ISOLATION AND IDENTIFICATION OF STREPTOMYCES BAARNENSIS MH-133 PRODUCE BIOACTIVE METABOLITE INHIBITING MULTIDRUG RESISTANT BACTERIA (MDRB)
Dr. Saad A.M. Moghannem*, Gamal M. El-Sherbiny and Mohamed H. Kalaba
ABSTRACT
In the present study five agriculture soil samples were collected from Empoli, Tuscany, Italy. Thirty-seven actinomycete isolates were obtained and selected from these samples according to their morphological characteristics and purified on starch nitrate agar medium. These isolates were screened for antibacterial activity against Multidrug Resistant Bacteria (MDRB), (E. faecalis and MRSA) as Gram positive bacteria and (E. coli, Klebsiella pneumonia, Acinetobacter baumanii, Pseudomonus aeruginosa, and Enterobacter cloacae) as Gram negative bacteria in addition to standard strain Bacillus subtilis ATCC-6633, Micrococcus luteus ATCC-4698 and Salmonella typhi ATCC-6539. Among tested actinomycete isolates only MH-133 isolate could inhibit the growth of all tested bacteria except Enterobacter cloacae. Morphological, physiological and biochemical identification results of MH-133 isolate indicated that, it belongs to the genus Streptomyces. The comparative analysis of 16S rDNA sequence and phylogenetic relationship showed that MH-133 isolates lies in a separate clade with Streptomyces baarnensis strain NRRL B-1902. MH-133 isolate was submitted to the GenBank, NCBI under the accession number, KY698030. Factors affecting antibacterial metabolite(s) were optimized to enhance the antibacterial activity. The optimum conditions were pH 8, temperature 30ºC, inoculum size 6% (v/v) on modified marine medium under shaking condition (150 rpm). The fermentation kinetic study was performed and the result showed that the maximum antibacterial activity was significantly achieved at the eighth day while both of carbohydrate consumption and biomass production were not shown significant changes starting from the sixth day. This study clearly proves that our isolate exhibit antibacterial activity against MDRB.
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