Studies on influence of natural biowastes on cellulase production by Aspergillus niger

The objective of this study was to determine the influence of natural biowaste substrates such as banana peel powder and coir powder at varying environmental parameters of pH (4-9) and temperature (20-50 degrees C) on the cellulase enzyme production by Aspergillus niger. The cellulase enzyme production was analyzed by measuring the amount of glucose liberated in IU ml(-1) by using the dinitrosalicylic acid assay method. The substrates were pretreated with 1% NaOH (alkaline treatment) and autoclaved. The maximum activity of the enzyme was assayed at varying pH with temperatures being constant and varying temperatures with pH being constant. The highest activity of the enzyme at varying pH was recorded at pH 6 for banana peel powder (0.068 +/- 0.002 IU ml) and coir powder (0.049 +/- 0.002 IU ml(-1)) and the maximum activity of the enzyme at varying temperature was recorded at 35 degrees C for both banana peel powder (0.072 +/- 0.001 IU ml(-1)) and coir powder (0.046 +/- 0.003 IU ml(-1)). At varying temperatures and pH the high level of enzyme production was obtained at 35 degrees C and pH 6 by using both the substrates, respectively. However among the two substrates used for the production of cellulases by Aspergillus niger banana peel powder showed maximum enzymatic activity than coir powder as substrate.     

一株产耐热纤维素酶菌株的筛选及酶学性质

采用纤维素刚果红平板法从大田蘑菇种植场建堆的稻草样中分离得到了1株能产具有较好温度耐受性和pH稳定性的纤维素酶的放线菌DY3.综合形态、生理生化特征以及16S rDNA序列分析,将其初步鉴定为嗜热裂孢菌(Thermobifida fusca).对该菌所产纤维素酶的性质研究表明:最适催化温度为65℃,在70℃保温60 min后仍有75%以上的活力;最适催化pH为7.5,在pH 5.5～10.0之间该酶的稳定性较好,pH 10.0的条件下仍有80%的活力;最适作用底物是羧甲基纤维素钠.研究可为木质纤维素的生物预处理提供一定参考价值.     

轻度氧化处理纤维素生物降解性的初步研究

以纤维素为原料，通过二氧化氮和过碘酸化学氧化方法，在不同的低取代度条件下，有选择性地在纤维素葡萄糖残基的不同碳原子部位导入特定的取代基（羧基和二醛基），探讨不同的取代基对纤维素生物降解性能的影响．并将处理后所得的纤维素试验，通过土壤埋没，利用土壤中的微生物自然降解，然后测定分子量的变化，定量分析纤维素在不同取代基，不同程度化学处理后，其生物降解性能的变化。实验结果表明：（１）在纤维素葡萄糖残基Ｃ６     

Substrate concentration and enzyme allocation can affect rates of microbial decomposition

A large proportion of the world's carbon is stored as soil organic matter (SOM). However, the mechanisms regulating the stability of this SOM remain unclear. Recent work suggests that SOM may be stabilized by mechanisms other than chemical recalcitrance. Here, we show that the mineralization rate of starch, a plant polymer commonly found in litter and soil, is concentration dependent, such that its decomposition rate can be reduced by as much as 50% when composing less than approximately 10% of SOM. This pattern is largely driven by low activities of starch-degrading enzymes and low inducibility of enzyme production by microbial decomposers. The same pattern was not observed for cellulose and hemicellulose degradation, possibly because the enzymes targeting these substrates are expressed at constitutively high levels. Nevertheless, given the heterogeneous distribution of SOM constituents, our results suggest a novel low-concentration constraint on SOM decomposition that is independent of chemical recalcitrance. These results may help explain the stability of at least some SOM constituents, especially those that naturally exist in relatively low concentrations in the soil environment.     

