A novel bacterial strain of acetic acid bacteria capable of producing riboflavin was isolated from the soil sample collected in Wuhan, China. The isolated strain was identified as Gluconobacter oxydans FBFS97 based on several phenotype characteristics, biochemicals tests, and 16S rRNA gene sequence conducted. Furthermore, the complete genome sequencing of the isolated strain has showed that it contains a complete operon for the biosynthesis of riboflavin. In order to obtain the maximum concentration of riboflavin production, Gluconobacter oxydans FBFS97 was optimized in shake flask cultures through response surface methodology employing Plackett-Burman design (PBD), and Central composite design (CCD). The results of the pre-experiments displayed that fructose and tryptone were found to be the most suitable sources of carbon and nitrogen for riboflavin production. Then, PBD was conducted for initial screening of eleven minerals (FeSO 4 , FeCl 3 , KH 2 po 4 , K 2 HPO 4 , MgSO 4 , ZnSO 4 , NaCl, CaCl 2 , KCl, ZnCl 2 , and AlCl 3 .6H 2 O) for their significances on riboflavin production by Gluconobacter oxydans strain FBFS97. The most significant variables affecting on riboflavin production are K 2 HPO 4 and cacl 2 , the interaction affects and levels of these variables were optimized by CCD. After optimization of the medium compositions for riboflavin production were determined as follows: fructose 25 g/L, tryptone 12.5 g/L, K 2 HPO 4 9 g/L, and CaCl 2 0.06 g/L with maximum riboflavin production 23.24 mg/L. Riboflavin or the so-called vitamin B2 is a water-soluble vitamin that belongs to the B vitamins complex group, a vital component of the energy metabolism, and a bioactive molecule that has an important role in various cellular functions 1,2. In addition, to its role as the precursor of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), the major products of riboflavin that act a fundamental role in metabolism, acting as cofactors for a wide variety of enzymes intermediating many redox reactions in the cell 3,4. In contrast, to many microorganisms and plants, humans and animals cannot synthesize this vitamin, and thus need to supply their diet with external riboflavin to meet their nutritional requirements 5. Riboflavin is used on a large scale as food and feed additives, food colorant, and pharmaceutical preparations. The commercial production of this vitamin can be accomplished by chemical synthesis or biological synthesis, yet in recent times the chemical synthesis has totally replaced to the microbial fermentation because of its cost-effectiveness, reduction in waste and energy requirements, and the use of renewable resources 6. At present, several species of bacteria and fungi are harnessed
The present study aimed to characterize melanin pigment extracted from Gluconobacter oxydans FBFS 97. After 14 days of culture at 28 °C in GY (glucose and yeast extract) liquid-state medium, G. oxydans FBFS97 produce the maximum melanin, up to about 12–15 mg/L. The physicochemical characteristics of the extracted melanin showed an ability to dissolve in 1 mol/L NaOH or 1 mol/L KOH, and insolubility in water and most organic solvents, such as chloroform and petroleum ether. The extracted melanin was confirmed to be exact melanin by ultraviolet-visible spectrophotometry, Fourier-transform infrared spectroscopy, thin-layer chromatography, elemental analysis, and scanning electron microscopy. The UV-visible spectrum of G. oxydans FBFS97 exhibited a maximum absorption peak at 230 nm. Extracted melanin demonstrated significant free radical-scavenging activity by DPPH and ABTS methods. The IC50 value of the extracted melanin for scavenging 50% DPPH radicals was 36.94 μg/mL, and the IC50 value of antioxidant activity for ABTS was 4.06 μg/mL. Hence, G. oxydans FBFS97 has the potential to be a new candidate for melanin production.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
334 Leonard St
Brooklyn, NY 11211
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.