真菌漆酶基因研究进展

漆酶是一种含铜的多酚氧化酶,也是木质素生物合成的关键酶之一,目前已发现多种生物能产生漆酶,包括植物、真菌、昆虫、细菌等。其中,以真菌中的白腐菌研究最多。近年来,由于漆酶在生物漂白、农作物秸秆利用以及环境垃圾处理方面具有广阔的应用前景,漆酶研究越来越受到国际上的重视。同时,随着分子生物学相关技术的发展,漆酶研究已深入基因水平,已有多种漆酶基因获得克隆,一些漆酶基因也实现了异源表达。本文概述了真菌漆酶基因研究的最新进展。     

真菌漆酶性质、分子生物学及其应用研究进展

漆酶是一种含铜的多酚氧化酶。目前发现多种生物能够产生漆酶,包括植物、真菌、昆虫和细菌等,其中,以真菌中的白腐真菌研究最多。由于漆酶在生物漂白、农作物秸秆利用以及环境污染处理等方面具有广阔的应用前景,漆酶研究受到越来越多的关注。同时,随着分子生物学技术的发展,漆酶研究已经深入到基因水平,多种漆酶基因已经成功获得克隆,一些漆酶基因也实现了异源表达。现针对真菌漆酶的生物学性质、分子生物学及其应用的研究进展进行了概括总结,并对其前景进行了展望。     

真菌漆酶及其介体系统：来源、机理与应用

漆酶是一类含铜氧化酶,广泛分布于植物、真菌、细菌、昆虫中,它们能够高效催化芳香族和非芳香族化合物氧化降解,并最终将分子氧还原为水作为副产物。一些小分子介体能够进一步提高漆酶的降解底物范围、催化效率和稳定性。它们与漆酶构成漆酶/介体系统（laccase mediator systems, LMS）,能够更有效地降解非酚类、多环芳烃类等难降解化合物,在造纸制浆与漂白、染料脱色、环境脱毒等领域有着巨大的应用前景,成为近年来的研究热点之一。对漆酶的来源与功能、真菌漆酶结构与反应机理、介体类型与作用机理、LMS的应用进行了综述,以期为漆酶的应用研究提供参考。     

真核生物来源漆酶的异源表达研究进展

漆酶属于多铜氧化酶家族中的一种,广泛存在于昆虫、植物、真菌和细菌中。由于其作用的底物范围较广,因此在纺织、制浆、食品以及木质素的降解等方面有广阔的应用前景。但是自然界中的漆酶存在表达量和酶活低、高温易失活等问题,限制了它的应用。对漆酶进行大量高效的异源表达,是解决这一问题的有效途径。近年来,越来越多不同来源的漆酶基因被克隆,并在不同宿主中异源表达。但这些大多局限于实验室研究,还未达到工业化生产的水平。笔者对真核生物来源漆酶的异源表达研究进展进行综述,重点介绍了真核生物来源的漆酶在不同表达系统中的异源表达情况以及在酵母细胞中表达漆酶时提高表达量和酶活性能的方法,以期为研究者们提供参考。     

中国栓孔菌属漆酶的筛选与应用

漆酶是一种含铜的多酚氧化酶[1],广泛分布于植物、真菌、少数昆虫和细菌中,可用于纸浆造纸、生物合成、食品、能源、木材加工、环保、改善纤维特性、生物检测等多个领域。鉴于其重要的应用价值,漆酶正日益受到重视。     

真菌漆酶的性质、生产及应用研究进展

作为一种含铜的多酚氧化酶,真菌漆酶比细菌漆酶、植物漆酶等具有更好的热稳定性、金属离子耐受性及更高的底物催化氧化性,在工农业及环境领域的应用中得到了较高的关注。目前普遍认为,限制漆酶广泛应用的因素在于漆酶的生产规模、成本与性质。真菌漆酶的生产模式包括固态发酵和液体发酵,工业生产基本以液体发酵为主。除了在染料脱色、染织废水处理、纸浆漂白等过程中的应用,最新的研究不断拓展了漆酶新的用途,对近年来真菌漆酶的发酵生产、酶学性质及应用研究中的最新结果进行了概述。     

