Perfect state of Rhodomyces dendrorhous (Phaffia rhodozyma)

After mother–daughter cell conjugation, formation of long holobasidia with terminal basidiospores was observed without mycelium production in Rhodomyces dendrorhous (including the type strain of Phaffia rhodozyma) on polyol-containing media. Basidiospores are not forcibly discharged and germinate by budding. A new genus Xanthophyllomyces (Filobasidiaceae, Tremellales) with a species, X. dendrorhous, is proposed for the telemorphic state of R. dendrorhous.     

Studies of astaxanthin biosynthesis in Xanthophyllomyces dendrorhous (Phaffia rhodozyma). Effect of inhibitors and low temperature

The effect of nicotine and diphenylamine on astaxanthin biosynthesis in Xanthophyllomyces dendrorhous was studied. The effects were analysed under standard and low temperature conditions. It was found that 10 mm-nicotine inhibits the cyclization of lycopene and de novo protein synthesis was not needed to reverse the inhibition. The oxidation of β-carotene was irreversibly inhibited by 10 μM -diphenylamine while the dehydrogenation of phytoene was reversibly inhibited by 60 μM -diphenylamine. The simultaneous exposure to low temperature (4°C) overcomes the inhibition of β-carotene oxidation at low diphenylamine concentration. © 1998 John Wiley & Sons, Ltd.     

Structural and phylogenetic analysis of the actin gene from the yeast Phaffia rhodozyma

The gene coding for actin from Phaffia rhodozyma was cloned and sequenced. The Phaffia actin gene contains four intervening sequences and the predicted protein consists of 375 amino acids. The structural features of the Phaffia actin introns were studied and compared with actin introns from seven fungi and yeasts with ascomycetous and basidiomycetous affinity. It was shown that the architecture of the Phaffia introns most resembles that of the basidiomycete Filobasidiella neoformans (perfect stage of Cryptococcus neoformans), whereas least resemblance occurs with the ascomycetous yeasts. Based on the intron structure, the ascomycetous yeasts can be accommodated in one group in that their splice site sequences are very similar and show less homology with the other fungi investigated, including Phaffia. It was demonstrated that the Phaffia actin introns cannot be spliced in Saccharomyces cerevisiae, which shows that the differences found in intron structure are significant. Alignment of the Phaffia actin gene with the actin sequences from the yeasts and fungi investigated showed a high level of homology both on the DNA level and on the protein level. Based on these alignments Phaffia showed highest homology with F. neoformans and both organisms were accommodated in the same cluster. In addition, the actin gene comparisons also supported the distant relationship of Phaffia with the ascomycetous yeasts. These results supported the usefulness of actin sequences for phylogenetic studies. The sequence presented here has been submitted to the EMBL data library under Accession Number X89898.     

红发夫酵母中3R,3’R-虾青素的分离纯化和结构鉴定

研究红发夫酵母中3R,3’R-虾青素的分离纯化工艺条件,并利用高效液相色谱串联大气压化学电离源质谱(high performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry,HPLCAPCI-MS)、核磁共振(nuclear magnetic resonance,NMR)和高效液相色谱-紫外光谱(high performance liquid chromatography-ultra violet,HPLC-UV)对纯化得到的虾青素结构进行鉴定。结果表明:利用细胞玻璃研磨器进行研磨提取、硅胶柱层析分离和结晶提纯相结合的方法,能够有效减少反式虾青素的异构化,得到的虾青素纯度高于95%。采用高效液相色谱-质谱仪(high performance liquid chromatography-mass spectrometry,HPLC-MS)、超导核磁共振谱仪(1H和13C NMR)以及Chiralpak IC手性固定化纤维柱分析,显示制备的反式虾青素几乎都以3R,3’R结构组成。     

基于亚甲基蓝还原法指导酵母的培养

亚甲基蓝还原实验法(MBRT)是一种新的评价酵母活力的方法,该文首次使用该方法考察了几种主要离子及无机氮源对酒精酵母生长的影响,并指导了劣质原料木薯渣糖化清液中高活力酵母的培养.从几种主要离子及无机氮源对酵母活力的影响结果初步分析得出如下结论,酵母生长过程中K+的作用最为明显,最适浓度为0.015mol/L;Mg2+是必须的,但当浓度超过0.004mol/L时,就会抑制酵母生长;低浓度的Na+与Ca2+对酵母生长有促进作用,最适浓度分别为0.0025mol/L、0.001mol/L.与硫酸铵相比,尿素是较好的无机氮源,最适浓度为2g/L.利用木薯渣糖化清液培养酵母时,添加2g/L的尿素及0.015moi/L钾离子后,可使培养出的酵母数增加6倍,酵母活力值为105s(空白为256s).     