Experimentelle Untersuchungen zur Produktion und Aktivität cellulolytischer Enzyme bei höheren Pilzen aus dem Meer- und Brackwasser

Twenty isolations of marine higher fungi were examined in regard to their cellulolytic capabilities. Application of the viscosimetric method produced detailed information on the cellulolytic activities of marine fungi. However, only the C _x -component of the total cellulase-complex could be estimated by this method. The most active species were Dendryphiella salina, Chaetomium ramipilosum, Asteromyces cruciatus and Humicola alopallonella. Only very slight or no C _x -activity was observed in Cirrenalia macrocephala, Monodictys pelagica and Zalerion maritimum. This finding reveals no correlation between the cellulolytic activity of the fungi in vitro and their frequency on wood-substrates in situ. For example, differences in the intensity of C _x -cellulase production of D. salina are caused by variations in salinity and composition of the nutrient broth, especially by the kind of cellulose added for enzyme induction and by the addition or absence of glucose. Most of the C _x -cellulase produced is present in the cell-free culture-filtrate. Only a small quantity is absorbed by the cellulose particles or the fungal mycelia. Parallel to the mycelial growth, and accompanied by a shift in pH, the C _x -cellulase-activity rises continuously, attaining a maximum after several weeks. During further cultivation, the maximum remains more or less constant for a long period. Tests using different methods, e.g. cellulose-powder-agarplates, proved unsuitable because of spreading hyphal growth, dark pigmentation, heavy sexual or asexual sporulation and relatively low cellulase production during short culture periods.     

添加剂对绿色木霉JQF-04纤维素酶热稳定性的影响

如何提高酶蛋白的热稳定性是分子生物学、微生物学、生化工程学等学科长期所关注的重要研究课题之一.本文研究了多种添加剂对绿色木霉纤维素酶热稳定性的影响.在60℃的溶液中,多元醇(乙二醇、甘油、赤藓糖醇、木糖醇和山梨糖醇)能提高该酶的热稳定性,随着浓度的增加,赤藓糖醇、木糖醇和山梨糖醇促进酶的热稳定性呈线性增高;适当的多元醇分子长度对该酶的热稳定性有最优的保护效应;不同浓度和不同分子量的聚乙二醇对该酶的热稳定性具有明显的影响;在无机盐中,单价金属阳离子比二价金属阳离子更能显著地提高该酶的热稳定性;酶液溶剂的改变直接影响着该酶的热稳定性,该酶在D2O溶液中比在水溶液中稳定,其酶活半衰期延长了2.6倍.研究表明,热环境使酶蛋白分子的螺旋结构发生变化而失活,但某些溶质和溶剂的存在可能通过作用于蛋白质分子的三维结构而影响该酶的热稳定性.图7参15     

靛蓝的微生物合成研究新进展

靛蓝是一种广泛应用于印染、医药等行业的有机色素,利用微生物法合成靛蓝已引起国内外学者的广泛关注.本文综述了微生物法合成靛蓝的研究进展及动态.靛蓝的微生物合成可归纳为3个阶段:野生型微生物催化合成、基因工程菌全细胞催化转化及代谢工程调控转化.多数芳烃降解菌及其编码酶均具备催化吲哚合成靛蓝的能力,采用定向进化、宏基因组技术以及两相体系等对已知酶资源进行深尺度研究,将为靛蓝生物合成过程注入新的活力.同时,靛蓝合成过程中产生的羟基吲哚及靛蓝衍生物是新型药物及化工中间体,也具有较大的研究价值.然而,由于靛蓝合成过程涉及的中间产物及副产物间转化关系及合成脉络仍不明晰,靛蓝产率低,因此将分子生物学及代谢工程手段融入到靛蓝合成机理及产业化应用的探索将成为该方向的研究重点.     

Soil enzyme activities and their indication for fertility of urban forest soil

To reveal the biological characteristics of urban forest soil and the effects of soil enzyme on soil fertility as well as the correlation between physicochemical properties and enzyme activities, 44 urban forest soil profiles in Nanjing were investigated. Basic soil physicochemical properties and enzyme activities were analyzed in the laboratory. Hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase were determined by potassium permanganate titration, TTC (C₁₉H₁₅N₄·Cl) colorimetry, phenyl phosphate dinatrium colorimetry, and anthrone colorimetry, respectively. The result showed that soil pH, organic carbon (C), and total nitrogen (N) had great effects on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 0–20 cm thick soil. However, pH only had great effect on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 20–40 cm thick soil. Hydrogen peroxidase, dehydrogenase, and alkaline phosphatase were important biological indicators for the fertility of urban forest soil. Both in 0–20 cmand 20–40 cmsoil, soil enzyme system (hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase) had a close relationship with a combination of physicochemical indicators (pH, organic C, total N, available K, available P, cation exchange capacity (CEC), and microbial biomass carbon (C_mic)). The more soil enzyme activities there were, the higher the fertility of urban forest soil.     

