Barley anther culture: Pretreatment on mannitol stimulates production of microspore-derived embryos

A period of four days preincubation at 25 °C on a medium containing mannitol was found to be superior to those pretreatments requiring incubation at 4 °C. In addition, the yield of green plants was improved by orienting anthers flat on the medium during mannitol preincubation, and reducing the number of anthers cultured per dish.     

不同预处理及发酵方式对提高蔗渣发酵产物蛋白含量的研究

采用不同的预处理方法对蔗渣进行预处理,并测定了其各个组分的含量。利用霉菌对蔗渣进行微生物降解,并讨论了不同发酵方式对产物中蛋白含量的影响。结果表明,木霉与热带假丝酵母共发酵时蛋白含量最高,为17．74％。     

Mild alkaline/oxidative pretreatment of wheat straw

A new mild alkaline/oxidative pretreatment of wheat straw prior to enzymic hydrolysis was carried out. It consists of a first alkaline (1% NaOH for 24 h) step, which mainly solubilises hemicellullose and renders the material more accessible to further chemical attack, and a second alkaline/oxidative step (1% NaOH and 0·3% H₂O₂ for 24 h), which solubilises and oxidises lignin to minor polluting compounds. The entire process was carried out at low temperature (25–40°C) using a low concentration of chemicals, resulting in a relatively low cost and waste liquors containing only trace amounts of dangerous pollutants derived from lignin. Recovery of cellulose after the double pretreatment reached 90% of that contained in the starting material, with a concomitant 81% degradation of lignin. The action of a commercial cellulase on the cellulose obtained produced a syrup with a high concentration of reducing sugars (220 mg/ml), of which a large percentage was glucose.     

Purification and culture characteristics of 36 benthic marine diatoms isolated from the Solthörn tidal flat (Southern North Sea)

Marine benthic diatoms growing in biofilms on sediment surfaces generally occur associated with heterotrophic bacteria, whereas modern molecular techniques and analyses of species‐specific physiology create a demand for axenic cultures. Numerous benthic diatoms were isolated from surface sediments during a monitoring of the Solthörn tidal flat (southern North Sea, Germany) from May 2008 to May 2009. Of these, around 50% could be purified from the accompanying heterotrophic bacteria using different antibiotics combined with physical separation methods (vortexing, ultrasound). Overall, seven different antibiotics were tested at different concentrations, and a best working protocol was developed. The axenic strains were stable on average for only around 15 months, indicating a symbiotic interaction between the benthic diatoms and the associated bacteria. While most short‐term effects during the purification process were restricted to differences in growth rates among xenic and axenic diatom strains, long‐term cultivation led to distinct changes in cell volumes and growth characteristics of the axenic strains.     

重金属污染土壤总DNA提取方法的研究——土壤预处理和硫酸铵铝在DNA提取中的应用

【目的】从土壤中获得高纯度、高得率和完整性好的总DNA,为重金属污染土壤微生物群落多样性的分析奠定基础。【方法】将一定浓度的硫酸铵铝增补入DNA提取液中,分别联合不同方式的土壤预处理,对所提取的土壤总DNA进行完整性、纯度和得率分析。【结果】TENP-AlNH4(SO4)2法、ABG-AlNH4(SO4)2法、Wash-AlNH4(SO4)2法和试剂盒4种提取方法获得的DNA片段均在23 kb左右,总DNA完整;Wash-AlNH4(SO4)2法提取的DNA纯度较高,A260/A230达到2.00,A260/A280达到1.62;ABG-AlNH4(SO4)2法的DNA得率最高,达到1 010μg/g土壤;这两种方法提取的DNA在纯度和浓度上均达到后续PCR等分子实验要求。通过扩增提取的土壤总DNA中16S rRNA基因,表明合适浓度的硫酸铵铝能有效去除土壤中的PCR干扰因子。【结论】本研究将土壤的预处理和一定浓度的硫酸铵铝联合使用,获得理想的重金属污染土壤的总DNA。     

Do furanic and phenolic compounds of lignocellulosic and algae biomass hydrolyzate inhibit anaerobic mixed cultures? A comprehensive review

