Susceptibility and Resistance of Several Fungi to Microbial Lysis

Potgieter, H. J.; Alexander, Martin

doi:10.1128/jb.91.4.1526-1532.1966

Cited by 125 publications

(24 citation statements)

References 17 publications

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“…Enzymatic degradation is inhibited by melanin in moulds, including Rhizoctonia spp. (Lockwood, 1960;Potgieter and Alexander, 1966;Bloomfield and Alexander, 1967), Sclerotinia spp. (Lockwood, 1960;Bloomfield and Alexander, 1967), Verticillium sp.…”

Section: Role Of Melanin In Environmental Protectionmentioning

confidence: 99%

The contribution of melanin to microbial pathogenesis

Nosanchuk

Casadevall

2003

Cellular Microbiology

554

454

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SummaryMelanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of pathogenic bacteria, fungi and helminthes. The study of melanin is difficult because these pigments defy complete biochemical and structural analysis. Nevertheless, the availability of new reagents in the form of monoclonal antibodies and melaninbinding peptides, combined with the application of various physical techniques, has provided insights into the process of melanization. Melanization is important in microbial pathogenesis because it has been associated with virulence in many microorganisms. Melanin appears to contribute to virulence by reducing the susceptibility of melanized microbes to host defence mechanisms. However, the interaction of melanized microbes and the host is complex and includes immune responses to melanin-related antigens. Production of melanin has also been linked to protection against environmental insults. Interference with melanization is a potential strategy for antimicrobial drug and pesticide development. The process of melanization poses fascinating problems in cell biology and provides a type of pathogenic strategy that is common to highly diverse pathogens.

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Section: Role Of Melanin In Environmental Protectionmentioning

confidence: 99%

The contribution of melanin to microbial pathogenesis

Nosanchuk

Casadevall

2003

Cellular Microbiology

554

454

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“…The initial products of oxidation are usually o-quinones, which being highly unstable, undergo polymerization to yield dark melanin-like pigments of high molecular mass. The relationship between the presence of melanin, or melanin-like pigments in fungi and resistance to microbial lysis has been demonstrated [20][21][22][23][24][25]. Bull [25] reported that melanins can function as a physical barrier, preventing access by cell wall-degrading enzymes of other organisms.…”

Section: Phenoloxidase Localizationmentioning

confidence: 99%

Extracellular enzyme localization during interspecific fungal interactions

White¹

1992

FEMS Microbiology Letters

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showed spatially and temporally heterogeneous patterns of laccase-a-naphthol and peroxidase activities. These activities were coincident in axenic cultures, but were not always so during interaction. Confrontation between species resulted in induction of phenoloxidase activities, even within coenocytic colony regions of Phlebia species which were normally void of such activities in axenic culture. These events resulted in restriction of C. versicolor growth during interaction with P. rufa.

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“…Chet et al (1967) found that sclerotial walls of Sclerotium rolfii contain a melanin-like pigment which is absent from hyphal walls and they suggested that this pigment is important in providing resistance to biological and chemical degradation. Support for this has been given by Potgieter & Alexander (1966) (i) The chitin and probably also the glucans and other components of the hyphal wall are protected by the melanin secreted by the protoplast, either as a deposit on the outer surface of the hyphae and/or by the formation of a complex, particularly with chitin, in the cell wall.…”

Section: (B) Enzymesmentioning

confidence: 98%

“…Some fungi are particularly susceptible to lysis by other micro-organisms while others are resistant to microbial degradation. Chlamydospores and sclerotia are particularly resistant (Potgieter & Alexander, 1966) as are the pigmented hyphae of Helminthosporium sativum, Rhizoctonia solani and Alternaria solani (Lockwood, 1960). Much evidence indicates that melanin or related substances may have great ecological significance in reducing damage by the lytic action of micro-organisms.…”

Section: (B) Enzymesmentioning

confidence: 99%

The Survival of Fungal Sclerotia Under Adverse Environmental Conditions

Willetts

1971

Biological Reviews

143

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Summary 1. Sclerotia have been found to survive under adverse environmental conditions for long periods. Their viability is retained at low and subzero temperatures, while it is progressively reduced at temperatures above about 15° C. Dry conditions and lack of competition from other organisms favour survival. Depletion of food reserves results in loss of resistance to environmental factors. 2. The majority of sclerotia consist of an outer layer of thickened, close‐fitting, often pigmented cells that form a rind over a tissue of closely interwoven hyphae. A cortex and medulla is often discernible. 3. Features of sclerotia that are important in overcoming the harmful effects of desiccation and extremes of temperature include: the presence of a rind and sometimes an additional covering of either fungal or host tissue; the compact nature of the sclerotium; miscellaneous protectants on the surface of and in the hyphae; melanized hyphal walls; high intracellular osmotic concentrations; slow air‐drying to lower moisture content. Also the buffering action of the soil and the protection afforded by vegetation and plant debris are important. 4. The active exudation of water, the accumulation and secretion of soluble carbohydrates during sclerotium development and maturation, and the formation of large amounts of mucilage are of significance in resistance to desiccation, extremes of temperature and radiations. 5. The nature and the pigmentation of the rind together with the site of sclerotium development may give protection against harmful radiations. 6. The loss of sclerotium viability caused by toxic chemicals in the soil and atmosphere or by the enzymic activities of other organisms is reduced by the rind and the melanization of hyphal walls. 7. Survival under starvation conditions is achieved by the accumulation of abundant food reserves (lipids and/or carbohydrates) and a low level of metabolic activity. In the presence of a compatible host exogenous sources of energy are sometimes used. 8. Although the sclerotium is highly adapted to survive adverse conditions for long periods, sometimes micro‐environmental conditions may be so severe that only a few sclerotia can retain their viability. However, even a few such comparatively large bodies, rich in food reserves, have a considerable inoculum potential.

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Susceptibility and Resistance of Several Fungi to Microbial Lysis

Cited by 125 publications

References 17 publications

The contribution of melanin to microbial pathogenesis

The contribution of melanin to microbial pathogenesis

Extracellular enzyme localization during interspecific fungal interactions

The Survival of Fungal Sclerotia Under Adverse Environmental Conditions

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