ABSTRACT
To obtain a kind of microbial pigment with high yield and variety coloration by regulating the pigment synthesis pathway in this experiment, Lasiodiplodia theobromae was used to induce pigment secretion by prolific inducing factors (tyrosinase, Cu2+, stilbene glycoside) and pleochromatic inducing factors (L-tyrosine, L-cysteine, tricyclazole). The results showed that through single factor and compound culture, the most reasonable inducing formula was 150 ku/L tyrosinase, while tricyclazole at 10 mg/L for 30 days had a maximum color difference of 42.92 NBS with a reddish-brown color in 10 days. The melanin content increased gradually with the extension of culture time, and the pleochromatic inducing group was up to 3.47 mg/mL, higher than that of the prolific inducing group. However, the poor solubility of purified melanin with a diameter of 100-200 nm was observed in conventional solvents. Through effective induction, it is expected that L. theobromae can secrete melanin stably and be widely used in printing, dyeing, electronics, and the chemical industry.
Subject(s)
Melanins , Monophenol Monooxygenase , ThiazolesABSTRACT
The technology of dyeing wood by microorganisms is a kind of pollution-free and sustainable wood dyeing technology. To achieve fast and rich dyeing of Lasiodiplodia theobromae on the surface of poplar wood, tyrosinase and tricyclazole were used as induction factors in this experiment. The results showed that L. theobromae had a better induction effect in the cross-section of poplar wood and induced with tricyclazole. The surface color of poplar ranged from light yellow dyeing to gray and brown, the chromatic aberration of the cross-section of wood was above 44.5 NBS, and the infected area was over 50%, while the dyed parts of radial and tangential sections of wood were only on the surface of the wood after 30 days of infection. The induced infection of L. theobromae on poplar wood had little effect on the chemical components of poplar and had good colorfastness to washing and light. Therefore, microbial dyeing of wood showed a beneficial application prospect in the field of wood dyeing.
ABSTRACT
Dyeing methods that conform to environmental protection requirements and adapt to the development of industry are investigated using bleached poplar wood dyed with melanin secreted by Lasiodiplodia theobromae in this paper. Prolonging the dyeing time of coarse melanin can improve the dye uptake of veneers, and the brightness value increases, and the reflectivity declines with the increase of dyeing time. The stained surface of the vessel is gradually covered by coarse melanin dye, and more melanin particles can be clearly observed accumulating together on the stained surface with agar. Infrared measurements show that the absorption peak of -C=O in carboxylic acid disappears at 1740 cm-1, which can be attributed to the fact that -C=O (1776 cm-1) in an anhydride or ketone group is formed by further oxidation and condensation of agar and NaOH. The veneer dyed for 6 h showed a well light and water resistance. Additionally, dyeing can improve the wettability of water, phenolic resin, and urea formaldehyde resin on the surface of veneer. These results support the use of pigment secreted by stain fungi for wood and provide data for evaluating their use as sustainable materials for other applications.
