外加碳源对蚯蚓-污泥系统细菌群落结构的影响

蚯蚓是土壤生态系统中有机物质的重要分解者,并可通过物理运动和排泄蚓粪改变土壤的微生物群落组成。为研究蚓粪与污泥中微生物的相互关系,利用赤子爱胜蚓(Eisenia foetida)和人工湿地基质构建蚯蚓-污泥系统,采用高通量测序技术比较分析添加葡萄糖、乳糖、淀粉、纤维素4种碳源后污泥和蚓粪的细菌多样性及群落结构变化。结果表明,污泥的Chao和ACE指数明显高于蚓粪,添加不同碳源实验组间污泥的Chao和ACE指数差别不大,但均高于污泥对照组;添加葡萄糖、淀粉和纤维素实验组间蚓粪的Chao和ACE指数相近且高于蚯蚓对照组,乳糖实验组蚓粪的Chao和ACE指数则明显低于蚓粪对照组。添加葡萄糖、乳糖、淀粉和纤维素能够增加污泥中细菌多样性;添加葡萄糖、淀粉和纤维素能够增加蚓粪中细菌多样性,但添加乳糖会导致蚓粪中细菌多样性降低。蚓粪与污泥细菌群落结构组成存在明显差异,污泥中变形菌门、拟杆菌门、厚壁菌门、放线菌门、绿弯菌门、酸杆菌门、芽单胞菌门为优势菌门;除乳糖组外,蚓粪中变形菌门、拟杆菌门、厚壁菌门、放线菌门、疣微菌门为优势菌门(其中变形菌门和拟杆菌门占绝对优势),蚓粪乳糖组检测到柔膜菌门(2.6%),其他实验组均未检出。添加碳源后,污泥和蚓粪中能分解相应碳源的菌群增加,如葡萄糖实验组Lactococcus piscium,乳糖组Flavobacterium reichenbachii,淀粉组Alkanindiges illinoisensis和Zobellella taiwanensis,纤维素组Cellvibrio gandavensis等。     

A comparison of features and the microbial constitution of the fresh feces of pigs fed diets supplemented with or without dietary microbes

The features and the constitution of the microbial population of fresh feces were compared between pigs fed a diet supplemented with dietary microbes and pigs given nonsupplemented diets. The former were reared on farm C and the latter on farms A and B. The concentrations of ammonia-N, indole, and skatole of fresh feces were not significantly different between pigs reared on farm C and those raised on farms A and B, but the concentrations of ammonia-N and the skatole of fresh feces were significantly different between pigs reared on farms A and B. The total VFA (volatile fatty acids) concentration of fresh feces in pigs on farm C was slightly lower than in those on farms A and B. Moreover, the molar proportion of the acetic acid in feces in pigs on farm C was lower; inversely, that of propionic and butyric acids was higher in comparison with those on farms A and B. No differences were evident in the total viable counts of feces among pigs reared on the three different farms. Clostridium perfringens was abundant in feces of pigs raised on farms A and B, but it was not detected in pigs reared on farm C. Megasphaerae, bifidobacteria, and clostridia except for C. perfringens were more abundant in the feces of pigs fed a diet supplemented with dietary microbes on farm C, compared with pigs given the nonsupplemented diets on farms A and B.     

Analysis of bile acids in conventional and germfree rats.

The well-known bile acid analysis technique used by us and others (Grundy, Ahrens, and Miettinen. 1965. J. Lipid Res. 6:397-410) does not allow for the detection of hyodeoxycholic acid, a product of quantitative importance in rodent feces. Using updated methodology, it was established that hyodeoxycholic acid and omega-muricholic acid, both apparent conversion products of beta-muricholic acid, occur in apppreciable amounts in intestinal contents and feces of conventional Wistar type Lobund rats. In conventional rats, these bile acids comprise about 50% of fecal bile acids; they are not found in intestinal contents or feces of germfree rats. Others have demonstrated that hyodeoxycholic acid if formed by combined action of gut flora and liver. A new method for the separation of conjugated and free bile acids in biological samples was developed. Results with this method confirmed the total conjugation of bile acids in the germfree rat, and the almost total deconjugation that takes place in the cecum of the conventional rat.     

