The combined synergistic effects of a cellulase-producing Micromonospora carbonacea and an antibiotic-producing Streptomyces violascens on the suppression of root-rot disease of Banksia grandis caused by Phytophthora cinnamomi

Abstract

Three polyvalent Streptomyces phages were used to isolate four Micromonospora species (M. carbonacea, M. chalcea, M. purpureochromogenes and M. inositola) from rhizosphere soils from a rehabilitated bauxite mine in Western Australia. Streptomyces violascens was isolated using the selective dry heat technique. M. carbonacea, M. chalcea and M. purpureochromogenes were found to produce cellulases in vitro and cause lysis of Phytophthora cinnamomi hyphae. Glasshouse trials showed that a cellulase-producing M. carbonacea isolate used in conjunction with an antibiotic-producing isolate of S. violascens, had a synergistic effect on the suppression of Phytophthora root-rot, and significantly promoted the growth of Banksia grandis. This study illustrates the importance of combining potential biological control agents with different antagonistic abilities, to control soil-borne plant pathogens