Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Botany Microbiology

Bibliography: Pages 191-228.

Myrosinase hydrolyzes glucosinolates giving various products depending on the physiological conditions.The hydrolysis products especially isothiocyanates have antibacterial, antifungal, anticancer activity, act as soil biofumigant, natural pesticides and food preservatives. Myrosinase is mainly found in cruciferous plants but few literatures reported its production by both fungi and bacteria. In this study, 94 microbial isolates from E.sativa and its soil rhizosphere were screened for myrosinase, 25% of the screened bacterial isolates (9 isolates) and 62.07% of the screened fungal isolates (36 isolates) had myrosinase activity. About 22.22% of the endophytic bacterial isolates from E.sativa roots and 63.63% of the endophytic bacterial isolates from E.sativa leaves were able to produce myrosinase but none of soil rhizosphere and epiphytic bacterial isolates were able. On the other hand, 72.41% of the E.sativa fungal isolates of soil rhizosphere, 50% of the endophytic fungal isolates from E.sativa roots, 37.5% of the endophytic fungal isolates from E.sativa leaves and 63.64% of the epiphytic isolates had myrosinase activity.This indicated that both endophytic bacterial and fungal population of E.sativa leaves and roots are good reservoir for myrosinase activity and the fungal community of the soil rhizosphere and the plant surfaces of E.sativa seemed to have myrosinase activity rather than the bacteria living there. The nine myrosinase producing bacterial isolates were phenotypically characterized and identified based on 16S rRNA sequencing.They all belonged to the genus Bacillus and they were given the following accession numbers LC589981, LC589982, LC589983, LC589984, LC589985, LC589986, LC589987, LC589988 and LC589989 on NCBI. They were all most closely related to Bacillus siamensis and Bacillus velezensis with identity percent > 99%. The fungal myrosinase producers were identified morphologically and they belonged to six different genera: Aspergillus, Penicellium, Fusarium, Eumericella, Alternaria and Sclerotium

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