ABSTRACT

Rhizobium is a Gram positive bacterium equipped with many beneficial roles to humans and plants such as symbiotic behaviors, combating different pathogens and many other effects. For such importance, there is an urgent need to isolate and explore new Rhizobium sp. for their biological activities especially having antitumor activities and in the same time to influence broad symbiotic activities being able to grow and tolerate harsh environmental and industrial conditions like that existing in Egypt. A number of 35Rhizobium sp. were isolated and allowed to grow under different stress conditions including high salt and different pH. The maximum tolerance capability was recorded in two strains; ES-BM9 and ES-CS4.PCR amplification and sequencing of the 16S rRNA gene of ES-BM9 and ES-CS4 was performed and they were identified as Rhizobium leguminosarum and Rhizobium pusense, respectively. Fermentation and extraction of metabolites containing exopolysaccharide (EPS) were managed and evaluated for their cytotoxicity against HepG-2, MCF-7 andCaco-2 cell lines. Extracts of ES-BM9 showed the highest cytotoxicity against all cell lines.LC-HRESIMS analysis revealed presence of several compounds with key biological applications.To the best of our knowledge, this is the first study to identify Octapeptin-A2, Fortimicin, Chalcomycin and Lipopeptide being recovered from Rhizobium sp. and the first study to report antitumor activities from Rhizobium sp. isolated from Egypt. Keywords: Rhizobium, Exopolysaccharides, Cytotoxicity, Stress response, Bioproducts
Publication date: 01/09/2020

https://ijbpas.com/pdf/2020/September/MS_IJBPAS_2020_5175.pdf

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https://doi.org/10.31032/IJBPAS/2020/9.9.5175