Toward Reliable Estimates of Abundance: Comparing Index Methods to Assess the Abundance of a Mammalian Predator

Due to time and financial constraints indices are often used to obtain landscape-scale estimates of relative species abundance. Using two different field methods and comparing the results can help to detect possible bias or a non monotonic relationship between the index and the true abundance, providing more reliable results. We used data obtained from camera traps and feces counts to independently estimate relative abundance of red foxes in the Black Forest, a forested landscape in southern Germany. Applying negative binomial regression models, we identified landscape parameters that influence red fox abundance, which we then used to predict relative red fox abundance. We compared the estimated regression coefficients of the landscape parameters and the predicted abundance of the two methods. Further, we compared the costs and the precision of the two field methods. The predicted relative abundances were similar between the two methods, suggesting that the two indices were closely related to the true abundance of red foxes. For both methods, landscape diversity and edge density best described differences in the indices and had positive estimated effects on the relative fox abundance. In our study the costs of each method were of similar magnitude, but the sample size obtained from the feces counts (262 transects) was larger than the camera trap sample size (88 camera locations). The precision of the camera traps was lower than the precision of the feces counts. The approach we applied can be used as a framework to compare and combine the results of two or more different field methods to estimate abundance and by this enhance the reliability of the result.     

人的粪便、血浆、唾液、呼出气体中短链脂肪酸的分析

目的建立一种顶空气相色谱-串联质谱法(HS-GC/MS)快速检测人的粪便、血浆、唾液、呼出气体中短链脂肪酸(SCFAs)的方法,初步探索人的粪便、血浆、唾液、呼出气体中短链脂肪酸的相关性。方法样品无需处理直接封存于顶空进样瓶中,顶空进样;采用DB-FFAP毛细管柱(30 m×0.25 mm×0.25μm)分离;全扫描模式检测。结果人的粪便、血浆、唾液、呼出气体中均含有短链脂肪酸。在人的粪便、唾液样本中均检测到8个短链脂肪酸(乙酸、丙酸、异丁酸、丁酸、异戊酸、戊酸、异己酸、己酸);血浆、呼出气体样本中均检测到7个短链脂肪酸(未检测到异己酸)。结论初步推测人的粪便、血浆、唾液、呼出气体中的短链脂肪酸具有一定的相关性。本方法简单、快速、灵敏,可用于人的生物样品中短链脂肪酸的快速检测。     

A technique for extraction and thin layer chromatography visualization of fecal bile acids applied to neotropical felid scats

Fecal bile acid patterns have been used successfully to identify scats. Neotropical felid scats are capable of this biochemical identification because they present low concentrations of plant pigments that would interfere in fecal bile acids detection. However, neotropical felid scats have poor quantities of bile acids, so we developed in this work a proper technique for their extraction, visualization and determination. Twenty eighth feces of seven different felid species, collected from Zoological and Wildlife Parks, were dried and pulverized. The procedure for analyzing feces is: Take one g of pulverized feces and shake for 3 hr at room temperature in 20 ml benzene:methanol; filter and evaporate to 5 ml. Spot on TLC plate and develop in toluene:acetic acid:water. Dry and visualize with anisaldehyde. Field collected scats could be identified by the bile acids pattern revealed by this specific technique and, then, used as a source of information for distribution, density and food habits studies.     

Metabolism of hydroxy fatty acids in dogs with steatorrhea secondary to experimentally produced intestinal blind loops

Several aspects of the metabolism of hydroxy fatty acids were studied in dogs with steatorrhea resulting from an experimentally produced jejunal blind loop. In these animals hydroxy acids were present in the stool in amounts far above normal. These acids disappeared from the feces during tetracycline administration and after exclusion of the blind loop-both procedures that corrected the steatorrhea apparently by reducing bacterial overgrowth. Hydroxy acids persisted in higher than normal amounts, however, after administration of taurocholic acid, which also corrected the steatorrhea, but by a different mechanism. Both in normal dogs and in those with blind loops, hydroxy acid constituted a higher percentage of total fatty acids in the jejunum. A possible conclusion is that hydroxy fatty acids have an enterohepatic circulation via the portal system. When hydroxy acids were fed to normal dogs, steatorrhea was not produced and absorption in amounts similar to that of unsubstituted stearic acid was observed. Isotopic oleic and linoleic acids were converted to hydroxy acids both in vivo and during in vitro incubation with feces; stearic acid was not. These findings support the idea that hydroxy acids arise by the addition of water across double bonds, this addition being catalyzed by enzymes of intestinal bacteria.     