秸秆污泥堆肥产纤维素酶细菌的筛选及产酶条件优化

从添加秸秆进行堆肥处理的污泥中采集样品,通过富集培养和刚果红平板染色法筛选分离出具有纤维素降解能力的细菌,再通过酶活力测定从中分离筛选出1株相对高活性的产纤维素酶细菌CI;通过基于16S rRNA基因序列的系统发育分析,初步确定该菌株为Devosia sp..利用单因素试验对目的菌株C1进行产纤维素酶发酵条件优化,结果表明菌株C1产纤维素酶的最佳发酵时间、培养温度、摇床转速以及最适初始pH值分别为60 h、30℃、130 r·min^-1和7.2～7.5,且在该条件下其滤纸酶（FPase）和羧甲基纤维素酶（CMCase）活力分别达23.10和54.97 U·mL^-1.     

Interactions among lignin, cellulose, and nitrogen drive litter chemistry-decay relationships

Litter decay rates often correlate with the initial ratios of lignin:nitrogen (N) or lignin:cellulose in litter. However, the chemical and microbial mechanisms that give rise to these patterns are still unclear. To identify these mechanisms, we studied the decomposition of a model plant system, Arabidopsis thaliana, in which plants were manipulated to have low levels of lignin, cellulose, or litter N. Nitrogen fertilizer often increases the loss of cellulose, but it suppresses the breakdown of lignin in plant litter. To understand the mechanisms driving these patterns, we decomposed plants in litterbags for one year in control and N-fertilized plots in an Alaskan boreal forest. We found that litter N had a positive effect on total mass loss because it increased the loss of lignin, N, and soluble C. Lignin had a negative effect on rates of total litter mass loss due to decreases in the loss of cellulose and hemicellulose. Cellulose had a positive effect on lignin loss, supporting the concept of a "priming effect" for lignin breakdown. However, the low-cellulose plants also lost more of their original cellulose compared to the other plant types, indicating that decomposers mined the litter for cellulose despite the presence of lignin. Low-lignin litter had higher fungal biomass and N-acetyl glucosaminidase (NAG, a chitinase) activity, suggesting that lignin restricted fungal growth and may have influenced competitive interactions between decomposers. Nitrogen fertilization increased NAG activity in the early stages of decay. In the later stages, N fertilization led to increased cellulase activity on the litters and tended to reduce lignin losses. The transition over time from competition among decomposers to high cellulase activity and suppressed lignin loss under N fertilization suggests that, in N-limited systems, N fertilization may alter decomposer community structure by favoring a shift toward cellulose- and mineral-N users.     

Characterization of protease from Alcaligens faecalis and its antibacterial activity on fish pathogens

Alcaligens faecalis AU01 isolated from seafood industry effluent produced an alkaline protease. The optimum culture conditions for growth as well as enzyme production were 37 degrees C and pH 8. The partially purified protease had specific activity of 9.66 with 17.77% recovery with the molecular weight of 33 kDa and it was active between 30-70 degrees C and optimum being at 55 degrees C and pH 9. The enzyme retains more than 85% activity at 70 degrees C and 78% even at pH 10. The enzyme inhibited the growth of fish pathogens such as Flavobacterium sp., Pseudomonas fluorescens, Vibrio harveyi, Proteus sp. and Vibrio parahaemolyticus. From the present study it can be concluded that Alcaligens faecalis AU01 has the potential for aquaculture as probiotic agent and other several applications.     

