低温秸秆降解复合微生物菌剂的研究进展

我国东北地区冬季寒冷,秸秆产量巨大,但综合利用率较低,利用高酶活性微生物将低温环境中的秸秆降解变废为宝,是一项循环利用的有效途径。研究表明,通过生物学技术手段,筛选高酶活性菌株,深入研究降解机理,优化功能微生物培养条件,提高纤维素酶活性,是提高降解率,秸秆资源化利用的最佳途径。复合微生物菌剂产生的酶活值普遍高于单一微生物菌,真菌菌丝体产生的酶活值高于细菌。实际应用中,选择适合的复合菌剂是低温环境下提高秸秆降解效率的有效途径。系统地归纳了低温条件下降解秸秆的微生物技术、分析了不同条件下降解秸秆的菌株类型和促进秸秆纤维素降解菌酶活力特征、并总结了低温环境下生物菌剂降解秸秆的技术应用效果,旨为低温环境下秸秆的资源化利用提供一定的技术参考。     

外源微生物及辅料对秸秆降解效果的影响

研究加入外源微生物及添加辅料对秸秆降解率的影响。通过秸杆固体培养进行了降解试验,结果显示,加入外源微生物后纤维素降解率明显提高,嗜热侧孢霉可提高34.76%,放线菌可提高18.99%。通过在秸秆中加入辅料香菇菌糠,培养后秸秆的纤维素含量由原来的32.11%降至14.19%,降解率达55.81%。加入外源微生物的秸秆降解过程具有升温快、温度高及高温维持时间长等优点。加入微生物的秸秆降解高温维持8 d,对照为6 d。秸秆降解过程中的最高温度分别为63℃和58℃。为下一步外源微生物的进一步研究及菌糠的大量利用提供参考。     

关于秸秆微生物降解的文献计量分析

随着可再生生物质能源研究的快速发展,秸秆的微生物降解成为世界范围内的研究热点。客观分析当前秸秆微生物降解领域的发展态势,可为我国秸秆降解领域工作人员提供情报动态,推进我国在新型生物质能源方面的深入研究。本文基于WebofScience数据库,利用HisCite和VOSviewer软件分析工具,对世界范围内关于秸秆微生物降解领域的发文数量、高发文国家、高发文期刊及高发文机构等数据进行分析。分析结果发现秸秆微生物降解研究自21世纪以来出现逐年递增的趋势,全球范围内对秸秆微生物降解的研究主要集中在应用微生物、农业和生物技术等方面。其中,美国、中国、德国和日本在秸秆微生物降解研究领域处于国际领先地位。美国的发文量和发文的影响力位列首位。我国在该领域发文量位列第二名,表明我国在秸秆微生物降解领域的研究具有一定的基础,但影响力较低,需要加强高水平的研究,带动我国在该领域研究实力的整体提升。     

平菇类食用菌对农作物秸秆生物降解转化饲料的研究进展

综述了近年来国内外利用平菇类食用菌降解农作物秸秆的有关研究进展情况,主要包括限制秸秆饲料化的主要因素及提高秸秆饲料利用率的途径,平菇类食用菌降解秸秆的优势及其降解秸秆转化饲料的效果。并就笔者课题组近年来的研究总结了利用平菇类食用菌降解农作物秸秆的制约因素,以加快其应用于实际生产中。     

低温秸秆降解微生物菌剂的研究进展

秸秆的成分主要有纤维素、半纤维素和木质素等,降解秸秆的微生物包括细菌、放线菌和真菌。低温秸秆降解微生物的选育方法有直接从自然界中筛选、诱变育种、原生质体融合育种、基因工程育种等。目前,筛选获得的低温秸秆降解菌株的数量有限,降解秸秆的能力不高,低温条件下菌株的降解机理都需要进一步的研究。综述了低温条件下秸秆降解微生物菌剂的研究进展。     

秸秆的生物降解机理及其功能微生物菌群研究进展

秸秆对人类社会发展具有极其重要的作用, 特别是在当今能源紧缺的背景下, 寻找新型可再生能源显得尤为重要。通过对秸秆生物降解机制的简单介绍, 以及对秸秆降解原理及微生物菌群研究状况的详细阐述, 为今后秸秆的高效降解及工业化大规模降解的研究和利用提供理论基础。     

