Toward A Method For Measuring Instantaneous Fungal Growth Rates In Field Samples

Abstract

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The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic: a microcosm simulation experiment

“…Bacterial growth rates were estimated on 0.5 g of soil by 3 H-leucine incorporation into protein (Kirchman et al 1985) adapted for soil (Bååth et al 2001;Rousk et al 2009), after incubation for * 2 h at 17°C. Fungal growth rate was measured by estimating 14 Clabelled acetate incorporation in ergosterol on 0.5 g of soil incubated for * 4 h at 17°C, which also yielded fungal biomass estimated from total ergosterol content (Newell and Fallon 1991;Bååth et al 2001;Rousk et al 2009). Gross N-mineralisation was measured as the change in 15 N/ 14 N ammonium pools over a * 20 h incubation period (17°C) after adding 67 ll 15 NH 4 Cl solution (45 lg N ml -1 ) to larger subsamples (3 g).…”

Initial Colonization, Nutrient Supply, and Fungal Activity on Leaves Decaying in Streams

“…We combined absolute increase of leafassociated mycelia and released conidia to estimate a fungal yield coefficient, defined as cumulative fungal production divided by loss of leaf mass (15). Provided that losses of fungal biomass (from death, invertebrate feeding, and sloughing off) are low, this approach is strongly correlated with estimates based on an instantaneous growth rate (37), which is measured by the incorporation of radiolabeled acetate into ergosterol (25). The fungal yield coefficient was 31% for stream-incubated leaves (Allen Creek); in laboratory-treated leaves, it varied between 1 (N0P0) and 23% (N2P2).…”

Archaeal Abundance across a pH Gradient in an Arable Soil and Its Relationship to Bacterial and Fungal Growth Rates

“…After a 2-h incubation step at 22°C, growth was terminated with trichloroacetic acid, and samples were washed (3), after which the level of incorporated radioactivity was determined using liquid scintillation. Fungal growth was assessed by measuring acetate incorporation into ergosterol (32,37) by the use of [1-14 C]acetate (sodium salt; Amersham) (7.4 MBq ml Ϫ1 , 2.04 GBq mmol Ϫ1 ) combined with unlabeled sodium acetate to create a final concentration of 220 M in a soil slurry and an incubation time of 5 h at 22°C, after which growth was terminated by addition of formalin. Ergosterol was extracted, separated, and quantified using high-performance liquid chromatography (HPLC) with a UV detector (39), and the ergosterol eluent was collected to determine its radioactivity by the use of liquid scintillation.…”