Fig. 1
Heatmap presenting antibacterial activity against at least one tested pathogenic bacteria of endophytic actinobacteria isolated from Aegiceras corniculatum.
BC – Bacillus cereus ATCC® 11778™, PA – Pseudomonas aeruginosa ATCC® 9027™, MRSE – methicillin-resistant Staphylococcus epidermidis ATCC® 35984™, EA – Enterobacter aerogenes ATCC® 13048™, EC – Escherichia coli ATCC® 11105™, ST – Salmonella typhimurium ATCC® 14028™.
Fig. 2
Identification of endophytic strain SX6.
A) Scanning electron microscopy of hyphae of strain SX6 grown on ISP2 medium; B) phylogenetic tree based on 16S rRNA gene sequences of strain SX6 and closely related Streptomyces strains.
Fig. 3
Biological activities determined in the Streptomyces parvulus SX6 extract.
A) Selective antibacterial activity against MRSE ATCC® 35984™ and Pseudomonas aeruginosa ATCC® 9027™; B) cytotoxic activity against A549, Hep3B, MCF-7, and HEK-293 cell lines; C) and D) antioxidant activities, including DPPH free radical scavenging and hydroxyl radical scavenging were determined in the SX6 extract. Mean values and SD of three independent experiments are shown and p-values were calculated by the Student’s unpaired two-tailed t-test by the graph prism software (nsp > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001).
Table I
Features of the SX6 and other Streptomyces parvulus genomes.
| Species | Size (Mb) | GC (%) | Genes | CDSs | tRNAs | rRNAs |
|---|---|---|---|---|---|---|
| S. parvulus SX6 | 7.69 | 72.8 | 6,952 | 6,779 | 68 | 11 |
| S. parvulus JCM 4068 | 7.69 | 71.5 | 6,881 | 6,866 | 66 | 3 |
| S. parvulus 2297 | 7.15 | 72.7 | 6,951 | 6,773 | 66 | 18 |
| S. parvulus LP03 | 7.74 | 72.5 | 7,030 | 6,832 | 66 | 3 |
Fig. 4
Genome characterization of Streptomyces parvulus SX6.
A) Clusters of Orthologous Groups (COGs) of protein functions; B) whole genome-based phylogenetic classification of S. parvulus SX6. The numbers on the branches are GBDP pseudo-bootstrap support values of > 60% from 100 replications, with average branch support of 96.6%.
Fig. 5
Cryptic secondary metabolite biosynthetic gene clusters identified in the genome of Streptomyces parvulus SX6.
Fig. 6
Biosynthetic pathway of daidzein and genistein in Streptomyces parvulus SX6.
A) Using genome mining, the proposed biosynthetic pathways of daidzein and genistein present in S. parvulus SX6; B) identification of genes involved in daidzein and genistein biosynthesis across S. parvulus genomes; C) HPLC-DAD-MS chromatogram of reference compounds and the extract of mangrove endophytic S. parvulus SX6.