Reciprocal N ((NH4+)-N-15 or (NO3-)-N-15) transfer between nonN(2)-fixing Eucalyptus maculata and N-2-fixing Casuarina cunninghamiana linked by the ectomycorrhizal fungus Pisolithus sp.

Two-way N transfers mediated by Pisolithus sp. were examined by excluding root contact and supplying (NH4+)-N-15 or (NO3-)-N-15 to 6-month-old Eucalyptus maculata or Casuarina cunninghamiana grown in two-chambered-pots separated by 37 m screens. Mycorrhizal colonization was 35% in Eucalyptus and 66% in Casuarina (c. 29% N-2-fixation). Using an environmental scanning electron microscope, living hyphae were observed to interconnect Eucalyptus and Casuarina. Biomass and N accumulation was greatest in nodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, less in nonnodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, and least in nonnodulated nonmycorrhizal Casuarina/nonmycorrhizal Eucalyptus pairs. In nonnodulated mycorrhizal pairs, N transfers to Eucalyptus or to Casuarina were similar (2.4-4.1 mg per plant in either direction) and were 2.6-4.0 times greater than in nonnodulated nonmycorrhizal pairs. In nodulated mycorrhizal pairs, N transfers were greater to Eucalyptus (5-7 times) and to Casuarina (12-18 times) than in nonnodulated mycorrhizal pairs. Net transfer to Eucalyptus or to Casuarina was low in both nonnodulated nonmycorrhizal (< 0.7 mg per plant) and nonnodulated mycorrhizal pairs (< 1.1 mg per plant). In nodulated mycorrhizal pairs, net transfer to Casuarina was 26.0 mg per plant. The amount and direction of two-way mycorrhiza-mediated N transfer was increased by the presence of Pisolithus sp. and Frankia, resulting in a net N transfer from low-N-demanding Eucalyptus to high-N-demanding Casuarina.

Transfer of a supernumerary chromosome between vegetatively incompatible biotypes of the fungus Colletotrichum gloeosporioides

Two biotypes (A and B) of Colletotrichum gloeosporioides infect the tropical legumes Stylosanthes spp. in Australia. These biotypes are asexual and vegetatively incompatible. However, field isolates of biotype B carrying a supernumerary 2-Mb chromosome, thought to originate from biotype A, have been reported previously. We tested the hypothesis that the 2-Mb chromosome could be transferred from biotype A to biotype B under laboratory conditions. Selectable marker genes conferring resistance to hygromycin and phleomycin were introduced into isolates of biotypes A and B, respectively. A transformant of biotype A, with the hygromycin resistance gene integrated on the 2-Mb chromosome, was cocultivated with phleomycin-resistant transformants of biotype B. Double antibiotic-resistant colonies were obtained from conidia of these mixed cultures at a frequency of approximately 10(-7). Molecular analysis using RFLPs, RAPDs, and electrophoretic karyotypes showed that these colonies contained the 2-Mb chromosome in a biotype B genetic background. In contrast, no double antibiotic colonies developed from conidia obtained from mixed cultures of phleomycin-resistant transformants of biotype B with biotype A transformants carrying the hygromycin resistance gene integrated in chromosomes >2 Mb in size. The results demonstrated that the 2-Mb chromosome was selectively transferred from biotype A to biotype B. The horizontal transfer of specific chromosomes across vegetative incompatibility barriers may explain the origin of supernumerary chromosomes in fungi.

Aspergillicins A-E: five novel depsipeptides from the marine-derived fungus Aspergillus carneus

A search for new antiparasitic agents from a strain of the fungus Aspergillus carneus isolated from an estuarine sediment collected in Tasmania, Australia, yielded the known terrestrial fungal metabolite marcfortine A ( 1) as an exceptionally potent antiparasitic agent. This study also yielded a series of new depsipeptides, aspergillicins A - E ( 2 - 6) and the known terrestrial fungal metabolite acyl aszonalenin ( 7). Marcfortine A ( 1) and acyl aszonalenin ( 7) were identified by spectroscopic analysis, with comparison to literature data. Complete stereostructures were assigned to aspergillicins A - E ( 2 - 6) on the basis of detailed spectroscopic analysis, together with ESIMS analysis of the free amino acids generated by acid hydrolysis, and HPLC analysis of Marfey derivatives prepared from the acid hydrolysate. The peptide amino acid sequence for all aspergillicins was unambiguously assigned by MSn ion-trap ESI mass spectrometry.

