Onychomycosis due to saprophytic fungi

Twenty five cases of onychomycosis due to filamentous saprophytic agents were diagnosed within the period 1981–1982 in two mycology laboratories in Medellín, Colombia. These cases represented 4.5% and 9.5% respectively of the total fungal nail lesions (FNL) seen at those institutions. No explanation was found for the high frequencies, which sharply contrast with the previous local experience with the disease (0.4% of FNL). The responsible agents belonged to the following genera in decreasing order of frequency: Fusarium, Aspergillus, Scopulariopsis, Penicillium and Lasiodiplodia; two patients were infected with unidentified dematiaceous fungi and two more had the association of a saprophyte and a dermatophyte. In every case direct KOH preparations revealed septate hyphae, associated in 14 patients (56%) with chlamydoconidia. The only predisposing factors that were common to all these patients were age above 20 years and the use of footwear.     

The influence of saprophytic competition on nematode predation by nematode-trapping fungi

Competivive stress imposed by common soil saprophytes may cause an increase in predation by the nematode-trapping fungi, Arthrobotrys oligospora and Monacrosporium cionopagum, on the bacteria-feeding nematode Acrobeloides buetschli. Nematode-trapping species grown with saprophytic competitors in an artificial soil substrate increased their trapping activity compared to control cultures. The results support the hypothesis that competition stimulates the predatory activity of nematode-trapping fungi as an adaptation to overcome their low competitive saprophytic ability.     

Assessment of root endophytic aquatic hyphomycetous fungi on plant growth

The role of root endophytic aquatic hyphomycetous fungi in plant health was studied by employing pot experiments. Three aquatic hyphomycetous fungi Heliscus lugdunensis, Tetrachaetum elegans and Tetracladium nainitalense isolated as root endophytes of riparian plants were artificially inoculated into two test plants viz., Solanum melongena and Hibiscus esculentus. T. elegans and H. lugdunensis showed significant effects (fresh weight, dry weight and length of shoots and roots) on both test plants, whereas T. nainitalense had no effect.     

Effect of some common rhizosphere fungi on root growth of seedlings

Summary The effect of some common rhizosphere fungiviz Aspergillus niger, A. terreus, A. flavus, Fusarium nivale, Cunninghamella echinulata, Trichoderma viride andPaecilomyces fusisporus on the root growth of seedlings ofDichanthium annulatum andSetaria glauca was studied. The seedlings grown in modified Crone's nutrient medium were inoculated with the test fungi. In uninoculated control tubes, seedlings showed normal root growth. The different fungi exceptF. nivale were found to reduce root growth considerably. WithA. niger besides reduction in root length, the leaves of the seedlings were found to turn yellow. The reduction in root growth in the presence of fungi was statistically significant.     

Toxigenic saprophytic fungi in marine shellfish farming areas

Toxigenic saprophytic fungi were isolated from samples of shellfish, sediment and seawater obtained from marine shellfish farming areas. The 456 strains identified included 12 different genera, with a clear predominance (68%) of Penicillium, Aspergillus, Trichoderma and Cladosporium. To assess the risk of poisoning due to the presence of these fungi in shellfish farming areas, the strains were cultured in liquid medium, filtered, and tested on larvae of Artemia salina, a small crustacean highly sensitive to mycotoxins. Thirty-five point five percent of the strains proved active with this test. This study confirms the existence of fungi in shellfish farming areas, as suggested by our earlier work showing that filter-feeding shellfish accumulate toxic metabolites of fungal origin. The presence of fungi in the marine environment represents a real risk of poisoning through the consumption of contaminated shellfish.This revised version was published online in October 2005 with corrections to the Cover Date.     

Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala

Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp.     

The effect of soil compaction on the saprophytic growth of Rhizoctonia solani

The increase in bare patch of cereals associated with minimum tillage practices prompted an investigation of the relationship between soil compaction and saprophytic growth of Rhizoctonia solani. In soils wetter than 10 kPa there was a greater density of hyphae in compacted than in non-compacted soil. In relatively dry soil, however, there was wider exploration by hyphae in non-compacted than in compacted soil. The implications of these findings for disease management are discussed.     