漆酶介导生物体内酚类氧化偶联的基本原理及其在绿色合成中的应用

漆酶(Laccase,p-diphenol dioxygen oxidoreductases,EC 1.10.3.2)是一类包含三核铜簇位点的多酚氧化还原酶,广泛存在于细菌、真菌、高等植物和昆虫体内。该类酶不仅能够促进生态系统中高分子木质素和腐殖质聚合物的生物分解,还可以催化有机体内单酚和多酚类化合物参与黑色素、木质素、黄酮类和角质层等功能酚聚合物的生物合成。漆酶介导有机物的分解代谢和合成代谢机制有益于生态环境中碳循环和生物形态发生变化。在生物体内,漆酶催化天然酚类单电子氧化形成苯氧活性自由基或醌类中间体,随后这些活性中间体发生自我偶联或交叉偶联反应,生成多种结构复杂的大分子C-C、C-O-C或C-N-C功能聚合产物。因此,通过人工模拟漆酶催化生物体内的绿色合成代谢机理和路径,合理设计和定向改造漆酶在生物体外催化酚类底物偶联形成大分子功能聚合产物的结构和特性,有望为拓展和研发漆酶在绿色合成化学中的多功能应用提供丰富的参考价值和新颖的见解思路。     

灰树花漆酶酶学性质的初步研究

漆酶是一种具有广泛应用前景的多功能酶,但能否大规模工业化生产成了制约其应用开发的主要瓶颈之一。担子菌类真菌是分泌漆酶的主要来源之一,灰树花隶属于担子菌,但有关其分泌漆酶的研究鲜有报道。本文初步探讨了pH值、温度及不同阴、阳离子等因素对灰树花孢外漆酶酶学特性的影响,结果表明灰树花孢外漆酶最适反应pH值为2.2,最适反应温度65℃,且反应体系中缓冲液的组成也会影响灰树花漆酶的活性。灰树花漆酶具有较强的热稳定性,但反应体系中若存在卤族离子则会强烈抑制灰树花漆酶的活性。本研究为今后开发利用灰树花漆酶提供了借鉴。     

猴头菌和金针菇漆酶对不同染料的降解

利用漆酶(laccase)处理染料废水是近年来研究的热点.本研究以猴头菌Hericium erinaceus和金针菇Flammulina filiformis的发酵液为试验材料,通过硫酸铵沉淀、离子交换层析和超滤等方法,对发酵液中的漆酶进行了初步的分离纯化,然后分别研究了两种初提纯漆酶及其与小分子介体组成的漆酶介体系统...     

彩绒革盖菌漆酶产酶条件研究

本文研究了碳源、氮源、愈创木酚、香兰素及培养条件对漆酶分泌的影响;结果表明,淀粉作碳源、干酪素作氮源有利于漆酶的分泌,适宜浓度的愈创木酚和香兰素等对漆酶的产生有一定的作用;pH在3.0～8.0的范围内对漆酶的分泌影响差别不大,培养温度、接种量、通气量对漆酶的分泌有较大影响。     

木质素降解菌BYL-7的筛选及降解条件优化

【背景】微生物降解木质素因其具有降解效率高和环保等特点而备受关注。【目的】筛选高效木质素降解真菌,并对其降解条件进行优化。【方法】通过愈创木酚-马铃薯葡萄糖琼脂(potato dextroseagar,PDA)和苯胺蓝平板法筛选高效木质素降解菌株,利用单因素筛选及响应面试验对培养条件进行优化。【结果】筛选到一株高效木质素降解菌BYL-7,经形态和多序列分析初步确定为Trametes versicolor。单因素试验证明初始pH、温度和接种量为降解木质素显著影响因子,响应面试验确定降解木质素最优条件为:初始pH 6.7,温度25°C,接种量8%。在此条件下,碱性木质素降解率为36.5%,比未优化前提高54.0%;水稻秸秆木质素、半纤维素和纤维素降解率分别为32.8%、21.5%、13.2%,其中木质素降解率比未优化前提高36.1%;漆酶活性在第6天达到峰值120.0 U/L,比未优化前提高25.0%;木质素过氧化物酶活性在第6天达到峰值1343.8U/L,比未优化前提高36.0%;锰过氧化物酶活性在第5天达到峰值463.8U/L,比未优化前提高31.7%。【结论】研究结果为木质素的降解提...     

