Production of chlamydospores and conidia by Trichoderma spp in liquid and solid growth media

Abstract

Isolates of Trichoderma spp grew and produced chlamydospores as well as conidia in molasses-corn steep liquor (M-CSL), sucrose nitrate (SN), and glucose tartrate (GT) media. In M-SCL, isolates of T. hamatum, T. viride, and T. harzianum formed 10.4, 5.9 and 1.1 × 10 8 chlamydospores g −1 dry weight of mycelium. Fewer chlamydospores formed in SN and GT. Although T. harzianum formed the least number of chlamydospores, it produced the highest number of conidia in all three media. Molasses-corn steep liquor was superior to SN or GT in supporting development of both spore types. Spore production was not influenced by initial pH of the media or by continuous maintenance of the media at pH 4 or 7. Equal numbers of chlamydospores were formed in liquid media incubated in shake or static culture. Conidia formation, however, was stimulated in static culture. Chlamydospores and conidia of several naturally occurring isolates and induced biotypes of Trichoderma spp were abundantly produced on a variety of solid substrates moistened with liquid nutrients or water, preferably at pH 4. Bran, cornmeal, and peanut hull meal were better than eight other solid substrates for production of chlamydospores and conidia. A u.v.-induced, benomyl-resistant biotype of T. viride (T-1-R9) formed 22 × 10 7 and 18 × 10 8 chlamydospores and conidia, respectively, g −1 of bran-SN. The ratio of conidia to chlamydospores was always greater in solid than liquid media. In solid media, 10 times more conidia than chlamydospores were formed, whereas in liquid only two or three times more were formed. Chlamydospores from liquid and solid fermentations were viable ( ca 80%) and fresh chlamydospores germinated well ( ca 75%) on nutrient agar. Although dried chlamydospores were viable, as determined with tetrazolium bromide, their germination on agar was poor ( ca 8%).