腐生真菌的消长规律

论述了腐生真菌的演替及一般消长规律。腐生真菌分解落叶、枯枝真菌的消长规律以及粪生真菌的消长规律。介绍了影响真菌消长规律的环境因素和腐生真菌在自然界物质循环的作用     

Fungitoxic effects of nonprotein imino acids on growth of saprophytic fungi isolated from the leaf surface of Calliandra haematocephala.

Four saprophytic and pathogenic fungi were isolated from the leaf surface of Calliandra haematocephala, a tropical legume known to contain large amounts of rare nonprotein imino acids in its leaves and seeds. The fungi Aspergillus niger, Aspergillus sp., Curvularia sp., and Penicillium sp. were cultured in the laboratory and tested for susceptibility to leaf extracts of the host plant and to proline, pipecolic acid, cis-5-hydroxypipecolic acid, and 2,4-trans-4,5-cis-4,5-dihydroxypipecolic acid. Fungal spore germination and germ tube growth were measured. Aspergillus sp. was inhibited by plant extracts and by pipecolic acid and cis-5-hydroxypipecolic acid. Curvularia sp. growth was stimulated by plant extracts and by pipecolic acid. The other two fungi were unaffected by any of the treatments. The data indicate that imino acids may play a role in the specific resistance of Calliandra spp. to Aspergillus sp.     

Interactions between Glomus mosseae and arbuscular mycorrhizal sporocarp-associated saprophytic fungi

The saprophytic fungi Wardomyces inflatus (Marchal) Hennebert, Paecilomyces farinosus (Holm & Gray) A. H. S. Brown & G. Sm., Gliocladium roseum Bain., sterile dark mycelium (SDM-54), Trichoderma pseudokoningii Rifai and Trichoderma harzianum Rifai were isolated from sporocarps of Glomus mosseae. The effect of saprophytic fungi on G. mosseae spore germination was tested on water agar. Wardomyces inflatus decreased the percent germination of G. mosseae spores; G. roseum, T. pseudokoningii and T. harzianum had no effect on germination; and P. farinosus and SDM-54 increased the percentage of spore germination of G. mosseae after 4 d. Wardomyces inflatus significantly decreased hyphal length of spores which germinated, but no other saprophytic fungi affected hyphal growth. Trichoderma pseudokoningii, T. harzianum, P. farinosus and SDM-54 increased the number of auxiliary cells formed by G. mosseae. The effect of saprophytic fungi on arbuscular mycorrhizal colonization of soybean was studied in a greenhouse trial. The percentage of soybean root length colonized was decreased by W. inflatus, unaffected by SDM-54 and T. harzianum, and increased by P. farinosus. Gliocladium roseum decreased root length colonized when plants were 12 wk old, and T. pseudokoningii increased colonization of roots when plants were 4 wk old. Antagonistic, synergistic and neutral actions of G. mosseae upon the saprophytic fungi were observed. The population of T. harzianum decreased and the populations of T. pseudokoningii and SDM-54 increased in the presence of G. mosseae. Our results indicate a complex interaction between G. mosseae and associated saprophytic fungi.     

A leaf-rolling weevil benefits from general saprophytic fungi in polysaccharide degradation

