Degradation of 14C-lindane by a mold culture]

The metabolism of 14C-lindane, its short-lived main metabolite gamma-2,3,4,5,6-pentachlorocyclogexene and penta-/hexachlorobenzene was followed in a mould culture after 6, 17, 30 and 52 days. The distribution in the culture medium was also investigated.     

Contamination of the environment with hexachlorobenzene]

The causes of hexachlorobenzene (HCB) contamination of the environment are of complex nature. Besides the microbial metabolism of lindane to HCB, the pyrolysis of pentachlorophenol (wood impregnation), the chlorine treatment of lignin-containing lyes and possible contaminations with active agents which are industrially synthetized from polychlorbenzenes must be regarded as causes being in part still hypothetical.     

Primary metabolites and organic acid metabolism in apple (Malus sylvestris) fruit callus culture

In-vitro culture cells were obtained from seven different varieties of Indian apples (Malus sylvestris L). The cultivar Golden Delicious showed the highest yield of callus tissue followed by Maharaji and American Epirouge. Cultured apple cells exhibited some deviation from the apple fruit in primary metabolism as well as primary metabolite profiles. In callus cultures, the pool size of free amino acids and organic acids increased considerably while the free sugar pool decreased drastically compared with apple fiuit. There was higher incorporation of ¹⁴C acetate, ¹⁴C citrate, ¹⁴C malate and ¹⁴C succinate into the CO₂, lipid, protein, carbohydrate and amino acid fractions and lower incorporation into the free sugar fraction in cultured cells compared with the explant. The incorporation of ¹⁴CO₂ showed a similar trend. Qualitatively, there was some similarity between the callus and explant in free amino acid and sugar profiles and dissimilarity in organic acids. Compounds such as citrate, succinate and fumarate and also some amino acids (methionine, arginine, leucine and proline) were present at higher concentration in callus cultures whereas they were almost absent in the original tissue. There were also differences in the carbohydrate and protein profiles of explant ana callus as judged by their sugar and amino acid make-up respectively.     

Identification of [14C]carmoisine metabolites in bacterial suspension of rat faeces

An in vitro system consisting of a bacterial suspension of human or rat faecal microflora brought about the biological reduction of the red azo dye [14C]carmoisine to 1-naphthyl-amine-4-sulphonic acid (NA) and 2-amino-1-naphthol-4-sulphonic acid (ANA). These metabolites have been unequivocally identified by radio-HPLC, spectroscopic methods, dilution with cold authentic standards and evidence that the specific activity of the diluted compounds remained constant throughout repeated crystallization, acetylation and purification. The results clearly indicated that samples derived from anaerobic incubations have to be processed for analysis in the complete absence of oxygen. In the presence of oxygen, the formation of a complex pattern of compounds in addition to NA was observed as a consequence of the chemical decomposition of ANA.     

Influence of yeast culture on ruminal microbial metabolism in continuous culture

A continuous culture study was conducted to evaluate the effect of two different yeast cultures on ruminal microbial metabolism. The treatments were a) control lactation ration, b) yeast culture 1 (YC1, Diamond-V XP) and c) yeast culture 2 (YC2, A-Max), both fed at an equivalent of 57 g/head per day. The results showed that both yeast culture products increased dry matter (DM) digestion, propionic acid production, and protein digestion compared with the control. Yeast culture 1 demonstrated an increase in molar percentage of propionic acid, a reduction in acetic acid, and a lower mean nadir (daily low) pH compared with YC2. Ruminal cultures treated with YC digested more protein and contributed less bypass N than control. Supplementing YC2 resulted in a tendency for higher microbial N/kg DM digestion than YC1. Yeast culture 1 resulted in production of rumen microbes containing less protein and more ash than YC2. These results support previous research findings that yeast culture does influence microbial metabolism, and specific yeast cultures may have different modes of action.     

