Germination of concentrated suspensions of spores from Aspergillus niger

Barrios-González, Javier; Martínez, Carlos Meza; Aguilera, A.; Raimbault, Maurice

doi:10.1007/bf01040034

Cited by 32 publications

(13 citation statements)

References 3 publications

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“…10) spores could be found. Spore density on a plate was not controlled but as the proximity to other spores can affect germinability (Hobot and Gull 1980;Barrios-Gonz ales et al 1989;Chitarra et al 2004), we avoided counting areas with very high spore density.…”

Section: Treatments and Culturingmentioning

confidence: 99%

Spore sensitivity to sunlight and freezing can restrict dispersal in wood‐decay fungi

Norros

Karhu

Nordén

et al. 2015

Ecology and Evolution

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Assessment of the costs and benefits of dispersal is central to understanding species' life-history strategies as well as explaining and predicting spatial population dynamics in the changing world. While mortality during active movement has received much attention, few have studied the costs of passive movement such as the airborne transport of fungal spores. Here, we examine the potential of extreme environmental conditions to cause dispersal mortality in wood-decay fungi. These fungi play a key role as decomposers and habitat creators in forest ecosystems and the populations of many species have declined due to habitat loss and fragmentation. We measured the effect of simulated solar radiation (including ultraviolet A and B) and freezing at −25°C on the spore germinability of 17 species. Both treatments but especially sunlight markedly reduced spore germinability in most species, and species with thin-walled spores were particularly light sensitive. Extrapolating the species' laboratory responses to natural irradiance conditions, we predict that sunlight is a relevant source of dispersal mortality at least at larger spatial scales. In addition, we found a positive effect of spore size on spore germinability, suggesting a trade-off between dispersal distance and establishment. We conclude that freezing and particularly sunlight can be important sources of dispersal mortality in wood-decay fungi which can make it difficult for some species to colonize isolated habitat patches and habitat edges.

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Section: Treatments and Culturingmentioning

confidence: 99%

Spore sensitivity to sunlight and freezing can restrict dispersal in wood‐decay fungi

Norros

Karhu

Nordén

et al. 2015

Ecology and Evolution

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“…Conidia are dispersed into the air but do not germinate before they reach a suitable substrate. Invariably, germination is inhibited when spores are present in high densities, an effect observed for example in Aspergillus niger and the zygomycete Syncephalastrum racemosum (3,19). This is designated as the crowding effect.…”

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confidence: 99%

“…From the mucilage that surrounds the conidia of this fungus, a self-inhibitor of germination named mycosporine-alanine has been identified and characterized (26). Germination is also retarded in pustules of rust fungi (Basidiomycetes) where cisferulic acid methyl ester and cis-3,4-dimethoxycinnamic acid methyl ester have been identified (28, 36).Self-inhibitors have been characterized in Puccinia, Uromyces, Colletotrichum, Dictyostelium, Fusarium oxysporum, and Aspergillus and can be volatile or nonvolatile (2,3,16,24,28).They also can influence other fungal processes, for example, mycosporine-alanine produced by Colletotrichum graminicola prevents appressorium formation (25, 26). The self-inhibitors produced by Glomerella cingulata and Dictyostelium discoideum inhibit protein synthesis (2, 27).…”

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confidence: 99%

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Germination of Penicillium paneum Conidia Is Regulated by 1-Octen-3-ol, a Volatile Self-Inhibitor

