Showing papers on "Mycelium published in 2007"

An extracellular matrix glues together the aerial-grown hyphae of Aspergillus fumigatus.

Abstract: Summary Pulmonary infections due to Aspergillus fumigatus result from the development of a colony of tightly associated hyphae in contact with the air, either in the alveoli (invasive aspergillosis) or in an existing cavity (aspergilloma). The fungal ball observed in vivo resembles an aerial colony obtained in agar medium in vitro more than a mycelial mass obtained in liquid shaken conditions that have been classically used to date to study A. fumigatus physiology. For this reason, we embarked on an analysis of the characteristics of A. fumigatus colonies grown in aerial static conditions. (i) Under static aerial conditions, mycelial growth is greater than in shaken, submerged conditions. (ii) The colony surface of A. fumigatus revealed the presence of an extracellular hydrophobic matrix that acts as a cohesive linkage bonding hyphae into a contiguous sheath. (iii) The extracellular matrix is composed of galactomannan, α1,3 glucans, monosaccharides and polyols, melanin and proteins including major antigens and hydrophobins. (iv) A. fumigatus colonies were more resistant to polyenes than shake, submerged mycelium. This is the first analysis of the three dimensional structure of a mycelial colony. Knowledge of this multicellular organization will impact our future understanding of the pathobiology of aerial mold pathogens.

Differences in the species composition of arbuscular mycorrhizal fungi in spore, root and soil communities in a grassland ecosystem

Abstract: Summary Most studies on the species composition of arbuscu- lar mycorrhizal fungi (AMF) have solely analysed mycorrhizal roots or AM spores collected from soil samples. However, the spore production rate and pro- portions of AMF mycelium in roots and soils have all been shown to vary substantially in a taxon-specific manner. Therefore, in the study presented here we used a molecular approach to analyse the species composition of AMF in spores, intra-radical and extra- radical mycelium in an intensively farmed meadow in central Germany. By polymerase chain reaction and sequencing of the ITS region members of seven dif- ferent families and species groups within Glomero- mycota were identified. The data revealed remarkable differences in the composition of AMF taxa both between the spores and the mycelia, and between the two types of mycelia. Glomus group Ab was dominant in roots and spores, in accordance with previous research. However, members of this group were rarely detected as extra-radical mycelium, in which Paraglomeraceae were dominant, although we found no evidence for the presence of Paraglomeraceae in roots or spores, even when a specific primer set was used. These results may be interpreted as a further indication that AMF are not necessarily obligate sym- bionts of plants.

Antifungal effects of essential oils from oregano and fennel on Sclerotinia sclerotiorum.

Abstract: Aims: The antifungal effects of essential oils of oregano (Origanum syriacum var. bevanii) and fennel (Foeniculum vulgare) were evaluated against Sclerotinia sclerotiorum. Effects of the essential oils on morphological structures of hyphae and sclerotia were studied under light and scanning electron microscopes (SEM). Methods and Results: Inhibitory effects of volatile and contact phases of the essential oils used were determined on hyphae and sclerotia. Both essential oils have a marked antifungal effect against S. sclerotiorum. Soil amendment with essential oils has significant effect on reducing sclerotial viability. Both essential oils significantly inhibited the fungal growth in soil, thereby increasing the number of surviving tomato seedling by 69·8% and 53·3%, respectively. Light and SEM observations on pathogen hyphae and sclerotia revealed considerable morphological alterations in hyphae and sclerotia. Conclusions: The significant reduction in the mycelial growth and germination of sclerotia would greatly reduce the pathogen inoculum source. This may influence the rate of disease development in soil. Significance and Impact of the Study: Considering the reduction in the number of diseased plants in infested soil amended with essential oils, we concluded that oregano and fennel essential oils could be used as possible bio fungicides alternative to synthetic fungicides against phytopathogenic fungi.

