Microbial counts and characteristics of Streptoverticillium strains isolated from soils in the Jordan valley

A microbial survey of total bacterial count, agrobacteria, streptomycetes, and fungi was carried out in six locations in the Jordan Valley. The highest microbial counts for the four populations were in spring, the lowest mostly in autumn. No significant differences at p < 0.05 were observed either in the counts between the six locations, or in the seasonal counts of agrobacteria and streptomycetes between the six locations as well as within each location. The total bacterial counts (at p < 0.01) and fungi (at p < 0.05) differed significantly in the six locations. Microbial counts and the studied environmental conditions showed no significant regression. Of 552 streptomycetes strains isolated from soils collected from these locations, 58 belonged to the genus Streptoverticillium. They were distributed in five colour series grey (41%), red (31%), green (17%), blue (7%) and white (3%). Forty-eight strains had biverticillium spore bearing hyphae while only 10 had monoverticillium. While 28 strains produced distinctive reverse side pigment, only 8 and 6 strains produced soluble pigment and melanin pigment, respectively. Most strains utilized arabinose followed by fructose, mannitol, rhamnose, xylose, sucrose, inositol, and raffinose. Sixty-nine per cent of the strains exhibited activity in vitro test against Pseudomonas aeruginosa, and 45, 41, 28, and 7% against Staphylococcus aureus, Bacillus cereus, Agrobacterium tumefaciens and Escherichia coli, respectively.