Fungi in Antarctica

Fungi are generally easily dispersed and are able to colonize a very wide variety of different substrata and to withstand many different environmental conditions. Because of these characteristics they spread all over the world. The Antarctic mycoflora is quite diversified within the different climatic regions of the continent. Most Antarctic microfungi are cosmopolitan; some of them are propagules transported to Antarctica but unable to grow under the Antarctic conditions, while others, termed indigenous, are well adapted and able to grow and reproduce even at low temperatures, mostly as psychrotolerant, or fast sporulating forms, able to conclude their life-cycles in very short time. In the most extreme and isolated areas of the continent, such as the Antarctic Dry Valleys, endemic species showing physiological and morphological adaptations have locally evolved. Most Antarctic fungi, as well as fungi from other dry and cold habitats, are adapted to low temperatures, repeated freeze and thawing cycles, low water availability, osmotic stress, desiccation, low nutrients availability and high UV radiation. Sometimes single strategies are not specific for single stress factors and allow these microorganisms to cope with more than one unfavourable condition.     

Biodegradation of Lignin by White Rot Fungi

A review is presented related to the biochemistry of lignocellulose transformation. The biodegradation of wood constituents is currently understood as a multienzymatic process with the mediation of small molecules; therefore, this review will focus on the roles of these small molecular compounds and radicals working in concert with enzymes. Wood rotting basidiomycetous fungi penetrate wood and lead to more easily metabolized, carbohydrate constituents of the complex. Having a versatile machinery of enzymes, the white rot fungi are able to attack directly the "lignin barrier." They also use a multienzyme system including so-called "feed back" type enzymes, allowing for simultaneous transformation of both lignin and cellulose. These enzymes may function separately or cooperatively.     

白腐菌选择性降解竹基质中木质纤维素的研究

对竹基质白腐菌选择性降解进行了初步研究。结果表明,菌株B1对竹基质中木质素和半纤维素有明显的降解选择性。降解55 d木质素和半纤维素降解率分别达44.4%和47.1%;降解20 d降解选择性最好,木质素和半纤维素降解率选择系数分别是2.08和1.98。从FTIR图谱中木质纤维素相关谱峰(2 924、1 6351、6011、5101、165、1 045、666/cm等)的明显变化也可以得出相同结论。     

不同木质纤维素基质上白腐菌降解特性的研究

通过测定木质素、纤维素、半纤维素和漆酶分泌的变化,研究白腐菌在稻草、木屑、粗纤维素、滤纸、黑液木素基质上的降解特性。结果表明,除黑液木素上白腐菌不能生长外,在前25d,各基质中纤维素、半纤维素和木质素含量呈持续下降趋势,之后,降解速率减少,其中木质素的降解速率大于纤维素和半纤维素的降解速率。漆酶分泌在生长初期呈快速上升趋势,第10d酶活达到最大,第10～20d快速下降,其后基本不变,基质中酶活大小顺序为稻草基质、木屑基质、粗纤维和滤纸基质,显示了木质素存在对漆酶分泌的诱导作用。     

Soft Rot Erwinia Bacteria in the Atmospheric Bacterial Aerosol

Using a Casella High Volume Airborne Bacteria Sampler, the soft rot coliform bacteria Erwinia carotovora var. carotovora and E. carotovora var. atroseptica were caught from the open air during rainfall in mid to late summer, autumn and early winter, but not in late winter, spring or early summer. They were not found every time it rained, and never when the weather was dry. The bacteria were caught close to potato crops, but there were several occasions when they were found at sites where there were no such crops or at times of year after potato crops had been harvested. The sources of the organisms are uncertain, but those obtained close to potato crops may have originated there. The results are considered to provide further evidence that airborne spread and subsequent deposition of viable bacteria could cause contamination of Erwinia -free potato stocks, and suggest that rainfall is a major generator of the general atmospheric bacterial aerosol.     

