磁场调控丝状真菌生长发育及代谢产物合成的研究进展

磁场作为一种普遍存在的环境因子,影响着微生物的生长及代谢。丝状真菌是一类重要的异养型真核生物,在食品工业和生物医药领域有广泛应用。目前,采用磁场处理丝状真菌已成为工业重要研究目标,而红曲霉、黑曲霉和黄曲霉是丝状真菌常用的典型菌种。本文分别介绍了磁场调控红曲霉、黑曲霉、黄曲霉等丝状真菌生长及代谢的研究进展,通过不同磁场类型、作用时间、磁场强度等多种磁场参数分析三种丝状真菌磁场磁效应,阐述了磁场对三种典型丝状真菌的生长发育及其代谢物影响规律和代谢关系。探讨了磁场多方面多层次调控丝状真菌代谢产物的研究思路,下一步将展开说明磁场对丝状真菌的菌丝体形态结构、酶结构变化以及转录组学的作用机制,为探明磁场调控丝状真菌代谢产物合成机制提供参考,同时为丝状真菌的综合利用和开发提供理论基础。     

碳源对一株酵母菌产生纤维素酶的影响

对分离的一株产纤维素酶的假丝酵母进行了研究.为了探讨培养基中碳源对该菌株产纤维酶的影响,文章以蔗糖、葡萄糖、山梨糖、木糖、果糖等可溶性和细菌纤维素、蔗渣、椰棕、玉米芯等不可溶性碳源分别进行了产酶效果的实验研究.结果表明细菌纤维素0.9%、椰子水5%、(NH4)2SO4 0.2%;KH2PO40.1%、MgSO4 0.05%、CaCl2 0.03%、pH自然,作为产酶培养基,所产纤维素酶活可达76.68U/mL.     

丝状真菌全局转录调控因子研究现状及发展

丝状真菌的次级代谢产生的有益或有害于人类的代谢产物,已成为生物医药和食品发酵领域的研究热点。丝状真菌的次级代谢是一个复杂的、多层次的调控过程,其中全局性转录调控因子发挥着至关重要的作用。当面临不同环境胁迫情况时,丝状真菌通过启动全局性转录调控因子对菌体生长、繁殖及相关主代谢途径和次级代谢进行适应性转录调控,从而影响不同的次级代谢产物合成和分泌。针对已发现的丝状真菌不同类型全局性转录调控因子及其在提高菌体耐受性、调控菌体生长形态及次级代谢产物合成的研究现状展开论述,为丝状真菌在发酵生产过程中提高菌株耐受性和增加目的代谢产物等方面提供研究思路。     

利用等离子诱变技术改造纤维素酶生产丝状真菌工业菌株

为了降低纤维素乙醇工业中的用酶成本,必须改良纤维素酶生产菌株,提高丝状真菌的纤维素酶生产效率。我们首先对草酸青霉的工业菌株进行紫外线诱变,通过纤维素双层平板初筛和摇瓶复筛,获得了纤维素降解能力有一定的提高的草酸青霉,随后再对紫外线诱变过的菌株进行等离子诱变,摇瓶培养,依据胞外蛋白浓度进行初筛,继续摇瓶复筛,得到了一株较为理想的变异菌株PQ-5,滤纸酶活(FPA)较出发株提高28.2%。这是第一次报道采用常压室温等离子体(ARTP)诱变技术可有效提高草酸青霉纤维素酶生产能力。     

苹果酸-乳酸发酵过程酒酒球菌碳源代谢分析研究进展

葡萄酒苹果酸-乳酸发酵(malolactic fermentation,MLF)中碳源物质的利用及其产物、副产物的形成对葡萄酒感官品质有很大影响。其中,酒酒球菌参与的葡萄糖代谢、有机酸代谢及相关产物的形成和流向对葡萄酒MLF影响重大,决定着葡萄酒的最终品质。环境条件也是影响酒酒球菌生长的重要因素。苹果酸、柠檬酸和pH值三者在一定范围内相互作用,影响酒酒球菌生长。SO2会抑制酒酒球菌细胞ATP酶活性,高含量乙醇能增加细胞膜流动性,这些都会阻碍酒酒球菌生长,而溶解氧不仅不利于酒酒球菌生长,还会使醋酸菌等有害微生物大量繁殖,乙酸、双乙酰等不良产物含量上升,使葡萄酒败坏。本文就葡萄酒MLF过程中酒酒球菌的苹果酸代谢、柠檬酸代谢、糖代谢和乳酸、乙酸、双乙酰、乙偶姻等的产生途径及影响因素进行总结。     