Nowadays there is a growing interest on the use of both lignocellulosic and algae biomass to produce biofuels (i.e. biohydrogen, ethanol and methane), as future alternatives to fossil fuels. In this purpose, thermal and thermo-chemical pretreatments have been widely investigated to overcome the natural physico-chemical barriers of such biomass and to enhance biofuel production from lignocellulosic residues and, more recently, marine biomass (i.e. macro and microalgae). However, the pretreatment technologies lead not only to the conversion of carbohydrate polymers (ie cellulose, hemicelluloses, starch, agar) to soluble monomeric sugar (ie glucose, xylose, arabinose, galactose), but also the generation of various by-products (i.e. furfural and 5-HMF). In the case of lignocellulosic residues, part of the lignin can also be degraded in lignin derived by-products, mainly composed of phenolic compounds. Although the negative impact of such by-products on ethanol production has been widely described in literature, studies on their impact on biohydrogen and methane production operated with mixed cultures are still very limited.     

Embryo formation and regeneration in Triticum turgidum ssp. durum anther culture

Field grown Moroccan genotypes of durum wheat were tested for their capacity for androgenesis. The cultivar '1726' gave the best results with 25.37% embryos (embryos per 100 anthers) whereas '1715' was the least favorable with 3.17%. Spikes excised in early spring gave the best percentages of embryos. A chemical hybridizing agent (CHA) treatment of donor plants doubled the yield of embryos for almost all genotypes. A thermal pretreatment of spikes at 3 °C for 8 days improved androgenetic capacity. The C17 medium for embryo induction was consistently the best. Two media containing potato extract (BPTG and P2) gave intermediate results and N6 gave the lowest response. The highest percentage regeneration was obtained on C17 medium containing regulatory and amino substances, using embryos about 1 mm in diameter transferred to regeneration medium 21 days after their appearance. Regenerated plants were albino except for two green plants from cultivars 'Marzak' and '1658'. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enhancement of Pfr-mediated responses by light pretreatments: persistence of the pretreatment effects

Abstract. In germinating seedlings of Sinapis alba , nitrate reductase activity is under phytochrome control and becomes accessible to phytochrome at about 15 h from sowing. The induction of the enzyme with pulses of light is strongly affected by pretreatments given prior to 15 h, also acting through phytochrome. It is shown that the effects of these pretreatments can persist undiminished for a considerable time (>40 h) but do not alter the pattern of the subsequent responsiveness to P_fr. The nitrate reductase response is compared with other data pertaining to a similar response.     

不同种子预处理对10种沙拐枣植物萌发的影响

为了确定沙拐枣植物种子的萌发特性及最优播前预处理方法,在实验室条件下,对10种沙拐枣植物的种子进行了磨砺、硫酸和热水浸泡、冷藏、种子浸出液处理,然后进行发芽实验研究。萌发实验的结果表明,10种沙拐枣植物对于不同的种子预处理,均表现出相似的萌发反应。磨砺、硫酸浸泡和冷藏处理对种子萌发有明显地促进作用。与对照相比,种子浸出液处理对种子的发芽率、发芽速度均具有明显地抑制作用,并能增强种子的休眠。冷藏处理具有打破有活力的种子休眠、促进种子萌发的作用,但它与热水浸泡处理一样,对有活力种子表现出一定的致死作用。沙拐枣植物的萌发模式在不同种子预处理问均表现出明显的差异性。机械磨擦和硫酸处理能够促进种子的萌发率及发芽势。泡果沙拐枣(Callingonum junceum)在本项实验中表现出很强的萌发能力。     

Pretreatment and enzymic saccharification of water hyacinth cellulose

Water hyacinth was pretreated, under variable conditions, with NaOH, alkaline H₂O₂, peracetic acid and sodium chlorite. Combined pretreatments included sodium chlorite with each of NaOH, alkaline H₂O₂ and peracetic acid. Combined pretreatment with 0.1% NaClO₂ for 1 h at 100 °C and peracetic acid at 100 °C for 15 min afforded the most promising sample. The recovered lignin, cellulose and hemicellulose of this sample was 2.56%, 96.69%, and 81.38%, respectively. The same sample, by cellulase hydrolysis showed the highest cellulose conversion (80.8%) and 90% saccharification using 200 FPU/g substrate. Some ambient factors affecting saccharification of pretreated water hyacinth were investigated. Enzymic saccharification after 6 h was about 50% of that at 48 h, indicating a slow hydrolysis rate by time. Addition of 8% glucose at the beginning of the enzymic hydrolysis decreased the saccharification to about its half while addition of 8% ethanol brought about complete inhibition of the enzyme. Addition of cellobiase to the reaction mixture increased cellulose conversion and saccharification by 10%.