液态发酵原位酶解糖化水稻秸秆工艺优化

为探究以原位酶解方式整合产酶菌株的发酵条件和酶解条件差异的可行性,以木质纤维结构典型的水稻秸秆为对象,里氏木霉为产酶微生物,通过研究液态发酵原位酶解糖化水稻秸秆,对发酵过程和酶解过程协同控制条件进行优化。结果显示,最优产酶发酵条件为水稻秸秆添加量30 g/L,发酵温度30℃,初始pH 6.5,发酵时间48 h;最优酶解条件为酶解pH 4.8,酶解温度50℃,酶解时间24 h,最终的秸秆比产糖量为0.350 g/g。通过在酶解阶段时补加少量的粗酶液(体积分数5%),可以提升最终的比产糖量,由0.332 g/g提升至0.400 g/g,约提升了20%。原位酶解糖化秸秆纤维素是实现水稻秸秆高效降解利用的可行方式。该研究可为纤维素酶解工艺提供技术参考,为秸秆纤维素资源化利用提供一定理论依据。     

酿醋固态废弃物的循环利用

采用先液后固的工艺酿醋时会产生大量富含纤维的废渣,该废渣具有很好的固态发酵特性。文中分析了该残渣的理化性质,以其为培养基,利用两种康氏木霉菌种固态发酵生产纤维素酶,并在此基础上水解醋渣中的纤维素获取还原糖。实验中研究了醋渣的理化性质和含水量、发酵时间以及氮源种类对纤维素酶合成的影响,获得了最高大于4IU/g的酶活。实验还证明了搅拌对水解具有促进作用,并最终获得了大于1%的还原糖溶液,将该溶液用于酿醋的糖化过程,可以取得可观的经济效益。     

抑制油菜菌核萌发的真菌分离及其生防研究初报

从武汉地区种植油菜的灰潮土土壤中分离得到三种真菌,分别是短帚霉（Scopulariopsis brevicaulis）、哈茨木霉菌（Trichoderma harzianum）和棘孢曲霉（Aspergillus aculeatus）。25℃共培养2周后发现,三种真菌的菌株对油菜核盘菌菌核的致死率分别为95.6%、78.9%和83.3%。用哈茨木霉菌Tri-1和棘孢曲霉Asp-1制作而成的生防制剂用于盆栽试验,结果表明盆栽芝麻（旱地作物）和水稻（水田作物）种植60d后,土壤中埋植的菌核萌发率分别下降27.3%和38.0%;继而后作油菜60d后,重新埋植的菌核萌发率分别下降16.1%和18.3%。     

绿色木霉液体发酵产纤维素酶的培养基优化

研究液体摇瓶发酵产纤维素酶的最佳培养基组成。通过单因素实验确定了培养基中氮源、碳源和诱导碳源的种类,采用正交试验确定了培养基中4种主要营养成分的组成。结果表明,摇瓶液体发酵产纤维素酶的最佳产酶培养基的种类和组成为：有机氮源蛋白胨和无机氮源硫酸铵的含量分别为11g／L和13g／L,葡萄糖6g/L,磷酸二氢钾10．5g/L,爆破的稻草为13．4g/L;纤维素酶的滤纸酶活为19．22U／mL。     

Fungistatic Activity of Ruta graveolens Extract and Its Allelochemicals

The biological activity of an extract of Ruta graveolens and its allelochemicals [8-methoxypsoralen (8-MOP), 5-methoxypsoralen (5-MOP) and 4-hydroxycoumarin] (previously isolated) was evaluated gainst pathogenic fungi: Fusarium solani, Pyrenochaeta lycopersici, and Trichoderma viride. In addition a rue lyophilized extract was also tested against Penicillium sp., Thielaviopsis basicola, and Verticillium dahliae. We determined that 5 g rue lyophilized extract/liter, the lowest concentration tested, inhibited the mycelial growth of P. lycopersici and V. dahliae by 63.6% and 47%, respectively, with IC₅₀ (the concentration required to inhibit growth 50%) values of 4.16 and 6.5 g/liter, respectively. Moreover, the rue lyophilized extract was shown to reduce radial growth of all six fungal species significantly at concentrations ranging from 5.0 to 40.0 g/liter. Mycelial growth of Penicillium sp. was promoted at 5.0 g lyophilized rue extract/liter and inhibited at higher concentrations. 4-OH coumarin had no effect on the growth of these fungi at concentrations ranging from 0.32 to 2.60 mg/liter, whereas 8-MOP and 5-MOP inhibited the mycelial growth of F. solani and T. viride with IC₅₀ values of 6 mg/liter (5-MOP) and 27 mg/liter (8-MOP) for both fungi, respectively. A mixture of 5-MOP and 8-MOP, tested at 64.8 mg/liter (as they naturally occur in the crude rue extract) significantly inhibited the growth of all tested fungal species. These results suggest potential role for the rue extract and its allelochemicals in controlling pathogenic fungal infections.     

木聚糖成分对木聚糖酶合成的影响

分别以两种含有不同组成的木聚糖为碳原进行产酶研究,结果发现木聚精成分对里氏木霉产木聚糖酶的效果具有重大影响。实验结果表明,用全组分的木聚糖（即用酒精等有机溶剂沉淀下来的木聚糖）诱导合成本聚糖酶的效果要比仅以水不溶性高聚合度木聚糖的效果好。当以全组分的木聚糖为碳源产酶时,不仅产酶周期缩短（仅需2．5d）,而且有利于提高木聚糖酶活力,酶活力、比活力、酶得率及酶产率分别达到34．27IU／mL、78．21;IU／g蛋白质、4895．7IU／g木聚糖和13708．0IU／L·d,酶活力和酶产率分别是以水不溶性木聚糖为碳源时的2．7倍和3．3倍。     

Simultaneous saccharification and fermentation of pretreated Antigonum leptopus (Linn) leaves to ethanol

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM‐9414 (Celluclast® from Novo) and Saccharomyces cerevisiae NRRL‐Y‐132 cells. Contrary to the saccharification optima (2.5% w/v substrate concentration, 50 °C, 4.5 pH, 40 FPU cellulase g⁻¹ substrate and 24 h reaction time), the SSF optima was found to be somewhat different (10% w/v substrate, 40 °C, 100 FPU cellulase g⁻¹ substrate and 72 h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with β‐glucosidase. © 1999 Society of Chemical Industry     

木霉及其代谢产物在果蔬保鲜中的应用研究进展

采后果蔬在贮藏运销过程中极易被病原菌侵染发生严重的腐烂,而木霉及其代谢产物能抑制果蔬中常见病原菌的生长繁殖,起到抑菌防腐保鲜的作用。木霉对生物体无毒、无害、对环境无污染,是一种有发展前景的生物保鲜法。该文对近年来木霉在果蔬保鲜中的应用研究进展进行综述,包含木霉的种类、木霉保鲜机理,木霉及代谢产物在果蔬保鲜上的应用效果和木霉商业化产品,以及利用木霉开发保鲜产品中存在的问题及解决方法。