Characterization of trisubstituted cholanoic acids in human feces

The trisubstituted cholanoic acids in human feces have been studied by gas chromatography-mass spectrometry. The following bile acids have been identified: 3 Beta,7alpha,12alpha-trihydroxy-, 3 Beta,7 Beta,12alpha-trihydroxy-, 3alpha,7alpha-dihydroxy-12-keto-5 Beta-cholanoic acids and 3alpha,7alpha,12alpha-trihydroxy-5alpha-cholanoic acid. The presence in human feces of 3alpha,7alpha,12alpha-trihydroxy-, 3alpha,7,12alpha-trihydroxy-, and 3alpha,12alpha-dihydroxy-7-keto-5 Beta-cholanoic acids has been confirmed. The composition of bile acids in human feces is summarized and possible metabolic interrelationships suggested.     

General methods for the analysis of metabolic profiles of bile acids and related compounds in feces

A general method is described for the detailed qualitative and quantitative analysis of bile acids and related compounds from feces. The technique utilizes a novel combination of liquid-gel and liquid-solid extraction, lipophilic ion exchange chromatography, and capillary column gas-liquid chromatography coupled to mass spectrometry, which permits the detailed composition of bile acids in feces in terms of both the individual bile acids present and their mode of conjugation in the original fecal sample. The extraction, purification, and isolation procedures have been evaluated using fecal samples containing endogenous radioactive bile acid metabolites and from the addition of radiolabeled standards to fecal homogenates. The applicability of the general procedure is illustrated with examples from the analysis of bile acids and sterols in the feces collected from normal healthy subjects, patients with chronic diarrhea, and an adult female Sprague-Dawley rat. The flexibility of the method, and the general problems encountered in the extraction, purification, and isolation of bile acids and related classes of compounds from feces for subsequent analysis of gas-liquid chromatography are discussed in detail.     

Effects of common forage phenolic acids on Escherichia coli O157:H7 viability in bovine feces

Ruminant animals are carriers of Escherichia coli O157:H7, and the transmission of E. coli O157:H7 from cattle to the environment and to humans is a concern. It is unclear if diet can influence the survivability of E. coli O157:H7 in the gastrointestinal system or in feces in the environment. Feces from cattle fed bromegrass hay or corn silage diets were inoculated with E. coli O157:H7, and the survival of this pathogen was analyzed. When animals consumed bromegrass hay for <1 month, viable E. coli O157:H7 was not recovered after 28 days postinoculation, but when animals consumed the diet for >1 month, E. coli O157:H7 cells were recovered for >120 days. Viable E. coli O157:H7 cells in feces from animals fed corn silage were detected until day 45 and differed little with the time on the diet. To determine if forage phenolic acids affected the viability of E. coli O157:H7, feces from animals fed corn silage or cracked corn were amended with common forage phenolic acids. When 0.5% trans-cinnamic acid or 0.5% para-coumaric acid was added to feces from silage-fed animals, the E. coli O157:H7 death rate was increased significantly (17-fold and 23-fold, respectively) compared to that with no addition. In feces from animals fed cracked corn, E. coli O157:H7 death rates were increased significantly with the addition of 0.1% and 0.5% trans-cinnamic acid (7- and 13-fold), 0.1% and 0.5% p-coumaric acid (3- and 8-fold), and 0.5% ferulic acid (3-fold). These data suggest that phenolic acids common to forage plants can decrease viable counts of E. coli O157:H7 shed in feces.     

Identification and Characteristics of Actinomycetes Useful for Semicontinuous Treatment of Domestic Animal Feces

Selected strains of actinomycetes useful for practicing semicontinuous treatment of swine and poultry feces were identified as Streptomyces antibioticus S-4, S. puniceus N-50-2, S. nigrifaciens N-9-3, Thermoactinomyces vulgaris HIR-60, and Thermomonospora viridis HIR-50. These five obligately aerobic strains grew preferably on nonsterilized fresh swine feces in 24 h without any additives. They assimilated offensive volatile fatty acids in the swine and poultry feces. Cultures of these five strains were mixed and used as seed for the practical treatments of 1 ton of swine feces over the wide temperature range of 15 to 60°C. Strain HIR-50 grew most predominantly on both fresh swine and poultry feces at 50 to 55°C and decomposed uric acid. For the efficient penetration of mycelia into the feces, manures were mixed once a day so as not to break the solid mass, and the dehydration rate of feces had to be controlled in proportion to the mycelial growth rate. The actinomycete biofertilizer thus manufactured in 10 days was odorless and promotive of plant growth.     

