Streptomyces zaomycetitus strain GH90: a source of violet pigment with metabolic profiling and potential application in textile: in vitro supported by in silico studies and molecular docking

Abstract

Dyes are used daily in the culinary, textile, paper, leather, and agricultural sectors. Synthetic colors pollute the environment and have harmful effects. Microorganism-produced pigments are more cost-effective and environmentally benign than animal, plant, and synthetic pigments. The present study focuses on isolating a pigment-producing actinomycete, a novel violet pigment produced by a local isolate strain identified as S. zaomycetitus GH90, using 16 S rRNA from Egyptian soil. Optimizing violet pigment yield necessitated the precise adjustment of various growth parameters. Streptomyces zaomyceticus GH90 achieved optimal production under specific conditions. pH 8.0, agitation at 180 rpm, temperature at 37 °C, 1.5% starch concentration, ammonium sulfate, dipotassium hydrogen phosphate, 2% inoculum, 20% medium volume, and a 10-day incubation period. Ethanol served as the solvent for pigment extraction. Thermal analysis indicated no degradation at 40 °C. At 50 °C, retention was 98.7% and remained stable at 97.5% when subjected to temperatures between 60 and 80 °C for 1 h. Retention remained above 91% at temperatures of 90 and 100 °C, indicating significant heat stability. The pigment preserved its color integrity in an aqueous solution at pH 8.0. The UV-Vis spectra exhibited a maximum wavelength (λmax) at 580 nm. LC-MS analysis revealed the presence of indole, scopoletin, myricetin, and phosphorylated compounds, which are likely contributors to color and bioactivity. The pigment exhibited superior textile dyeing characteristics, including vivid coloration, high durability, and significant antibacterial activity, establishing it as a versatile and effective dye for antimicrobial textiles. Moreover, the most prevalent molecule, has high permeability, moderate solubility, and selective enzyme interactions, making it a suitable therapeutic candidate. Molecular docking shows significant OMPA and OprD binding affinities, supported by hydrophobic, π-π stacking, and hydrogen bond interactions. The obtained results clearly show how important Streptomyces is as a source of bioactive metabolites with potential applications.

Keywords: Streptomyces sp.; And molecular docking; Fermentation conditions; Textile printing; Violet pigment.

Fig. 1

a Isolated colony morphology. b Violet Pigment produced by S. zaomycetitus GH90. c Phylogenetic tree of S. zaomycetitus GH90 based on 16 S rRNA gene sequences

Fig. 2

a Effect of different pH value, b Effect of incubation temperature, c Effect of (r.p.m) and d Effect of different starch concentration on the violet pigment production by S.zaomycetitus GH90. Rotation per minute (r.p.m)

Fig. 3

a Effect of organic nitrogen sources, b Effect of nitrogen sources, c Effect of different phosphorus sources, and d Effect of different seed inoculum size % (v/v) on the violet pigment production by S. zaomycetitus GH90

Fig. 4

a Effect of volume ratio % (v/v), b Effect of incubation period (day), and c Effect of different heavy metals on the violet pigment production by S. zaomycetitus GH90

Fig. 5

a Violet pigment extracted by ethanol solvent, b dried pigment after ethanol extraction, c heat treatment effect on violet pigment stability, d effect of pH on retention of brown pigment, e the UV absorption spectrum of extracted violet pigment

Fig. 6

TIC chromatogram for total violet pigment extract of S. zaomycetitus GH90 isolate

Fig. 7

Antibacterial activity of treated fabrics

Fig. 8

a Boiled egg chart b Bioavailability radar chart

Fig. 9

Molecular docking simulation between the most abundant compound and a E. coli OMPA and b P. aeruginosa OprD