Streptomyces species are aerobes and chemoorganotrophic bacteria. These microorganisms produce a wide range of industrially significant compounds, specifically antibiotics and anti fungal substances. The objective of this study was to characterise soil-borne
Streptomyces isolates using morphological and molecular traits in order to identify them to species level, and leverage from their potential to suppress the growth of
Aspergillus flavus
,
Fusarium oxysporum
and
Penicillium italicum
. Twenty-seven soil-borne putative
Streptomyces, which elicited comprehensive antimicrobial activity against
Aspergillus flavus,
Fusarium oxysporum and
Penicillium italicum, in a previous study, were evaluated. On the basis of morphology, the bacteria resembled the genus
Streptomyces. Initially, colonies phenotypically appeared to have a relatively smooth surface but as growth progressed the bacteria developed a weft of aerial mycelium granular, powdery or velvety in appearance. Bacteria produced a wide variety of pigments which in turn were responsible for the colour of the vegetative and aerial mycelia, colour ranged from white to cream or buff shades and yellow to orange or brown. Microscopic analyses and morphological characteristics generated sub-groups of the isolates and clustered them according to their similarities. One bacterial strain was randomly selected from each cluster and investigated using molecular characteristics. Partial 16S rDNAs from the selected representative isolates from each subgroup, were sequenced and phylogenetic analysis performed. The 16S rDNA sequences of the isolates indicated that they were related to
Streptomyces species:
S. bungoensis
,
S. thermocarboxydus
,
S. corchorusii
and
S. lasaliensis,
that are known secondary metabolite producers possessing antimicrobial activity against plant pathogens.
