Abstract
ABSTRACT: The genus Streptomyces is associated with the ability to produce and excrete a variety of bioactive compounds, such as antibiotic, antifungal and antiviral. Biological active polyketide and peptide compounds with applications in medicine, agriculture and biochemical research are synthesized by PKS-I and NRPS genes. The evaluation of the presence of these genes associated with the biosynthesis of secondary metabolites in different phytopathogenic Streptomyces strains were performed using degenerated primers. The positive signal was observed in 58/63 Streptomyces strains for NRPS gene, 43/63 for PKS-I, and for PKS-II all the 63 strains showed positive signal of amplification. These strains also were tested with double layer agar-well technique against bacterial with clinical importance, and it was possible to observe the Streptomyces spp. strains were able to inhibit the growth of 14, 20, 13 and 3 isolates Gram-positive and Gram-negative bacteria, Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 14579), Pseudomonas aeruginosa (ATCC 27853) and Escherichia coli (ATCC 11775) respectively. The Streptomyces sp. strains IBSBF 2019 and IBSBF 2397 showed antibacterial activity against all four bacteria-target tested.
Highlights
MATERIAL AND METHODSBacteria belonging to the Streptomyces genus comprise about 854 species within the actinomycete group (PARTE, 2018)
This study aimed to evaluate the presence of polyketide synthases (PKS) and non-ribosomal peptide synthetase (NRPS) genes in different phytopathogenic Streptomyces strains and verify their antimicrobial activity against bacteria associated to hospital infections and clinical diseases, such as Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa and E. coli
In the antimicrobial activity assays, 14 Streptomyces strains were able to inhibit the growth of Staphylococcus aureus (ATCC 25923), 20 against Bacillus cereus (ATCC 14579), 13 for Pseudomonas aeruginosa (ATCC 27853) and 3 for E. coli (ATCC 11775)
Summary
Bacteria belonging to the Streptomyces genus comprise about 854 species within the actinomycete group (PARTE, 2018) They are gram-positive, have a filamentous structure, spores and plasmids with sizes ranging from 8 to 10 Mb, and most of them may have 20 gene cluster associated with the biosynthesis of secondary metabolites (LIN et al, 1993). It’s possible to name: streptomycin (SELMAN; SCHATZ, 1994), cephalosporin (WILLIAMS, 1987), terramycin (FINLAY et al, 1950), and vancomycin (HIGGINS et al, 1958) These substances have been extensively investigated from their biosynthetic pathways by amplifying genes like polyketide synthases (PKS) and non-ribosomal peptide synthetase (NRPS). These studies allowed a preliminary classification of Streptomyces strains based on their abilities to produce natural compounds belonging to aromatic group of polyketide, through the employment of primers targeted to this genus (METSÄ-KETELÄ et al, 1999)
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