Insects, especially those feeding on leaf litter, widely form symbiosis with fungi. As dead plant tissues provide insects with poor-quality diets, which contain relatively high levels of indigestible lignin and cellulose, some saprophytic fungi may increase nutrient availability by polysaccharide degradation. Although the inherited, obligate bacterial symbionts are well documented, the non-inherited, facultative fungal symbionts are relatively overlooked. Females of the leaf-rolling weevil Heterapoderopsis bicallosicollis, a specialist of Triadica sebifera, construct leaf-rolls that serve as retreats from which larvae feed internally. We found that fungi associated with leaf-rolls were not transported by the female, but likely originated from the soil. To determine the effects of fungi on H. bicallosicollis development, fungal growth was reduced by a dry treatment. This treatment decreased adult weight and survival, and prolonged larval duration significantly. We further tested the hypothesis that fungi degrade leaf-roll polysaccharides, by a fungus inoculation experiment. Three dominant fungi (Penicillium sp., Aspergillus sp. and Cladosporium sp.) decreased the levels of soluble carbohydrate, cellulose, and lignin in inoculation experiments. Soluble carbohydrate, cellulose, and lignin of leaf-rolls all were found to decrease gradually during insect development. We conclude that these saprophytic fungi form facultative associations with H. bicallosicollis and benefit weevil nutrition by polysaccharide decomposition. Our study highlights the significance of fungal symbionts in insect nutritional ecology.     

Cell-cell recognition of host surfaces by pathogens. The adsorption of maize (Zea mays) root mucilage by surfaces of pathogenic fungi.

The adsorption of radioactive mucilage by pathogenic fungi was shown to be dependent upon time, the composition of mucilage, the type of fungal surface (conidia, hyphae, hyphal apices), fungal species, pH and bivalent cations. All fungal adhesins were inactivated by either proteinase or polysaccharase treatments. Adsorption was not inhibited by the numberous mono-, di- and oligo-saccharides that were tested individually, but it was inhibited absolutely by several polysaccharides. This suggested that adsorption of mucilage by pathogens involved conformational and ionic interactions between plant and fungal polymers but not fungal lectins bound to sugar residues of mucilage. Several fractionation schemes showed that pathogens bound only the most acidic of the variety of polymers that comprise mucilage. There was not any absolute distinction between ability to bind radioactive mucilage and type of pathogen or non-pathogen. However, there were notable differences in characteristics of adsorption between two types of pathogen. Differences were revealed by comparison of the adsorption capacities of conidia and germinant conidia and chromatography of radioactive mucilage on germinant conidia. An ectotrophic root-infecting fungus (a highly specialized pathogen) bound a greater proportion of mucilage than did a vascular-wilt fungus (of catholic host and tissue range) with more than one class of site for adsorption. In contrast with the vascular-wilt fungus, sites for adsorption on the specialized pathogen were present solely on surfaces formed by germination.     

5种优势腐生真菌降解华山松针叶的酶活测定

【目的】分析腐生真菌降解华山松落针过程中各种酶活性变化与酶间关系,探索真菌对华山松落针的降解能力。【方法】通过形态学观察和转录间隔区ITS序列分析,鉴定分离自华山松凋落物的5种优势菌株。以此为供试菌株,华山松落针为底物,通过发酵纯培养方法,测定底物总有机物质(Total organic matter,TOM)质量损失率及在发酵过程中产生的内切葡聚糖酶(Endoglucanase,EG)、木聚糖酶(Xylanase,Xyl)、木质素过氧化物酶(Lignin peroxidase,Li P)、锰过氧化物酶(Manganese peroxidase,Mn P)和酸性磷酸酶(Acid phosphatase,AP)活性。【结果】5种菌株分别为Mucor sp.、Pestalotiopsis sp.、Allantophomopsis sp.、Phoma sp.和Hypocrea sp.。5种菌引起的针叶TOM质量损失率在6.63%-15.77%之间,Pestalotiopsis sp.具有最高的AP酶活性,且EG酶、Xyl酶和Li P酶3种酶活性较高。Allantophomopsis sp.的Li P酶活性最高,并具有很高的Mn P酶活。Hypocrea sp.分泌的EG酶、Xyl酶活性低,但能产生Li P酶且有较高的AP酶活。相关性分析表明菌株分泌的AP酶活性与TOM质量损失率负相关,EG酶、Xyl酶及AP酶3种酶之间存在协同作用,特别是EG与AP之间。【结论】5种腐生真菌对华山松针叶均有降解作用,降解能力:Pestalotiopsis sp.>Allantophomopsis sp.>Hypocrea sp.>Phoma sp.>Mucor sp.。酶活大小及酶协同作用共同影响针叶降解,Pestalotiopsis sp.、Allantophomopsis sp.和Hypocrea sp.能产生木质纤维素降解酶并能引起较高的质量损失率,因此这3株菌为木质纤维素降解真菌。     

