Screening Of Streptomyces Isolates From Mau Forest Complex For Antimicrobial Activity Against Selected Plant Pathogens

ABSTRACT

The search for new principles in bio-control of plant pathogens different from the classical fungicides is of worldwide interest. The genus Streptomyces is the producer of about 80% of all known world antibiotics. It is of a major interest in bio control of plant pathogens. The study consisted of three steps: (i) collection of soil samples from different sites in the Mau Forest Complex and isolation of Streptomyces from these samples, (ii) screening for antimicrobial activity of the isolates against selected plant pathogen in the laboratory i.e. Fusarium moniliforme and Ascochyta rabie; Erwinia carotovora, Xanthomonas campestris and Pseudomonas savastanoi pv. phaseolicola and other indicator reference cultures which were : Staphylococcus aureus ATCC 25923; Escherichia coli ATCC2 5922; Pseudomonas aeruginosa ATCC 27853 and Bacillus subtilis ATCC 6633. (iii) Identification of the isolates most effective in inhibiting the growth of the pathogens. A total of 270 isolates were screened for antimicrobial activity, 14 of the isolates showed antibacterial activity against the test bacteria while 39 isolates had antifungal activity. Most of the selected isolates had more effective inhibitions to fungal plant pathogens than bacterial plant pathogens. Ethyl acetate extracts of culture filtrates from the isolates produced significantly different (P