Effect of Fungal Hyphae on the Access of Bacteria to Phenanthrene in Soil

Abstract: The effect of fungal hyphae on the mobilization of soil-dwelling bacteria and their access to hydrophobic phenanthrene in soil was tested in columns containing air-filled agricultural soil. The experimental design included a spatial separation between zones of bacterial inoculation and contamination. Motile Pseudomonas putida PpG7 (NAH7) and fast-growing, hydrophilic Pythium ultimum were used as the model phenanthrene-degrading and vector organisms, respectively. Efficient translocation of strain PpG7 in the range of centimetres in presence of P. ultimum indicated that the fungal mycelia bridged air-filled pores and thereby provided a continuous network of water-paths that enabled bacteria to spread in the soil. Biodegradation of the soil-associated phenanthrene was found only in the presence of the fungal mycelia, hence proving that the fungal network facilitated the access of the bacteria to the contaminant. Our data suggest that the specific stimulation of indigenous fungi is a promising method to mobilize pollutant degrading bacteria and thereby improve soil bioremediation in-situ.

Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Abstract: A combination of two compatible micro-organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper. The population of the pathogen in soil was reduced by 75% as a result. Vegetative growth of the mycelium of P. capsici was inhibited in vitro on the second day after P. capsici and T. harzianum were placed on the opposite sides of the same Petri plate. Trichoderma harzianum was capable of not only arresting the spread of the pathogen from a distance, but also after invading the whole surface of the pathogen colony, sporulating over it. Scanning electron microscopy showed the hyphae of P. capsici surrounded by those of T. harzianum, their subsequent disintegration, and the eventual suppression of the pathogen's growth. Streptomyces rochei produced a zone of inhibition, from which was obtained a compound with antioomycete property secreted by the bacteria. When purified by high-pressure liquid chromatography, this compound was identified as 1-propanone, 1-(4-chlorophenyl), which seems to be one of the principal compounds involved in the antagonism. A formulation was prepared that maintained the compound's capacity to inhibit growth of the pathogen for up to 2 years when stored at room temperature in the laboratory on a mixture of plantation soil and vermiculite. The two antagonists, added as a compound formulation, were effective at pH from 3.5 to 5.6 at 23-30°C. The optimal dose of the antagonists in the compound formulation was 3.5 x 10 8 spores/ml of T. harzianum and 1.0 x 10 9 FCU/ml of S. rochei. This is the first report of a compound biocontrol formulation of these two antagonists with a potential to control root rot caused by P. capsici.

Presymbiotic growth and sporal morphology are affected in the arbuscular mycorrhizal fungus Gigaspora margarita cured of its endobacteria

Abstract: Summary Some arbuscular mycorrhizal fungi contain endocellular bacteria. In Gigaspora margarita BEG 34, a homogenous population of β-Proteobacteria is hosted inside the fungal spore. The bacteria, named Candidatus Glomeribacter gigasporarum, are vertically transmitted through fungal spore generations. Here we report how a protocol based on repeated passages through single-spore inocula caused dilution of the initial bacterial population eventually leading to cured spores. Spores of this line had a distinct phenotype regarding cytoplasm organization, vacuole morphology, cell wall organization, lipid bodies and pigment granules. The absence of bacteria severely affected presymbiotic fungal growth such as hyphal elongation and branching after root exudate treatment, suggesting that Ca. Glomeribacter gigasporarum is important for optimal development of its fungal host. Under laboratory conditions, the cured fungus could be propagated, i.e. could form mycorrhizae and sporulate, and can therefore be considered as a stable variant of the wild type. The results demonstrated that – at least for the G. margarita BEG 34 isolate – the absence of endobacteria affects the spore phenotype of the fungal host, and causes delays in the growth of germinating mycelium, possibly affecting its ecological fitness. This cured line is the first manipulated and stable isolate of an arbuscular mycorrhizal fungus.