Antioxidant activity of sugarcane molasses against 2,2′-azobis(2-amidinopropane) dihydrochloride-induced peroxyl radicals

Sugarcane molasses is a rich source of antioxidant materials with peroxyl radical scavenging effects. To explore the potent antioxidant activity of sugarcane molasses against 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced peroxyl radicals, 7 methanolic fractions of sugarcane molasses (F1–F7) were separated via bioassay-guided fractionation and evaluated by oxygen radical absorbance capacity (ORAC), cellular antioxidant activity (CAA), and oxidative DNA damage protective activity assays. The ORAC values of sugarcane molasses fractions ranged from 4399 to 6266 μmol TE/g, whilst the EC₅₀ values for CAA ranged from 3.7 to 5.9 μg/ml. Moreover, it was found that sugarcane molasses fractions, particularly F6 and F7, could protect against oxidative DNA damage caused by peroxyl radicals at an effective concentration of 100 μg/ml. Ten phenolic constituents were identified in the fractions, including known antioxidative compounds, viz., schaftoside, isoschaftoside, ferulic acid, p-coumaric acid, and p-hydroxybenzaldehyde.     

高产2,5-二甲基-4-羟基-3(2H)-呋喃酮(DMHF)酵母菌株的选育

从酒曲中筛选到1株高产2,5-二甲基-4-羟基-3(2H)-呋喃酮(DMHF)的酵母菌株(SX-21).高浓度NaCl和外源添加1,6-二磷酸果糖有利SX-21菌合成DMHF,其产量为100mg/L,达到文献报道的最高产量.经NTG诱变,筛选到1株突变株(NTG-SX-103),其产量提高到320 mg/L.SX-21菌株经18S rRNA鉴定为季也蒙毕氏酵母.     

Carbohydrate composition of developing grains of the high-lysine barley mutant (notch-2) and its parent (NP 113)

Barley variety NP 113 had higher accumulations of dry matter (DM) and starch than its high-lysine mutant, Notch-2, during grain development. Protein, amylose and amylopectin content per grain were lower in Notch-2 than NP 113. Reducing sugars, free glucose, total fructose and non-reducing sugars were 1.57–3.15-fold in Notch-2 grain as compared with NP 113 grain. DM, protein, starch, amylose and amylopectin per grain increased during grain development. Soluble sugar contents per grain were maximum at 24 days after anthesis. Lower DM accumulation in the Notch-2 mutant as compared with its parent, NP 113, is due to lower starch deposition. Further, the limitation of starch synthesis in the Notch-2 mutant is not due to any limitation in the supply of soluble sugar precursors.     

甲型H1N1流感解读

2009年3月底墨西哥暴发了"人感染猪流感"疫情,该疫情迅速在全球范围内蔓延,对人类造成了巨大的威胁,引起了世界各国的重视。本文介绍了上世纪以来全球暴发的主要流感疫情,并对此次流感疫情的病原学、流行病学、防控以及治疗措施做了详细介绍。     

利用有活力和无活力的啤酒废酵母生产酵母抽提物

以两种形态的啤酒废酵母(有活力的和无活力的)为原料,制备酵母抽提物。实验表明,采用自溶法处理啤酒废酵母液(有活力的),最佳作用条件是在温度45℃、pH 5.5下,自溶28 h,所得酵母抽提液的氨基氮含量为5.16 g/L,氨基氮得率为6.77%,产品得率为69.01%;酶采用酶水解法添加木瓜蛋白处理啤酒废酵母粉(无活力的),最佳作用条件是在木瓜蛋白酶添加量2.5%(以酵母干重计)、温度55℃p、H 4.5下,酶水解时间18 h,所得酵母抽提液的氨基氮含量为3.35 g/L,氨基氮得率为4.31%,产品得率为76.66%。     

Distribution of nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine] and 2-chloro-6-(dichloromethyl)-pyridine in red beet treated with nitrapyrin

In red beet (Beta vulgaris L. var. conditiva) the main degradation product of added nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine] has been shown to be 2-chloro-6-(dichloromethyl)-pyridine. The distribution of these two compounds in beet was also studied. The highest content of nitrapyrin residues (dry weight) was found in the root tips and the petioles; the peel contained more than the leaf laminae or other parts of the root. The higher the nitrapyrin content, the higher was the ratio of nitrapyrin to its dechloro form. No clear linear correlation was observed between the content of nitrapyrin and its dechloro form. The amounts of nitrapyrin residues in beet treated with Ca(NO₃)₂ were smaller than in the respective samples of beet fertilised with urea or NH₄NO₃.     

