Bio-prospecting for potential microbial biocontrol agents from composted waste materials

C.F. McGee, O. Doyle, M.T. Gaffney
Culturable fungal species (93) were isolated from 15 composted materials and identified to the genus level based on morphological characteristics. The suppressive properties of the fungal isolates were tested against three soil borne plant pathogens (Pythium ultimum, Phytophthora erythroseptica and Fusarium oxysporum) using dual culture techniques. Phytophthora erythroseptica was found to be the most susceptible pathogen to suppression by fungal isolates, with 48 isolates found to be capable of inhibiting mycelial growth. Yeast species, which were not found to be suppressive to P. ultimum or F. oxysporum, accounted for a large proportion of the suppressive isolates (6) which inhibited growth of P. erythroseptica. Pythium ultimum and F. oxysporum were found to be suppressed by 31 and 34 fungal isolates, respectively. The genus Aspergillus accounted for the largest proportion of suppressive fungal isolates (14), followed by the genus Trichoderma (6) and Penicillium (3). Trichoderma isolates were characterised for mechanisms of suppression such as production of volatile and diffusible suppressive metabolites. Neither P. ultimum nor F. oxysporum were found to be suppressed by volatile metabolites, though mycelial growth of P. erythroseptica was significantly inhibited by volatile metabolites of three isolates. The production of suppressive diffusible metabolites accounted for a broader range of suppression with two isolates; CS30-01 and CS31-08 significantly suppressing mycelial growth in both P. ultimum and P. erythroseptica, while CS21-02 inhibited growth in P. ultimum only. Suppression of F. oxysporum by diffusible metabolites was not detected in this study.
McGee, C.F., Doyle, O. and Gaffney, M.T. (2016). Bio-prospecting for potential microbial biocontrol agents from composted waste materials. Acta Hortic. 1112, 335-342
DOI: 10.17660/ActaHortic.2016.1112.45
compost, disease suppression, plant protection, Pythiaceae

Acta Horticulturae