大曲丝状真菌的物种多样性及其次级代谢产物的合成潜力

通过高通量测序研究了大曲中丝状真菌的物种多样性,并结合荧光定量PCR对丝状真菌进行了定量分析;此外,还通过纯培养对高温曲中的丝状真菌进行筛选,并使用简并引物对分离株的次级代谢产物合成酶基因进行扩增。结果表明,Thermomyces属的丰度随大曲温度的升高而上升,而Aspergillus属的丰度随大曲温度的升高而下降;丝状真菌在大曲中的生物量同样随大曲温度的升高而下降;利用纯培养的方法从高温大曲中分离得到50株丝状真菌,隶属于10个属(Aspergillus、Monascus、Byssochlamys、Lichtheimia、Rhizomucor、Mucor、Arthrinium、Alternaria、Thermomyces和Rasamsonia),并且这些丝状真菌含有多种次级代谢产物合成酶表达基因;大曲来源的丝状真菌具有强大的次级代谢产物合成潜力,大曲是优良的微生物和次级代谢产物生物合成的基因库,可能成为挖掘新天然产物的新来源。     

谷物酚酸合成途径及代谢调控研究进展

酚酸广泛存在于高等植物中,大量研究表明酚酸具有较强的抗氧化、抗炎、抗癌、提高免疫力等多种药理活性。近年来,随着全谷物概念的深入,谷物酚酸成为食品研究领域热点之一。本文综述了谷物中酚酸的存在形式及组成分布、生物合成途径及代谢调控,并对其研究方向进行了展望。     

红曲色素代谢调控的研究进展

针对目前红曲色素代谢调控研究中的情况,介绍了气体、营养物质的选取、水分含量、pH值和化学环境的环境条件对红曲色素代谢的影响。说明了红曲色素生产中的几种代谢调控方法：对大气环境的调控、对桔霉素的代谢途径的调控、筛选不产桔霉素的菌种及应用固定化法生产。对控制过程中建立的数学模型作了简单介绍。     

链霉素发酵的代谢调控育种及研究进展

链霉菌在生产抗生素方面的特殊作用使它成为放线菌中遗传育种的核心,近年来的进展主要在于原生质体融合、脂质体的使用、质粒及其它载体的发现和克隆技术工业应用.本文综述了链霉素生物合成途径、代谢调节机制、链霉素发酵的代谢调控育种及其进展.     

啤酒酿造中双乙酰的代谢调控的研究进展

双乙酰是啤酒酿造过程中酵母合成缬氨酸和亮氨酸的代谢途径中产生的啤酒风味缺陷物质。简要综述了啤酒酿造中双乙醚的代谢调控的研究进展。     

Recent studies of protein secretion by filamentous fungi

Filamentous fungi have been widely exploited for the homologous and heterologous protein production, because of the high capacity of their protein secretion machinery. However, the production of heterologous proteins is often limited while the production of homologous proteins can be very high. Various researches have reported the methods for overcoming this problem and some techniques, such as the fusion gene system, improve the production of heterologous proteins. Recently, the molecular biological study of solid-state culture attracts the attention, because the long history of biological studies has shown that the productivity of protein in the solid-state culture frequently exceeds the productivity of protein in the submerged culture. The recent researches of solid-state culture have revealed the new aspects of protein production in filamentous fungi. Solid-state specific gene expression was observed in the glaB and pepA genes of Aspergillus oryzae. A GC-box and HSE element of the glaB promoter region affected solid-state specific gene expression of this gene. Solid-state culture-specific release of enzymes from the cell wall was also observed in the production of beta-glucosidases in Aspergillus kawachii. Extracellular soluble polysaccharide (ESP) from A. kawachii was concerned with the location of beta-glucosidases. Moreover, ESP and the cell wall fraction of A. kawachii were shown to be involved in the stability of beta-glucosidases. The knowledge of the molecular biology of solid-state culture should provide new approaches for the production of both homologous and heterologous proteins in both submerged culture and solid-state culture of filamentous fungi.     