热塑性水凝胶纤维素的制备

用水溶性纤维纱衍生物－－－羟丙基纤维素（ＨＰＣ）和羟乙基纤维素（ＨＥＣ）作为初始原料，在不同取代度（ＤＳ）条件下，轻度导入特定的疏水性取代基，旨在使其具有一定的热塑性；并对处理后所得到的新型纤维素衍生物的热塑性及水溶性进行分析探讨。实验结果表明：ＨＰＣ和ＨＥＣ在特定的取代基和ＤＳ条件下，均能获得良好的热塑性和水凝胶性，其中，ＨＰＣ在取代基Ｃ６ＨＮＣＯ－，ＤＳ为０．１２－０．２１；ＨＥＣ在取代基Ｃ４     

氟害大豆超氧化物歧化酶活性与叶绿素含量及叶片脱落的关系

采用人工HF熏气的方法研究了盆栽大豆 (Glycinemax )超氧化物歧化酶 (SOD)活性与叶绿素含量、乙烯产生量、纤维素酶活性之间的关系。结果表明 :(1)HF通过抑制SOD活性降低了叶绿素的含量 ;(2 )HF对参与叶片脱落的纤维素酶的活性诱导是通过抑制SOD活性进而合成大量乙烯实现的。     

Monolignol biosynthesis and genetic engineering of lignin in trees, a review

This paper summarizes our previous and current research on genetic engineering of lignin biosynthesis for the purposes of improving wood pulping and bleaching efficiency. For these purposes, our targets were to produce transgenic trees with low content of lignin that is also chemically reactive (high lignin S/G ratio). Using aspen as a model species, we have characterized the biochemical functions of various genes and the kinetic properties of these gene products involved in monolignol biosynthetic pathway. The results of these characterizations proved strong evidence for a principle phenolic flux leading to the formation of monolignols. Biochemical evidence further demonstrated that, in this principle flux, 4CL could be the enzyme limiting total lignin accumulation, whereas CAld5H might control the lignin S/G ratio. These propositions were fully supported by the in vivo functions of these enzymes. Transgenic trees with inhibited 4CL enzyme activity exhibited 5–45% reduction in lignin contents. The chemical structure of the resulting lignin remained essentially unchanged. More importantly, the lignin reduction was compensated for by a concomitant increase in cellulose content. When antisense 4CL and sense coniferaldehyde 5-hydroxylase (CAld5H) genes were simultaneously transferred into aspen via Agrobacterium, transgenic trees expressing each one and both of the transgenes were produced. Lignin reductions up to 55% were achieved in antisense 4CL plants and up to 3-fold S/G increases were observed in sense CAld5H plants. These effects were independent but additive, with plants expressing both transgenes having less lignin and higher S/G ratio. Consistent with our previous results, lignin reduction has always resulted in an increase in cellulose content. These transgenics could be potentially valuable for pulp production. But more importantly, these benchmark transgenics are rich sources of information for functional genomics and metabolic engineering, allowing the generation of the ultimate raw materials for wood pulp production.     

Utilization of banana agricultural waste: production of cellulases by soil fungi

Banana a major cash crop of Maharashtra is cultivated over 46900 hectares generating large amount of agro waste after the harvest. Attempts were made to utilize these agro wastes for production of cellulases. Of the 127 fungi isolated from the soil of banana field, 12 fungi were found to utilize cellulose as source of carbon. Trichoderma lignorum showed appreciable cellulolytic activity. It produced Cl, Cx and beta glucosidase in Carboxymethyl Cellulose Peptone medium as well as on agro waste based medium containing leaves, stem and rhizome powders. T. lignorum (0. 45 U/ml) produced maximum enzymes on leaf based medium.     

黑胸散白蚁纤维素酶的体外酶学特性

采用DNS法研究了我国广泛分布的一种低等木食性白蚁——黑胸散白蚁纤维素酶的体外酶活特性以了解其纤维素降解机制.结果表明,内切β-1,4-葡聚糖酶(EG)、纤维二糖水解酶(CBH)和β-葡萄糖苷酶(BG)这3种酶的最佳反应时间均为15 min,最佳底物浓度为1%,最适反应pH为5.6,最适反应温度为35℃.在最适反应条件下,EG、CBH和BG的活性分别达到71.3(±13.9)U/mg、5.8(±0.8)U/mg和4.1(±0.7)U/mg.EG在体外的热稳定性较差,在50℃及更高温度酶活很低或完全失活,但该酶对pH稳定性较好,在pH 3.2～8.0范围内酶活力变化不大.Native-PAGE电泳检测到该白蚁体内至少有8种不同的EG活性条带,肠道不同部位纤维素酶活性条带种类不同.这些研究表明,木食性白蚁降解纤维素是一个复杂的过程,需要多种纤维素酶的共同作用.     