Enzymatic Evidence for the Key Role of Arginine in Nitrogen Translocation by Arbuscular Mycorrhizal Fungi

Abstract: Key enzymes of the urea cycle and (15)N-labeling patterns of arginine (Arg) were measured to elucidate the involvement of Arg in nitrogen translocation by arbuscular mycorrhizal (AM) fungi. Mycorrhiza was established between transformed carrot (Daucus carota) roots and Glomus intraradices in two-compartment petri dishes and three ammonium levels were supplied to the compartment containing the extraradical mycelium (ERM), but no roots. Time courses of specific enzyme activity were obtained for glutamine synthetase, argininosuccinate synthetase, arginase, and urease in the ERM and AM roots. (15)NH(4)(+) was used to follow the dynamics of nitrogen incorporation into and turnover of Arg. Both the absence of external nitrogen and the presence of L-norvaline, an inhibitor of Arg synthesis, prevented the synthesis of Arg in the ERM and resulted in decreased activity of arginase and urease in the AM root. The catabolic activity of the urea cycle in the roots therefore depends on Arg translocation from the ERM. (15)N labeling of Arg in the ERM was very fast and analysis of its time course and isotopomer pattern allowed estimation of the translocation rate of Arg along the mycelium as 0.13 microg Arg mg(-1) fresh weight h(-1). The results highlight the synchronization of the spatially separated reactions involved in the anabolic and catabolic arms of the urea cycle. This synchronization is a prerequisite for Arg to be a key component in nitrogen translocation in the AM mycelium.

Spatial differentiation in the vegetative mycelium of Aspergillus niger.

Abstract: Fungal mycelia are exposed to heterogenic substrates. The substrate in the central part of the colony has been (partly) degraded, whereas it is still unexplored at the periphery of the mycelium. We here assessed whether substrate heterogeneity is a main determinant of spatial gene expression in colonies of Aspergillus niger. This question was addressed by analyzing whole-genome gene expression in five concentric zones of 7-day-old maltose- and xylose-grown colonies. Expression profiles at the periphery and the center were clearly different. More than 25% of the active genes showed twofold differences in expression between the inner and outermost zones of the colony. Moreover, 9% of the genes were expressed in only one of the five concentric zones, showing that a considerable part of the genome is active in a restricted part of the colony only. Statistical analysis of expression profiles of colonies that had either been or not been transferred to fresh xylose-containing medium showed that differential expression in a colony is due to the heterogeneity of the medium (e.g., genes involved in secretion, genes encoding proteases, and genes involved in xylose metabolism) as well as to medium-independent mechanisms (e.g., genes involved in nitrate metabolism and genes involved in cell wall synthesis and modification). Thus, we conclude that the mycelia of 7-day-old colonies of A. niger are highly differentiated. This conclusion is also indicated by the fact that distinct zones of the colony grow and secrete proteins, even after transfer to fresh medium.

A new cytotoxic agent from solid-state fermented mycelium of Antrodia camphorata.

Abstract: Antroquinonol ( 1), an ubiquinone derivative, was isolated from the solid-state fermented mycelium of Antrodia camphorata (Polyporaceae, Aphyllophorales), a parasitic fungus indigenous to Taiwan. The structure of compound 1 was elucidated by the analysis of their spectroscopic data. Its cytotoxic activities were evaluated against MCF-7, MDA-MB-231 (human breast carcinoma), Hep3B, HepG2 (human liver carcinoma) and DU-145, LNCaP (human prostate carcinoma) cell lines, and the IC (50) values ranged from 0.13 +/- 0.02 to 6.09 +/- 0.07 microM.

