Violacein is a pigment synthesized by microorganisms with multiple interesting biological activities (antibacterial, antioxidant, antiviral, ...). Current limitations in its use are mainly due to low yields and high production costs. Using agro-industrial co-products is then a sustainable and interesting strategy when it comes to the production of violacein.

It is in this context that the "Pigments" PhD thesis was financed by la Fondation du site Paris-Reims et la Fondation de France. This PhD is centred on microorganisms able to directly use agro-industrial co-products as carbon source and produce pigments. Part of this PhD was dedicated to the study of the bacteria Chromobacterium vaccinii, a natural producer of violacein which has previously been shown to grow on wheat bran. The use of the constituents of plant biomass for growth by C. vaccinii was investigated. This highlighted that the proteins of co-substrates (such as cakes, brans...) are the main carbon source for this species.

Furthermore, by varying the concentrations in co-products (wheat bran, rapeseed and soy cakes) and in the violacein precursor, tryptophan, it was shown that protein content has a great impact on that pigment production. Overall, all the results presented in this article offer a novel perspective on microbial degradation by agro-industrial co-products.

Article : Cassarini, M. et al. (2022). Protein-Rich Agro-Industrial Co-products are Key Substrates for Growth of Chromobacterium vaccinii and its Violacein Bioproduction. Waste Biomass Valor. https://doi.org/10.1007/s12649-022-01798-7

Contacts : Caroline Rémond, caroline.remond@univ-reims.fr ; Ludovic Besaury, ludovic.besaury@univ-reims.fr ; Mathieu Cassarini mathieu.cassarini@univ-reims.fr