Fast and efficient alkaline peroxide treatment to enhance the enzymatic digestibility of steam-exploded softwood substrates.

The enzymatic digestibility of steam-exploded Douglas-fir wood chips (steam exploded at 195 degrees C, 4.5 min, and 4.5% (w/w) SO(2)) was significantly improved using an optimized alkaline peroxide treatment. Best hydrolysis yields were attained when the steam-exploded material was post-treated with 1% hydrogen peroxide at pH 11.5 and 80 degrees C for 45 min. This alkaline peroxide treatment was applied directly to the water-washed, steam-exploded material eliminating the need for independent alkali treatment with 0.4% NaOH, which has been traditionally used to post-treat wood samples to try to remove residual lignin. Approximately 90% of the lignin in the original wood was solubilized by this novel procedure, leaving a cellulose-rich residue that was completely hydrolyzed within 48 h, using an enzyme loading of 10 FPU/g cellulose. About 82% of the originally available polysaccharide components of the wood could be recovered. The 18% of the carbohydrate that was not recovered was lost primarily to sugar degradation during steam explosion.     

压力蒸汽灭菌指示剂的筛选和效果验证

利用结晶物质在一定温度下熔融的特性,通过对几种灭菌指示剂内容物进行熔点测定,选出苯甲酸化学试剂和升华硫化学试剂作为高压灭菌指示剂和灭菌参考指示剂。试验表明,这两种指示剂终点明确,简便快速,价格便宜,能满足121℃高压灭菌的温度要求,可以对高压灭菌的日常监测提供依据。     

Effects of colchicine on anther and microspore culture of bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

The aim of this work was to study the effects of colchicine application on chromosome doubling and androgenic response in anther and microspore culture of different bread wheat genotypes. Colchicine was applied during a mannitol stress pretreatment or during the first 48 h of culture at concentrations of 0, 150 and 300 mg l⁻¹. When colchicine was applied during stress pretreatment, the percentage of doubling depended on genotype and concentration. A significant increase in doubling was observed with 300 mg l⁻¹ in the low androgenic responding cv. Caramba. Colchicine incorporation during the first hours of culture improved percentage of doubling in all genotypes, in both anther and microspore culture. Application of 300 mg l⁻¹ colchicine improved the percentage of doubling in the two low responding genotypes, to 118% of control in DH24033, and 75% in Caramba in microspore and anther culture, respectively. Concerning the androgenic response, the effect of colchicine on embryo formation and percentage of green plants depended on the genotype and on the culture method. In cv. Pavon, a 2- and a 3-fold increase in percentage of embryogenesis and green plants, respectively, were obtained with 300 mg l⁻¹ colchicine in microspore culture. However, no significant differences in these two variables were observed in anther culture. The number of green doubled haploid (DH) plants reflects the index of success of the procedure. Regardless of the culture method, when colchicine was incorporated during the first hours of culture, the number of green DH plants increased significantly in three of four genotypes. These results confirm the usefulness of colchicine application during the first hours of culture in wheat breeding programs.     

Enhanced enzymatic hydrolysis of hydrothermally pretreated empty fruit bunches at high solids loadings by the synergism of hemicellulase and polyethylene glycol

In enzymatic hydrolysis, high lignocellulose loadings are required to obtain high sugar titers. However, the high solids loadings limit enzymatic hydrolysis. In this study, to overcome this limitation, the promoting and synergistic effects of the accessory agents of hemicellulase (i.e., Cellic HTec2) and polyethylene glycol (PEG) 8000 were investigated in the enzymatic hydrolysis of hydrothermally pretreated empty fruit bunches (EFBs). After the optimal addition of Cellic HTec2 and PEG, high enzymatic digestion of the pretreated EFBs was achieved owing to their synergistic effects, even at high solids loadings. For example, the enzymatic digestibility of pretreated EFBs at a 21.7% (w/v) solids loading with 10 FPU of Cellic CTec2/g glucan reached 72.5% when 2.7 mg of Cellic HTec2/g glucan and 62.5 mg of PEG/g glucan were used as the accessory agents. These results suggested that the optimal addition of accessory agents is effective for the enhanced hydrolysis of lignocellulose using even a commercial cellulase preparation.     

NaCl预处理提高两种铁线子属果树耐寒性的研究

古巴牛乳树和人心果是铁线子属具有开发前景的热带珍稀果树。为了将这两种果树在亚热带地区推广种植,该研究在已知这两种果树具有较高耐盐性的研究基础上,采用盆栽试验法,对3年生幼苗设置10‰、20‰的Na Cl预处理,一定时间后依次进行9℃、3℃的低温胁迫,分析比较其叶片中多种渗透调节物质含量及抗氧化酶活性的变化。结果表明:两种果树叶片渗透调节物质含量及抗氧化酶活性的变化趋势是一致的。在9℃、3℃的低温胁迫下,10‰、20‰Na Cl预处理叶片中的游离脯氨酸、可溶性糖和可溶性蛋白质含量及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均明显高于对照组,同一低温条件下,耐寒性强弱依次为10‰20‰对照(CK)。因此推断Na Cl预处理可以有效提高铁线子属果树的耐寒性,其中以10‰预处理最为理想,此时古巴牛乳树和人心果的实际盆土盐度分别为2.46‰、1.14‰。     

