Molecular Identification of Selected Streptomyces Strains Isolated from Mexican Tropical Soils and their Anti-Candida Activity

Abstract

The increasing incidence of Candida albicans infections and resistance to current antifungal therapies has led to the search for new and more effective antifungal compounds. Actinobacterial species from the Streptomyces genus are recognized as some of the major producers of antimicrobial compounds. Therefore, the aims of this study were: (1) the identification of Streptomyces strains isolated from Mexican tropical acidic soils, (2) the evaluation of their antifungal activity on C. albicans, and (3) the exploration of the presence of polyketide synthase genes in their genome and antifungal secondary metabolites in their extracts. Four actinobacterial strains, isolated from previously unexplored soils with antibacterial antecedents, were selected. These strains were identified as Streptomyces angustmyceticus S6A-03, Streptomyces manipurensis S3A-05 and S3A-09, and Streptomyces parvisporogenes S2A-04, according to their molecular analyses. The ethanol extract of the lyophilized supernatant of S. parvisporogenes displayed the most interesting antifungal activity against C. albicans, with a minimum inhibitory concentration (MIC) of 0.5 mg/mL. Type I polyketide synthase (PKS-I) and non-ribosomal peptide synthase (NRPS) genes were detected in all strains. In addition, type II PKS genes (PKS-II) were also found in S. manipurensis S3A-05 and S. parvisporogenes. LC-UV-HRMS analysis of the active organic extract of S. parvisporogenes indicated the presence of the known antifungal compound carbazomycin G as the major component.

Multiple strain analysis of Streptomyces species from Philippine marine sediments reveals intraspecies heterogeneity in antibiotic activities

“…Members of the genus Streptomyces remain as the powerhouse of structurally diverse antibiotics 4 – 7 . In the tropics, most antibiotic-producing actinomycete studies were focus on terrestrial soil 44 , 45 , mangrove communities 46 and marine sediments 23 , 24 . The Philippine archipelago lies within the Coral Triangle or the world's center for marine biodiversity and is considered as a biogeographic realm of tropical oceanogeographic features that provide different marine ecosystems for diverse marine macrofauna and microbial community 47 .…”

Differential Synthesis of Secondary Metabolites by Streptomyces chrestomyceticus Strain ADP4 in Response to Modulation in Nitrogen Source and Its Anti-Candida Activity

“…Furthermore, the activity of SDB with CDH-peptone was found to be higher as compared to the recently reported Streptomyces spp. [7,8].…”

“…It has a high content of tryptophan along with the presence of other amino acids that supports the growth of the microorganisms including Streptomyces chrestomyceticus [6]. However, the composition of peptone depends on the source and condition of extraction that may vary from manufacture to manufacture and even in among lots of the same manufacturer [7].…”

Revealing Genome-Based Biosynthetic Potential of Streptomyces sp. BR123 Isolated from Sunflower Rhizosphere with Broad Spectrum Antimicrobial Activity

“…The PKS-I, PKS-II, and NRPS genes were amplified using the following primer sets, K1F (5′-TSAAGTCSAACATCCGBCA-3′)/M6R (5′-CGCAGGTTSCSGTACCAG TA-3′) [ 20 ], KSα (5′-TSGCSTGCTTGGAYGCSATC-3′)/KSβ (5′-TGGAANCCGCCGAABCCGCT-3′), and A3F (5′-GCSTACSYSATSTACACSTCSGG-3′)/A7R (5′-SASGTCVCCSGTSGCGTA S-3′). The reaction for NRPS and PKS genes was made with the final volume of 50 µL containing 1.5 µL of extracted genomic DNA, 1 µL of each primer (10 pmol), 21.5 µL of nuclease-free water, and 25 µL of dream taq (PCR master mix).…”