Kinetics and mechanism of As2S3(am) dissolution under N2

Arsenic presence in ground and surface waters poses a risk to ecosystem and human health; consequently, detailed information is needed on the factors that govern arsenic fate and transport in the environment. As2S3 is commonly found in hydrothermal and geothermal environments, hot springs, and in gold deposits, but the dominant reaction pathways and rates of dissolution are not well understood. The objectives of this research were as follows: (1) to understand the effect of pH on the dissolution of As2S3 under nitrogen-purged conditions, (2) to examine arsenic and sulfur speciation upon dissolution, and (3) to develop kinetic data for modeling the dissolution of As2S3. Studies were performed in batch reactors for a range of pH from 2 to 8. Results indicate that As2S3 dissolution is kinetically slow but very much dependent on pH. A J-shaped dissolution rate versus pH curve is described by the following expression: rate (microM h(-1)) = 0.9 + 610[OH-](0.3). Rate trends seem to follow As2S3 solubility as a function of pH. A surface dissolution mechanism is proposed, leading to dissolved As(III) species. Results indicate that under anaerobic conditions, an increase in pH will act to promote the arsenic sulfide dissolution rate.     

Comparative effect of red yeast rice (Monascus purpureus), red beet root (Beta vulgaris) and betanin (E‐162) on colour and consumer acceptability of fresh pork sausages packaged in a modified atmosphere

Fresh pork sausages containing natural colorants, red yeast rice powder (Monascus purpureus; Frame^®) or a crude red beet root (Beta vulgaris) juice or commercial betanin (E‐162), at different concentrations, were packaged in an atmosphere containing 80% O₂ and 20% CO₂ and stored in the dark for 20 days. The following parameters were measured at 4 day intervals: instrumental colour (CIE L*, a*, b*, a*/b*, C* and h*), reflectance spectra, sensory discoloration (trained panel) and acceptability and willingness to purchase (habitual and non‐habitual consumer panels) under two different lighting displays (standard fluorescent and Promolux^® lamp). The use of colorants improved the colour properties of fresh pork sausages. Sausages with red yeast rice, red beet root juice and betanin had lower L* and h* and higher a* and a*/b* values than control samples. The colour properties of sausages with red beet root were the closest to control sausages, while sausages with red yeast rice had significantly lower b* values. Both natural colorants and betanin protected sausages from discoloration and extended acceptability and willingness to purchase by about 4 days, according to evaluation by habitual consumers under two different types of lighting display. Therefore, red beet root juice may be envisaged as the most suitable natural colorant for use in fresh pork sausages. Copyright © 2005 Society of Chemical Industry     

Colour changes and consumer acceptability of bulk packaged pork retail cuts stored under O(2), CO(2) and N(2)

A centralised bulk packaging technique, utilising various gas mixtures, c. 100% CO₂ + oxygen scavenger, c. 80% O₂:20% CO₂ and c. 25% CO₂:50% N₂:25% O₂, was evaluated in terms of consumer acceptability and colour. The inclusion of an oxygen scavenger ensured that pork retail chops bulk packaged in a 100% CO₂ were as acceptable after 0, and 14 days bulk storage and subsequent retail display than chops stored in oxygen-enriched atmospheres. The study also indicated that a saturation level of 10 and higher indicated that the appearance of the pork chop was acceptable to the consumer panel. From the results of this study it is apparent that consumers find pork retail packs, bulk packaged in oxygen depleted atmospheres, as acceptable as pork chops stored in oxygen enriched atmospheres.     

Sequence of the yeast protein expression plasmid pEG(KT)

The plasmid pEG(KT) is a widely used plasmid for expressing high levels of GST fusion proteins in the yeast Saccharomyces cerevisiae. Unfortunately, a complete sequence file has been lacking, thus complicating efforts to design cloning projects or to modify the plasmid for other uses (e.g. exchanging selection markers, epitope tags or protease cleavage sites to remove the epitope tag). Here, the complete sequence of the pEG(KT) plasmid is reported, thus facilitating its use. Additionally, its use as a vector backbone for high‐level expression of a TAP‐tagged protein is shown. Copyright © 2009 John Wiley & Sons, Ltd.     