Fungi Associated with Root Rot of Winter Wheat in Alabama

Winter wheat plants were sampled during the spring and autumn to identify fungi associated with root rot in Alabama. Samples were taken from 61 fields in the major wheat-producing areas of the state; 179 fungi were isolated, identified, and tested for pathogenicity. Of the fungi identified, 46 (26%) were Gaeumannomyces graminis var. tritici , 37 (21%) were Cochtiobolus sativus , and 55 (31%) were Fusarium species of which 37 (21%) were Fusarium oxysporum . Other fungi identified that were pathogenic on wheat were Rhizoctonia solani, Sderotium rolfsii , and Pythium spp. G. g. var. tritier was the main pathogen associated with diseased root and lower stem tissue of wheat in Albama.     

Changes in Molecular Size Distribution of Cellulose during Attack by White Rot and Brown Rot Fungi

The kinetics of cotton cellulose depolymerization by the brown rot fungus Postia placenta and the white rot fungus Phanerochaete chrysosporium were investigated with solid-state cultures. The degree of polymerization (DP; the average number of glucosyl residues per cellulose molecule) of cellulose removed from soil-block cultures during degradation by P. placenta was first determined viscosimetrically. Changes in molecular size distribution of cellulose attacked by either fungus were then determined by size exclusion chromatography as the tricarbanilate derivative. The first study with P. placenta revealed two phases of depolymerization: a rapid decrease to a DP of approximately 800 and then a slower decrease to a DP of approximately 250. Almost all depolymerization occurred before weight loss. Determination of the molecular size distribution of cellulose during attack by the brown rot fungus revealed single major peaks centered over progressively lower DPs. Cellulose attacked by P. chrysosporium was continuously consumed and showed a different pattern of change in molecular size distribution than cellulose attacked by P. placenta. At first, a broad peak which shifted at a slightly lower average DP appeared, but as attack progressed the peak narrowed and the average DP increased slightly. From these results, it is apparent that the mechanism of cellulose degradation differs fundamentally between brown and white rot fungi, as represented by the species studied here. We conclude that the brown rot fungus cleaved completely through the amorphous regions of the cellulose microfibrils, whereas the white rot fungus attacked the surfaces of the microfibrils, resulting in a progressive erosion.     

Biodestruction of Phthalic Acid Esters by White Rot Fungi

Applied Biochemistry and Microbiology - The ability of white rot fungi from different ecophysiological groups (primary wood-destroying saprotroph Trametes hirsuta, secondary wood-destroying...     

1株产漆酶白腐真菌的筛选和鉴定

从不同的生境采集生物样品,利用Bavendamm反应反复筛选产漆酶的白腐真菌。利用真菌通用引物对ITS1/ITS4扩增菌株rDNAITS区序列,对扩增产物进行测序。测序结果在GenBank中进行同源性搜索,下载部分具有代表性种的ITS序列进行序列比对,利用软件MEGA4构建分子系统发育树,通过序列分析,并结合形态学鉴定出4220为香栓孔菌(Trametes suaveolens)。     

Solubilization and Mineralization of Lignin by White Rot Fungi

The white rot fungi Lentinula edodes, Phanerochaete chrysosporium, Pleurotus sajor-caju, Flammulina velutipes, and Schizophyllum commune were grown in liquid media containing ¹⁴C-lignin-labelled wood, and the formation of water-soluble ¹⁴C-labelled products and ¹⁴CO₂, the growth of the fungi, and the activities of extracellular lignin peroxidase, manganese peroxidase, and laccase were measured. Conditions that affect the rate of lignin degradation were imposed, and both long-term (0- to 16-day) and short-term (0- to 72-h) effects on the production of the two types of product and on the activities of the enzymes were monitored. The production of ¹⁴CO₂-labelled products from the aqueous ones was also investigated. The short-term studies showed that the different conditions had different effects on the production of the two products and on the activities of the enzymes. Nitrogen sources inhibited the production of both products by all species when differences in growth could be discounted. Medium pH and manganese affected lignin degradation by the different species differently. With P. chrysosporium, the results were consistent, with lignin peroxidase playing a role in lignin solubilization and manganese peroxidase being important in subsequent CO₂ production.     

