微生物耐受乙醇与丁醇机制及其在生物燃料生产与生物转化中的应用

生物法获取乙醇与丁醇过程中有机溶剂的毒性是生产菌重要环境胁迫因素之一,且当有机溶剂超过一定浓度时便会抑制微生物的生长,甚至引起微生物的死亡,因此提高工业微生物的有机溶剂耐受性对工业生产具有重要的意义。对微生物乙醇及丁醇耐受机制的研究可为选育具有较强溶剂耐受菌提供理论基础。本文系统介绍了微生物耐受乙醇与丁醇的机制,并对其在生物燃料生产及生物转化中面临的机遇与挑战等问题进行简要的评述。     

海因酶与氨甲酰水解酶产生菌的鉴定及分布

利用Biolog微生物鉴定系统和16S rDNA序列分析相结合的方法对自行筛选的24株海因酶和氨甲酰水解酶产生菌进行了鉴定。海因酶与氨甲酰水解酶产生菌主要分布在Bacillus,Geobacillus,Brevibacillus,Aneurinibacillus,Microbacterium,Pseudomonas,Kurthia和Empedobacter等菌属,特别的是,Kurthia和Empedobacter是新的海因酶和氨甲酰水解酶产生菌属,说明海因酶和氨甲酰水解酶产生菌在细菌中分布较广泛。进一步分析比较发现,D-海因酶产生菌主要分布于Pseudomonas,Agrobacterium等菌属中,而大部分L-海因酶产生菌分布于Bacillus,Geobacillus,Microbacterium等菌属中,说明D-海因酶产生菌与L-海因酶产生菌分布特点具有一定的种属倾向性。这些工作不仅提供了多种海因酶和N-氨甲酰水解酶的生物材料,而且对双酶的结构与功能及分子进化研究等具有重要意义。     

生物转化对天然药物进行结构修饰的研究进展

利用生物转化对天然药物进行结构修饰,是筛选活性化合物的有效途径之一。本文根据生物体系中酶的多样性和特异性以及生物转化具有副产物少、选择性和专一性强等特点,系统性的综述了近几年来在天然药物资源开发利用研究中生物转化进行结构修饰的常见反应类型:羟基化、糖基化、水解和环氧化反应等,并简述了生物转化法在开发具有活性的新药物和改变天然药物活性如改变细胞毒性、增强抗耐药性、减小毒副作用或提高生物利用率等方面的实际应用。     

禾谷镰刀菌蛋白激酶研究进展

由禾谷镰刀菌引起的小麦赤霉病是小麦生产最重要的真菌病害之一,除了造成严重的产量损失外,其病原菌还会产生多种真菌毒素危害人畜健康。蛋白激酶在禾谷镰刀菌生长发育、植物侵染和胁迫应答等方面具有重要作用。综述了禾谷镰刀菌主要蛋白激酶在生物学功能和分子作用机制等方面的研究进展,并对未来禾谷镰刀菌蛋白激酶的研究趋势进行了展望,以期为今后禾谷镰刀菌蛋白激酶的研究与小麦赤霉病的防治提供理论参考。     

南沙链霉菌来源细胞色素P450酶CYP154C34的表征及生物转化

【目的】P450酶作为一种多功能生物催化剂,可在温和条件下高区域和立体选择性地催化复杂化合物中未活化的C-H键,因此P450酶在化工原料合成、环境污染物降解及药物合成等领域都具有重要作用。本文对南沙链霉菌基因组中的一个新颖的P450酶CYP154C34进行研究,通过构建异源表达和全细胞生物转化重组菌探究其功能。【方法】构建2种全细胞生物转化BL21(DE3)重组菌(含p ET28a-CYP154C34-RhFRED和pET28a-CYP154C34+pACYCDuet-Pdx/PdR)和1种异源表达BL21(DE3)重组菌(含pET28a-CYP154C34)。通过全细胞生物转化的方式筛选底物,分析催化功能及产物结构。比较2种全细胞生物转化重组菌和体外酶反应对底物的转化率。分析CYP154C34和不同底物及底物类似物的亲和力。【结果】通过底物筛选和产物鉴定发现CYP154C34可催化包括孕酮、睾酮、雄烯二酮在内的9种甾体化合物16α位羟基化。通过2种不同还原伴侣的全细胞体系及体外酶反应对底物转化率的比较,发现含有pET28a-CYP154C34-RhFRED的BL21(DE3)重组菌的...     