Novel sesquiterpenes from the fungus lactarius piperatus

Four novel sesquiterpenes, namely 7alpha,8beta,13-trihydroxy-5,13-marasmanolide (2), isoplorantinone (5), 4,8,14-trihydroxyilludala-2,6,8-triene (6), and 8-hydroxy-8,9-secolactara-1,6-dien-5,13-olide (10), together with six known ones, 7alpha,8beta-dihydroxy-5,13-marasmanolide (1), 7alpha,8alpha-dihydroxy-5,13-marasmanolide (3), isolactarorufin (4), blennin A (7), blennin D (8), and lactarorufin (9), were isolated from the ethanolic extract of Lactarius piperatus. The structures of these sesquiterpenes, representing diversified structural types, were determined mainly by spectroscopic methods, especially 2D-NMR techniques. The structure of 6 was further confirmed by a single-crystal X-ray-diffraction determination.

Use of confocal scanning laser microscopy to measure the concentrations of aerial and penetrative hyphae during growth of Rhizopus oligosporus on a solid surface

In order to develop a method for use in investigations of spatial biomass distribution in solid-state fermentation systems, confocal scanning laser microscopy was used to determine the concentrations of aerial and penetrative biomass against height and depth above and below the substrate surface, during growth of Rhizopus oligosporus on potato dextrose agar. Penetrative hyphae had penetrated to a depth of 0.445 cm by 64 h and showed rhizoid morphology, in which the maximum biomass concentration, of 4.45 mg dry wt cm(-3), occurred at a depth of 0.075 cm. For aerial biomass the maximum density of 39.54 mg dry wt(-3) occurred at the substrate surface. For both aerial and penetrative biomass, there were two distinct regions in which the biomass concentration decayed exponentially with distance from the surface. For aerial biomass, the first exponential decay region was up to 0.1 cm height. The second region above the height of 0.1 cm corresponded to that in which sporangiophores dominated. This work lays the foundation for deeper studies into what controls the growth of fungal hyphae above and below the surfaces of solid substrates. (C) Wiley Periodicals, Inc.

Use of confocal microscopy to follow the development of penetrative hyphae during growth of Rhizopus oligosporus in an artificial solid-state fermentation system

Two methods were compared for determining the concentration of penetrative biomass during growth of Rhizopus oligosporus on an artificial solid substrate consisting of an inert gel and starch as the sole source of carbon and energy. The first method was based on the use of a hand microtome to make sections of approximately 0.2- to 0.4-mm thickness parallel to the substrate surface and the determination of the glucosamine content in each slice. Use of glucosamine measurements to estimate biomass concentrations was shown to be problematic due to the large variations in glucosamine content with mycelial age. The second method was a novel method based on the use of confocal scanning laser microscopy to estimate the fractional volume occupied by the biomass. Although it is not simple to translate fractional volumes into dry weights of hyphae due to the lack of experimentally determined conversion factors, measurement of the fractional volumes in themselves is useful for characterizing fungal penetration into the substrate. Growth of penetrative biomass in the artificial model substrate showed two forms of growth with an indistinct mass in the region close to the substrate surface and a few hyphae penetrating perpendicularly to the surface in regions further away from the substrate surface. The biomass profiles against depth obtained from the confocal microscopy showed two linear regions on log-linear plots, which are possibly related to different oxygen availability at different depths within the substrate. Confocal microscopy has the potential to be a powerful tool in the investigation of fungal growth mechanisms in solid-state fermentation. (C) 2003 Wiley Periodicals, Inc.

Endemic infection of the amphibian chytrid fungus in a frog community post-decline

The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

Nodulated N-2-fixing Casuarina cunninghamiana is the sink for net N transfer from non-N-2-fixing Eucalyptus maculata via an ectomycorrhizal fungus Pisolithus sp using (NH4+)-N-15 or (NO3-)-N-15 supplied as ammonium nitrate