丝状真菌对3-苯氧基苯甲酸降解能力及特性的研究

以实验室保存的产黄青霉QH、米曲霉MAY、高大毛霉MHC、黑根霉GH、啤酒酵母Y1和假丝酵母Y2等6株真菌为出发菌株,在PD培养基中振荡培养48h,QH、MAY、MHC和GH对100mg/L 3-苯氧基苯甲酸（3-PBA）的降解率分别为77.12%、77.19%、55.46%和72.38%;而Y1和Y2对3-PBA无降解。在MM培养基中振荡培养48h,6株真菌均未生长,对3-PBA无降解。14株已知霉菌和从环境中分离的12株霉菌及4株酵母菌进行3-PBA降解实验,测试的26株霉菌在PD培养基中对3-PBA均有不同程度的降解,4株酵母菌未有降解,推测丝状真菌可能具有降解3-PBA的共性。由HPLC谱图可知,不同种类霉菌降解3-PBA的产物不同,可能有不同的3-PBA降解途径与机制。此外,3-PBA对本研究所测试的丝状真菌的生长都有一定的抑制作用。      

碳源对裂殖壶菌类胡萝卜素积累的影响

本文研究了葡萄糖和甘油分别作为单一碳源对裂殖壶菌ATCC20888发酵过程中脂质和类胡萝卜素变化特性的影响,初步讨论了在裂壶藻中类胡萝卜素与脂质代谢之间的关系。结果表明,作为碳源,葡萄糖相比甘油更有利于菌体生长,而甘油更有利于脂质,尤其是DHA的积累。此外,碳源不同,总类胡萝卜素的含量及组成也会因此而不同。当发酵7 d时,以甘油作碳源发酵得到的β-胡萝卜素含量是以葡萄糖作碳源时的3.25倍。而以葡萄糖为碳源发酵得到的番茄红素和虾青素含量分别是甘油发酵1.60倍和2.81倍。并且,在不同碳源发酵条件下,进入脂质反耗阶段后,菌体内PKS途径的脂肪酸比例均与总类胡萝卜素含量呈正相关,因此表明类胡萝卜素对细胞内多不饱和脂肪酸的稳定性发挥着积极作用。      

明串珠菌的碳代谢调控研究进展

明串珠菌是韩国泡菜、德国泡菜和腌菜等发酵蔬菜中的优势细菌,保持产品的质量中起着重要作用,在各种乳制品中也有它的应用,因此近年来在内地对其的研究开始活跃.为明串珠菌的碳代谢调控研究提供第一手资料,该文综述了明串珠菌的碳代谢途径、发酵调控和基因表达调控.     

不同碳源诱导绿色木霉产双功能酶的表达差异分析

采用酶活力分析、SDS-PAGE、RT-PCR等手段对不同碳源诱导Trichodrma viride XW01产双功能酶的差异表达进行分析。结果表明,酶的合成受培养基中碳源的影响。绿色木霉在不溶性多糖类独立碳源诱导条件下对双功能酶CCBE(66kDa)的合成量要优于可溶性碳源;其中羧甲基纤维素钠(CMC-Na)为碳源时发酵液中壳聚糖酶活力最高,发酵96d后活力达8.29U/mL;壳聚糖次之,麸皮再次之;3种碳源均直接诱导绿色木霉产壳聚糖酶,以CBHE为主;微晶纤维素不能直接诱导产生壳聚糖酶,而是通过其水解产物间接诱导绿色木霉产生壳聚糖酶,发酵液中CBHE所占比例较低,组分中壳聚糖酶CCBEⅡ(52kDa)和Csn(45kDa)含量较高;且绿色木霉两种酶活力的合成和表达调节并不是协同发生的。可溶性淀粉和乳糖为碳源时,绿色木霉生长迅速,但是基本上不产双功能酶。     

Carbon source induces growth of stationary phase yeast cells,independent of carbon source metabolism