天然活性先导化合物生物转化研究进展

天然活性先导化合物生物转化是利用生物催化剂(如：酶、微生物、动植物细胞)将加入到生物反应系统中的天然活性先导化合物进行特异性的分子结构修饰以获得高效、低毒新化合物的方法。该方法可以有效地提高已知的天然活性先导化合物的活性、降低毒副作用、改善水溶性和生物利用度,也可以用来生产具有重要应用价值的微量天然活性先导化合物,同时可用于药物代谢机制的研究。国内外学者已经针对甾体、醌类、黄酮类、萜类等化合物开展了天然活性先导化合物生物转化研究,筛选出一批有重要应用价值的生物转化反应类型,但针对天然活性先导化合物生物转化的机制、生物转化过程工程以及生物转化产物活性等方面的研究较少。将现代生命科学技术(如：生物催化剂的定向改造、高通量筛选、组合生物转化、非水相生物转化)引入天然活性先导化合物生物转化研究中,必将推进天然活性先导化合物的快速发展。     

乙醇生物标志物检测技术研究

乙醇作为一种常见的饮用酒精，在代谢过程中会产生多种生物标志物，这些标志物在酒精滥用诊断、疾病研究和药物评估等领域具有重要的应用价值。文章旨在系统地探讨乙醇生物标志物的检测技术，包括不同检测方法的原理与应用，以及这些方法在临床和研究中的应用情况。文章重点阐述了液相色谱-质谱法、气相色谱-质谱法、核磁共振技术和生物传感器技术在乙醇生物标志物检测中的原理及应用，分析了乙醇生物标志物检测技术面临的挑战，如技术局限性、数据整合和个体差异等，并指出了这项技术未来的发展方向。综合来看，乙醇生物标志物检测技术在医学与科研领域具有广阔的应用前景。     

海藻酸分解菌研究进展

海藻酸分解菌是一类能够自身合成海藻酸裂解酶,能够降解并同化海藻酸的微生物。海藻酸分解菌是海藻酸裂解酶的重要来源,其产生的海藻酸裂解酶具有种类多、反应条件温和、酶活高和易于大规模生产等优点,并且在生物、医疗、化工等领域有重要的应用价值。在过去的几十年里,海藻酸分解菌一直作为海藻酸裂解酶生产者的角色被研究和应用。但随着近年来能源危机的加剧,以海藻酸等海藻生物质为原料转化生物能源成为解决能源危机的潜在途径,因此,海藻酸分解菌又有了崭新的研究领域,即海藻酸分解菌利用海藻酸发酵生产生物能源。本文从海藻酸分解菌及其海藻酸裂解酶的种类和特性、海藻酸分解菌的代谢以及海藻酸分解菌基因工程等方面,介绍海藻酸分解菌的研究现状,并展望未来的发展趋势。     

镰刀菌真菌毒素产生与调控机制研究进展

镰刀菌是一种重要的植物病原菌,给世界范围内农作物生产带来巨大破坏。除导致产量下降外,由其产生的镰刀菌真菌毒素能够污染农产品品质,给动物和人类食物安全造成严重隐患。单端孢霉烯族毒素（Trichothecenes）、伏马菌素（Fumonisin）和玉米赤霉烯酮（Zearalenone）是三种最重要的镰刀菌真菌毒素。镰刀菌真菌毒素的生物合成与生产受到体内一系列相关功能基因的调控;此外,pH值、碳氮比等环境条件也能影响真菌毒素的产量。本文简述了镰刀菌真菌毒素在产生机理、主要分类、致病性以及调控因素等方面的研究进展。     

纳米材料固定化酶的研究进展

近年来,纳米技术为酶固定化提供了多种纳米级材料,纳米材料固定化酶不仅具有高的酶负载量,而且具有良好的酶稳定性。本文基于纳米材料固定化酶,对纳米材料的种类进行了总结,分析了纳米材料对固定化酶性能的影响,并介绍了纳米级固定化方法及纳米材料固定化酶在生物转化、生物传感器、生物燃料电池等领域的应用。     

