibited by IM. From among 5FT and IM resistant mutants, the best strain, AJ 11979, which produced 9.0 g/liter of l-Trp from 13% glucose on 120hr cultivation, was selected.