Purification, Characterization And Properties Of A Natural Pigment From Fusarium Sp. B158

Natural pigments are certain sort of bioactive compounds that possess of natural colors; they are widespread, basically safe and harmless to human beings and eco-friendly, some of which may also have high nutritional values and certain biological activities. Fermenting natural pigments by microorganisms can solve the problems of raw materials shortage and high production cost caused by extracting natural pigments from plants and animals, which limit the large-scale usage and sustainable development of natural pigments. This paper originated from a natural pigment producing fungus Fusarium sp. B158. Subsequently, the submerged fermentation conditions and medium of Fusarium sp. B158 for producing natural pigment and the extraction and purification methods of the natural pigment were investigated; its properties, structure and potential industrial applications were also analyzed.Through mono-factor design experiments of carbon sources, nitrogen sources and inorganic salts, the basic submerged fermentation condition and medium of Fusarium sp. B158 for producing natural pigment were identified as follows: temperature: 26℃; rotary speed: 200 r/min; liquid volume: 50 ml of 250 ml Erlenmeyer flask; inoculums concentration: 3% (v/v);seed culture time: 36 h; initial pH: nature; fermentation period: 72 h, medium (g/L): potato 200, glucose 30, yeast extract 3, KH₂PO₄ 1.The paper studied the extraction and purification methods of the natural pigment and a feasible and effective method was proposed: the natural pigment was extracted by acidic ethanol (pH 2), deposited by 1 mol/L NaOH solution and purified by reversed-phase HPLC(GalaksilUP-C18 column, H₂O/CH₃OH=30/70). After the process of separation and purification, the purity of the purified pigment was more than 97%.The results of physical and chemical color reaction analysis using 1% FeCl₃ and Pb(CH₃COO)₂ solutions showed that the pigment possessed phenolic-OH group(s), and possibly could be a kind of hydroxyl-anthraquinone compounds. The MS spectra suggested that the molecular weight of the pigment was 500.3, combined with the elemental analysis result; the possible molecular formula of the pigment could be concluded as C₂₇H₃₂O₉, and to the best of our knowledge, it was reported for the first time. The UV spectrum told the existence of benzene ring(s) in the pigment structure; C=C, C=O, -N=N-, -NO₂, -C=S and other chromophores with lone electron pairs might also existed.It was found that the pigment was soluble well in acidic ethanol and methanol. The color value ( ) of the pigment was 56.27. The pigment was stable under acidic conditions and showed a good stability to heat and light, but was sensitive to sunlight, oxidants, reducers and metal ions of Fe³⁺ and Cu²⁺. Some common food additives and preservatives showed color protection and enhancement effects on the pigment. The application studies suggested that the pigment was a kind of potential antioxidants and preservatives with relatively strong antioxidant and good antimicrobial activities.