堆肥过程中有机质和微生物群落的动态变化

利用3个容积约为50 L的平行生物反应装置研究堆肥过程中温度、湿度（水分含量）、pH值和有机质的动态变化情况。按照Van Soest方法根据有机质不同的溶解特性将其分为：溶于沸水的有机质H2O、溶于中性试剂的有机质SOLU、半纤维素（HEMI）、纤维素（CELL）和木质素（LIGN）。结果表明：反应装置内环境湿度调控在60%左右时,堆肥系统内借助生化反应,温度最高可达到约50℃。堆肥材料在反应初期呈现偏酸性（pH=6.5）,而随着反应的发生,pH逐渐变为中性或弱碱性（pH=7.4）。经过20 d的堆肥实验,有机质总量降解了约47%。在微生物作用下的各类有机质的降解率不同,按大小排序为H2O〉HEMI〉CELL〉SOLU〉LIGN,其降解率分别是85%、56%、36%、32%和27%。为了深入理解堆肥过程中有机质的降解机制,文章采用磷脂脂肪酸（PLFAs）技术对体系中的微生物群落变化进行了初步分析,发现微生物优势群落随反应温度的改变发生明显变化,在堆肥初期和堆肥中期,细菌占优势,而堆肥末期时真菌比例较高。在堆肥的过程中,革兰氏阴性菌的比例呈下降趋势,而革兰氏阳性菌的比例呈上升趋势。     

乳酸氧化酶转化乳酶产丙酮酸

从土壤样品中富集、筛选和纯化获得了3株能产生乳酸氧化酶的菌株，其中SM-10#菌株的产酶活力最高，经初步鉴定，该菌株属腐生葡萄球菌（Staphylococcus saprophyticus），对SM-10#菌株还进行了破壁条件的优化、生长曲线的分析和酶液稳定性研究，并初步探讨了其酶液的底物转化效率，4h最高转化率达到80%，该研究结果为将这种有价值的酶源推向生产打下基础。     

几种有效硅测定方法对不同母质水稻土的适宜性研究

本研究以湖北省十二种典型母质发育的水稻土为对象，比较了常见几种土壤有效硅提取方法对不同母质水稻土的适宜性．研究结果表明，ｐＨ４．０酸－醋酸钠提取法对性质相差较大的不同母质水稻土的测定，不仅能反映土壤性状对有效硅含量的影响，而且测定精密度高，与其它有效硅测定方法比较，在缺硅诊断中可适用于较为广泛的水稻上类型．     

Physico-chemical characteristics of fine fraction materials from an old crystal glass dumpsite in Sweden

Physico-chemical characteristics of waste, particularly fine fraction (FF), from an old crystal glass waste dump in Sweden were studied to assess recycling or disposal alternatives. Hand-sorting of the waste indicated glass content of 44.1% while sieving established the FF as a more soil-like mix of glass and other materials constituting 33.3% of all excavated waste. The FF was around neutral pH with 24.4% moisture content, low values of Total Dissolved Solids, Dissolved Organic Carbon and fluorides, but hazardous concentrations of As, Cd, Pb and Zn according to the Swedish Environmental Protection Agency guidelines. While the FF leached metals in low concentrations at neutral pH, it leached considerably during digestion with nitric acid, implying leaching risks at low pH. Thus, the waste requires safe storage in hazardous waste class ‘bank account’ storage cells to avoid environmental contamination as metal recovery and other recycling strategies for the glass waste are being developed. The study could fill the information gap regarding preservation of potential resources in the on-going, fast-paced excavation and re-landfilling of heavy metal contaminated materials in the region.