Microsomal Transformation of Organophosphorus Pesticides by White Rot Fungi

The enzymatic mechanism for the transformationof organophosphorus pesticides (OPPs) by differentwhite-rot fungi strains was studied. With theexception of Ganoderma applanatum 8168,all strains from a collection of 17 different fungicultures were able to deplete parathion. Threestrains showing the highest activities were selectedfor further studies: Bjerkandera adusta 8258,Pleurotus ostreatus 7989 and Phanerochaetechrysosporium 3641. These strains depleted 50 to96% of terbufos, azinphos-methyl, phosmet andtribufos after four-days exposure to the pesticides.In order to identify the cellular localization of thetransformation activity, the extracellular andmicrosomal fractions of Pleurotus ostreatus7989 were evaluated in vitro. While the activitiesof ligninolytic enzymes (lignin peroxidase,manganese peroxidase and laccase) weredetected in the extracellular fraction, noenzymatic modification of any of the fivepesticides tested could be found, suggestingthe intracellular origin of the transformationactivity. In accordance with this observation themicrosomal fraction was found able to transformthree OPPs with the following rates:10 mol mg prot^-1 h^-1 forphosmet, 5.7 mol mg prot^-1 h^-1 forterbufos, and 2.2 mol mg prot^-1 h^-1 forazinphos-methyl. The products from these reactions andfrom the transformation of trichlorfon and malathion,were identified by mass-spectrometry. These results,supported by specific inhibition experiments and thestringent requirement for NADPH during the in vitroassays suggest the involvement of a cytochrome P450.     

我国马铃薯软腐病防治的研究进展

马铃薯软腐病是马铃薯细菌性病害中最严重的一种,简要介绍了我国马铃薯软腐病的病原菌、病害性状以及对病害的防治方法。利用现代生物技术手段人为地操纵细菌群体感应系统,将会成为提高植物抗病性的新方法、新途径。     

Decolorization of Alcohol Distillery Wastewater by Thermotolerant White Rot Fungi

To determine a thermotolerant fungus strain for decolorization of alcohol distillery wastewater (ADW), 38 fungus strains were studied. Capacity for ligninolytic enzyme production was examined at 35 and ⁴³C on agar media containing 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and MnCl₂. At 43°C, four Pycnoporus coccineus strains showed a higher potential for ADW decolorization both on agar media and in liquid media. Immobilized mycelia on polyurethane foam removed about threefold more total phenol than did free mycelia under conditions of shaking at 43°C. Moreover, immobilized mycelia removed nearly 50% more color than did free mycelia.     

Production and Degradation of Oxalic Acid by Brown Rot Fungi

Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted ¹⁴C-labeled oxalic acid to CO₂ during cellulose depolymerization. The other brown rot fungi also oxidized ¹⁴C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize ¹⁴C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi.     

Ultrastructure of Laticifers Modifications in Hevea brasiliensis Infected with Root Rot Fungi

This paper presents some aspects of latex coagulation inside latice vessels of roots of Hevea brasiliensis infected by two fungi: Rigidoporus lignosus and Phellinus noxius. Three stages are described in latex coagulation: the phase of latex destabilisation characterized by the bursting of vacuoles and lysosomes membranes; the phase of latex coagulation characterized by the fusion of rubber particles and the disorganization of the cytoplasm; the formation of shots of rubber clumps indicating the final stage of coagulation.     

Phenolic Compound Utilization by the Soft Rot Fungus Lecythophora hoffmannii

Nine phenolic compounds were metabolized by the soft rot fungus Lecythophora hoffmannii via protocatechuic acid and subsequently cleaved by protocatechuate 3,4-dioxygenase as determined by oxygen uptake, substrate depletion, and ring cleavage analysis. Catechol was metabolized by catechol 1,2-dioxygenase. Fungal utilization of these aromatic compounds may be important in the metabolism of wood decay products.     

白腐菌液体深层培养条件的研究

实验研究了碳源、氮源和无机盐及培养条件对白腐菌液体深层培养的影响。应用正交试验确定了最佳培养基组成为玉米粉 2 .0 % ,玉米浆 2 .0 % ,(NH4 ) 2 SO4 0 .0 1% ,KH2 PO4 0 .0 5 % ,MgSO4 ·7H2 O 0 .0 5 % ,VB1 0 .0 5 % ;最适培养条件为种子培养时间 72h,培养液初始pH5 .5 ,装液量 10 0ml 2 5 0ml三角瓶 ,接种量 10 % ,培养温度 30℃ ,摇床转速 180r min,培养时间 72h ,其最大生物量为 12 .6g L。同时进行了 5L自动发酵罐培养条件的初步研究。