家蝇幼虫对两种秸秆的消化及利用研究

本文旨在探明家蝇Musca domestic幼虫对高粱秸秆和小麦秸秆营养成分利用和木质纤维素的降解情况,以及不同配比秸秆饲料对家蝇生物学指标的影响,为今后产业化利用家蝇来生物降解秸秆类有机废弃物奠定理论基础.本研究采用70％高粱秸秆粉、70％麦秸秆粉和纯麦麸作为饲料,每种饲料各设置对照组、发酵组和家蝇幼虫取食组3种处理,检测并分析3种饲料各处理组中一般营养成分和木质纤维素的含量及变化;同时采用7种配比饲料喂养家蝇,观察各组家蝇不同发育阶段的体长、体重、存活率和发育历期等.结果表明:(1)3种饲料的各处理组中,一般营养成分和木质纤维素的含量均呈现:对照组>发酵组>家蝇取食组的趋势,此外除高粱秸秆组粗蛋白外,其余各组成份均差异显著(P<0.05);(2)小麦秸秆的木质纤维素含量>高粱秸秆>麦麸,且各组间均差异显著(P<0.05);(3)在相同秸秆配比条件下,高粱秸秆饲喂的家蝇其各虫态体长、体重、总存活率和发育历期均要优于麦秸秆喂养,且总存活率和发育历期与麦麸喂养相比差异不显著(P>0.05);(4)纯高粱秸秆喂养下家蝇仍能保持正常的生长发育,而在90％小麦秸秆喂养下,家蝇则无法存活.综上所述,家蝇适合作为生物转化器用于秸秆、尤其是高粱秸秆的降解,且降解效果优于单纯的微生物发酵降解,研究结果为今后规模化利用家蝇降解秸秆类有机废弃物提供了理论依据和科学基础.     

微生物降解秸秆木质素的研究进展

我国秸秆资源丰富，每年产生逾8亿t作物秸秆。通过秸秆直接还田或肥料化还田不仅可以减少化肥的施用量，缓解农业污染压力，还能实现农作物秸秆的循环利用。木质素结构复杂，且与纤维素和半纤维素相互缠绕，因此秸秆的自然腐解过程中，木质素是主要的限速因子，为了提高降解效率，木质素降解菌的发掘和降解机制也逐渐成为研究热点。本文综述了降解木质素的真菌和细菌的研究现状，对比其真菌和细菌降解特性的优缺点并分析复合降解菌群的优势。随后对木质素降解酶系的酶学性质、在不同微生物中的表达特性进行总结，对木质素降解机制及衍生芳烃代谢路径的研究进展进行综述。最后整理木质素降解微生物在秸秆肥料化技术中的应用进展，并探讨了微生物降解秸秆木质素的应用前景和未来的研究方向。     

产纤维素酶耐高温真菌在有机肥料生产中的潜在价值

农作物秸秆是农作物生产中一种富含氮、磷、钾、钙、镁和有机质等有效成分的可再生资源,我国每年的农作物秸秆废弃物产量巨大,因此,如何有效地"转废为宝",实现对农作物秸秆废弃物的再利用一直是我国学者关注的问题.秸秆堆腐还田技术是有机废弃物再利用的理想途径之一,其作用原理是利用微生物的分解作用,促使农作物秸秆发酵腐熟后成为优良的绿色有机肥.农作物秸秆属于高纤维素含量废弃物,且纤维素的结构复杂、降解困难,如何加速纤维素的分解是实现农作物秸秆堆肥物料快速分解、达到腐熟的关键问题.已有研究表明,在堆肥中接种高温或耐高温降解菌可促进有机物降解,提高堆肥高温期温度,延长高温期,加快堆肥腐熟.     

微生物菌群协同提高水稻秸秆转化机制的解析

单一微生物降解水稻秸秆效果不明显,多种微生物组合在一起的微生物菌群能够有效降解水稻秸秆,是当前降解秸秆类废物的首要选择。【目的】探究微生物菌群比单一菌株转化秸秆效率提高的种间协作机制,为改善秸秆类物质的生物降解过程提供理论参考。【方法】通过菌种组合,以水稻秸秆减重率为指标人工构建出降解效果优于单菌培养的微生物群体组合,利用分子生物学方法对实验菌株进行鉴定,结合纤维素酶活性、发酵产物GC-MS分析等指标得出水稻秸秆降解时微生物群体的种间协作机制。【结果】菌株B (Bacillus cereus)在30℃培养8 d水稻秸秆降解率为50.9%,菌株B与菌株D_2(Bacillus amyloliquefaciens)、W_1(Ochrobactrum intermedium)、G_1降解(Bacillus licheniformis)组合构成4株菌BD_2W_1G_1的复合菌群,在30℃培养8 d水稻秸秆降解率为73.3%,比B单菌株分解能力提高22.4%。发酵产物分析结果表明,菌株B单独培养产生大量酸、酚等物质。B+D_2联合培养,发酵液内酸类相对减少87.4%,酚类相对减少61.9%(十五烷酸、正十六烷酸、2,4二叔丁基酚和6-叔丁基对甲酚减少明显),水稻秸秆降解率为64.6%。当B+D_2+W_1联合培养,发酵液内酚类进一步减少15.7%(6-叔丁基对甲酚减少明显),水稻秸秆降解率为71.0%。当B+D_2+W_1+G_1联合培养,酚类继续减少10.7%,水稻秸秆降解率为73.3%。【结论】十五烷酸、正十六烷酸、2,4二叔丁基酚和6-叔丁基对甲酚等酸、酚类物质会抑制菌株B分解水稻秸秆的效率,菌株D_2、W_1、G_1能够减少包括4种物质在内的酸、酚类含量(酸类共减少82.9%,酚类共减少88.2%),来提高分解效率(共提升22.4%的分解效果)。水稻秸秆成分复杂,具有不同功能的菌种组合成复合菌剂,减少反馈抑制形成代谢互补,能有效提高水稻秸秆生物降解效果。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.