鸡舍环境中镰孢菌的种类分布及潜在产单端孢霉烯族毒素菌株的检测

采用AGI-30生物采样器收集鸡舍空气样本,同时采集鸡舍中饲料、积尘、土壤和饮用水在内的环境基质样品。采用形态学方法对分离获得的镰孢菌菌株进行鉴定,利用tri5-PCR技术对镰孢菌菌株中产单端孢霉烯族毒素的菌株进行检测,目的是探明鸡舍环境中镰孢菌种类的分布特征和产毒菌株。结果表明,从采集的50份样品中分离获得139个镰孢菌菌株,鸡舍空气和基质中的优势菌株均为Fusarium verticillioides;在各基质中,土壤中镰孢菌总浓度最高,为4×102–1.35×104CFU/g,其次为饲料和饮用水;采用tri5-PCR技术筛选到42株tri5阳性镰孢菌菌株,其中以F. graminearum所占比例最高。研究明确鸡舍中镰孢菌种类及其分布特征对鸡只疾病控制及保障人类和动物的健康具有重要意义。     

Recent Advances in Isolation,Synthesis and Biological Evaluation of Terrein

Terrein is a small-molecule polyketide compound with a simple structure mainly isolated from fungi. Since its discovery in 1935, many scholars have conducted a series of research on its structure identification, isolation source, production increase, synthesis and biological activity. Studies have shown that terrein has a variety of biological activities, not only can inhibit melanin production and epidermal hyperplasia, but also has anti-cancer, anti-inflammatory, anti-angiopoietic secretion, antibacterial, insecticidal activities, and so on. It has potential application prospects in beauty, medicine, agriculture and other fields. This article reviews the process of structural identification of terrein since 1935, and summarizes the latest advances in its isolation, source, production increase, synthesis, and biological activity evaluation, with a view to providing a reference and helping for the in-depth research of terrein.     

Biological constraints in algal biotechnology

In the past decade, considerable progress has been made in developing the appropriate biotechnology for microalgal mass cultivation aimed at establishing a new agro-industry. This review points out the main biological constraints affecting algal biotechnology outdoors and the requirements for making this biotechnology economically viable. One of them is the availability of a wide variety of algal species and improved strains that favorably respond to varying environmental conditions existing outdoors. It is thus just a matter of time and effort before a new methodology like genetic engineering can and will be applied in this field as well. The study of stress physiology and adaptation of microalgae has also an important application in further development of the biotechnology for mass culturing of microalgae. In outdoor cultures, cells are exposed to severe changes in light and temperature much faster than the time scale required for the cells to acclimate. A better understanding of those parameters and the ability to rapidly monitor those conditions will provide the growers with a better knowledge on how to optimize growth and productivity. Induction of accumulation of high value products is associated with stress conditions. Understanding the physiological response may help in providing a better production system for the desired product and, at a later stage, give an insight of the potential for genetic modification of desired strains. The potential use of microalgae as part of a biological system for bioremediation/detoxification and wastewater treatment is also associated with growing the cells under stress conditions. Important developments in monitoring and feedback control of the culture behavior through application of on-line chlorophyll fluorescence technique are in progress. Understanding the process associated with those unique environmental conditions may help in choosing the right culture conditions as well as selecting strains in order to improve the efficiency of the biological process.     

DNA microarray to detect and identify trichothecene- and moniliformin-producing Fusarium species

AIMS: To develop a DNA microarray for easy and fast detection of trichothecene- and moniliformin-producing Fusarium species. METHOD AND RESULTS: A DNA microarray was developed for detection and identification of 14 trichothecene- and moniliformin-producing species of the fungal genus Fusarium. The array could also differentiate between four species groups. Capture probes were designed based on recent phylogenetic analyses of translation elongation factor-1 alpha (TEF-1alpha) sequences. Particular emphasis was put on designing capture probes corresponding to groups or species with particular mycotoxigenic synthetic abilities. A consensus PCR amplification of a part of the TEF-1alpha is followed by hybridization to the Fusarium chip and the results are visualized by a colorimetric Silverquant detection method. We validated the Fusarium chip against five naturally infected cereal samples for which we also have morphological and chemical data. The limit of detection was estimated to be less than 16 copies of genomic DNA in spiked commercial wheat flour. CONCLUSIONS: The current Fusarium chip proved to be a highly sensitive and fast microarray for detection and identification of Fusarium species. We postulate that the method also has potential for (semi-)quantification. SIGNIFICANCE AND IMPACT OF THE STUDY: The Fusarium chip may prove to be a very valuable tool for screening of cereal samples in the food and feed production chain, and may facilitate detection of new or introduced Fusarium spp.     

