Degradation and bioconversion of complex municipal solid waste streams into human biotherapeutics and biopolymers

Abstract

The use of biomass and organic waste as a feedstock for the production of fuels, chemicals and materials offers great potential to support the transition to net-zero and circular economic models. However, such renewable feedstocks are often complex, highly heterogeneous, and subject to geographical and seasonal variability, creating supply-chain inconsistency that impedes adoption. Towards addressing these challenges, the development of engineered microorganisms equipped with the ability to flexibly utilise complex, heterogenous substrate compositions for growth and bio-production would be greatly enabling. Here we show through careful strain selection and metabolic engineering, that Pseudomonas putida can be employed to permit efficient co-utilisation of highly heterogeneous substrate compositions derived from hydrolysed mixed municipal-like waste fractions, with remarkable resilience to compositional variability. To further illustrate this, one pot enzymatic pre-treatments of the five most abundant, hydrolytically labile, mixed waste feedstocks was performed - including food, plastic, organic, paper and cardboard, and textiles - for growth and synthesis of exemplar bio-products by engineered P. putida. Finally, prospective life cycle assessment and life cycle costing illustrated the climate change and economic advantage, respectively, of using the waste-derived feedstock for biomanufacturing compared to conventional waste treatment options. This work demonstrates the potential for expanding the treatment strategies for mixed municipal waste to include engineered microbial bio-production platforms that can accommodate variability in feedstock inputs to synthesise a range of chemical and material outputs.