Hepatic overexpression of cholesteryl ester hydrolase enhances cholesterol elimination and in vivo reverse cholesterol transport

Neutral cholesteryl ester hydrolase (CEH)-mediated hydrolysis of cellular cholesteryl esters (CEs) is required not only to generate free cholesterol (FC) for efflux from macrophages but also to release FC from lipoprotein-delivered CE in the liver for bile acid synthesis or direct secretion into the bile. We hypothesized that hepatic expression of CEH would regulate the hydrolysis of lipoprotein-derived CE and enhance reverse cholesterol transport (RCT). Adenoviral-mediated CEH overexpression led to a significant increase in bile acid output. To assess the role of hepatic CEH in promoting flux of cholesterol from macrophages to feces, cholesterol-loaded and [(3)H]cholesterol-labeled J774 macrophages were injected intraperitoneally into mice and the appearance of [(3)H]cholesterol in gallbladder bile and feces over 48 h was quantified. Mice overexpressing CEH had significantly higher [(3)H]cholesterol radiolabel in bile and feces, and it was associated with bile acids. This CEH-mediated increased movement of [(3)H]cholesterol from macrophages to bile acids and feces was significantly attenuated in SR-BI(-/-) mice. These studies demonstrate that similar to macrophage CEH that rate-limits the first step, hepatic CEH regulates the last step of RCT by promoting the flux of cholesterol entering the liver via SR-BI and increasing hepatic bile acid output.     

Hydrolysis of Conjugated Bile Acids by Cell-Free Extracts from Aerobic Bacteria

By means of an aerobic enrichment culture technique, several bacteria that hydrolyze conjugated bile acids and modify the formed deconjugates were isolated from feces of man, rat, and chicken and from soil. Hydrolase activity was intracellular and extractable, and the yield of the enzymes was increased by adding the conjugated bile acids to the culture media. The hydrolase from bacterium of human origin was stable, having a pH optimum at about 7.0. All bile acid conjugates were hydrolyzed linearly as a function of time.     

堆肥对土壤重金属垂直分布的影响与污染评价

对不同畜禽粪便堆肥与土壤重金属垂直分布的关系进行了研究．结果表明,在畜禽粪便堆肥过程中,粪堆下土壤pH值和有机质显著增加,其pH和有机质含量的垂直分布表现为从表层到底层逐渐降低．各种畜禽粪便粪堆下土壤Zn、Cd含量明显增高,且从表层到底层呈逐渐减小的趋势．鸡粪和猪粪堆下土壤Cu含量随土层深度增加而降低;牛粪堆下土壤Cu含量随土层深度增加没有明显的变化．自然条件下Cd和Zn在土壤系统中的迁移能力大于Cu．各粪堆下的部分土层Cu、Zn、Cd含量超过我国土壤环境质量一级标准．应用地质积累指数法对各土层污染评价的结果表明,只有肉鸡粪堆下0～10cm土壤和蛋鸡粪堆下0～40cm土壤受到轻度Zn污染,其它粪堆下各土层均未受到Cu、Zn、Pb和Cd污染．     

A freshwater clam (Corbicula fluminea) extract improves cholesterol metabolism in rats fed on a high-cholesterol diet

The effect of a freshwater clam (Corbicula fluminea) extract (FCE) on cholesterol metabolism in rats fed on a high-cholesterol diet was investigated. When rats were fed various amounts of FCE in addition to the high-cholesterol diet for 2 wk, the serum and hepatic cholesterol levels were gradually reduced in a dose-dependent manner, as compared with the control group. The excretion of neutral sterols and bile acids into the feces was increased by feeding FCE. Several phytosterols were detected in the feces of rats fed on the FCE-containing diet. In addition, substantial amounts of phytosterols were found in FCE. Cholesterol 7alpha-hydroxylase (CYP7A1) mRNA in the liver of the rats fed on the FCE-containing diets was higher than that of rats fed on the high-cholesterol diets without FCE. These results may suggest that enhanced cholesterol degradation and the excretion of neutral sterols and bile acids contributed to the hypocholesterolemic effect of FCE observed in the hypercholesterolemic rats fed on the high-cholesterol diet.     