片烟贮藏期霉菌的分子鉴定及杀菌剂的室内毒力测定

对108个霉变烟叶样品进行霉菌分离、纯化、保存,获得5种病原真菌的纯培养,通过病原菌的显微镜检鉴定,观察霉菌形态特征、测定孢子大小,并提取真菌DNA,对18S rDNA的ITs进行PCR扩增并克隆产物,测定序列后,通过BLAST搜索比对,确定5种霉菌为镰刀菌(Fusarium sp.)、米曲霉(Aspergillus oryzae)、土生曲霉(Aspergillus terreus)、黑曲霉(Aspergillus niger)、桔青霉(Penicillium citrinum)。在药剂试验中,选用75%达科宁、40%核星、10%世高、100%富马酸二甲酯等药剂测试对烟草霉菌的抑制效果。通过室内生物测定,40%核星的抑菌谱和抑菌效果最好,在浓度为130.32 mg/kg时,对5种霉变微生物的抑制率均达95%以上。     

一株蝗虫抗菌内生菌的初步鉴定与研究

随着抗生素的广泛使用和细菌耐药性的不断出现，人们必须不断寻找新药，以保障人类的健康。文章介绍了从蝗虫体内分离纯化得到的具有产生新抗菌物质能力的内生菌，并对其性质进行初步研究。     

一株蝗虫抗菌内生菌的初步鉴定与研究

随着抗生素的广泛使用和细菌耐药性的不断出现,人们必须不断寻找新药,以保障人类的健康。文章介绍了从蝗虫体内分离纯化得到的具有产生新抗菌物质能力的内生菌,并对其性质进行初步研究。     

一株产胆固醇氧化酶酵母菌的鉴定及发酵条件优化

从富含胆固醇环境的土壤等中进行采样,经富集培养后,以胆固醇为单一碳源的筛选培养基进行筛选,得到不同形态的5株菌株。挑选产酶量最高的一株进行菌种鉴定,并对其发酵产酶条件进行优化。结果表明,该高产胆固醇氧化酶菌株属于季也蒙毕赤酵母属(P.guilliermondii)。其最适发酵培养基组成为:玉米淀粉0.7%,酵母膏1.5%,胆固醇0.2%,吐温801%;理想的培养条件为:培养基pH7.5,37℃条件下培养,装液量为75mL于250mL三角瓶中。优化发酵条件后产酶量达到3501U/L,比发酵前提高了1.5倍。     

Effects of intravenous triacylglycerol emulsions on hepatic metabolism and blood metabolites in fasted dairy cows

The objective was to determine the effects of intravenous infusion of triacylglycerol (TAG) emulsions derived from different lipid sources on energy metabolism during a 4-d fast. Six nonpregnant, nonlactating multiparous Holstein cows were randomly assigned to treatments in a replicated 3 x 3 Latin Square design. Treatments included intravenous infusion of tallow, linseed oil, or fish oil emulsions at a rate of 0.54 g of TAG/kg of body weight per day; infusions were concurrent with a 4-d fast. The emulsions were administered for 20 to 30 min every 4 h throughout the 4-d fast. Cows were fed ad libitum for 24 d between the fast/infusion periods. Infusion of tallow, linseed oil, or fish oil emulsions increased plasma concentrations of palmitic acid, linolenic acid, and eicosapentaenoic and docosahexaenoic acids, respectively. Infusion of linseed oil emulsion decreased plasma TAG concentrations compared with tallow and fish oil treatments, which were similar. Infusion of the tallow emulsion resulted in the highest concentrations of plasma nonesterified fatty acid (NEFA), insulin, and glucose, whereas the infusion derived from linseed oil had the lowest NEFA and beta-hydroxybutyric acid concentrations. The different TAG emulsions had no effect on total or peroxisomal oxidation of [1-(14C)]oleic acid in liver homogenates. Liver TAG content increased 12.0, 7.8, and 14.1 microg/microg of DNA during the fast for tallow, linseed oil, and fish oil treatments, respectively; linseed oil was different from fish oil and tended to be different from tallow.     

Identification of metabolites of dieldrin (HEOD) in the faeces and urine of rats

Two metabolites of HEOD have been isolated by chromatographic techniques, one from the faeces and one from the urine of rats fed for six months on a diet containing HEOD. The molccular formulae of the urinary and faecal metabolites are respectively C₁₂ H₇ O₂ Cl₅ and C₁₂ H₈ O₂ Cl₆. Structural formulae for the two compounds are suggested.     

A general model of yeast energy metabolism in aerobic chemostat culture

The pattern of energy metabolism of different types of yeasts (obligate aerobes and facultative anaerobes) in aerobic chemostat cultures has been evaluated and interpreted on the basis of a coupling of metabolic fluxes between glycolytic and oxidative components. A model has been formulated which defines glycolytic and oxidative subunits through which the substrate C-flux (gram-atom g^?1 h^?1) is calculated, stating that a relative imbalance between glycolytic flux and subsequent oxidative steps alone is sufficient to account for the onset of oxidoreductive metabolism in any type of yeast, irrespective of the maximum respiratory capacity. The model is able to reproduce the patterns of behaviour reported for the different types of yeasts, and the individual features of each strain are explained on the basis of metabolic differences which are defined by a set of normalized parameters. The model can be applied to different substrates and conditions, providing a methodological basis for more detailed studies of the steps controlling yeast energy metabolism.     

