Mycangial fungus benefits the development of a leaf-rolling weevil, Euops chinesis

While a wide array of insects form symbiotic relationships with microbes, the underlying mechanisms of these relationships are various and complex. In this study, we investigated the role that the mycangial fungus Penicillium herquei plays in the development of the leaf-rolling weevil Euops chinesis, which feeds on the knotweed Fallopia japonica. The weevil inoculates the fungus during oviposition into a leaf-roll that it creates for its larvae. We found that removal of P. herquei inocula from leaf-rolls significantly decreased the weevil's survival rate especially in the larval stage. Although inoculation with P. herquei had no effect on the plant's lignin content, it significantly decreased the cellulose content of the knotweed leaves. P. herquei also showed antibiotic properties against two fungi (Rhizopus sp.) that attack the weevil's leaf-rolls. Our results suggest that the mycangial fungus may help alter leaf chemical components and protect against pathogens thus improve leaf-rolls for the development of E. chinesis.     

Contribution of symbiotic mycangial fungi to larval nutrition of a leaf-rolling weevil

Some phytophagous insects have been known to inoculate certain fungi on plant substrates. In many cases of such insect–fungi relationships it has been considered that fungi contribute to insects by decomposing lignin or polysaccharides, and that the insects feed on the decomposition products or fungi themselves. Females of the leaf-rolling weevil in the genus Euops (Attelabidae) store spores of symbiotic fungi in the mycangia and inoculate them on leaf rolls. To determine the effect of mycangial fungi on larval nutrition in E. lespedezae, the nutritional value was compared between leaves with and without mycangial fungi. Two Penicillium species were isolated from the mycangia. These mycangial fungi showed little effect on the decomposition of lignin and polysaccharides, and showed little effect on enhancement of soluble sugars within leaves. Thus, the mutualism between Euops and its mycangial fungi contrasts with the mainly nutritional mutualisms between wood-infesting insects (termites, bark/ambrosia beetles, and wood wasps) and lignin/polysaccharide-decomposing fungi.     

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.     

Degradative ability of 2,4,6-tribromophenol by saprophytic fungi Trametes versicolor and Agaricus augustus isolated from chilean forestry

Trametes versicolor and Agaricus augustus, with a maximum tolerable concentration (MTC) of 80 μg ml⁻¹ tribromophenol (TBP), were selected to evaluate TBP biodegradation capacity. These fungi were capable of decreased TBP concentrations and A. augustus was also capable of biotransforming TBP to tribromoanisole (TBA). Peroxidase and laccase activities were observed in the T. versicolor supernatant but not in that of A. augustus. These tolerance levels could be due to either lignolytic enzymes that degrade TBP or the ability of the fungi to biotransform TBP to tribromoanisole, respectively. The sustained ability of T. versicolor to degrade TBP (total of 40 μg ml⁻¹) in the presence of an additional carbon source suggests that it may have potential applications in the degradation of forestry industry waste.     

Lignin-modifying enzymes from selected white-rot fungi: production and role from in lignin degradation

Abstract: White-rot fungi produce extracellular lignin-modifying enzymes, the best characterized of which are laccase (EC 1.10.3.2), lignin peroxidases (EC 1.11.1.7) and manganese peroxidases (EC 1.11.1.7). Lignin biodegradation studies have been carried out mostly using the white-rot fungus Phanerochaete chrysosporium which produces multiple isoenzymes of lignin peroxidase and manganese peroxidase but does not produce laccase. Many other white-rot fungi produce laccase in addition to lignin and manganese peroxidases and in varying combinations. Based on the enzyme production patterns of an array of white-rot fungi, three categories of fungi are suggested: (i) lignin-manganese peroxidase group (e.g. P. chrysosporium and Phlebia radiata ), (ii) manganese peroxidase-laccase group (e.g. Dichomitus squalens and Rigidoporus lignosus ), and (iii) lignin peroxidase-laccase group (e.g. Phlebia ochraceofulva and Junghuhnia separabilima ). The most efficient lignin degraders, estimated by ¹⁴CO₂ evolution from ¹⁴C-[Ring]-labelled synthetic lignin (DHP), belong to the first group, whereas many of the most selective lignin-degrading fungi belong to the second, although only moderate to good [¹⁴C]DHP mineralization is obtained using fungi from this group. The lignin peroxidase-laccase fungi only poorly degrade [¹⁴C]DHP.     

