蓝光作用下黑曲霉形态发育与消减文库的分析

以持续黑暗培养为对照,采用扫描电镜观察了蓝光对黑曲霉孢子发育的影响,结果表明蓝光处理使菌丝粗壮,孢囊增大。以黑暗培养至36h再经蓝光处理3~4h的菌丝为实验组,对应时间段的黑曲霉菌丝为对照组,采用抑制性消减杂交(SSH)方法,构建了蓝光作用下黑曲霉的差异表达基因的cDNA文库。阳性克隆菌落经PCR扩增出200~500bp差异表达基因的cDNA片段,对序列进行同源性分析后发现两个差异表达的未知基因片段,为进一步研究蓝光诱导下黑曲霉差异表达的未知基因的功能提供依据。差异表达的基因片段大都与黑曲霉线粒体氧化还原酶类同源;荧光定量PCR分析结果表明所选取的部分差异基因片段在蓝光诱导下表达量均有提高。     

Expression of recombinant Aspergillus niger xylanase A in Pichia pastoris and its action on xylan

The mature peptide of Aspergillus niger xylanase A (AnxA) was successfully expressed in Pichia pastoris at high levels under the control of AOX1 promoter. The recombinant AnxA (reAnxA) was secreted into culture medium. After 96-h 0.25% methanol induction, the activity of reAnxA in the culture supernatant reached the peak, 175 U/mg, which was 1.9 times as high as that of the native AnxA (92 U/mg). Studies on enzymatic properties showed that the optimum temperature and optimum pH of reAnxA were 50 degrees C and 5.0, respectively. The reAnxA was very stable in a wide pH range of 3.0-8.0. After incubation at the pH 3.0-8.0, 25 degrees C for 1h, all the residual activities of reAnxA were over 80%. The K(m) and k(cat) values for reAnxA were 4.8 mg/ml and 123.2s(-1), respectively. HPLC analysis showed that xylotriose was the main hydrolysis product of birchwood xylan and bran insoluble xylan by reAnxA.     

烟曲霉与宿主细胞相互作用规律的初步研究

目的研究烟曲霉侵入宿主细胞过程中的基本规律及宿主细胞肌动蛋白骨架的变化情况。方法利用表达绿色荧光的烟曲霉ATCC13073,研究烟曲霉侵入上皮细胞和被巨噬细胞吞噬随时间的变化规律。结果烟曲霉侵入吞噬细胞和非吞噬细胞的量随时间呈现完全不同的规律,烟曲霉侵入上皮细胞A549能力较弱,在7h后侵染量才有明显的增加,为原始接种量的（0.09±0.01）%。前3h,鼠巨噬细胞J774吞噬量迅速升高,然后侵染量缓慢下降。烟曲霉侵入宿主细胞过程中会引起宿主细胞肌动蛋白骨架的重排,侵入过程中伴有吞噬杯的形成。结论巨噬细胞吞噬烟曲霉和烟曲霉侵入上皮细胞规律有明显不同,侵入过程都伴随肌动蛋白骨架的重排。     

黄曲霉致鼻-眼-耳-脑侵袭性曲霉病的抗真菌治疗

报告1例抗真菌治疗有效的重症鼻、眼、耳、脑侵袭性曲霉病。患者男,37岁,因右眼眶肿物11a,右眼视力下降8a,失明伴头痛、头晕进行性加重1a就诊。11a前曾行右上颌窦根治术。临床表现为右眼球突出眼眶,角膜混浊,球结膜充血,眼球内可见白色絮状团块,并有大量透亮稀薄液态分泌物流出。右眼球不能自主活动,完全无光感。右眼眶下方、右上颌窦骨质缺损,塌陷。右侧外耳道骨壁、乳突均受累及。右侧鼻道及外耳道亦见较多透亮稀薄液态分泌物。右眼、右鼻腔、右耳分泌物真菌涂片均见菌丝及孢子,培养结果均为同一黄曲霉。经两性霉素B及伊曲康唑、氟胞嘧啶联合抗真菌治疗6周后,予口服伊曲康唑维持治疗近18个月,目前病变区显著缩小,头痛、头晕症状消失。     

L-xylo-3-hexulose reductase is the missing link in the oxidoreductive pathway for D-galactose catabolism in filamentous fungi