Proton production and consumption pathways in yeast metabolism. A chemostat culture analysis

In this investigation, a method for the accurate quantitative determination of net proton production or consumption in biological cultures has been devised. Cells are cultured under constant pH conditions. The specific rate of proton production or consumption by the culture (qH⁺, mmol h^?1 per g biomass) is proportional to the mmol of base or acid required to maintain constant pH per unit time, and this equivalence is independent of the buffering capacity of the culture medium. The above method has been applied to chemostat cultures of Candida utilis growing on glucose or glycerol as carbon source, and different nitrogen sources. The results indicate that the nitrogen assimilation pathway alone determines the value of qH⁺, and a fixed stoichiometric relationship between nitrogen uptake rate qN (meq h^?1 per g biomass) and qH⁺ has been found for each nitrogen source employed. Thus, qH⁺/qN values of +1, 0 and ? 1 were found for ammonium ions, urea and nitrate respectively. Under oxidative metabolism, the contribution of carbon catabolism to the value of qH⁺ was undetectable. Since qN may be related to growth and production of type 1 compounds in fermentation processes, the parameter qH⁺ was incorporated into a model of growth and energy metabolism in chemostat culture (Castrillo and Ugalde, Yeast 10 , 185–197, 1994), resulting in adequate simulations of experimentally observed culture performance. Thus, it is suggested that qH⁺ may be employed as a simple and effective control parameter for biotechnological processes involving biomass-related products.     

Glucose metabolism,enzymic analysis and product formation in chemostat culture of Hanseniaspora uvarum

The physiology of Hanseniaspora uvarum K₅ was studied in glucose-limited chemostat cultures and upon glucose pulse. Up to a dilution rate of 0·28 h^?1, glucose was completely metabolized in biomass and CO₂. Above this value, increase in the dilution rate was accompanied by sequential production of metabolites (glycerol, acetate and ethanol) and decrease in cell yield. Similar results were observed upon glucose pulse. From the enzyme activities (pyruvate dehydrogenase, pyruvate decarboxylase, NAD and NADP-dependent acetaldehyde dehydrogenases, acetyl coenzyme A synthetase and alcohol dehydrogenase) and substrate affinities, the following conclusions were drawn with respect to product formation of cells: (1) pyruvate was preferentially metabolized via pyruvate dehydrogenase, when biomass and CO₂ were the only products formed; (2) acetaldehyde formed by pyruvate decarboxylase was preferentially oxidized in acetate by NADP-dependent aldehyde dehydrogenase; acetate accumulation results from insufficient activity of acetyl-CoA synthetase required for the complete oxidation of acetate; (3) acetaldehyde was oxidized in ethanol by alcohol dehydrogenase, in addition to acetate production.     

Sources of polycyclic aromatic hydrocarbons and hexachlorobenzene in spruce needles of eastern Alaska

The concentrations of phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, and hexachlorobenzene (HCB) were measured in spruce needles at 36 sites in eastern Alaska during early spring. Concentrations of each polycyclic aromatic hydrocarbon (PAH) varied by an order of magnitude. Samples taken from near the city of Fairbanks had higher concentrations than samples taken from more rural areas. Anthropogenic activities near Fairbanks are most likely a source of PAHs. Variation in the concentration ratios of isomeric PAHs indicates the relative importance of combustion and petrogenic sources. The relative combustion contribution is largest in coastal samples and smallest near Fairbanks. In contrast, the concentration of HCB varied by only a factor of 2. Lipid content of needles and distance from the coast were the major factors correlated with the concentration of HCB.     