To determine the effects of nitrogen source on rates of net N transfer between plants connected by a common mycorrhizal network, we measured transfer of N supplied as (NH4NO3)-N-15-N-14 or (NH4NO3)-N-14-N-15 in three Casuarina/Eucalyptus treatments interconnected by a Pisolithus sp. The treatments were nonnodulated nonmycorrhizal/nonmycorrhizal; nonnodulated mycorrhizal/mycorrhizal; and nodulated mycorrhizal/mycorrhizal. Mycorrhization was 67% in Eucalyptus and 36% in Casuarina. N-2 fixation supplied 38% of the N in Casuarina. Biomass, N and N-15 contents were lowest in nonmycorrhizal plants and greatest in plants in the nodulated/mycorrhizal treatment. Nitrogen transfer was enhanced by mycorrhization and by nodulation, and was greater when N was supplied as (NH4+)-N-15 than (NO3-)-N-15. Nitrogen transfer rates were lowest in the nonmycorrhizal treatment for either N-15 source, and greatest in the nodulated, mycorrhizal treatment. Transfer was greater to Casuarina than to Eucalyptus and where ammonium rather than nitrate was the N source. Irrespective of N-15 source and of whether Casuarina or Eucalyptus was the N sink, net N transfer was low and was similar in both nonnodulated treatments. However, when Casuarina was the N sink in the nodulated, mycorrhizal treatment, net N transfer was much greater with (NH4+)-N-15 than with (NO3-)-N-15. High N demand by Casuarina resulted in greater net N transfer from the less N-demanding Eucalyptus. Net transfer of N from a non-N-2-fixing to an N-2-fixing plant may reflect the very high N demand of N-2-fixing species.

Depolymerisation and biodegradation of a synthetic tanning agent by activated sludges, the bacteria Arthrobacter globiformis and Comamonas testosteroni, and the fungus Cunninghamella polymorpha

Degradation of a synthetic tanning agent CNSF (a condensation product of 2-naphthatenesulfonic acid (2-NSA) and formaldehyde) by four activated sludges, two previously characterised bacterial strains, Arthrobacter sp. 2AC and Comamonas sp. 4BC, and the fungus Cunninghamella polymorpha, was studied in batch culture at 25 degrees C by determining the changes in the concentrations of CNSF and its component monomers and oligomers (n2-n11). The loss of individual oligomers was correlated with the length of the NSA-CH2 chain. Approximately 25% of the total CNSF was degraded (i.e. mineralised) by the microbes contained in the four activated sludges and by the two bacterial isolates but with different lag phases and at different overall rates. The decline in CNSF concentration was due almost entirely to the biodegradation of the monomers (34.3% of CNSF) and, in particular, 2-NSA (27% of CNSF). There was no change in the n2-n 11 components. The growth of C. polymorpha, on the other hand, arose from extracellular depolymerisation of CNSF oligomers and the biodegradation of the lower molecular mass products. Between 38% and 42% of total CNSF was degraded by C. polymorpha at 25 degrees C. The order of oligomer degradation was inversely related to degree of polymerisation. Eighty percent and 90% of the n4 and n5 and 100% oligomers n6-n11 were degraded after 120 h. At a higher temperature (37 degrees C) oligomers n4-n11 were degraded completely after 120 h. A combination of biodegradation (75%) and sorption to fungal biomass (25%) accounted for the measured loss of all oligomers from the solution phase. The CNSF degradation rates and the volume of fungal biomass produced (and therefore the extent of biosorption) were dependent on the presence of a second carbon source (both optimum at glucose 5 g/l). This is the first report that identifies and distinguishes between depolymerisation, sorption and biodegradation processes in the removal of CNSF and its component oligomers. The use of combinations of the depolymerising fungus C. polymorpha, and the monomer-degrading bacteria, Arthrobacter sp. 2AC and Comamonas sp. 4BC, have potential for wastewater treatment.

Notes on the type, synonyms, and other specimens of the balansioid fungus, Nigrocornus scleroticus

The type, and other specimens of the balansioid fungus, Nigrocornus scleroticus, its synonyms, and similar fungi studied during extensive research on the taxonomy and biology of the fungus, are described. Two hypocrealean fungi found parasitising the ascostromata of N. scleroticus are also discussed.

Australian Glow-worms in Caves

Glow-worms are the larvae of a fly from the family Keroplatidae. Their closest relatives are the “fungus flies” that seek out mushrooms for their larvae to consume. Glow-worms have gone out on an evolutionary limb, albeit a successful one. They have lost their association with fungi and have instead become carnivorous. The unique feature of glow-worms is their ability to bioluminesce—to produce light.