An Improved Method for Establishing Accurate Water Potential Levels at Different Temperatures in Growth Media

Abstract

NaCl, KCl, or PEG (polyethylene glycol)-amended potato dextrose broth (PDB), and potato dextrose agar (PDA) are essential for pure culture studies of water stress on fungi. Direct information on the actual water potential (WP) of this salt-amended PDB and PDA is lacking. Much fungal research in the past calculated WP of these salt-amended growth media by adding the WP of their constituents taken from individual salt dilution studies. But the WP of any complex solution will be modified by the level of synergism between its solutes. This study presents evidence of change in NaCl concentration due to synergism for attaining the same level of WP in NaCl solution, and NaCl amended PDB and PDA. The relation between WP and temperature and WP and salt concentration is also modified depending on the number of solutes in a growth medium. The WP of PEG-amended PDB increases with rising temperature, while that of NaCl/KCl amended PDB and PDA decreases with the increase of temperature. These results can be useful for doing pure culture studies on the biology and modeling the growth of air, water, and soil-borne fungi important in the food and agriculture industry and in terrestrial and aquatic ecosystems.

Salinity and Temperature Influence Growth and Pigment Production in the Marine-Derived Fungal Strain Talaromyces albobiverticillius 30548

“…Since our interest was to test the tolerance of marine-derived fungi to high salt stress and the reaction towards pigments production, we have used artificial sea salts to study T. albobiverticillius growth and production in liquid media. From Aujla [52], the water potential of PDB can be evaluated around −0.32 MPas (1 Mega Pascal = 10 bars) at 25 °C. Sea-salts mix from Difco mimics the composition of salt mixture in sea water, whose salinity is approximately 36.5 g/L in tropical regions.…”

Estimating Impact of Salinity on Soil Water Potential Dynamics using a Novel Approach

“…An increase in the total potential is also attributed to rise in temperature. However, a controlled microenvironment which is feasible for microorganism activities should be provided to avoid difficulties in measuring water potential (Aujla and Paulitz, 2017). Proper measurement of the water potential induced by saline water is essential to manage the microenvironment of the soil for proper crops growth.…”

“…The machine can measure samples with internal temperature control from 15 to 40°C. Similarly, it can measure the water potential from 0 to −300 MPa with a very high accuracy (Aujla and Paulitz, 2017). The soil sample is placed inside the sealed chamber with the mirror, the mirror is cooled until dew is formed, the dew point is detected with photoelectric cell.…”

Novel Trichoderma Isolates Alleviate Water Deficit Stress in Susceptible Tomato Genotypes

“…Supplementation of growth medium with PEG is designed to measure the effect of water potential on the growth of fungi ( Jin et al, 1991 ; Aujla and Paulitz, 2017 ). We screened 44 isolates and identified some isolates which exhibited the ability to survive and sporulate under different osmotic stress conditions ( Figures 2A–C and Supplementary Table 2 ).…”

“…Desiccation conditions were created by dissolving polyethylene glycol 8000 MW (PEG) in Potato Dextrose Agar (PDA) medium (Sigma- Aldrich Inc., St. Louis, MO, United States) according to the procedure described by Aujla and Paulitz (2017) . Different matric water potentials (0.0, –2.8, –4.8, and –8.5 Ψ) were generated by adding 0, 400, 600, and 800 g PEG (8,000 MW, Fisher Scientific Co., Pittsburgh, PA, United States) into 1 l of PDA, respectively.…”