木质素的微生物降解机制

研究微生物降解木质素的反应机理,可以从根本上解释微生物或酶对木质素的作用过程,对提高木质素降解效率,治理环境污染等具有非常重要的意义。从木质素结构的差异出发,总结了近年来研究木质素微生物降解机制所采用的主要模型化合物、研究方法,概述了微生物对木质素的三大作用机理:侧链氧化、去甲基化和芳香环断裂,以及参与这三个反应的主要微生物。     

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。     

耐高温木质素降解菌筛选及降解效果研究

为提高育苗基质中废弃物木质素降解速率,在废弃物堆腐生产育苗基质高温阶段取样,筛选耐高温木质素降解菌,并对菌种进行鉴定,同时测定其对秸秆木质素和菌糠木质素的降解效果。获得了1株较好的木质素高温降解菌HZ11,鉴定为解淀粉芽胞杆菌（Bacillus amyloliquefaciens）,结果显示,该菌株对秸秆木质素和菌糠木质素降解效果较好,50 ℃条件下,20 d木质素降解率分别为46.7%和42.4%。菌株HZ11在降解秸秆和菌糠方面具有很好的应用潜力,为利用农业废弃物生产育苗基质提供更加丰富的菌种资源,具有重要的参考价值。     

Lignin degradation by microorganisms: A review

Lignin is an abundant plant-based biopolymer that has found applications in a variety of industries from construction to bioethanol production. This recalcitrant branched polymer is naturally degraded by many different species of microorganisms, including fungi and bacteria. These microbial lignin degradation mechanisms provide a host of possibilities to overcome the challenges of using harmful chemicals to degrade lignin biowaste in many industries. The classes and mechanisms of different microbial lignin degradation options available in nature form the primary focus of the present review. This review first discusses the chemical building blocks of lignin and the industrial sources and applications of this multifaceted polymer. The review further places emphasis on the degradation of lignin by natural means, discussing in detail the lignin degradation activities of various fungal and bacterial species. The lignin-degrading enzymes produced by various microbial species, specifically white-rot fungi, brown-rot fungi, and bacteria, are described. In the end, possible directions for future lignin biodegradation applications and research investigations have been provided.     

细菌降解木质素的研究进展

木质素是自然界最丰富的芳香化合物,其分解与陆地上碳循环密切相关。提取木质纤维素中的葡萄糖使其转化成乙醇,是生产第二代生物能源的关键步骤。但是由于木质素是一种非常稳定的化合物,难以降解是实现生物乙醇转化的主要屏障,因此关于木质素的生物降解研究具有非常重要的意义。真菌降解木质素的研究已经深入的进行了多年,并取得丰富的成果,但是关于细菌降解木质素的研究还处在初级阶段。由于广泛的生长条件和良好的环境适应能力,细菌在木质素降解方面深受研究人员的关注。本文通过总结前人的研究成果,讨论了木质素的降解机制、代谢途径及细菌降解木质素的工业应用前景,同时还展望了分子生物学及生物信息学在木质素降解方面的应用前景。     

Microbial degradation of lignin

The transformations of lignin that occur during its biodegradation are complex and incompletely understood. Certain fungi of the white-rot group, and possibly other fungi and bacteria, completely decompose lignin to carbon dioxide and water. Other fungi and bacteria apparently degrade lignin incompletely. Differences in lignin-degrading abilities observed for different organisms may result from differences in the completeness of their ligninolytic enzyme systems. Not all lignin components may be attacked by a particular organism. Alternatively, different organisms may differ in their basic mechanisms of attack on lignin. The basic pathways of lignin degradation have been elucidated only for certain representatives of the white-and brown-rot fungi. Although it is known that each of the principal structural components of lignin is attacked by other fungi and bacteria, the biochemistry of that attack has not been elucidated. Work with low molecular weight lignin models has provided only limited information on possible pathways of lignin degradation by microorganisms. There is little evidence to suggest a correlation between abilities to degrade single-ring aromatic or lignin model compounds and the ability to degrade polymeric lignin. More evidence has come from analysis of spent culture media for lignin breakdown products and from comparative chemical analyses of sound lignins versus decayed lignin residues. Accumulated evidence with the most thoroughly studied white-rot fungi suggests that with these fungi lignin degradation proceeds by way of extracellular mixed-function oxygenases and dioxygenases, which catalyse demethylations, hydroxylations and ring-fission reactions within a largely intact polymer, concomitant with some release of low molecular weight lignin fragments. There are also apparent relationships between lignin, carbohydrate and nitrogen metabolism for some organisms, but the relationships may vary from one organism to another. Although research is now mostly at a basic level, industrial applications may result from lignin degradation research. Considerable potential exists for the development of bioconversions which might produce low molecular weight chemicals from waste lignins, and thereby reduce our dependence on petroleum as a source of these chemicals. Alternatively, such bioconversions might produce chemically altered forms of polymeric lignin that may be valuable industrially.     

