Relationship between thermotolerance and hydrophobin-like proteins in aerial conidia of Beauveria bassiana and Paecilomyces fumosoroseus as fungal biocontrol agents.
OBJECTIVE
This study was to illustrate the relationship between the thermotolerance and the contents of hydrophobin-like or formic-acid-extractable (FAE) proteins in aerial conidia of Beauveria bassiana and Paecilomyces fumosoroseus produced on rice-based substrate.


RESULTS
Survival indices of 11 isolates were separately assessed as a ratio of the viability of conidia after 3-150 min thermal stress at 48 degrees C over that of unstressed conidia and fitted well to a survival model (r(2) >/= 0.97). For a given isolate, the fitted model generated an LT(50), the time for 50% viability loss under the stress. The LT(50)s of six B. bassiana isolates (10.1-61.9 min) and five P. fumosoroseus isolates (2.8-6.2 min) were correlated (r(2) = 0.81) with FAE protein contents (6.9-23.4 microg mg(-1)). The survival indices of a fixed B. bassiana isolate after 45-min thermal stress at 48 degrees C were also correlated to the FAE protein contents from conidia produced on glucose-, sucrose-, or starch-based substrate (0.79 </= r(2) </= 0.86). Three bands of 12.0, 15.0 and 17.5 kDa were recognized from SDS-PAGE profiles of protein extracts from different isolates or from the fixed isolate grown on the three carbon sources, but the 12 kDa was less likely related to the thermotolerance.


CONCLUSIONS
Approximately 80% of variability in conidial thermotolerance was attributed to either 15.0- or 17.5-kDa FAE protein or both.


CONCLUSIONS
The relationship between conidial thermotolerance and FAE protein contents implicates a new way to search for fungal biocontrol agents with more thermotolerance and environmental persistence.
Ying
S-H
SH
Institute of Microbiology, College of Life Sciences, Zhejiang University, Zhejiang, China.
Feng
M-G
MG
D015169:Colony Count, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D005561:Formates / Q000378:metabolism; D005656:Fungal Proteins / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D006999:Hypocreales / Q000254:growth & development / Q000502:physiology*; D010143:Paecilomyces / Q000254:growth & development / Q000502:physiology*; D010572:Pest Control, Biological; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
D005561:Formates; D005656:Fungal Proteins; C030544:formic acid; D013395:Sucrose; D013213:Starch; D005947:Glucose