The Bioactivity of Actinomycetes Isolate Streptomyces variabilis H2 Against Some Bacterial Pathogens: Optimization and Applications

Author

Abstract

The most valuable prokaryotes, both biotechnologically and monetarily, are actinomycetes. S. variabilis H2 demonstrated a broad spectrum of antagonistic effects against all tested Gram-negative and Gram-positive bacteria, exhibiting inhibition zones of 18mm against Escherichia coli, 16mm against Bacillus subtilis, 16mm against Staphylococcus aureus, 14mm against Pseudomonas aeruginosa, 14mm against Enterococcus faecalis, and 12mm against Klebsiella pneumoniae. Using Plackett-Burman design and one variable at a time approach and testing against the six different bacterial pathogens, one sought a maximal synthesis of the bioactive chemical. The highest antagonistic activity of S. variabilis H2 metabolites was observed against E. coli, where productivity increased by up to 1.3-fold when the strain was grown in an optimized medium composed of: starch (30g/ L), KNO₃ (1.5g/ L), K₂HPO₄ (0.75g/ L), MgSO₄∙7H₂O (0.25g/ L), FeSO₄ (0.015g/ L), NaCl (5.0g/ L), and an inoculum size of 2mL (10³ colony-forming units/mL) for 7 days at 37°C and pH 8. Moreover, the anticancer activity of S. variabilis H2 crude extract was tested against three different cell lines: Lung carcinoma cells, Hepatocellular carcinoma cells and breast carcinoma cells. The inhibition activities were 61.57 and 44.51% for lung and Hepatocellular cells, respectively. In addition, the S. variabilis H2 crude extract acted as antifungal and anti-biofouling agent, but it failed to act as antiviral agent. The primary components of the crude extract of S. variabilis H2 were identified using gas-liquid chromatography-mass spectrometry (GC-MS). The identified compounds included phthalic acid, di(2-propylpentyl) ester, octadecanoic acid methyl ester, and hexadecenoic acid methyl ester.

Keywords

Files

Share

How to cite

Statistics