Fungal transformations of uranium oxides

Abstract: The biogeochemical activities of free-living and symbiotic fungi must be acknowledged in attempts to understand uranium cycling and dispersal in the environment. Although the near-surface geochemistry of uranium is very complex and a wide variety of mineral phases is known, uranium trioxide (UO3) and triuranium octaoxide (U(3)O(8)) can be used as well characterized models in the study of biotransformations. We have used a complex methodological approach involving advanced solid state speciation and scanning electron microscopy to study the ability of saprotrophic, ericoid and ectomycorrhizal fungi to transform these model oxides. This study has revealed that fungi exhibit a high uranium oxide tolerance, and possess the ability to solubilize UO3 and U(3)O(8) and to accumulate uranium within the mycelium to over 80 mg (g dry weight)(-1) biomass. X-ray absorption spectroscopy of uranium speciation within the biomass showed that in most of the fungi the uranyl ion was coordinated to phosphate ligands, but in ectomycorrhizal fungi mixed phosphate/carboxylate coordination was observed. Abundant uranium precipitates associated with phosphorus were found in the mycelium and encrusted the hyphae. Some of the fungi caused the biomineralization of well-crystallized uranyl phosphate minerals of the meta-autunite group. This is the first experimental evidence for fungal transformations of uranium solids and the production of secondary mycogenic uranium minerals.

GintMT1 encodes a functional metallothionein in Glomus intraradices that responds to oxidative stress.

Abstract: A full-length metallothionein (MT) gene (GintMT1) was isolated from Glomus intraradices extraradical mycelium. This is the first MT gene reported in the genus Glomus, third in the Glomeromycota. Functional analysis of GintMT1 in a MT-defective Saccharomyces cerevisiae strain indicates that it encodes a functional MT. Gene expression analyses revealed that the transcript levels of GintMT1 were elevated in mycelia treated with 5 mM Cu or paraquat but inhibited in mycelia treated with 50 μM Cu or 450 μM Cd. The elevated expression of GintMT1 in the 5 mM Cu-treated mycelia together with the ability of GintMT1 to provide tolerance to a Cu-sensitive yeast suggests that GintMT1 might afford protection against Cu. Induction of GintMT1 expression by paraquat and 5 mM Cu, treatments that also produced an oxidative damage to the fungal membranes, suggests that GintMT1 may play a role in the regulation of the redox status of the extraradical mycelium of G. intraradices.

The Course of Colonization of Two Different Vitis Genotypes by Plasmopara viticola Indicates Compatible and Incompatible Host-Pathogen Interactions.

Abstract: Unger, S., Buche, C., Boso, S. and Kassemeyer, H.-H. 2007. The course of the colonization of two different Vitis genotypes by Plasmopara viticola indicates compatible and incompatible host–pathogen interactions. Phytopathology 97:780-786. The course of colonization of leaf mesophyll by the causal agent of grapevine downy mildew, Plasmopara viticola, in a susceptible and a resistant grapevine genotype was examined in order to characterize the development of the pathogen in compatible and incompatible host–pathogen interactions. Within a few hours after inoculation, the pathogen was established in the susceptible Vitis vinifera cv. Muller-Thurgau and formed primary hyphae with a first haustorium. No further development occurred in the following 10 to 18 h. The next step, in which the hyphae grew and branched to colonize the intercellular space of the host tissue, was observed 1.5 days after inoculation. After 3 days, the intercostal fields were entirely filled with mycelium and sporulation was abundant under favorable environmental conditions. The first infection steps were essentially the same in the resistant V. rupestris. However, the invasive growth of P. viticola was delayed, and further development ceased before the intercostal fields were filled with mycelium. Additional keyword: resistance.

