云南松外生菌根真菌分离培养研究

就滇中一带云南松林进行了多次调查,共采集、鉴定标本130余号;从中选取13科, 19属, 33种真菌进行了菌种分离、培养的研究。选用并修改4种培养基进行了外生菌根真菌分离、培养的比较,结果共有11科, 17属, 25种真菌分离获得成功,成功率高达75.8%, 4种培养基的分离成功率依次为36.4%、63.6%、33.3%和57.6%。其中,修改PDA培养基和松针、玉米培养基较适宜于云南松外生菌根真菌的分离、纯化和培养。     

油松根际外生菌根真菌龟裂秃马勃的分离鉴定及培养

该研究采用组织分离法对黄土高原子午岭林区连家砭林场油松根际外生菌根真菌进行了分离,并采用ITS序列对分离的真菌进行鉴定,研究了菌根真菌的培养条件,为菌剂的生产奠定基础。结果表明:子午岭林区油松根际分离培养出的真菌为龟裂秃马勃(Handkea utriformis),能够与油松形成外生菌根。采用MMN培养基为基础培养基,纯培养条件下,龟裂秃马勃生长的最适pH为6.0,最适温度为25℃。以蔗糖为唯一碳源的培养基中龟裂秃马勃生长速度最快,其次是麦芽糖和葡萄糖,生长最慢的为乳糖,在以几丁质和碳酸氢钠为碳源的培养基上不生长。有机氮源中,对脯氨酸为唯一氮源的利用能力最好,其次是酪蛋白,尿素最差;无机氮源中,以磷酸氢二铵为唯一氮源时生长最好,其次是硝酸钙,最差为酒石酸铵。该研究首次报道了黄土高原子午岭林区外生菌根真菌龟裂秃马勃,并初步确定了其最佳培养条件。     

钾对外生菌根真菌的分泌作用及氮、磷、钾含量的影响

用无钾、低钾、中钾和高钾的液体培养基培养外生菌根真菌14～21d,随着钾离子浓度的降低,外生菌根真菌分泌H^ 和草酸的速率提高。由于H^ 能取代2：1型粘粒矿物品层和晶格内的钾,草酸能络合矿物中的Fe,Al离子,促进Al-O八面体风化,推测菌根真菌和菌根活化土壤无效钾的能力在低钾时较强,在高钾时较弱。在外生菌根真菌分泌的H^ 中,草酸电离可能不是它们的主要来源,而是一些目前尚未知道的有机酸。此外,液体培养基中的钾离子不同程度地影响外生菌根真菌体内的氮、磷、钾含量,看来环境中的钾离子供应影响了真菌菌丝对养分的吸收。     

我国部分造林树种外生菌根真菌的初步调查研究

<正> 植物菌根的研究在国际上引起了人们的重视。现已发现80％以上的植物都有菌根,树木的菌根大部分是外生菌根。树木形成外生菌根后,增强了对养分、水分的吸收能力和抗逆能力。据不完全统计,能和树木共生形成外生菌根的真菌约有520种以上,其中大部分是担子菌纲(Basidiomycetes)中伞菌目(Agaricales)的真菌。已获得纯培养菌种的外生菌根真菌约有80种(COOKE,1977)。在我国分布的外生菌根真菌约有172种。1978年以来,我们对我国东北、华中、华南、华东等地区的部分重要造林树种的外生菌根真菌进行了初步调查研究,现将结果报道如下:     

两种纯培养外生菌根真菌对柴油的降解效率

采用紫外法和GC-MS,研究了柴油污染情况下（10 g·L^-1）外生菌根真菌铆钉菇和双色蜡蘑的生长特点及对柴油的降解效率.结果表明：铆钉菇和双色蜡蘑均能利用柴油作为唯一碳源生长.经过14 d培养,在柴油含量为10 g·L^-1液体培养基内,铆钉菇和双色蜡蘑的质量降解率分别为31.32%和39.90%,且主要减少的是16～21碳烃.不同培养基对外生菌根真菌的降解能力也有显著影响.虽然外生菌根真菌在含有葡萄糖的培养基上的生物量是对照（未添加葡萄糖）的2～5 倍,但其对柴油的降解能力明显受到抑制.高浓度的无机氮对外生菌根真菌的降解效率有一定的提高作用,但效果不明显.     