烟草废弃物中的难降解有机物的微生物降解研究进展

烟草废弃物的资源化利用及无害处理过程,需要利用微生物高效降解其中的难降解物质,如木质素与尼古丁。本文主要综述烟草废弃物中难降解物质的生物降解研究进展。迄今,已经发现了不少木质素和尼古丁的微生物降解菌株,对其降解机理及应用已有不少研究报道,但其在烟草废弃物处理中的应用方面报道较少。木质素和尼古丁降解菌可以用于废次烟叶（烟梗）木质素的消减和尼古丁去除,但同时也需要考察菌株的降解能力和应用环境的适用性。具备降解木质素和尼古丁双重功能的菌株更有应用前景,但迄今发现较少。基于全基因组分析和微生物组学技术的复合菌群的研究也是重要的研究方向,将推动含木质素和尼古丁等多种难降解物质的废次烟叶的处置技术发展和实际应用。     

Factors influencing fungal degradation of lignin in a representative lignocellulosic,thermomechanical pulp

This research examined culture parameters influencing the rate of degradation of lignin in lignocellulosic substrates by the Basidiomycete Phanerochaete chrysosporium. Thermomechanical pulps prepared from western hemlock (Tsuga heterophylla) and red alder (Alnus rubra) were chosen as model substrates. Degradation of lignin in shallow, liquid-phase, stationary cultures was 10 times as rapid as in agitated cultures. Lignin degradation was at least 50% more rapid in cultures under 100% O₂ than in those under air. Addition of 0.12% nutrient N (dry pulp basis) increased the rate of lignin degradation two- to fivefold; 1.2% added N at first suppressed, then stimulated, lignin degradation. Lignin in the alder pulp was degraded over five times as rapidly as in the hemlock pulp. Addition of glucose (35% of dry pulp) to the pulps containing 0.12% added N completely suppressed polysaccharide depletion during two weeks, but did not influence lignin degradation. The maximum rate of lignin degradation was 3%/day over a two-week incubation, or approximately 2.9 mg/mg fungal cell protein/day. The influence of the examined parameters was in complete accord with those found earlier for synthetic ¹⁴C-lignin metabolism by P. chrysosporium.     

Biotransformation of lignin: Mechanisms,applications and future work

As one of the most abundant polymers in biosphere, lignin has attracted extensive attention as a kind of promising feedstock for biofuel and bio-based products. However, the utilization of lignin presents various challenges in that its complex composition and structure and high resistance to degradation. Lignin conversion through biological platform harnesses the catalytic power of microorganisms to decompose complex lignin molecules and obtain value-added products through biosynthesis. Given the heterogeneity of lignin, various microbial metabolic pathways are involved in lignin bioconversion processes, which has been characterized in extensive research work. With different types of lignin substrates (e.g., model compounds, technical lignin, and lignocellulosic biomass), several bacterial and fungal species have been proved to own lignin-degrading abilities and accumulate microbial products (e.g., lipid and polyhydroxyalkanoates), while the lignin conversion efficiencies are still relatively low. Genetic and metabolic strategies have been developed to enhance lignin biodegradation by reprogramming microbial metabolism, and diverse products, such as vanillin and dicarboxylic acids were also produced from lignin. This article aims at presenting a comprehensive review on lignin bioconversion including lignin degradation mechanisms, metabolic pathways, and applications for the production of value-added bioproducts. Advanced techniques on genetic and metabolic engineering are also covered in the recent development of biological platforms for lignin utilization. To conclude this article, the existing challenges for efficient lignin bioprocessing are analyzed and possible directions for future work are proposed.