Isolation and characterisation of Streptomyces sp. Strain GLD25 with antimicrobial and antioxidant effects from Gueldaman cave (GLD1), Akbou-Algeria

Abstract

Objectives: The present study aimed to isolate potential antimicrobial and antioxidant Streptomyces sp from cave areas of Algeria. Methods: Streptomyces sp.GLD25 was identified by biochemical, physiological and molecular analysis. The antimicrobial activity has been carried out by well diffusion method, microplates method has been used to perform the MIC values of the organic extracts. The antioxidant capacity of the extract was tested by DPPH and FRAP methods. GC–MS analysis was used to study the chemical profile of the crude active extract. Results: The novel strain Streptomyces sp. GLD25 was isolated from Gueldaman cave in Algeria showed potential antioxidant and antimicrobial properties. According to the results of morphological, biochemical characteristics and complete 16S rRNA sequence, the strain revealed 99.71% of similarity with Streptomyces cyaneofuscatus strain WKFF71. The significant inhibition zone of the crude extract and MIC value were 30 mm and 0,015 mg/mL respectively against Staphylococcus aureus and Bacillus subtilis. In addition, the extract showed good antioxidant activity with IC50 = 20,12 mg/mL ± 2,05 for DPPH and IC50 = 8,80 mg/mL ± 0,2 for ferric reducing activity. The fundamental metabolites of the active extract were identified using GC–MS were Diisooctyl-phthalate, 6-hydroxy-heptanoic acid, Hexadecanoic acid, Benzeneacetic acid and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid. Conclusion: Overall, the Streptomyces sp.GLD25 isolated from Gueldamen cave have the potential to produce antimicrobials and antioxidants compounds with important biotechnological and medical applications.

Keywords

• Streptomyces
• Cave
• Antimicrobial
• Antioxidant
• GC–MS