Decomposition rate of organic substrates in relation to the species diversity of soil saprophytic fungi

Despite the great interest concerning the relationship between species diversity and ecosystem functioning, there is virtually no knowledge as to how the diversity of decomposer microbes influences the decomposition rate of soil organic matter. We established a microcosm study in which the number of soil fungi was investigated in relation to the systems ability to (i) degrade raw coniferous forest humus, and (ii) use resources that were either added to the systems or released into the soils after a disturbance (drought). With the exception of the most diverse treatment, in each of the six replicates of each of the six diversity treatments (1, 3, 6, 12, 24 or 43 taxa), fungal taxa were randomly chosen from a pool of 43 commonly isolated fungal species of raw humus. Two months after initiation of the study CO₂ production increased as fungal diversity increased, but in the species-poor end of the diversity gradient only. Addition of various energy resources to the microcosms generally increased the level of soil respiration but did not affect the shape of the diversity-CO₂-production curve. Rewetting the soil after severe drought resulted in a rapid flush of CO₂, particularly in the most diverse communities. The biomass of the fungi in the non-disturbed soils, and soil NH₄-N concentration and soil pH in both disturbed and non-disturbed systems were slightly but significantly higher in the diverse than in the simple systems. Fungal species richness had no influence on the organic matter content of the humus at the end of the experiment. The results suggest that the functional efficiency of fungal communities can increase with the number of fungal taxa. This diversity effect was, however, significant at the species-poor end of the diversity gradient only, which implies considerable functional equivalency (redundancy) among the decomposer fungi.     

A new method for isolation of saprophytic cultures ofClaviceps fusiformis from sclerotia

The proposed method includes primary and secondary treatments. Of the various disinfectants tested, 1-propanol and 1-butanol as a primary treatment and phenol, resorcinol, HgCl₂ or NaCl as a secondary treatment completely eliminated the contamination hazard. 1-Butanol and phenol were not useful disinfectants since they inhibited the growth ofC. fusiformis along with the other contaminants. Primary and secondary treatment of sclerotia with 1-propanol and resorcinol, respectively, produced the maximum of stable cultures. Out of 120 cultures tested, 5 cultures demonstrated an appreciable yield of alkaloids under submerged cultural conditions.     

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.     

In vitro degradation of wheat straw by anaerobic fungi from small ruminants

Abstract

Anaerobic ruminal fungi may play an active role in fibre degradation as evidenced by the production of different fibrolytic enzymes in culture filtrate. In the present study, 16 anaerobic fungal strains were isolated from ruminal and faecal samples of sheep and goats. Based on their morphological characteristics they were identified as species of Anaeromyces, Orpinomyces, Piromyces and Neocallimastix. Isolated Neocallimastix sp. from goat rumen showed a maximum activity of CMCase (47.9 mIU ml^?1) and filter paper cellulase (48.3 mIU ml^?1), while Anaeromyces sp. from sheep rumen showed a maximum xylanolytic activity (48.3 mIU ml^?1). The cellobiase activity for all the isolates ranged from 178.0 – 182.7 mIU ml^?1. Based on the enzymatic activities, isolated Anaeromyces sp. from sheep rumen and Neocallimastix sp. from goat rumen were selected for their potential of in vitro fibre degradation. The highest in vitro digestibility of NDF (23.2%) and DM (34.4%) was shown for Neocallimastix sp. from goat rumen, as compared to the digestibility of NDF and DM in the control group of 17.5 and 25.0%, respectively.     

In vitro degradation of wheat straw by anaerobic fungi from small ruminants

Anaerobic ruminal fungi may play an active role in fibre degradation as evidenced by the production of different fibrolytic enzymes in culture filtrate. In the present study, 16 anaerobic fungal strains were isolated from ruminal and faecal samples of sheep and goats. Based on their morphological characteristics they were identified as species of Anaeromyces, Orpinomyces, Piromyces and Neocallimastix. Isolated Neocallimastix sp. from goat rumen showed a maximum activity of CMCase (47.9 mIU ml(-1)) and filter paper cellulase (48.3 mIU ml(-1)), while Anaeromyces sp. from sheep rumen showed a maximum xylanolytic activity (48.3 mIU ml(-1)). The cellobiase activity for all the isolates ranged from 178.0-182.7 mIU ml(-1). Based on the enzymatic activities, isolated Anaeromyces sp. from sheep rumen and Neocallimastix sp. from goat rumen were selected for their potential of in vitro fibre degradation. The highest in vitro digestibility of NDF (23.2%) and DM (34.4%) was shown for Neocallimastix sp. from goat rumen, as compared to the digestibility of NDF and DM in the control group of 17.5 and 25.0%, respectively.     

杉木解酚菌的研究

从杉木林土壤中筛选到5株高效解酚菌(F2、F3、F4、F7、F15),结果表明,F4、F33d,F2、F155d能将600rng     

Changes in mutagenicity during crude oil degradation by fungi

Two fungal strains, Cunninghamella elegans and Penicillium zonatum, that grow with crude oil as a sole carbon source were exposed to three crude oils that exhibit a range of mutagenic activity. At regular time intervals following fungal incubation with the various crude oils, extracts were tested for the presence of mutagenic activity using the spiral Salmonella assay. When the most mutagenic of the oils, Pennsylvania crude oil, was degraded by C. elegans or by P. zonatum, its mutagenicity was significantly reduced; corresponding uninoculated (weathered) controls of Pennsylvania crude remained mutagenic. West Texas Sour crude oil, a moderately mutagenic oil, exhibited little change in mutagenicity when incubated with either C. elegans or P. zonatum. Swanson River Field crude oil from Cook Inlet, Alaska is a slightly mutagenic oil that became more mutagenic when incubated with C. elegans; weathered controls of this oil showed little change in mutagenicity. Mycelial mat weights measured during growth on crude oils increased corresponding to the biodegradation of about 25% of the crude oil.     

