title: Statistical approach to determine the effect of combined environmental parameters on conidial development of Trichoderma atroviride (T-15603.1).
abstract: Trichoderma atroviride (T-15603.1) is a promising fungal agent for biological control of wood decay fungi in urban tree wounds. The aim of this work was to determine the combined effects of water activity (a(w), 0.998-0.892), temperature (10-30 °C) and pH (3-7) on the development of conidia on low-nutrient agar (LNA). Lag phase prior to germination (h), germination rates (µ(m)) and germ-tube elongation were obtained at each set of conditions. The experimental data were used to fit a response surface model for predicting the germination rates of T-15603.1 and to analyze the effect of the abiotic parameters tested. The polynomial response surface model was mathematically evaluated using graphical plots and several statistical indices (RMSE, %SEP, A(f), B(f), pRE). Data analyses showed a highly significant effect on conidial development of a(w) and temperature (P < 0.001), whereas no significant effect of pH (P ≥ 0.05) was observed. The germination rate dropped and the lag prior to germination increased as the temperature and a(w) decreased, but T-15603.1 appeared to be more sensitive to a(w) reduction than to temperature. The minimum a(w) level for germination was 0.910 at 15-25 °C, and maximum germination rates were obtained at a(w) = 0.998, 25-30 °C and pH 5. The response surface model was useful and widely accurate (R² = 0.983) for predicting the germination rate of T-15603.1 and complemented the experimental results. These findings contribute to better understanding how combined environmental factors affect the environmental parameter tolerance levels of T-15603.1 and to the development of an adequate delivery system for optimized application of T-15603.
authors.affiliation: EMPA, Swiss Federal Laboratories for Materials Science and Technology, Wood Laboratory, Group of Wood Protection and Biotechnology, St. Gallen, Switzerland. mark.schubert@empa.ch
authors.forename: M
authors.initials: M
authors.lastname: Schubert
authors.forename: S
authors.initials: S
authors.lastname: Mourad
authors.forename: F W M R
authors.initials: FW
authors.lastname: Schwarze
mesh_terms: D003198:Computer Simulation; D004783:Environmental Microbiology; D006863:Hydrogen-Ion Concentration; D015233:Models, Statistical; D013172:Spores, Fungal / Q000254:growth & development*; D013696:Temperature; D014242:Trichoderma / Q000254:growth & development*; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water