Identification of novel metabolites from Aspergillus flavus by high resolution and multiple stage mass spectrometry

The filamentous fungus Aspergillus flavus is one of the most important species in the Aspergillus genus and is distributed worldwide as a prevalent aflatoxin-producing food and feed contaminant. A. flavus contains more than 55 gene clusters that are predicted to encode proteins involved in secondary metabolite production. One of these, cluster 27, contains a polyketide synthase (pks27) gene that encodes a protein that is highly homologous to the aflatoxin cluster PKS. Comparative metabolomics, using ultra-high performance liquid chromatography (UHPLC) coupled to high resolution Orbitrap mass spectrometry (MS) was used to detect metabolites differentially expressed in the A. flavus wild-type and ?pks27 mutant strains. Metabolite profiling was aided by a statistical differential analysis of MS data using SIEVE software. This differential analysis combined with accurate mass data from the Orbitrap and ion trap multiple stage MS allowed four metabolites to be identified that were produced only by the wild-type culture. These included asparasone A (358 Da), an anthraquinone pigment, and related anthraquinones with masses of 316, 340 and 374 Da. These latter three compounds had similar fragmentation patterns to that of asparasone A. The 316 Da anthraquinone is particularly interesting because it is most likely formed by incorporation of seven malonyl-CoA units rather than the eight units required for the formation of asparasone A. The 340 and 374 Da metabolites are the dehydration and an oxy-derivative of asparasone A, respectively. Asparasone A was also identified in extracts from several other Aspergillus species.     

Interactions of trace elements during their metabolism]

On the basis of the analysis of the literature data and results of own examinations the following conclusion is made: even practically healthy people can have deficiency of trace elements, and the change of trace elements proportion in a ration can influence essentially homeostasis of trace elements with subsequent damage to body functions. The basic cause of deficiency of trace elements in the body is unbalanced relation of various food components intensifying or inhibiting assimilation of trace elements, inadequate consumption of trace elements and their losses during vital activity.     

两相培养用于提高植物次生代谢物产量的研究进展

论述了两相培养的原理,及运用两相培养来提高次生代谢产物所取得的一些成果,对两相培养今后的研究发展进行了展望。     

试论根霉菌在制曲上的特征

根霉在生命活动中能产生淀粉酶 ,所以它是酿酒制醋的糖化菌。根霉还有分解大豆蛋白质的蛋白酶 ,故此 ,又是制酱的菌种。我国及东南亚一带酿酒、制酱都是用曲子来完成的 ,而曲子的主力军就是根霉。我国人民利用根霉酿酒 ,历史悠久 ,技艺精湛。不论大曲、小曲、酒饼、根霉都是几千年经过长期生产考验的优良菌种。曲子就是根霉菌种的蓄存库。1989年小泉氏在我国西南地区采集 19种酒饼 ,回国后分离鉴定结果认为几乎都是霉菌 ,并以根霉为主。并在其中筛选出几株优良菌种 ,与日本既知菌株相比 ,液化力大 4.5倍 ;总糖化力大 2 .8倍 ;ｐＨ6蛋白酶大 …     

Insights into the metabolism and microbial biotransformation of dietary flavan-3-ols and the bioactivity of their metabolites

Flavan-3-ols, occurring in monomeric, as well as in oligomeric and polymeric forms (also known as condensed tannins or proanthocyanidins), are among the most abundant and bioactive dietary polyphenols, but their in vivo health effects in humans may be limited because of their recognition as xenobiotics. Bioavailability of flavan-3-ols is largely influenced by their degree of polymerization; while monomers are readily absorbed in the small intestine, oligomers and polymers need to be biotransformed by the colonic microbiota before absorption. Therefore, phenolic metabolites, rather than the original high molecular weight compounds found in foods, may be responsible for the health effects derived from flavan-3-ol consumption. Flavan-3-ol phenolic metabolites differ in structure, amount and excretion site. Phase II or tissular metabolites derived from the small intestine and hepatic metabolism are presented as conjugated derivatives (glucuronic acid or sulfate esters, methyl ether, or their combined forms) of monomeric flavan-3-ols and are preferentially eliminated in the bile, whereas microbial metabolites are rather simple conjugated lactones and phenolic acids that are largely excreted in urine. Although the colon is seen as an important organ for the metabolism of flavan-3-ols, the microbial catabolic pathways of these compounds are still under consideration, partly due to the lack of identification of bacteria with such capacity. Studies performed with synthesized or isolated phase II conjugated metabolites have revealed that they could have an effect beyond their antioxidant properties, by interacting with signalling pathways implicated in important processes involved in the development of diseases, among other bioactivities. However, the biological properties of microbe-derived metabolites in their actual conjugated forms remain largely unknown. Currently, there is an increasing interest in their effects on intestinal infections, inflammatory intestinal diseases and overall gut health. The present review will give an insight into the metabolism and microbial biotransformation of flavan-3-ols, including tentative catabolic pathways and aspects related to the identification of bacteria with the ability to catabolize these kinds of polyphenols. Also, the in vitro bioactivities of phase II and microbial phenolic metabolites will be covered in detail.