In addition to the well established Leloir pathway for the catabolism of d-galactose in fungi, the oxidoreductive pathway has been recently identified. In this oxidoreductive pathway, D-galactose is converted via a series of NADPH-dependent reductions and NAD(+)-dependent oxidations into D-fructose. The pathway intermediates include galactitol, L-xylo-3-hexulose, and d-sorbitol. This study identified the missing link in the pathway, the L-xylo-3-hexulose reductase that catalyzes the conversion of L-xylo-3-hexulose to D-sorbitol. In Trichoderma reesei (Hypocrea jecorina) and Aspergillus niger, we identified the genes lxr4 and xhrA, respectively, that encode the l-xylo-3-hexulose reductases. The deletion of these genes resulted in no growth on galactitol and in reduced growth on D-galactose. The LXR4 was heterologously expressed, and the purified protein showed high specificity for L-xylo-3-hexulose with a K(m) = 2.0 ± 0.5 mm and a V(max) = 5.5 ± 1.0 units/mg. We also confirmed that the product of the LXR4 reaction is D-sorbitol.     

A newly isolated fungal strain used as whole‐cell biocatalyst for biodiesel production from palm oil

A strain of Aspergillus niger isolated from atmospherically exposed bread and Jatropha curcas seed was utilized as a whole‐cell biocatalyst for palm oil methanolysis to produce fatty acid methyl esters (FAME), or biodiesel. The A. niger strain had a lipase activity of 212.58 mU mL^?1 after 144 h incubation at 25 °C with an initial pH value of 6.5, using 7% polypeptone (w/w on basal medium) as the nitrogen source and 3% olive oil (w/w on basal medium) as a carbon source. The A. niger cells spontaneously immobilized within polyurethane biomass support particles (BSPs) during submerged fermentation. Thereafter, the methanolysis of palm oil was achieved via a three‐step addition of methanol in the presence of BSPs‐immobilized with A. niger cells. The influence of water content, reaction temperature and enzyme concentration on reaction rate was investigated. An 8% water content and a temperature of 40 °C in the presence of 30 immobilized BSPs, resulted in an 87% FAME yield after 72 h.     

米曲霉葡萄糖淀粉酶基因glaB启动子研究概况

米曲霉表达系统与大肠杆菌表达系统和酵母表达系统相比有许多优点,目前绝大多数研究都关注如何提高米曲霉在液体发酵条件下生产蛋白质,但米曲霉在固体培养条件下生产多种蛋白的能力比在液体培养条件下强,这不仅与米曲霉在不同培养条件下的生长形态有关,还与不同代谢途径中特定基因的调控因子如启动子的特性有关。米曲霉葡萄糖淀粉酶基因glaB在固体培养条件下的表达效率明显高于其在液体培养条件下的效率,以葡萄糖淀粉酶基因glaB为例,综述了glaB启动子的研究概况,为今后更好地利用这类启动子提供参考。     

几丁质酶产生菌筛选鉴定及产酶性能研究

从土壤样品中筛选得到一株高产几丁质酶菌株C65-2,经形态学观察和18S rDNA序列测定,鉴定为Aspergillus fumigatus,对产酶培养基进行初步优化,测得最高酶活可达6.9U/ml,酶活力较优化之前提高了210%。酶学性质研究表明该几丁质酶分子量约为20kDa,酶在60℃下保温50min酶活降为0,最适酶反应温度是55℃,酶反应最适pH为7.0,Mg2+,Cu2+对酶反应有促进作用,Fe3+对酶反应有抑制作用。     

茶树内生真菌混合培养增强对植物病原真菌的拮抗作用

采用分离自健康茶树叶片组织中的2株内生真菌,长枝木霉CSN-18和曲霉CSN-3,研究了单独培养和混合培养条件下培养原液与培养原液乙酸乙酯萃取液对植物病原真菌的抑制作用。与2菌株单独培养相比,混合培养对稻瘟病菌Magnaporthe grisea、茶花褐斑病菌Phyllosticta camelliaecola和茶云纹叶枯病菌Guignardia camellia等8种植物病原真菌的抑制作用明显增强。混合培养原液的乙酸乙酯萃取液对茶花褐斑病菌、稻瘟病菌和茶云纹叶枯病菌的抑制率分别为79.48%±1.46%、76.99%±0.91%和71.51%±4.93%;对茶花褐斑病菌、茶云纹叶枯病菌和稻瘟病菌孢子萌发的抑制率分别为100.00%、90.90%±2.59%和84.00%±5.29%。混合培养原液对茶花褐斑病菌菌丝生长的抑制作用也比两菌株的单独培养液有明显增强;在低浓度下,混合培养原液对茶花褐斑病菌的孢子萌发有促进作用;但浓度超过40%,则明显抑制茶花褐斑病菌孢子的萌发。