The display life of retail packaged pork chops after their storage in master packs under atmospheres of N(2), CO(2) or O(2) + CO(2)

Commercial, bone-in pork loins were divided into four portions. One portion of each loin was vacuum packaged, then stored at -1.5 °C. The other portions were each divided into three chops, which were retail packaged. The retail packs were master packaged under atmospheres of N(2), CO(2) or O(2) + CO(2) (2:1, v/v), then stored at 2 °C. The pork was assessed after storage for up to 42 days. At each assessment, a vacuum pack and a master pack of each type, each containing product from the same loin, were withdrawn from storage. The vacuum packaged portion was cut into three chops, which were retail packaged. The chops from all packagings were displayed in a retail cabinet which maintained average air temperatures between 3 and 6 °C. The chops were assessed twice daily until they were judged to be of undesirable appearance. After storage for 1 or 2 days, the chops from all master packs appeared less desirable than the freshly cut chops. After all longer storage times, chops from N(2) and CO(2) atmospheres appeared as desirable as freshly cut chops, as did chops from O(2) + CO(2) that were stored for up to 16 days. However, chops stored under O(2) + CO(2) for 21 days appeared undesirable. Chops stored under N(2) or O(2) + CO(2) developed spoilage odours, after storage for 28 or 21 days, respectively. Bacteria were more numerous on the fat than on the muscle tissue. The numbers of bacteria were 10(7) cfu cm(-2) on the fat surfaces of chops stored under vacuum or N(2) for 42 days. The numbers of bacteria were 10(6) cfu cm(-2) on the fat surfaces of chops stored under CO(2) for 42 days or under O(2) + CO(2) for 21 days. At those times, only lactobacilli were isolated from chops stored under CO(2), but small or large fractions of enterobacteria were present in the flora on chops stored under vacuum or N(2), respectively, while the flora on chops stored under O(2) + CO(2) contained large fractions of Brochothrix thermosphacta and Gram negative, strictly aerobic, spoilage bacteria. After all storage times, chops cut from vacuum packaged portions remained of desirable appearance when displayed for 48 hr or longer. Chops stored under N(2) or CO(2) for between 2 and 35 days, or under O(2) + CO(2) for between 4 and 12 days, retained a desirable appearance during display for the same times as the freshly cut chops. Off-odours were apparent in chops after their display following storage under vacuum or CO(2) for 21 days, or under N(2) or O(2) + CO(2) for 12 days. The numbers of bacteria on the fat surfaces of chops spoiled by off-odours were ≥ 10(5) cfu cm(-2). The flora on chops removed from display were generally enriched for B. thermosphacta, enterobacteria and/or Gram negative aerobes as compared with the flora on the chops when they were removed from the storage packs. Those data indicate that the storage life of master packaged, display ready pork will probably be severely limited by the poor hygienic condition of commercial products, to little more than 1 week for product stored under N(2) or O(2) + CO(2) or < 3 weeks for product stored under CO(2).     

高色价红曲米色调定向培养条件的研究

目的:探讨不同外加营养源对红曲米色价和色调的影响,以获得不同色调高色价红曲米的培养条件。方法:通过固体培养,利用不同红曲霉菌株进行复合无机盐添加浓度和复合维生素溶液添加浓度对红曲米色价和色调影响单因素试验,利用正交试验和方差分析选定优化的培养条件。结果:定量添加复合无机盐,产品色价比常规工艺提高100%以上,黄色组分明显提高;定量添加复合维生素溶液,对产品的色价影响不大,但可明显提高红色组分比例;通过正交试验和方差分析,确定出优化培养组合为116-R菌株、添加复合无机盐浓度0.2%和添加复合维生素溶液溶液浓度0.4%。结论:在红曲固体培养中,定量添加复合无机盐可得到偏黄色调高色价红曲米;在优化工艺条件下,可得到偏红色调高色价红曲米。     

Antibacterial properties of polypropylene textiles modified by poly(2-(N,N-dimethyloamino ethyl) methacrylate)

Polypropylene nonwoven fabrics samples were modified using poly(2-(N,N-dimethyloamino ethyl) methacrylate) (PDAMA) and silver-containing layers. The structure of the material after modification was confirmed using scanning electron mocroscope, energy-dispersive X-ray spectroscopy, Fourier Transfer Infrared Spectroscopy (FTIR), and electro-kinetic measurements. It was found that samples with external PDAMA layers have excellent activity against Staphylococcus aureus under dynamic contact conditions. In contrast, samples finished with deposited silver showed little antimicrobial effect. Antibacterial tests conducted under static conditions showed no antibacterial activity irrespective of the deposited layers.