Enrichment of fungi and degradation of styrene in biofilters

Summary Experiments were set up in order to enrich styrene-degrading fungi in biofilters under conditions representative for industrial off-gas treatment. From the support materials tested, polyurethane and perlite proved to be most suitable for enrichment of styrene-degrading fungi. The biofilter with perlite completely degraded styrene when amounts ranging between 290 and 675 mg/m in the influent gas were present. An elimination capacity of at least 70 g styrene per m3 filter bed per hour was calculated.     

Cell wall degradation in the autolysis of filamentous fungi

A systematic study on autolysis of the cell walls of fungi has been made on Neurospora crassa, Botrytis cinerea, Polystictus versicolor, Aspergillus nidulans, Schizophyllum commune, Aspergillus niger, and Mucor mucedo. During autolysis each fungus produces the necessary lytic enzymes for its autodegradation. From autolyzed cultures of each fungus enzymatic precipitates were obtained. The degree of lysis of the cell walls, obtained from non-autolyzed mycelia, was studied by incubating these cell walls with and without a supply of their own lytic enzymes. The degree of lysis increased with the incubation time and generally was higher with a supply of lytic enzymes.Cell walls from mycelia of different ages were obtained. A higher degree of lysis was always found, in young cell walls than in older cell walls, when exogenous lytic enzymes were present.In all the fungi studied, there is lysis of the cell walls during autolysis. This is confirmed by the change of the cell wall structure as well as by the degree of lysis reached by the cell wall and the release of substances, principally glucose and N-acetylglucosamine in the medium.     

Isolation, characterization and fibre degradation potential of anaerobic rumen fungi from cattle

A total of 20 fungal cultures were isolated from the rumen of cattle fed a high fibre-containing diet. All of the isolates showed polycentric growth patterns and were identified as different strains of Orpinomyces and Anaeromyces. Enzyme assays of most of the isolates showed the highest carboxymethylcellulase (CMCase) and xylanase activities after 96 h of growth and highest avicelase activity after 120 h. Among all enzymes tested, xylanase activity was the highest, followed by CMCase and avicelase. The results of the in vitro fibre digestibility and rumen fermentation analyses revealed that the addition of fungal cultures significantly increased acetate, in vitro dry matter digestibility, partition factor values and microbial biomass synthesis levels. Overall, Orpinomyces spp. were found to be the better enzyme producers and fibre degraders than Anaeromyces spp.     

Studies of polysaccharide structure. I. A modification of the Smith degradation

The diagnostic value is considered of degradation products arising when the Smith degradation is modified by the introduction of a methylation stage after borohydride reduction of the periodate-oxidised polysaccharide. The bond types occurring in two clinical dextrans were examined by conventional periodate oxidation and methylation analysis, and by the modified Smith-degradation.     

Patterns in the occurrence of saprophytic fungi carried by arthropods caught in traps baited with rotted wood and dung

Fungi from approximately 1700 individual arthropods that had been captured in traps set in aspen-dominated woodland in western Canada and baited with coyote dung, moose dung, white-rotted wood, brown-rotted wood and fiberglass were isolated in pure culture and identified. These data were analysed with principal components analysis (PCA) to determine whether different types of substrate attracted specific arthropods and whether these animals carried unique assemblages of fungi with known proclivities for the new habitat. Mycobiotic agar was used to restrict the numbers of fungi isolated and resulted in the recovery of 1687 isolates representing 65 species across 12 orders. Isolates of cosmopolitan fungal taxa such as species of Cladosporium, Penicillium, and Beauveria were the most numerous. Taxa with predilections for specific substrates, such as Myxotrichum and Cryptendoxyla that are known inhabitants of cellulose-rich materials (i.e. rotted wood), and various representatives of the keratinophilic Onygenales were recovered from arthropods attracted respectively to baits rich in cellulose and keratin. When traps were analysed according to the identity and numbers of arthropods captured, there was considerable overlap among clusters representing specific bait types, with traps baited with coyote dung being the most divergent partly because they captured significantly more arthropods than those baited with moose dung or rotted wood. When bait type was examined according to the identity and numbers of fungi on trapped arthropods the degree of overlap was also high although a few trends could be discerned. In particular traps baited with brown-rotted wood and coyote dung diverged slightly indicating that arthropods visiting these bait types were carrying somewhat different suites of fungi.     

Novel oligosaccharides obtained by bacteriophage degradation of the polysaccharide from Klebsiella serotype K26

Bacteriophage phi 26 was used to depolymerize the polysaccharide of Klebsiella K26, yielding three oligosaccharides. The major product was the heptasaccharide repeating unit, with one of the minor products being the fourteen-sugar oligosaccharide corresponding to two repeating units. The other minor product was unusual since it was a hexasaccharide devoid of the terminal, pyruvate-containing galactose unit present in the side chain of the normal repeating unit. Phage phi 26 was shown to act as a beta-galactosidase, and hence it may have the ability to remove the terminal beta-galactose residue in the side chain.