Isolation of polyphenols from spent coffee grounds and silverskin by mild hydrothermal pretreatment

In this study, a new method for isolation of polyphenols (PP) from spent coffee grounds (SCG) and coffee silverskin (CS) is described. The method consisted of a mild hydrothermal pretreatment at 120°C, for 20 min, using a liquid-to-solid ratio of 20 mL/g. PP (determined as gallic acid equivalents, GAE) were the most abundant components in the extracts produced by this method, corresponding to 32.92 mg_GAE/g_SCG and 19.17 mg_GAE/g_CS, among which flavonoids corresponded to 8.29 and 2.73 mg quercetin equivalents/g of SCG and CS, respectively. Both extracts presented antioxidant activity but the results were higher for SCG extract, probably due to the highest content of PP present. Negligible effects (less than 1% solubilization) were caused by the hydrothermal pretreatment on cellulose, hemicellulose, and protein fractions of these materials. Some mineral elements were present in the extracts, with potassium being the most abundant. Hydrothermal pretreatment under mild conditions was demonstrated to be an efficient method to recover antioxidant PP from coffee residues.     

Enhanced poly(L-malic acid) production from pretreated cane molasses by Aureobasidium pullulans in fed-batch fermentation

Poly(L-malic acid) (PMA) is a natural polyester with many attractive properties for biomedical application. However, the cost of PMA production is high when glucose is used as a carbon source. To solve this problem, cane molasses as a low-cost feedstock was applied for the production of PMA. Six pretreatment methods were applied to cane molasses before fermentation. Pretreatment with combined tricalcium phosphate, potassium ferrocyanide, and sulfuric acid (TPFSA) removed significant amounts of metal ions from cane molasses. The PMA concentration increased from 5.4?g/L (untreated molasses) to 36.9?g/L (TPFSA-pretreated molasses) after fermentation in shake flasks. A fed-batch fermentation strategy was then developed. In this method, TPFSA-pretreated cane molasses solution was continuously fed into the fermentor to maintain the total sugar concentration at 20?g/L. This technique generated approximately 95.4?g/L PMA with a productivity of 0.57?g/L/hr. The present study indicated that fed-batch fermentation using pretreated cane molasses is a feasible technique for producing high amounts of PMA.     

The Fragrance Components of the Jasrninnm sambac (L.) Alton collected by Simultaneous Steam Distillation and Solvent Extraction

The volatile fragrance components of Jasminum sambac (L.) Aiton flower were collected by a modified simultaneous steam distillation and solvent extraction apparatus (SDE). The obtained extract was concentrated to 100 μL by the gas entrainment method in which the extract was distilled under reduced pressure with the influence of a steam of nitrogen. The concentrate was analyzed by GC-MS with PEG-20 M capillary column, and the Kovats indexes were determined at the same time whereby the nalkanes were added into extract. 28 compounds were identified. The major components were: linalool, benzyl acetate, ciscaryophyllene, cis-3-benzyl benzoate, methyl anthranilate and indole. These results show the components of the extract have no qualitative difference from absolute oil. The advantages of the above procedure were discussed in detail.     

2,4-Dichlorophenoxyacetic acid and kinetin in anther culture of cultivated and wild oats and their interspecific crosses: plant regeneration from A. sativa L.

The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin was studied in anther culture of oat Avena sativa L., wild oat A. sterilis L. and progeny of crosses between them. A high 2,4-D concentration (5–6 mg l^–1) increased embryo production in genotypes of both species and promoted plant regeneration in anther cultures of A. sterilis and A. sativa×A. sterilis progeny, while kinetin caused severe browning. However, a low concentration of kinetin was essential for initiation of regenerable embryos from anther culture of A. sativa cv. Kolbu: one green and one albino plant were produced. In addition, medium containing W₁₄ salts gave higher regenerant recovery compared with medium containing Murashge and Skoog salts, when cross progeny were tested. Received: 6 March 1998 / Revised: 30 April 1998 / Accepted: 16 November 1998     

玉米芯发酵法生物制氢

在批式培养试验中, 以牛粪堆肥为天然产氢菌源, 玉米芯为底物, 通过厌氧发酵生产氢气。系统考察了底物预处理条件、初始pH值和底物浓度对玉米芯产氢能力的影响。在初始pH 8.0, 1.0%盐酸预处理底物30 min, 底物浓度10 g/L的最佳产氢条件下, 玉米芯最大产氢能力〔每克TVS（总挥发性固体物）产氢量〕和最大产氢速率（每克TVS每小时产氢量）分别为107.9 mL /g、4.20 mL/g·h-1。玉米芯经酸预处理后半纤维素含量由42.2%下降至3.0%, 而酸预处理的玉米芯产氢前后纤维素、半纤维素和木质素含量只有少量变化。产氢菌主要用酸预处理产生的可溶性糖产氢, 故底物的酸预处理对玉米芯的发酵产氢非常重要。用傅里叶变换红外光谱(FTIR)分析显示酸预处理和产氢过程中玉米芯的特征峰发生变化, 酸预处理过程降解了底物纤维素的无定形区和半纤维素, 产氢微生物对纤维素的结晶区有破坏作用。