Optimization of pyoverdine pigment biosynthesis conditions from a locally isolated strain of Pseudomonas aeruginosa

Abstract

Color is the most prominent factor in any marketable product. Among microorganisms, Pseudomonas spp. produces four different types of pigments. The aim of this study is biosynthesis and optimization of pyoverdine from locally isolated Pseudomonas aeruginosa. Response surface methodology (RSM) was used to optimize two growth parameters, i.e., temperature (30–40 ℃) and pH (5–8). RSM predicted maximum yield of pyoverdine at pH 7 and temperature 37℃. Optimal growth media and incubation time required for pigment production was analyzed by spectroscopy. For this, three culture media (nutrient broth, King’s B, and synthetic citrate media) were inoculated with P. aeruginosa and incubated at 37℃ for 24–120 h. Maximum optical density 1.94 (in nutrient broth) at 420 nm indicated maximum production of pyoverdine, and time recorded for maximum production was 120 h. Growth of P. aeruginosa on nutrient broth, pH 7, incubation time 120 h at 37℃ yielded 2.5 g/L pyoverdine; that was extracted using chloroform. Spectroscopic analysis revealed presence of a chromophore that emits maximum light at 400 nm and thin-layer chromatography performed using n-butanol, acetic acid, and water 3:2:1 as solvent system indicated exhibition of florescent under UV lamp of 354 nm. Amine stretch (3232.46 cm⁻¹), carboxyl group (1628 cm⁻¹), and amide group (1402 cm⁻¹) were indicated by FT-IR, and peaks obtained from NMR spectra at 7.888 ppm, 7.1 ppm, and 7.26 ppm represent 1.6 proton of aromatic chain H-4, H-5, and H-8 chromophore 3a that has been derived from 2,3-diamino-hydroxyquinoline. All of these findings demonstrate that Pseudomonas aeruginosa has the capacity to manufacture pyoverdine under the aforementioned ideal cultivation circumstances.