Nutrients regulate the proliferation of many eukaryotic cells: in the absence of sufficient nutrients vegetatively growing cells will enter stationary (G₀ like) phase; in the presence of sufficient nutrients non-proliferative cells will begin growth. Previously we have shown that glucose is the critical nutrient which stimulates a variety of growth-related events in the yeast Saccharomyces cerevisiae (Granot and Snyder, 1991). This paper describes six new aspects of the induction of cell growth events by nutrients in S. cerevisiae. First, all carbon sources tested, both fermentable and non-fermentable, induce growth-related events in stationary phase cells, suggesting that the carbon source is the critical nutrient which stimulates growth. Second, the continuous presence of glucose is not necessary for the induction of growth events, but rather a short ‘pulse’ of glucose followed by an incubation period in water will induce growth events. Third, growth stimulation by glucose occurs in the absence of the SNF3 high affinity glucose transporter. Fourth, growth stimulation occurs independent of carbon source phosphorylation and carbon source metabolism. Fifth, growth induction by carbon source does not require protein synthesis or extracellular calcium. Sixth, following stimulation by carbon source, the cells remain induced for more than 2 h after removal of the carbon source. We suggest a general model in which different carbon sources act as signals to induce the earliest growth events during or following its entry into the cell and that these growth events do not depend upon metabolism of the carbon source.     

The effect of optimized carbon source on the synthesis and composition of exopolysaccharides produced by Lactobacillus paracasei

This study aimed to predict the optimal carbon source for higher production of exopolysaccharides (EPS) by Lactobacillus paracasei TD 062, and to evaluate the effect of this carbon source on the production and monosaccharide composition of EPS. We evaluated the EPS production capacity of 20 strains of L. paracasei under the same conditions. We further investigated L. paracasei TD 062, which showed the highest EPS-producing activity (0.609 g/L), by examining the associated biosynthesis pathways for EPS. Genomics revealed that fructose, mannose, trehalose, glucose, galactose, and lactose were carbon sources that L. paracasei TD 062 could use to produce EPS. We identified an EPS synthesis gene cluster that could participate in transport, export, and sugar chain synthesis, and generate 6 sugar nucleotides. Experimental results showed that the sugar content of the EPS produced using fermentation with the optimized carbon source (fructose, mannose, trehalose, glucose, galactose, and lactose) increased by 115%. Furthermore, use of the optimized carbon source changed the monosaccharide content of the associated EPS. The results of enzyme activity measurements showed significant increases in the activity of 2 key enzymes involved in the glycoside synthesis pathway. Our study revealed that optimizing the carbon source provided for fermentation not only increased the production of EPS, but also affected the composition of the monosaccharides by increasing enzyme activity in the underlying synthesis pathways, suggesting an important role for carbon source in the production of EPS by L. paracasei TD 062.     

海藻糖对纤维素酶的干燥保护作用

纤维素酶液中加入不同剂量的海藻糖作为干燥保护剂,喷雾干燥后纤维素酶活力的回收率由空白对照的63.7%提高到89.0%;硅藻土吸附酶液经50℃干燥后,空白对照的酶活力回收率为60.5%,海藻糖组的回收率为65.8%;90℃10min造粒后,纤维素酶活力的回收率由空白对照的62.4%提高到92.7%。造粒的纤维素酶置50℃保存240h后,空白对照的剩余酶活力为70.5%,而海藻糖组的酶活力仍保持在81.2%。结果表明,海藻糖在纤维素酶的干燥和保存过程中有较好的保护效果。      

发酵秸秆生产纤维素酶工艺条件的研究

阐述了绿色木霉发酵秸秆生产纤维素酶工艺条件的研究，通过正交试验得到最佳工艺参数，实验结果表明，最佳工艺参数是：原料配比为稻草：甘蔗渣：麸皮=4：4：2，水份含量为干料：水份=1：2，装量5％；接种量3％；30℃培养时间96h。     

纤维素酶对玉米淀粉生产中浸泡效果的影响

本研究通过使用纤维素粗酶制剂对湿法生产玉米淀粉的浸泡工艺的影响进行了研究,结果表明,纤维素粗酶制剂能够显著地缩短玉米淀粉生产的浸泡时间,降低了二氧化硫的使用浓度,在0.1%的二氧化硫浓度的浸泡液中添加0.3%纤维素粗酶制剂,作用时间为12h,其淀粉得率为57.0%,而使用传统的逆流法工艺(实验室模拟)浸泡48h的淀粉得率仅为54.1%。