Peroxidase-producing actinobacteria from Algerian environments and insights from the genome sequence of peroxidase-producing Streptomyces sp. S19.

Unique environments often serve as a source of novel microorganisms with novel chemistries. In this study, telluric samples collected from different regions of Algeria were processed for the isolation of novel peroxidase-producing actinobacterial strains. An agar-based screening identified 45 isolates with the ability to produce peroxidase. The 16S rRNA gene sequencing showed that most of the strains belong to the genus Streptomyces. Optimization of cultivation conditions was performed for the top five peroxidase-producing strains. Apart from strain 36 (optimal growth temperature of 30 °C) and strain 45 (optimal medium pH of 6.0), the strains exhibited optimal peroxidase production when cultivated for 5 days at 37 °C and in a medium at pH 7.0. Extracellular peroxidase production was induced by ferulic acid in three of the five strains, while the presence of canola lignocellulosic waste (CLW) induced peroxidase production in all strains. Strain 19 (S19) was selected for further optimization and the extracellular peroxidase purified using acid and acetone precipitation, followed by size exclusion chromatography. The purified fraction showed a single band on the polyacrylamide gel with an estimated molecular weight of 21.45 kDa. Genome analysis confirmed the assignment of S19 to the genus Streptomyces, the presence of genes encoding for peroxidases, and the presence of genes encoding for carbohydrate-active enzymes. The presence of biosynthetic gene clusters potentially encoding for biosurfactants further highlighted the great biotechnological potential of the strain.