Hydrolytic enzymes in aquaticHyphomycetes

Zemek, J.; Marvanová, Ludmila; Kuniak, Ľ.; Kadlečíková, B.

doi:10.1007/bf02927592

Cited by 43 publications

(22 citation statements)

References 15 publications

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“…These media differ only slightly in nitrogen and free glucose content. MEB contains high levels of other carbohydrates (8) (e.g., maltose) not found in GMS-VAA that can be readily broken down to glucose by aquatic hyphomycetes (21). In particular, such breakdown by ␣-D-glucoside glucohydrolase (EC 3.2.1.20) would result in about fourfold-higher glucose levels in MEB than in GMS-VAA (data not shown).…”

Section: Discussionmentioning

confidence: 94%

Effect of Culture Conditions on Ergosterol as an Indicator of Biomass in the Aquatic Hyphomycetes

Charcosset¹,

Chauvet²

2001

Appl Environ Microbiol

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Ergosterol is a membrane component specific to fungi that can be used to estimate fungal biomass using appropriate factors of conversion. Our objectives were to determine the limits of use of ergosterol content as a measure of biomass for aquatic hyphomycetes, and to evaluate a previously established ergosterol-to-biomass conversion factor. We varied inoculum quality, growth medium, and degree of shaking of four aquatic hyphomycete species. In cultures inoculated with homogenized mycelium, we found a significant effect of shaking condition and culture age on ergosterol content. In liquid cultures with defined medium, ergosterol content reached 10 to 11 g/mg of mycelium (dry mass) and varied by factors of 2.2 during exponential growth and 1.3 during stationary phase. The increase in ergosterol content during exponential phase could be attributed, at least in part, to rapid depletion of glucose. Oxygen availability to internal hyphae within the mycelial mass is also responsible for the differences found between culture conditions. Ergosterol concentration ranged from 0.8 to 1.6 g/mg in static cultures inoculated with agar plugs. Ergosterol content varied by a factor of 4 in two media of different richnesses. For different combinations of these parameters, strong (r 2 ‫؍‬ 0.83 to 0.98) and highly significant (P Ӷ 0.001) linear relationships between ergosterol and mycelial dry mass (up to 110 mg) were observed. Overall, the ergosterol content varied by a factor of 14 (0.8 to 11 mg/g). These results suggest that care must be taken when the ergosterol content is used to compare data generated in different field environments.Ergosterol is a membrane component of most fungi but is absent from vascular plants and metazoan animals (13). Its relative chemical instability suggests that it is rapidly degraded upon cell death and therefore provides a good quantitative measure of viable cells (19). Hence, ergosterol levels are commonly used to estimate fungal biomass on various substrates under a wide range of field and environmental conditions (4,6,9,10,11,20).Estimates of the importance of aquatic hyphomycetes have increased. Based on ergosterol and ATP assays, the biomass of these fungi is estimated to constitute up to 16% of the detrital dry mass of decomposing leaf litter (6). These estimates rely on conversion factors to estimate the amount of fungal biomass and are based on the amount of ergosterol measured. The accuracy of these conversion factors is critical, with values for aquatic hyphomycetes estimated to range from 2 to 16 g/mg (dry weight) (10). Based on liquid cultures of various species grown under laboratory conditions, a mean conversion factor of 5.5 g/mg of mycelium (dry mass) has been proposed (8).Ergosterol content depends on the physiological state and general growth conditions of the fungus. In several species of aquatic hyphomycete cultured in liquid media with different C/N ratios, ergosterol content was only slightly affected by culture age and medium composition (8). However, other factors also can i...

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Section: Discussionmentioning

confidence: 94%

Effect of Culture Conditions on Ergosterol as an Indicator of Biomass in the Aquatic Hyphomycetes

Charcosset¹,

Chauvet²

2001

Appl Environ Microbiol

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“…Establishing a direct connection between a species and its array of hydrolytic enzymes in aquatic hyphomycetes was pioneered by Suberkropp & Klug (1980), who demonstrated activity against cellulose, hemicelluloses and pectin in pure culture filtrates of five species. Activity against lignin or phenolics is generally weaker but fairly widespread in aquatic hyphomycetes (Suberkropp & Klug 1981;Chamier 1985;Zemek et al 1985;Abdel-Raheen & Ali 2004).…”

Section: Who Does What?mentioning

confidence: 96%

Aquatic hyphomycetes in a changing environment

Bärlocher

2016

Fungal Ecology

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“…The identity of the dominant species was manipulated within each of 2 fungal communities known to colonize litter at different decomposition stages, to overcome the issue of assembling species randomly without taking into account natural co-occurrence. Given that (1) our assemblages include aquatic hyphomycete species that differ in their degradative capabilities (Zemek et al 1985) and (2) dominant species play an important role in driving ecosystem processes, differences in rates of leaf processing by fungal assemblages differing in their dominant species are anticipated. If these changes happen, then impacts on litter processing in fresh waters might occur well before there is species loss due to anthropogenic activities.…”

Section: Introductionmentioning

confidence: 99%