Microbial dyeing for inoculation and pigment used in wood processing: Opportunities and challenges

Natural pigments have been used as color additives in wood since ancient times. The safety, non-toxicity, non carcinogenicity, and biodegradability of natural pigments have satisfied the increasing pursue of environmental friendliness and health toward people. Thus, microbial pigments will be chosen for industrialization due to their wide distribution, wide variety, fast reproduction speed, and cultivation without time and space restrictions. Two approaches are suitable for applying microbial pigments to the wood dyeing industry. The inoculation is one of the simple and effective ways to dye wood by depositing the pigment secreted by microorganisms on the surface or inside of wood, but the screening and induction of microorganisms is the industrial basis for inoculation dyeing, and requires supporting industrial equipment to complete industrial replicability. Another way is to use the method of extracting pigments secreted by microorganisms for wood dyeing, which is relatively easy to industrialize, but technical issues that need to be addressed include mass production, clean extraction and resoluble solvent of pigments, and deep staining and stability of wood.