DOI: 10.5285/cf3133fb-0bd5-48e5-a89c-d464bd5b90a3
title: Growth rates and specific cellulase activities of Antarctic Pseudogymnoascus roseus isolates exposed to constant and fluctuating temperatures - VERSION 2.0

description: Data on the growth rates and specific cellulase activities of 10 isolates of the fungus Pseudogymnoascus roseus from sub- and maritime Antarctica, exposed in vitro to fluctuating temperatures of 2-15 degrees Celsius, 2-18 degrees Celsius, 2-21 degrees Celsius and 2-24 degrees Celsius and their corresponding mean constant temperatures of 9.0 degrees Celsius, 10.7, 12.0 or 13.1 degrees Celsius, respectively, and constant temperatures of 2 degrees Celsius, 5.5 degrees Celsius, 8.5 degrees Celsius, 15.0 degrees Celsius, 18.0 degrees Celsius, 21.0 degrees Celsius and 24.0 degrees Celsius.

Funding:
UK Natural Environment Research Council (core funding to the British Antarctic Survey).
description: A total of 10 isolates of P. roseus were obtained from soils at Lewis Pass on South Georgia (two isolates, SG1 and SG2), The Backslope on Signy Island (two isolates, S1 and S2), Walton Terraces on Leonie Island (three isolates, L1-L3) and Mars Oasis on Alexander Island (three isolates, A1-A3). They were maintained on half-strength potato dextrose medium. 

Three experiments were conducted. In the first, each isolate was inoculated onto soil extract medium in eight Petri dishes, which were incubated at constant temperatures of 9.0 degrees Celsius, 10.7 degrees Celsius, 12.0 degrees Celsius or 13.1 degrees Celsius for one week. Colony fronts were then marked on dish reverses with a fine blade at x 10-15 magnification (accuracy c. 100 micrometers) and four dishes inoculated with each isolate were transferred to cabinets fluctuating daily from 2-15 degrees Celsius, 2-18 degrees Celsius, 2-21 degrees Celsius and 2-24 degrees Celsius. The other four dishes inoculated with each isolate were transferred back to the cabinets running at constant temperatures of 9.0 degrees Celsius, 10.7 degrees Celsius, 12.0 degrees Celsius or 13.1 degrees Celsius. Note that the constant temperatures were the means of the fluctuating temperatures (e.g., 9.0 degrees Celsius was the mean of the temperatures fluctuating from 2-15 degrees Celsius). Colony fronts were marked on dish reverses 24 hours and 48 hours later, and mean growth rate (mm / day) was calculated. 

In the second experiment, soil extract medium in eight Petri dishes was again inoculated with each of the 10 isolates, which were again incubated at constant temperatures of 9.0 degrees Celsius, 10.7 degrees Celsius, 12.0 degrees Celsius or 13.1 degrees Celsius for one week. Colony radii were then measured twice at right angles to each other at x 10-15 magnification. Four dishes per isolate that had been incubated at each of these temperatures were then placed into cabinets set to fluctuating temperatures of 2-15 degrees Celsius, 2-18 degrees Celsius, 2-21 degrees Celsius or 2-24 degrees Celsius, respectively, and the remaining four dishes per isolate were replaced in the cabinets set to constant temperatures of 9.0 degrees Celsius, 10.7 degrees Celsius, 12.0 degrees Celsius or 13.1 degrees Celsius. Colony radii were measured every 3-5 days over the next 21 days and mean growth rates (mm / day) were calculated by regressing colony radii against time. After 21 d, extracellular beta-glucosidase (cellulase) was extracted from colonies in 10 mM phosphate buffer. Protein concentrations in the buffer were measured using a Micro BCA Protein Assay (Thermofisher). Cellulase activity was measured and expressed as nmol of p-nitrophenol released from 4-nitrophenyl-beta-D-glucopyranoside / min / microgammes protein (Misiak et al. 2021, doi: 10.1111/gcb.15456).

In the third experiment, the 10 isolates were each inoculated onto soil extract medium in four Petri dishes, which were incubated at constant temperatures of 2.0 degrees Celsius, 5.5 degrees Celsius, 8.5 degrees Celsius, 15.0 degrees Celsius, 18.0 degrees Celsius, 21.0 degrees Celsius and 24.0 degrees Celsius for one week. Colony fronts were then marked at x 10-15 magnification on dish reverses as described above. The fronts were marked again after 24 hours and 48 hours and radial extension rate (mm / day), averaged over 48 hours, was calculated.
 
This dataset was updated to include additional data from the third experiment described above and to update the metadata accordingly.
description: Micro BCA Protein Assay (Thermofisher)
description: Data have not been cleaned. Data losses, indicated by MD (missing data) were caused by laboratory errors. Note that the accuracy of growth rate data measured at 12 degrees Celsius and 2-21 degrees Celsius over 0-48 hours was lower than for other growth rate data.