VIABILITY OF DRY TRICHODERMA-HARZIANUM SPORES UNDER STORAGE

Spores of the potential biocontrol agent Trichoderma harzianum P1 were prepared without (Mi) and with heat shock (40 degrees C for 90 min) a fter fermentation (M2), filtered into a paste and dried over silica ge l. M1 and M2 exhibited high viability (55%) and similar initial trehal ose contents (4.0 and 5.4%, respectively) after slow drying. No signif icant differences in viability were found between treatments during st orage for 110 days under different temperatures, T (8, 33 and 42 degre es C) and water activities, a(w) (0.03, 0.33 and 0.75). Viability of s pores, after storage at a(w) = 0.03 were 100 and 70% for 8 and 33 degr ees C, respectively. During storage, decrease in trehalose content and viability was faster at a(w) = 0.75 and 42 degrees C. Loss of viabili ty was modeled by a first order kinetic model depending on 1/T and a(w ). M2 (with heat shock) showed slightly higher trehalose contents than M1 which resulted in 100% viability after 52 days at 8 degrees C.