Wood-decay fungi in fine living roots of conifer seedlings

Abstract: The mycorrhizal basidiomycetes are known to have multiple, independent evolutionary origins from saprotrophic ancestors. To date, a number of studies have revealed functional resemblance of mycorrhizal fungi to free-living saprotrophs, but information on the ability of saprotrophic fungi to perform as mycorrhizal symbionts is scarce. Here, the objective was to investigate the ability of three wood-decay fungi, Phlebiopsis gigantea, Phlebia centrifuga and Hypholoma fasciculare, to colonize fine roots of conifer seedlings. For each fungus, mycorrhizal syntheses were attempted with Picea abies and Pinus sylvestris. After 24 wk, isolation of fungi and direct sequencing of fungal internal transcribed spacer (ITS) rDNA were carried out from healthy-looking surface-sterilized root tips that yielded both pure cultures and ITS sequences of each inoculated strain. Mycelial mantle of P. gigantea was frequently formed on root tips of P. abies, and microscopical examination has shown the presence of intercellular hyphae inside the roots. The results provide evidence of the ability of certain wood-decay fungi to colonise fine roots of tree seedlings.

Muscodor albus E-6, an endophyte of Guazuma ulmifolia making volatile antibiotics: isolation, characterization and experimental establishment in the host plant.

Abstract: Muscodor albus is an endophytic fungus, represented by a number of isolates from tropical tree and vine species in several of the world's rainforests, that produces volatile organic compounds (VOCs) with antibiotic activity. A new isolate, E-6, of this organism, with unusual biochemical and biological properties, has been obtained from the branches of a mature Guazuma ulmifolia (Sterculiaceae) tree growing in a dry tropical forest in SW Ecuador. This unique organism produces many VOCs not previously observed in other M. albus isolates, including butanoic acid, 2-methyl-; butanoic acid, 3-methyl-; 2-butenal, 2-methyl-; butanoic acid, 3-methylbutyl ester; 3-buten-1-ol, 3-methyl; guaiol; 1-octene, 3-ethyl-; formamide, N-(1-methylpropyl); and certain azulene and naphthalene derivatives. Some compounds usually seen in other M. albus isolates also appeared in the VOCs of isolate E-6, including caryophyllene; phenylethyl alcohol; acetic acid, 2-phenylethyl ester; bulnesene; and various propanoic acid, 2-methyl- derivatives. The biological activity of the VOCs of E-6 appears different from the original isolate of this fungus, CZ-620, since a Gram-positive bacterium was killed, and Sclerotinia sclerotiorum and Rhizoctonia solani were not. Scanning electron micrographs of the mycelium of isolate E-6 showed substantial intertwining of the hyphal strands. These strands seemed to be held together by an extracellular matrix accounting for the strong mat-like nature of the mycelium, which easily lifts off the agar surface upon transfer, unlike any other isolate of this fungus. The ITS-5.8S rDNA partial sequence data showed 99 % similarity to the original M. albus strain CZ-620. For the first time, successful establishment of M. albus into its natural host, followed by recovery of the fungus, was accomplished in seedlings of G. ulmifolia. Overall, isolates of M. albus, including E-6, have chemical, biological and structural characteristics that make them potentially useful in medicine, agricultural and industrial applications.

Morphological patterns of Aspergillus niger biofilms and pellets related to lignocellulolytic enzyme productivities

Abstract: Aims: To study the morphological patterns of Aspergillus niger during biofilm formation on polyester cloth by using cryo-scanning electron microscopy related to lignocellulolytic enzyme productivity. Methods and Results: Biofilm and pellet samples obtained from flask cultures were examined at −80°C in a LEO PV scanning electron microscope. Spore adhesion depends on both its rough surface and adhesive substances that form a pad between spore and support. An extracellular matrix surrounding germ tubes and hyphae was also seen. Biofilm mycelia showed an orderly distribution forming surface and inner channels, while pellets showed highly intertwined superficial hyphae and a densely packed deep mycelium. Morphological differences between both types of culture correlated with differences in enzyme volumetric and specific productivities. Biofilm cultures produced higher filter paper cellulase, endoglucanase, β-glucosidase and xylanase volumetric and specific productivities than submerged cultures. Conclusions: Fungal biofilms are morphologically efficient systems for enzyme production. Favourable physiological aspects are shared with solid state fermentation, but fungal biofilms present better possibilities for process control and scale-up. Significance and Impact of the Study: The results of this study support the importance of morphology in the productivity of fungal submerged processes, placing biofilms in a preferential category.

