Isolation of some Biocontrol Fungi from Saudi soil and their Beneficial Role as Bio-Fertilizers

Beneficial fungi found in the rhizosphere of cultivated plants next to some harmful microorganisms. These fungi which used in the vital biological control could be propagated and then put back again to the soil to get useful results for resisting plant diseases. The objective of this study was to isolate some biocontrol fungi to be used to reduce inhibitors phenols in olive press solid cake and convert it into a soil as biofertilizers. Twenty-five rhizosphere soil samples were collected from 25 locations in Khoaa village, Sakaka, Aljouf governorate, northern part of Saudi Arabia. A total of 3512 fungal isolates related to 11 genera were obtained from rhizosphere soil of alphalpha during November 2014. Four hundred and forty-two, 3 and 298 isolates of Gliocladium roseum, Pythium oligandrum and Trichoderma harzianum were isolated, respectively. Gliocladium roseum and Pythium oligandrum were capable to decompose phenols which is responsible for inhibiting cucumber seed germination. On the contrary, Trichoderma harzianum showed negative effect in reducing phenol content of the olive press cake, however, it showed its ability as a biocontrol. Gliocladium roseum and Pythium oligandrum can be used to convert the inhibitory olive press cake to media for the growth of cucumber seeds as well as a reservoir of biocontrol elements.