Rapid identification of Fusarium graminearum species complex using Rolling Circle Amplification (RCA)

Rolling Circle Amplification (RCA) of DNA is a sensitive and cost effective method for the rapid identification of pathogenic fungi without the need for sequencing. Amplification products can be visualized on 1% agarose gel to verify the specificity of probe-template binding or directly by adding fluorescent dyes. Fusarium Head Blight (FHB) is currently the world's largest threat to the production of cereal crops with the production of a range of mycotoxins as an additional risk. We designed sets of RCA padlock probes based on polymorphisms in the elongation factor 1-α (EF-1α) gene to detect the dominant FHB species, comprising lineages of the Fusarium graminearum species complex (FGSC). The method also enabled the identification of species of the Fusarium oxysporum (FOSC), the Fusarium incarnatum-equiseti (FIESC), and the Fusarium tricinctum (FTSC) species complexes, and used strains from the CBS culture collection as reference. Subsequently probes were applied to characterize isolates from wheat and wild grasses, and inoculated wheat kernels. The RCA assays successfully amplified DNA of the target fungi, both in environmental samples and in the contaminated wheat samples, while no cross reactivity was observed with uncontaminated wheat or related Fusarium species. As RCA does not require expensive instrumentation, the technique has a good potential for local and point of care screening for toxigenic Fusarium species in cereals.     

Saponins and their role in biological processes in plants

Saponins are steroid and triterpenoid glycosides that display diverse biological activities. The wide-spread occurrence in plants as well as the potential for pharmaceutical application has led to saponin extraction and identification in numerous species. Although these efforts are important to extend our knowledge of naturally occurring saponin structures, recent attention has been given to the biosynthesis and distribution in plants. In this review, we present recent advances on saponin production and distribution and highlight studies showing effects on the growth and development.     

An oligonucleotide microarray for the identification and differentiation of trichothecene producing and non-producing Fusarium species occurring on cereal grain

Cereal grain may be infected with a number of Fusarium species some of which are producers of highly toxic compounds such as the trichothecenes. Correct identification of these species is essential for risk assessment of cereal grain for human or animal consumption. Most of the available methods for identification are either time consuming or aimed at only one or a few target species. Microarray technology offers parallel analysis of a high number of DNA targets. In this study 57 capture oligonucleotides (CO) were designed based upon Fusarium ITS2 rDNA sequences, and used for microarray production. From this array COs could be selected that were able to hybridise specifically to labelled PCR products from the ITS region of Fusarium graminearum/Fusarium culmorum, Fusarium pseudograminearum, Fusarium poae, Fusarium sporotrichioides, Fusarium equiseti, Fusarium langsethiae and Fusarium tricinctum/Fusarium avenaceum. A few COs showed some cross hybridisation to non-target species. In a preliminary experiment it was shown that this cross hybridisation could be eliminated by increasing hybridisation stringency. The array could be used to detect individual Fusarium species in mixed samples and in environmental samples. This study demonstrates the feasibility of oligonucleotide microarrays for parallel detection of a number of Fusarium species.     

Modified Primers for the Identification of Nonpathogenic Fusarium oxysporum Isolates That Have Biological Control Potential against Fusarium Wilt of Cucumber in Taiwan

