A critical assessment of the validity of ergosterol as an indicator of fungal biomass

Bermingham, S.; Maltby, Lorraine; Cooke, R.C.

doi:10.1016/s0953-7562(09)80650-3

Cited by 93 publications

(39 citation statements)

References 19 publications

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“…This discrepancy could be due to the use of different strains or to the method of Bermingham et al (1), in which fungal mass and ergosterol were determined from separate samples. Fell and Newell (5) pointed out that much of the variation in ergosterol conversion factors in the study by Bermingham et al could be a consequence of imprecise dry mass determination.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, ergosterol synthesis requires molecular oxygen, and low oxygen tensions can dramatically reduce ergosterol concentration (14,15). The use of ergosterol as an indicator of fungal biomass has also been questioned in one study involving static cultures (1), but the unusual results obtained have been primarily attributed to the experimental procedures employed (5,6). The low ergosterol contents reported in reference 1 suggest that culture conditions other than those previously used (8) could significantly affect ergosterol content.…”

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confidence: 99%

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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: 99%

mentioning

confidence: 99%

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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“…Here, fungal biomass developing on leaves was estimated using concentration of ergosterol, a fungal-specific sterol present in cell plasma membrane. Although ergosterol content was shown to vary among species of hyphomycetes and with environmental conditions (Bermingham et al, 1995), it is considered as an appropriate descriptor of fungal biomass on submerged leaves Chauvet, 1993 andGessner, 2005). The observed increase in fungal biomass points to the hypothesis that drying stress could have selected for hyphomycete mycelia with thicker membranes (greater ergosterol accumulation) to resist desiccation.…”

Section: Effects Of Individual Stressors On Microbial Leaf Litter Decmentioning

confidence: 99%

Combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition

et al. 2016

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Highlights• The combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition (LLD) were assessed.• TBZ applied alone had no significant effect on LLD.• Drought strongly impacted the microbial LLD process and led to cascading effects on Gammarus feeding.• Structural and functional effects increased when drought and TBZ were applied simultaneously. AbstractLoss of biodiversity and altered ecosystem functioning are driven by the cumulative effects of multiple natural and anthropogenic stressors affecting both quantity and quality of water resources. Here we performed a 40-day laboratory microcosm experiment to assess the individual and combined effects of drought and the model fungicide tebuconazole (TBZ) on leaf litter decomposition (LLD), a fundamental biogeochemical process in freshwater ecosystems. Starting out from a worst-case scenario perspective, leaf-associated microbial communities were exposed to severe drought conditions (four 5-day drought periods alternated with 4-day immersion periods) and/or a chronic exposure to TBZ (nominal concentration of 20 µg L−1). We assessed the direct effects of drought and fungicide on the structure (biomass, diversity) and activity (extracellular enzymatic potential) of fungal and bacterial assemblages colonizing leaves. We also investigated indirect effects on the feeding rates of the amphipod Gammarus fossarum on leaves previously exposed to drought and/or TBZ contamination. Results indicate a stronger effect of drought stress than fungicide contamination under the experimental conditions applied. Indeed, the drought stress strongly impacted microbial community structure and activities, inhibiting the LLD process and leading to cascading effects on macroinvertebrate feeding. However, despite the lack of significant effect of TBZ applied alone, the effects of drought on microbial functions (i.e., decrease in LLD and in enzymatic activities) and on Gammarus feeding rates were more pronounced when drought and TBZ stresses were applied together. In a perspective of ecological risk assessment and ecosystem management for sustainability, these findings stress the need for deeper insight into how multiple stressors can affect the functioning of aquatic ecosystems and associated services.

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“…Consequently the validity of using chitin or ergosterol as markers of fungal biomass has been questioned (Sharma et al, 1977 ;Bermingham et al, 1995). However, there is a lack of data on variation in marker concentrations of mycorrhizal fungi while in the symbiotic state.…”

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confidence: 99%

Chitin and ergosterol combined to measure total and living fungal biomass in ectomycorrhizas

1998

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We have studied the chitin and ergosterol contents of ectomycorrhizal roots in three sets of experiments to evaluate them as indicators of fungal biomass. The first set of experiments showed that ageing had a marked effect on ergosterol concentrations. The ergosterol content of 7-month-old, brown, shrunken Pinus sylvestris L.-Paxillus involutus (Fr.) Fr. mycorrhizas was found to be only 10 % of that found in white, turgid, 1-or 4-month-old specimens. This supports the hypothesis that the compound is a good indicator of living fungal biomass. Ageing had a lesser effect on chitin concentrations since the chitin levels found in 7-month-old mycorrhizas were still 60 % of the levels found in 1-and 4-month-old specimens.Consequently, the chitin : ergosterol ratio increased from about 14 to 19 in 1-and 4-month-old mycorrhizas respectively to about 110 in 7-month-old mycorrhizas. In the second set of experiments, we found that variation in plant growth had no effect on the chitin : ergosterol ratio in whole root systems of either Alnus incana (L.) Moench or Pinus sylvestris mycorrhizal with Paxillus involutus. In the third set of experiments, we found a constant relationship between the two marker concentrations in 10-month-old root systems of Pinus sylvestris, regardless of fungal species involved, using Paxillus involutus, Piloderma croceum Erikss. & Hjorts and Suillus variegatus (Fr.) O. Kuntze as test organisms. Taken together, the results of this study suggest that both chitin and ergosterol give reliable, but different, relative measures of fungal biomass in mycorrhizal roots. Furthermore, we demonstrate that, in combination, the two chemical markers can be used to estimate both total and living fungal biomass (derived from the chitin : ergosterol ratio).

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A critical assessment of the validity of ergosterol as an indicator of fungal biomass

Cited by 93 publications

References 19 publications

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

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

Combined effects of drought and the fungicide tebuconazole on aquatic leaf litter decomposition

Chitin and ergosterol combined to measure total and living fungal biomass in ectomycorrhizas

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