外生菌根真菌促生微生物生态功能研究进展

菌根的形成及功能与菌根促生功能微生物密切相关。外生菌根不仅在森林生态系统中发挥至关重要的作用,而且部分外生菌根类大型真菌具有良好的食药用经济价值。根据已有研究,本文系统阐述了外生菌根真菌相关促生功能微生物对外生菌根真菌菌根化、菌丝生长及子实体形成的促进作用及机制;解析促生功能微生物对外生菌根真菌的特异定殖机制;探讨外生菌根真菌相关促生性微生物的作用条件特异性及生态功能,对外生菌根真菌和相关促生功能微生物的互作进行综述,并展望了外生菌根真菌促生微生物的研究前景。希望为外生菌根真菌生长、发育及其生态功能研究提供新的思路。     

净月潭国家森林公园针叶林根系共生真菌初步调查

采用菌根形态学及分子生物学手段对采自净月潭国家森林公园的红松Pinus koraiensis、落叶松Larix gmelinii和云杉Picea asperata根系共生真菌进行了初步调查。结果表明:外生菌根形态依据不同树种表现不同,红松外生菌根主要表现为淡黄色到褐色,不分支、偶有珊瑚状分支,外延菌丝丰富或浓密;云杉菌根颜色基本为淡黄色到黄色,末端膨大或等粗,表现为弯曲状或蜿蜒状,不分支或不规则分支、偶有羽状分支,外延菌丝少;落叶松菌根淡黄色到黄色,偶有红褐色,不分支、羽状分支或不规则分支,外延菌丝浓密,也有表现外延菌丝少量。共鉴定获得共生真菌9科9属,其中红松根系外生菌根真菌2种:美洲乳牛肝菌Suillus americanus和外生菌根真菌未定种1,内生真菌3种:Phialocephala fortinii,Cylindrocarpon pauciseptatum和Phialocephala helvetica;云杉根系外生菌根真菌5种:臭红菇Russula foetens、外生菌根真菌未定种2和外生菌根真菌未定种3,Tomentella sp.1和Tomentella sp.2;落叶松根系外生菌根真菌4种:平凹盘菌Peziza depressa、拟篦边红菇Russula pectinatoides、外生菌根真菌未定种4和外生菌根真菌未定种5。该研究结果丰富了针叶树根系共生真菌的多样性,可为进一步开展菌根形态解剖学以及菌根生态学等研究提供依据。     

外生菌根对干旱胁迫的响应

从外生菌根真菌、外生菌根共生体以及外生菌根的间接作用等方面阐述外生菌根如何抵制干旱胁迫,并对未来我国外生菌根的研究提出了建议。干旱可以抑制外生菌根真菌的生长并降低其群落中真菌的多样性,干旱胁迫下外生菌根真菌子实体可以利用深度30cm以下的土壤水,子实体的表面积和体积比可作为筛选抗旱真菌的一个重要因子;在遭受干旱胁迫时,外生菌根共生体可以发生形态变化来应对干旱,同时增加了植株水分的吸收并改善了植物的光合作用、活性氧以及激素等相关代谢;外生菌根对植物生长的促进作用、增加土壤碳汇以及对其他根际微生物生长的促进作用等对宿主植物应对干旱胁迫有利。未来我国外生菌根研究应加强对干旱区优良菌-树组合的筛选工作,同时加大对乡土外生菌根真菌资源的调查力度,未来研究应重点向分子生物学领域推进。     

外生菌根真菌利用碳素和氮素营养的研究

外生菌根真菌广泛地分布在森林土壤的表层。它们大部分属于担子菌纲,少数为子囊菌纲和半知菌类。据不完全统计,能形成菌根的真菌种类约有520种。分布在我国境内的约有160余种。因为这些真菌生长需要特殊的营养条件,因此能被人工分离培养的约有60种。其中有些在人工培培养基上虽生长,但不能长期保存。除非与树木根共生外,几乎不形成子实体菌根真菌纯培养菌在人工培养条件     

内蒙古地区白桦外生菌根形态类型及分子鉴定

以内蒙古不同地区白桦外生菌根为材料,采用形态解剖学方法和分子生物学手段对与白桦共生的外生菌根真菌多样性进行全面的调查,并经对所测序列与GenBank和Database比对。结果显示:在内蒙古地区与白桦共生的外生菌根真菌共13种,其中担子菌7种,子囊菌4种,分别来自于丝膜菌属、丝盖伞属、蜡壳耳属、毛革菌属、滑菇属和空团菌属、块菌属、地怀菌属。其中,菌根类型T₈和T₁₁未能提出其总DNA,根据其外生菌根形态类型并参照Agerer体视显微镜菌根图谱和Haug菌根图谱进行比较,分类鉴定为荷顿氏疣柄牛肝菌和白桦外生菌根真菌一种。结果表明,内蒙古地区白桦外生菌根真菌多样性相对较高,且与利用地上子实体鉴定的外生菌根真菌种类有一定的区别。     

