Speaker
Description
Purple phototrophic bacteria (PPB) are photosynthetic microorganisms that use light energy and organic substrates as carbon and electron sources. Found in lagoons, sediments, and organic-rich wastewaters, they grow under anaerobic but illuminated conditions. Their metabolic versatility enables the conversion of various waste (lactose, volatile fatty acids, and carbohydrates) into valuable bioproducts like single-cell protein, biohydrogen, carotenoids, and polyhydroxyalkanoates, making PPB key agents for waste valorization and resource recovery in the circular bioeconomy. Valorizing purple non-sulfur bacteria biomass from wastewater treatment into microbial protein provides a sustainable approach to resource recovery while enhancing food security, particularly in regions with limited agricultural productivity. 1 Recent advances in the metabolic engineering of purple phototrophic bacteria have expanded their potential applications in producing biohydrogen, carotenoids, and single-cell protein, highlighting their role as sustainable biocatalysts for circular bioeconomy systems. 2 It is demonstrated that valorizing dairy whey through purple phototrophic bacteria cultivation can substantially improve process economics by reducing substrate costs, generating high-value single-cell protein, and achieving positive environmental and energy balances. 3 Overall, the reviewed studies demonstrate that PPB can transform organic waste streams into high-value bioproducts while reducing treatment costs and environmental impact. Continued optimization of large-scale bioreactor systems and market integration of PPB-derived products is essential to establish their commercial feasibility in food processing waste valorization.
Keywords: purple phototrophic bacteria, waste valorization, circular bioeconomy
References:
1. Wada, Ojima & Onwusogh, U. & Vincent, A.S. & Mckay, Gordon & Mackey, Hamish. (2023). Valorization of purple non-sulfur bacteria biomass from anaerobic treatment of fuel synthesis process wastewater to microbial protein: a means of enhancing food security in arid climates. Biomass Conversion and Biorefinery. 13. 1-15. 10.1007/s13399-023-04518-w.
2. Policastro, G., Cesaro, A., & Fabbricino, M. (2024). Valorization of Purple Phototrophic Bacteria Biomass Resulting from Photo Fermentation Aimed at Biohydrogen Production. Molecules, 29(7), 1679. https://doi.org/10.3390/molecules29071679
3. Ali Amini, Andrea Remelli, Valiallah Amirian Mojarad, Mayline El Achkar, Matteo Dell’Anno, Luciana Rossi, Giorgio Mirra, Alessia Di Giancamillo, Francesca Grassi Scalvini, Gabriella Tedeschi, Katia Parati, Andrea Turolla, From cheese whey to single-cell protein production: By-product valorization through acidogenic fermentation and purple phototrophic bacteria,Bioresource Technology, Volume 435,2025,132894,ISSN 0960-8524, https://doi.org/10.1016/j.biortech.2025.132894