Chitarra

Abee

Rombouts

et al. 2004

Appl Environ Microbiol

189

118

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Penicillium paneum is an important contaminant of cereal grains which is able to grow at low temperature, low pH, high levels of carbon dioxide, and under acid conditions. P. paneum produces mycotoxins, which may be harmful to animals and humans. We found that conidia in dense suspensions showed poor germination, suggesting the presence of a self-inhibitor. A volatile compound(s) produced by these high-density conditions also inhibited mycelial growth of different species of fungi belonging to a variety of genera, suggesting a broad action range. The heat-stable compound was isolated by successive centrifugation of the supernatant obtained from spore suspensions with a density of 10 9 conidia ml ؊1 . By using static headspace analyses, two major peaks were distinguished, with the highest production of these metabolites after 22 h of incubation at 25°C and shaking at 140 rpm. Gas chromatography coupled with mass spectra analysis revealed the compounds to be 3-octanone and 1-octen-3-ol. Notably, only the latter compound appeared to block the germination process at different developmental stages of the conidia (swelling and germ tube formation). In this study, 1-octen-3-ol influenced different developmental processes during the P. paneum life cycle, including induction of microcycle conidiation and inhibition of spore germination. Therefore, the compound can be considered a fungal hormone during fungal development.The spore is an important vehicle for distribution or longterm survival of fungi. Conidia are nonmotile asexual spores, which can be produced in very large numbers by fungi belonging to the order Eurotiales. This order, which includes the genera Aspergillus and Penicillium (14), contains many species of food-related fungi. Conidia are dispersed into the air but do not germinate before they reach a suitable substrate. Invariably, germination is inhibited when spores are present in high densities, an effect observed for example in Aspergillus niger and the zygomycete Syncephalastrum racemosum (3,19). This is designated as the crowding effect. Also, in the formation of an adhesive bud on spores of the nematophagous fungus Drechmeria coniospora, there is a clear crowding effect (35). These observations suggest that intercellular signaling prevents premature germination.Acervuli of Colletotrichum spp. form large numbers of conidia embedded in mucilage but not germinating there. From the mucilage that surrounds the conidia of this fungus, a self-inhibitor of germination named mycosporine-alanine has been identified and characterized (26). Germination is also retarded in pustules of rust fungi (Basidiomycetes) where cisferulic acid methyl ester and cis-3,4-dimethoxycinnamic acid methyl ester have been identified (28, 36).Self-inhibitors have been characterized in Puccinia, Uromyces, Colletotrichum, Dictyostelium, Fusarium oxysporum, and Aspergillus and can be volatile or nonvolatile (2,3,16,24,28).They also can influence other fungal processes, for example, mycosporine-alanine produced by Colletotrichum graminic...

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“…This inhibition of growth at high conidia concentrations may be due to the fast depletion of nutrients by the high density of cells, or due to self-inhibition. 35 A. niger has been recorded to produce self-inhibitors, such as nonanoic acid 36 , that prevents premature and simultaneous germination of conidia and drastically decrease the germination rate when the cell density is above 10 6 cells mL -1 . 37,38 Corresponding iPRISM curves depict a pronounced decrease in intensity at a seeding suspension of 10 5 conidia mL -1 whereas intensity values for 0 and 10 4 conidia mL -1 are relatively stable.…”

Section: Optimization Of the Iprism Assaymentioning

confidence: 99%

Antifungal susceptibility testing ofAspergillus nigeron silicon microwells by intensity-based reflectometric interference spectroscopy

Heuer

Leonard

Nitzan

et al. 2019

Preprint

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The increasing number of invasive fungal infections among immunocompromised patients and the emergence of antifungal resistant pathogens has resulted in the need for rapid and reliable antifungal susceptibility testing (AFST). Accelerating antifungal susceptibility testing allows for advanced treatment decisions and the reduction in future instances of antifungal resistance.In this work, we demonstrate the application of a silicon phase grating as sensor for the detection of growth of Aspergillus niger (A. niger) by intensity-based reflectometric interference spectroscopy and its use as an antifungal susceptibility test. The silicon gratings provide a solid-liquid interface to capture micron-sized Aspergillus conidia within microwell arrays. Fungal growth is optically tracked and detected by the reduction in the intensity of reflected light from the silicon grating. The growth of A. niger in the presence of various concentrations of the antifungal agents voriconazole and amphotericin B is investigated by intensity-based reflectometric interference spectroscopy and used for the determination of the minimal inhibitory concentrations (MIC), which are compared to standard broth microdilution testing. This assay allows for expedited detection of fungal growth and provides a label-free alternative to standard antifungal susceptibility testing methods, such as broth microdilution and agar diffusion methods.

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Germination of concentrated suspensions of spores from Aspergillus niger

Cited by 32 publications

References 3 publications

Spore sensitivity to sunlight and freezing can restrict dispersal in wood‐decay fungi

Spore sensitivity to sunlight and freezing can restrict dispersal in wood‐decay fungi

Germination of Penicillium paneum Conidia Is Regulated by 1-Octen-3-ol, a Volatile Self-Inhibitor

Antifungal susceptibility testing ofAspergillus nigeron silicon microwells by intensity-based reflectometric interference spectroscopy

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