Acid Protease Production by Fungi Used in Soybean Food Fermentation

Growth conditions for maximum protease production by Rhizopus oligosporus, Mucor dispersus, and Actinomucor elegans, used in Oriental food fermentations, were investigated. Enzyme yields by all three fungi were higher in solid substrate fermentations than in submerged culture. The level of moisture in solid substrate must be at about 50 to 60%. Very little growth of these fungi was noted when the moisture of substrate was below 35%, whereas many fungi including most storage fungi generally grow well on solid substrate with that level of moisture. Among the three substrates tested—wheat bran, wheat, and soybeans—wheat bran was the most satisfactory one for enzyme production. The optimal conditions for maximum enzyme production of the three fungi grown on wheat bran were: R. oligosporus, 50% moisture at 25 C for 3 to 4 days; M. dispersus, 50 to 63% moisture at 25 C for 3 to 4 days; A. elegans, 50 to 63% moisture at 20 C for 3 days. Because these fungi are fast growing and require high moisture for growth and for enzyme synthesis, the danger of contamination by toxin-producing fungi would be minimal.     

不同真菌纤维素酶一些生物化学性质的比较

比较了属于6个属,即青霉(Penicillium)、曲霉(Aspergillus)、木霉(Trichoderma)、漆斑菌(Myrothecium)、镰孢霉(Fusarium)和腐质霉(Humicola),总计9株真菌在麦麸液体培养基中所产纤维素酶的一些生物化学性质。此外,还比较了这9株真菌在麦麸固体培养基上所产纤维素酶的活力以及对脱脂棉、水曲柳木屑、水曲柳木粉、废报纸和玉米芯糠醛废渣的糖化能力。     

银合欢叶作氮源栽培食用菌研究

以银合欢叶作氮源全部或部分取代基质中米糠或麸皮,栽培毛木耳、凤尾菇、金针菇、黑木耳、香菇和佛罗里达侧耳6种食用菌。结果表明,银合欢叶能促进菌丝生长。栽培中发现,含10%银合欢叶和17%麸皮的基质能使金针菇获得增产,而含10%或20%银合欢叶的基质可使其它5种食用菌产量提高11.4%~39.1%。     

Methane fermentation of Japanese cedar wood pretreated with a white rot fungus, Ceriporiopsis subvermispora

Methane fermentation of Japanese cedar wood was carried out after pretreatment with four strains of white rot fungi, Ceriporiopsis subvermispora ATCC 90467, CZ-3, CBS 347.63 and Pleurocybella porrigens K-2855. These fungi were cultivated on wood chip media with and without wheat bran for 4-8 weeks. The pretreated wood chip was fermented anaerobically with sludge from a sewage treatment plant. Pretreatments with C. subvermispora ATCC 90467, CZ-3 and CBS 347.63 in the presence of wheat bran for 8 weeks decreased 74-76% of beta-O-4 aryl ether linkages in the lignin to accelerate production of methane. After fungal treatments with C. subvermispora ATCC 90467 and subsequent 30-days methane fermentation, the methane yield reached 35 and 25% of the theoretical yield based on the holocellulose contents of the decayed and original wood, respectively. In contrast, treatment with the three strains of C. subvermispora without wheat bran cleaved 15-26% of the linkage and produced 6-9% of methane. There were no significant accelerating effects in wood chips treated with P. porrigens which has a lower ability to decompose the lignin. Thus, it was found that C. subvermispora, with a high ability to decompose aryl ether bonds of lignin, promoted methane fermentation of softwood in the presence of wheat bran.     

Changes in moisture content,mycoflora and aflatoxin content of rice bran during storage

The changes in moisture content, storage mycoflora and aflatoxin B₁ (AFB₁) in bran from untreated or raw rice (Rr) and parboiled rice (Pbr) stored in small lots in polyethylene bags were studied at 15-day intervals up to 60 days, using five lots of each type of bran. Deterioration was more rapid with reference to all the three parameters, in Rr bran compared to Pbr bran, the former becoming completely overgrown and caked with fungi by the end of 60 days.Aspergillus flavus was the dominant fungus in Pbr bran, whereasA. candidus andTrichoderma viride were abundant in Rr bran. The frequency of incidence as well as concentration of AFB₁ increased with storage time in both types of bran, but the rate of increase as well as overall concentration were much higher in Rr bran. Thus raw rice bran is unsuitable for prolonged storage.Abbreviations AFB₁ aflatoxin B₁ - MC moisture content - Pbr parboiled rice - Rr raw rice     