Temperature constraints on the growth and functioning of root organ cultures with arbuscular mycorrhizal fungi

In this study we investigated the effects of temperature on fungal growth and tested whether the differences in fungal growth were related to the effects of temperature on carbon movement to, or within, the fungus. Growth curves and C uptake-transfer-translocation measurements were obtained for three arbuscular mycorrhizal fungi (AMF) isolates cultured within a 6-30 degrees C temperature range. A series of experiments with a model fungal isolate, Glomus intraradices, was used to examine the effects of temperature on lipid body and 33P movement, and to investigate the role of acclimation and incubation time. Temperature effects on AMF growth were both direct and indirect because, despite clear independent root and AMF growth responses in some cases, the uptake and translocation of 13C was also affected within the temperature range tested. Root C uptake and, to a lesser extent, C translocation in the fungus, were reduced by low temperatures (< 18 degrees C). Uptake and translocation of 33P by fungal hyphae were, by contrast, similar between 10 and 25 degrees C. We conclude that temperature, between 6 and 18 degrees C, reduces AMF growth, and that C movement to the fungus is involved in this response.     

The effects of the arbuscular mycorrhizal fungusGlomus deserticola on growth of tomato plants grown in the presence of olive mill residues modified by treatment with saprophytic fungi

Olive oil extraction generates large amounts of olive mill residues (DOR) which may be used as fertilizer. The influence of arbuscular mycorrhizal (AM) on the phytotoxicity of dry olive residue (DOR) transformed with saprophytic fungi was studied. Aqueous extraction of DOR gave an (ADOR) fraction and an exhausted (SDOR) fraction, both of which had less phytotoxicity for tomato than the original DOR. The saprophytic fungiTrametes versicolor andPycnoporus cinnabarinus further decreased the phytotoxicity of ADOR and SDOR on tomato. The decrease of phenols concentration and the differences in the level of laccase activity caused by these fungi suggest did not account fully for the reduced phytoxicity but the fact that the higher hydrolytic enzyme activity ofP. cinnabarinus, paralleled the decrease of phytotoxicity, indicates that these enzymes seem to be involved. The AM fungusGlomus deserticola increased or exacerbated the beneficial effect of SDOR incubated with saprophytic fungi, in terms of dry weight of tomato plants. The percentage of root length colonized byG. deserticola strongly decreased in presence of DOR, but the level of mycorrhization was higher in presence of ADOR or SDOR. Our results suggest that the combination of aqueous extraction and incubation with saprophytic fungi will open the way for the use of olive oil extraction residues as organic amendment in agricultural soils.     

Studies on fungi in the root region

Summary Data are given on the fungi isolated from 30-day-old adventitious roots and seedling roots of severalAllium species by means of the root-washing technique. These fungi were typical root-surface forms includingCylindrocarpon, Fusarium, and sterile forms. The amount of root colonization observed, however, was not so great as with other higher plant roots.The nature and role of bulb surface contaminants is discussed in relation to the colonization of young roots, and is compared with the role of seed-coat contaminants in such colonization.     

Studies on fungi in the root region

Summary Tabulated information on the colonization of roots of barley, cabbage and dwarf bean by fungi during the first 10 days of root development is given. These data, obtained by isolation and direct observation studies, are discussed in relation to previous observations on the association of fungi with the roots of healthy crop plants.The results indicate that initial root colonization may be by any of a wide range of soil fungi, but that this mixed population rapidly gives way to a stable and typical root-surface mycoflora (dominated by such fungi asFusarium spp.,Cylindrocarpon radicicola, Gliocladium spp., andPenicillium spp.