Interactions between extraradical ectomycorrhizal mycelia, microbes associated with the mycelia and growth rate of Norway spruce (Picea abies) clones

Abstract: Despite their ecological relevance, field studies of the extraradical mycelia of ectomycorrhizal (ECM) fungi are rare. Here we examined in situ interactions between ECM mycelia and host vigour. Ectomycorrhizal mycelia were harvested with in-growth mesh bags buried under Norway spruce (Picea abies) clones planted in 1994 in a randomized block design. Mycelial biomass was determined and fungal species were identified by denaturing gradient gel electrophoresis (DGGE) and sequencing of the internal transcribed spacer 1 (ITS1) region. Microbial community structure in the mycelium was investigated by phospholipid fatty acid (PLFA) profiling. Compared to slow-growing spruce clones, fast-growing clones tended to support denser mycelia where the relative proportions of Atheliaceae fungi and PLFAs indicative of Gram-positive bacteria were higher. Ascomycetes and PLFAs representative of Gram-negative bacteria were more common with slow-growing clones. In general, the ECM mycelial community was similar to the ECM root-tip community. Growth rate of the hosts, the ECM mycelial community and the microbes associated with the mycelium were related, suggesting multitrophic interactions between trees, fungi and bacteria.

Anti-inflammatory and antitumour activities of cultured mycelium of morel mushroom, Morchella esculenta

Abstract: Mushrooms are nutritionally functional food and a source of physiologically beneficial and non-toxic medicines. They have been used in folk medicine throughout the world since ancient times. Morchella esculenta (L) Pers. is an edible and highly priced mushroom. Commercial cultivation of this mushroom has not been successful till now and hence its mycelium is extensively used as a flavouring agent. Anti-inflammatory and antitumour activities of ethanolic extract of cultured mycelium of M. esculenta were investigated. The extract showed significant dose-dependent inhibition of both acute and chronic inflammation. The activity was comparable to that of the standard reference drug, Diclofenac. Antitumour activity of the extract was determined using both DLA cell line-induced solid tumour and EAC cell line-induced ascites tumour models in mice. The extract exhibited significant antitumour activity against both ascites and solid tumours. The finding suggests the potential therapeutic use of aqueous-ethanolic extract of morel mushroom mycelium in chemotherapy.

Powdery mildew infection of wheat leaves changes host solute transport and invertase activity

Abstract: The effect of powdery mildew (Blumeria graminis) infection of wheat leaves on solute transport and invertase activity of the host tissue has been examined. Sugars (glucose, sucrose, maltose) and amino acids (glutamine, histidine) were taken up by leaf pieces, and radioactivity was transferred to the fungal mycelium. Infection had a marked effect on sugar uptake, particularly for glucose which was taken up into infected tissue at considerably higher rates than into uninfected tissues. In contrast, amino acid uptake rates into infected tissues were lower when compared with those into uninfected tissue. The increase in glucose uptake could be correlated with a change in sugar transporter gene expression as a wheat homologue of the monosaccharide carrier AtSTP4 was shown to increase in infected tissue. Efflux analysis showed a higher leakage of preloaded glucose from infected leaves in comparison with uninfected tissue and transfer to the mycelium was greater for glucose than for the other solutes measured. All types of invertase, measured enzymatically, showed an increase in infected tissue, with the highest proportional increase observed for cell-wall invertase. A partial-length complementary DNA, TaINV2, was isolated for a putative cell-wall invertase; expression studies indicated that levels for this or related sequences increased substantially 3 days after infection.