Previous investigations demonstrated that Fusarium oxysporum (Fo), which is not pathogenic to cucumbers, could serve as a biological control agent for managing Fusarium wilt of cucumber caused by Fo f. sp. cucumerinum (Foc) in Taiwan. However, thus far it has not been possible to separate the populations of pathogenic Fo from the nonpathogenic isolates that have biological control potential through their morphological characteristics. Although these two populations can be distinguished from one another using a bioassay, the work is laborious and time-consuming. In this study, a fragment of the intergenic spacer (IGS) region of ribosomal DNA from an Fo biological control agent, Fo366, was PCR-amplified with published general primers, FIGS11/FIGS12 and sequenced. A new primer, NPIGS-R, which was designed based on the IGS sequence, was paired with the FIGS11 primer. These primers were then evaluated for their specificity to amplify DNA from nonpathogenic Fo isolates that have biological control potential. The results showed that the modified primer pair, FIGS11/NPIGS-R, amplified a 500-bp DNA fragment from five of seven nonpathogenic Fo isolates. These five Fo isolates delayed symptom development of cucumber Fusarium wilt in greenhouse bioassay tests. Seventy-seven Fo isolates were obtained from the soil and plant tissues and then subjected to amplification using the modified primer pair; six samples showed positive amplification. These six isolates did not cause symptoms on cucumber seedlings when grown in peat moss infested with the isolates and delayed disease development when the same plants were subsequently inoculated with a virulent isolate of Foc. Therefore, the modified primer pair may prove useful for the identification of Fo isolates that are nonpathogenic to cucumber which can potentially act as biocontrol agents for Fusarium wilt of cucumber.     

Taxonomic identification of algae (morphological and molecular): species concepts,methodologies, and their implications for ecological bioassessment

Algal taxonomy is a key discipline in phycology and is critical for algal genetics, physiology, ecology, applied phycology, and particularly bioassessment. Taxonomic identification is the most common analysis and hypothesis‐testing endeavor in science. Errors of identification are often related to the inherent problem of small organisms with morphologies that are difficult to distinguish without research‐grade microscopes and taxonomic expertise in phycology. Proposed molecular approaches for taxonomic identification from environmental samples promise rapid, potentially inexpensive, and more thorough culture‐independent identification of all algal species present in a sample of interest. Molecular identification has been used in biodiversity and conservation, but it also has great potential for applications in bioassessment. Comparisons of morphological and molecular identification of benthic algal communities are improved by the identification of more taxa; however, automated identification technology does not allow for the simultaneous analysis of thousands of samples. Currently, morphological identification is used to verify molecular taxonomic identities, but with the increased number of taxa verified in algal gene libraries, molecular identification will become a universal tool in biological studies. Thus, in this report, successful application of molecular techniques related to algal bioassessment is discussed.     

Entomogenous Fusarium species

Fusarium species are known for their abundance in nature and their diverse associations with both living and dead plants and animals. Among animals Fusarium is found primarily in relationship with insects. This literature review of the past 50 years includes both non-pathogenic and pathogenic relationships between Fusarium and insects. Special attention is given to the host range, particularly between plant- and insect-hosts, and to the possible microbial potential of the fungus to control insect pests. Correct classification of this fungus has been difficult because of its diverse and non-uniform morphological features. However, by now a usable and reliable taxonomic system has been developed. The fungus can be easily cultured and mass produced. Among the non-pathogenic associations mutualism and allotrophy are found between Fusarium and wood-inhabiting and flour beetles, respectively, enhancing development and production of beetle larvae. Some insects contribute to the dispersal of the fungus in the environment by means of spore passage through their guts. Plant-pathogenic Fusarium species gain access to host tissue by plant-feeding insects. A large number of Fusarium spp. are entomopathogenic; some are weak, facultative pathogens, especially of the lepidopteran and coleopteran orders, and they will colonize their dead hosts as saprophytes. In a few cases pathogenicity to both plant and insect by one isolate was found. Strong pathogens were reported primarily from homopterans and dipterans from field observations of natural mortalities as well as from pathogenicity tests. Potential Fusarium isolates which cause high insect mortalities also show high host specificity and no damage to crop plants. The question of host invasion has been addressed by few investigators. Entrance of the fungus via the oral route, oviposition tubes, wounds, or ectoparasitic activity, were stated, but no claim for penetration of the insect cuticle. Mycotoxins, such as trichothecenes (T-2) and other secondary metabolites, contributed to mortalities of termites, mealworms, flour beetles, maize borers and blow flies, while zearalenone (F-2) exhibited a beneficial effect on egg production in flour beetles and a detrimental effect on fecundity in mammals. Studies on adverse effects of the fungus on beneficial organisms (including mammals and plants) revealed that both harmful as well as safe Fusarium isolates exist in nature. Highly host-specific and strongly entomopathogenic Fusarium isolates should be more extensively studied and tested for their possible use in biological control.