大豆品种香豆雌酚含量的分析

香豆雌酚是大豆生长过程中自然产生的化学物质,被认为可以治疗和预防一些人类依赖激素的疾病。为分析大豆品种中香豆雌酚含量,笔者利用高效液相色谱技术对来自中国、美国和日本的46个大豆品种香豆雌酚的含量进行测定分析。结果表明,不同品种中香豆雌酚的含量存在着较大差异,平均含量为0.587μg/g,其变幅在0.123~1.290μg/g之间。香豆雌酚含量的品种差异,为高含量资源的筛选及品种的选育提供依据。     

Production of chitinolytic enzymes with Trichoderma longibrachiatum IMI 92027 in solid substrate fermentation

Thirty Trichoderma strains representing 15 species within the genus have been screened for extracellular production of chitinolytic enzymes in solid substrate fermentation (SSF). T.longibrachiatum IMI 92027 (=ATCC 36838) gave the highest yield (5.0 IU/g dry matter of substrate) after 3 days of fermentation on wheat bran-crude chitin (9:1 mixture) medium. The optimum moisture content (66.7%), chitin content (20%), initial pH of the medium (2-5) and time course (5 d) of SSF were determ…     

Production of chitinases with Trichoderma harzianun isolates using solid substrate fermentation

Over forty Trichoderma harzianum isolates have been screened in solid substrate fermentation (SSF)for chitinase production. Strains were isolated from Asian soil and tree bark samples. Identification was performed in Canada and Austria by classical and molecular taxonomical methods.……     

Selection of Trichoderma mutants with enhanced cellulase production and resistant to catabolite repression

Due to high cost and relatively low efficiency of cellulase enzymes used for the saccharification of pretreated lignocelluloses, the improvement of cellulase secreting microorganisms is of vital importance. Trichoderma reesei QM 6a, an excellent source of cellulase was selected in the late 1960's. at Natick Laboratories by its performance on pure cellulose (Solka Floc, Avicel) . QM 6a is the wild parent strain of best existing hypercellulolytic mutants such as Rut C30, VTT-D-80133, L…     

Enzymes of Trichoderma and other origin in biopreparation of cotton

Preparation and bleaching are among the most energy and chemical intensive steps of the traditional cotton finishing. About 75% of the organic pollutants arising from textile finishing are derived from the preparation of cotton goods. Biopreparation may be a valuable and environmentally friendly alternative to harsh alkaline chemicals for preparing of cotton. Different enzymes i.e. cellulases, pectinases, lipases and proteases have been tested for biopreparation. Many papers have been publishe…     

Formation of secondary organic aerosols through photooxidation of isoprene

Detailed organic analysis of natural aerosols from the Amazonian rain forest showed considerable quantities of previously unobserved polar organic compounds, which were identified as a mixture of two diastereoisomeric 2-methyltetrols: 2-methylthreitol and 2-methylerythritol. These polyols, which have the isoprene skeleton, can be explained by OH radical-initiated photooxidation of isoprene. They have low vapor pressure, allowing them to condense onto preexisting particles. It is estimated that photooxidation of isoprene results in an annual global production of about 2 teragrams of the polyols, a substantial fraction of the Intergovernmental Panel on Climate Change estimate of between 8 and 40 teragrams per year of secondary organic aerosol from biogenic sources.     

Nitrogen metabolism in the large intestine of ruminants. 1. Metabolism of i.v. infused 15N-urea without additional carbohydrate supply to the large intestine

The experiments were carried out on 3 bulls (body weight: 172, 229 and 193 kg), equipped with ileo-caecal cannulas and with catheters in the jugular veins on both sides. The offered pelleted ration consisted of straw 73%, molasses 12%, cereals 10%, ammonium hydrogen carbonate 3% and urea 2%. Feed intake amounted to about 3 kg per animal and day. During a preliminary period of 5 days 50% of ileal digesta were collected for 12 hours daily, deep-freezed and stored. In the main experiment 15N-urea was infused intravenously for 24 hours. During this period and during the following 6 hours ileal digesta were collected and replaced by precollected, unlabelled digesta. The urea metabolism was estimated by the 15N-labelling of blood urea, by the 15N-excretion via faeces and urea, by the appearance of 15N in ileal digesta and by the 15N-labelling of faecal NAN, NH3 and bacterial fraction. The time course of the 15N-labelling of plasma urea during infusion can be described by an exponential function. The urea flux rate was estimated from the calculated plateau value. The flux rate for the 3 animals was 28.8, 30.7 and 34.8 mumol per minute per kg0.75, respectively. During the infusion of 15N-urea 1.0-2.4% of the infused amount of 15N' appeared in ileal digesta, half of it in the TCA precipitable fraction. At the same time the 15N-labelling of faecal NH3 increased sharply, however, the 15N-labelling of the faecal bacterial fraction was smaller by one order of magnitude. Deficiency of fermentable substrates and problems of inhomogenity of the NH3 pool are supposed as reasons for this result. 30 to 50% of the urea flux entered the digestive tract, the direct entry of urea into the large intestine seems to be only very low.     

Xylanase production by Trichoderma strains in solid substrate fermentation

The importance of microbial enzymes in pulp and paper manufacturing has grown significantly in the last two decades. Solid substrate fermentation (SSF) holds tremendous potential for the production of microbial enzymes of commercial interest. SSF can be of special interest in those processes where the crude fermented product (whole SSF culture, in situ enzyme) may be used directly as the enzyme source. Xylanase preparations practically free of cellulase activity are especially useful for …