Persistence of Phytophthora ramorum in Soil Mix and Roots of Nursery Ornamentals

Abstract: Shishkoff, N. 2007. Persistence of Phytophthora ramorum in soil mix and roots of nursery ornamentals. Plant Dis. 91:1245-1249. Although most Phytophthora species have a soilborne phase that is crucial for infection of roots and for survival away from the host, the details of the soil phase of Phytophthora ramorum are not yet fully understood. As mycelium ages, it becomes resistant to sterilization by acidic electrolyzed water (AEW), a product of the electrolysis which can be used as a disinfectant. Colonies of P. ramorum could be recovered from moist potting mix or sand for many months, whether buried as infected plant leaf tissue or as mycelium bearing chlamydospores, and the buried material was also resistant to treatment by AEW. There was no significant difference in recovery over time among treatments (sand or potting mix; infected plant tissue or mycelium); after approximately a year, colonies could be recovered at 0.8 to 14.3%. When excised roots were inoculated with P. ramorum sporangia and buried in mesh bags in potting mix, the pathogen was recovered from buried roots for at least 8 to 11 months, but it was not clear whether it was surviving as mycelium or chlamydospores. The roots of living plants of Acer macrophyllum, Buxus sempervirens, Camellia oleifera, C. sinensis, C. sasanqua, Lonicera hispidula, Taxus baccata, Umbellularia californica, Vaccinium macrocarpon, Viburnum davidii, V. tinus, V. × pragense, Rhododendron ‘Gloria’, and Syringa vulgaris were drenched with a sporangial solution of P. ramorum and incubated for a month; the pathogen could be recovered from roots of all plants except those of Buxus sempervirens and Lonicera hispidula. Recovery on selective agar medium (P5ARP) was from both washed and surface-sterilized roots, suggesting that the roots were internally infected. When chlamydospores were placed near roots and observed directly, they were seen to germinate, forming sporangia. Nearby roots became infected, the tips covered with sporangia. Therefore, P. ramorum appears to have a soil phase, at least under greenhouse and nursery conditions.

Role of antibiosis in suppression of charcoal rot disease by soybean endophyte Paenibacillus sp. HKA-15.

Abstract: Four defective (AFM−) mutants of Paenibacillus sp. HKA-15 that no longer produced the peptide antifungal metabolites were developed through ethyl methane sulfonate (EMS) mutagenesis and used for in vivo experimentation. Reduced percentage of seed germination by mutants DM1 and DM2 (22.5% and 25%, respectively) and a high percent of disease incidence (69.3% and 67%, respectively) compared to wild-strain HKA-15 (80% seed germination and 27% disease incidence) indirectly indicated the role of peptide metabolite on disease suppression. Plants treated with AFM− clones showed stunted growth and the presence of pepperlike microsclerotia in the stem tissues. Light and scanning electron microscopic studies clearly showed the effect of peptide antibiosis on hyphal morphology. Exposure to crude extracts of antibiotics produced abnormal contraction of fungal cytoplasm, granulation, and fragmentation of hyphal mycelia and cell lysis. The presence of bacterial cells in the lumen of degrading fungal mycelium suggested a direct involvement of Paenibacillus sp. HKA-15 in the lysis of Rhizoctonia bataticola.

Biodegradation of kerosene by Aspergillus ochraceus NCIM-1146

Abstract: The filamentous fungus Aspergillus ochraceus NCIM-1146 was found to degrade kerosene, when previously grown mycelium (96 h) was incubated in the broth containing kerosene. Higher levels of NADPH-DCIP reductase, aminopyrine N-demethylase and kerosene biodegradation activities were found to be present after the growth in potato dextrose broth for 96 h, when compared with the activities at different time intervals during the growth phase. NADPH was the preferred cofactor for enzyme activity, which was inhibited by CO, indicating cytochrome P450 mediated reactions. A significant increase in all the enzyme activities was observed when mycelium incubated for 18 h in mineral salts medium, containing cholesterol, camphor, naphthalene, 1,2-dimethoxybenzene, phenobarbital, n-hexane, kerosene or saffola oil as inducers. Acetaldehyde produced by alcohol dehydrogenase could be used as an indicator for the kerosene biodegradation.