Abstract:
Search for new principles in biocontrol of plant pathogens different from the
classical fungicides is of worldwide interest. Members of the genus
Streptomyces are known to produce about 80% of all known antibiotics in the
world. These antibiotics have been applied in medicine, veterinary and in
agriculture. Presumptive Streptomyces from the Mau Forest Complex were
isolated from soils obtained from different sites within the Mau Complex. 270
isolates were screened for antimicrobial activity against selected plant
pathogenic bacteria and two fungal plant pathogens i.e. Erwinia carotovora,
Xanthomonas campestris pv. campestris, Pseudomonas savastonoi pv.
phaseolicola, Fusarium moniliforme, Ascochyta rabie; the reference cultures
were: Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 25922;
Pseudomonas aeruginosa ATCC 27853 and Bacillus subtilis ATCC 6633. 14
(0.05%) of the isolates showed antibacterial activity against the test bacteria
while 39 (0.14%) isolates had antifungal activity. Ethyl acetate extracts of
culture filtrates from the isolates produced significantly different (P<0.05)
inhibitory effects to some of the tester microorganisms. Five of these isolates
had both antifungal and antibacterial activity. There were further characterized
using biochemical, microscopy and morphological methods. These methods
showed that they were Gram positive and had similarities to members of the
genus Streptomyces. The study found that soils from Mau Forest complex
harbor diverse group of bacteria including Streptomyces species that could be
exploited for control of plant diseases. There is need to establish their
effectiveness in green house and field studies.