Characterization of hemicellulases from thermophilic fungi

The thermophilic fungi Thermomyces lanuginosus, Malbranchea cinnamomea, Myceliophthora fergusii and the thermotolerant Aspergillus terreus were cultivated on various carbon sources, and hemicellulolytic and cellulolytic enzyme profiles were evaluated. All fungi could grow on locust bean galactomannan (LBG), Solka floc, wheat bran and pectin, except T. lanuginosus, which failed to utilize LBG for growth. Different levels of cellulase and hemicellulase activities were produced by these fungal strains. Depending on the carbon source, variable ratios of thermostable hydrolytic enzymes were obtained, which may be useful in various applications. All strains were found to secrete xylanolytic and mannanolytic enzymes. Generally, LBG was the most efficient carbon source to induce mannanase activities, although T. lanuginosus was able to produce mannanase only on wheat bran as a carbon source. Xylanolytic activities were usually highest on wheat bran medium, but in contrast to other investigated fungi, xylanase production by M. fergusii was enhanced on pectin medium. Preliminary thermostability screening indicated that among the investigated species, thermotolerant glycosidases can be found. Some of the accessory activities, including the α-arabinosidase activity, were surprisingly high. The capability of the produced enzymes to improve the hydrolysis of lignocellulosic pretreated substrate was evaluated and revealed potential for these enzymes.     

Use of chitin to improve a Beauveria bassiana alginate-pellet formulation

A study was undertaken to evaluate optimum concentrations of chitin in sodium alginate pellet formulations to enhance conidia production. Chitin concentrations tested were 0, 0.5, 1, 2, 3 and 4% (w/v), with (2%, w/v) or without wheat bran. The different chitin-wheat bran pellet combinations were prepared with Beauveria bassiana isolate Qu-B306 at 10⁸ conidia mL^-1. After 21 days of incubation in a humid chamber at 28°C, conidia production was assessed. Improvements up to three times the initial conidia number were achieved using 2% chitin and 2% wheat bran. Higher levels of chitin decreased the number of conidia per pellet. For all chitin concentrations, conidia number increased with the addition of wheat bran (P≤0.05). Contamination by saprophytic fungi was reduced by the incorporation of chitin in the pellet formulation.     

Physico-chemical,Sensory and Toxicity Characteristics of Dipeptidyl Peptidase-IV Inhibitory Peptides from Rice Bran-derived Globulin Using Computational Approaches

Rice processing industry released an enormous amount of the rice bran which is underutilized. Rice bran contains various proteins that can be used for the production of bioactive peptides. These bioactive peptides might be suitable ingredients for the development of functional food products. The objective of this study was to explore the potential of rice bran-derived globulin proteins as a suitable precursor of bioactive peptides with especially reference to dipeptidyl peptidase IV (DPP-IV) inhibitory peptides. The various computational approaches (BLAST, BIOPEP, PeptideRanker, PepDraw, Pepcalc, and ToxinPred) were used to predict the potential of the globulin proteins. Ficain protease majorly released the DPP-IV inhibitory peptides from rice bran-derived globulin proteins as compared with other proteases used in this study. Furthermore, primary structure, physico-chemical, sensory, and allergic characteristics of the theoretically release bioactive DPP-IV inhibitory peptides were also studied. The result of this study provides a theoretical basis for the development of rice bran globulin proteins as a suitable source for the generation of bio-functional ingredients for glycaemic management and further demonstrates the usefulness of computational approaches.     

Production of a New Type of Acid Carboxypeptidase of Molds of the Aspergillus niger Group

The ability of 88 fungi, which had been obtained as high-potency strains for acid proteinase production, to produce a new type of acid carboxypeptidase (having on optimal pH of about 3 for hydrolysis of benzyloxycarbonyl-glutamyltyrosine) in surface koji culture was determined. Among the aspergilli, substantial amounts of this new acid carboxypeptidase were produced by Aspergillus saitoi, A. usamii, A. awamori, A. inuii, and A. niger. Maximum yields of acid carboxypeptidase per gram of substrate were obtained by submerged culture in a medium containing 0.9% defatted soybean and 0.6% wheat bran. However, the maximum enzyme concentration per milliliter was obtained with a medium containing 3% defatted soybean and 2% wheat bran. The terminal pH could be controlled by varying the concentrations of soybean oil meal and wheat bran. The maximum enzyme production was reached after 4 days or more at 30 C.     

Hydrolytic potential of five fungal supernatants to enhance a commercial enzyme cocktail

Objectives

To evaluate the potential of enzyme cocktails produced by five filamentous fungi to supplement the industrial cellulase cocktail, Celluclast 1.5L, in order to improve the efficiency of saccharification.

Results

The fungi were cultivated on wheat bran and the resulting supernatants were combined with Celluclast in enzymatic hydrolysis experiments to test their ability to hydrolyze wheat bran and five cellulose-rich substrates. The supernatant showing the best performance was that from an Aspergillus niger cellulase mutant. The addition of β-glucosidase only to the Celluclast cocktail was not as beneficial.

Conclusion

Supplementing commercial cocktails with enzymes from carefully selected fungi may result in significantly more efficient saccharification of lignocellulosic materials. Furthermore, such an approach could lead to the identification of novel enzyme activities crucial for saccharification.