Gas-liquid chromatographic determination of human fecal bile acids

A method for the determination of total bile acids in human feces that is suitable for routine application is described and discussed. Bile acids are extracted from freeze-dried feces with acetic acid and toluene, in the presence of the internal standard 23-nordeoxycholic acid. After saponification of the extract, bile acids and the internal standard are methylated and converted by mild chromic acid oxidation into their ketonic derivatives. The resultant mixture of a few stable compounds can be separated and measured quantitatively by gas-liquid chromatography on a methylsiloxane polymer. A reference bile acid mixture including the internal standard is also taken through the entire procedure with each series of samples. It has been demonstrated that, in spite of the omission of the usual purification steps, the method is specific for bile acids.     

Genetic marking of Lactococcus lactis shows its survival in the human gastrointestinal tract.

A human feeding study was performed with Lactococcus lactis TC165.5, which is genetically marked by insertion of the sucrose-nisin conjugative transposon Tn5276 and chromosomal resistance to rifampin and streptomycin. The fate of strain TC165.5 and its nucleic acids was monitored by conventional plating methods and by molecular detection techniques based on specific PCR amplification of the nisin (nisA) gene from DNA extracted from human feces. A method was developed for the efficient extraction of microbial DNA from human feces. The results show that a fraction of viable cells of L. lactis TC165.5 survived passage through the human gastrointestinal tract. Only cells that passed within 3 days of ingestion could be recovered from the feces of the volunteers, and they accounted for approximately 1% of the total number of cells consumed. The presence of nisA in DNA extracted from feces could be detected up to 4 days, when viable cells were no longer present.     

Plate diffusion assay as a rapid method for dosimetry of mutagens.

In the feces of conventional rats, the amount of omega-muricholic and hyodeoxycholic acids vary according to the diet. To understand this phenomenon, we investigated the bacterial formation of these bile acids. The present paper reports the first isolation, from conventional rat feces, of a strain of Clostridium group III which transforms beta-muricholic acid, the main bile acid in germfree rats, into omega-muricholic acid.     

Effects of Tripalmitin and Safflower Oil on the Content of Short-chain Fatty Acids in the Cecum and on the Fecal Excretion of Lipids in Rats

The effects of feeding of saturated and unsaturated fatty acids on the contents of short-chain fatty acids (SCFAs) derived from bacterial fermentation in the colon were examined in rats. The concentration of lipids in the feces was also measured. Tripalmitin or safflower oil at the concentration of 10% (w/w) in the diet with 5% (w/w) corn oil were used as the source of saturated or unsaturated fatty acids, respectively.     

Metabolic products of arachidonic acid in rats

The pattern of eicosanoid metabolites appearing in urine and feces following oral administration of radioactive arachidonic acid was investigated using rats deficient in essential fatty acids. About 70-80% of the radioactivity in the urine during the first day after feeding was adsorbed to XAD-2 resin and represented eicosanoid metabolites, whereas the rest of the radioactivity was mainly 3H2O. The eicosanoid metabolites were fractionated into different polarity classes using reverse phase Sep-Pak C18 cartridges. Gas chromatographic analysis of the urinary metabolites following their derivatization into methyl ester-methoxime-tert-butyl-dimethylsilyl ethers revealed that nearly one-half of the metabolites had ECL values less than 22 and represented metabolites more oxidized than commonly described. Only 30% of the metabolites had ECL values between 26 to 32, corresponding to the values for the metabolites that originate from exogenously infused prostaglandins. A large portion of the eicosanoid metabolites was also excreted with the feces. The isotopic patterns from the reverse phase chromatography indicated that many of the fecal metabolites may be similar to those in urine although some metabolites in feces were not present in urine. Based on the specific radioactivity of the administered arachidonic acid, it appeared that at least 6 to 8 mg of eicosanoid metabolites were excreted through urine and feces within 24 hrs following an oral bolus of 60 mg arachidonic acid. The rapid increase and subsequent decrease in eicosanoid metabolite excretion after oral administration of arachidonate indicates that the dietary intake of polyunsaturated fatty acids may have a more rapid effect upon the endogenous production of eicosanoids than is generally recognized.