Characterization of Actinobacterial Communities from Arauca River Sediments (Colombia) Reveals Antimicrobial Potential Presented in Low Abundant Isolates

Abstract

Introduction:New strategies have been arisen to set a rapid and effective screening for selection of microorganism with bioactive potential. This study suggests that combination of physicochemical pretreatments and taxonomic dereplication of microbial collections through MALDI-TOF MS, facilitates the detection of low abundance actinobacteria with potential as a source of antimicrobial agents.Material and Methods:An unstudied microbial community from a tropical river sediment in Colombian Orinoquía is described, applying an extended cultivation strategy using physicochemical pretreatments, biological screenings and taxonomic dereplication through MALDI-TOF MS approach.Results:Actinobacteria-like isolates (790) were growth and their antimicrobial activity was assessed against methicillin-resistant Staphylococcus aureus, Vancomycin-resistant Enterococcus faecium, extended-spectrum β-lactamase Klebsiella pnumoniae, and clinical isolates of Cladosporium cladosporioides and Epicoccum nigrum. Seventy-eight isolates, belonging to the Streptomycetaceae family according to 16S rDNA analysis were found to have antimicrobial activity and were categorized as low abundance actinobacteria by MALDI-TOF MS.Conclusion:The results suggest that combination of physicochemical pretreatments and taxonomic dereplication of microbial collections through MALDI-TOF MS, facilitates the detection of low abundance actinobacteria with potential as a source of antimicrobial agents.

Production and Characterization of L-Asparaginases of Streptomyces Isolated from the Arauca Riverbank (Colombia)

“…They present pigmentation depending on the medium in which they are inoculated, which has been seen in other studies [43]. Each strain of Streptomyces presented above was identified by sequencing the 16S gene in a parallel study [38] and as previously reported, all strains showed an identity greater than 98.7% [44]. The strain 5 was identified as Streptomyces lunalinharesii, the strain 67 as Streptomyces puniciscabiei, the strain 112 as Streptomyces lacticiproducens, the strain 126 as Streptomyces phaeogriseichromatogenes, the strain 220 as Streptomyces phaeoluteigriseus, the strain 276 as Streptomyces griseofuscus and the strain 326 as Streptomyces mashuensis (Table S3).…”

“…Due to that, an analysis to determine an L-asparaginase production was performed on all these strains. According to other studies, high production of secondary metabolites could lead to better production of enzymes [38]. Therefore, from these results, 25 strains were highlighted due to high L-asparaginase/Lglutaminase activity presenting the production of the ammonium cation by the enzymatic action, which was determined by the color changing of phenol red indicator in the medium.…”

“…Previously in the work of Arango et al [38], seventy-eight isolates of the Arauca river banks in Colombia, belonging to the Streptomycetaceae were found to have antimicrobial activity. The isolation of the strains was made by pretreatments of the collected sediment river samples with calcium carbonate, phenol, thermal or heat, microwave and sonication.…”

“…The fractions were collected and examined for enzyme activity and protein content by procedures described earlier [28]. Fractions that showed a high activity of L-asparaginase were stored for later use [25,38]. SDS-PAGE electrophoresis was performed according to the Laemmli method [38], with a 12% separation acrylamide gel and 4% stacking gel.…”

“…Fractions that showed a high activity of L-asparaginase were stored for later use [25,38]. SDS-PAGE electrophoresis was performed according to the Laemmli method [38], with a 12% separation acrylamide gel and 4% stacking gel. The gel was stained with Coomassie brilliant blue R-250.…”