Probiotics, living microorganisms with demonstrated health benefits when administered in sufficient quantities, have a rich history as dietary supplements to benefit human health. Recently, understanding of their mechanisms in the gastrointestinal tract has prompted exploration of probiotics in treating human diseases. However, the effective and precise delivery of probiotics remains a significant challenge in therapeutic applications. Here, we review the mechanisms of action of probiotics in human health and the most advanced strategies for efficient probiotic delivery. We also discuss the potential applications of engineered probiotics in disease treatment. This review contributes insights into the evolving landscape of probiotic research for therapeutic applications.

Plastics are indispensable to modern life, but their widespread use has created an environmental crisis due to inefficient waste management. Mixed plastic waste, comprising diverse polymers, presents significant recycling challenges due to the high costs of sorting and processing, leading to ecosystem accumulation and harmful by-product generation. This study addresses this issue by engineering a synthetic bacterial consortium (SBC) designed to degrade mixed plastic monomers. The consortium pairs Escherichia coli Nissle 1917, which uses ethylene glycol (EG), a monomer derived from polyethylene terephthalate (PET), as a carbon source, with Pseudomonas putida KT2440, which metabolizes hexamethylenediamine (HD), a monomer from nylon-6,6, as a nitrogen source. Adaptive evolution of the SBC revealed a novel metabolic interaction where P. putida developed the ability to degrade both EG and HD, while E. coli played a critical role in degrading glycolate, mitigating its by-product toxicity. The evolved cross-feeding pattern enhanced biomass production, metabolic efficiency, and community stability compared to monocultures. The consortium’s performance was validated through flux balance analysis (FBA), high-performance liquid chromatography (HPLC), and growth assays. These findings highlight the potential of cross-feeding SBCs in addressing complex plastic waste, offering a promising avenue for sustainable bioremediation and advancing future polymer degradation strategies.

Probiotics, living microorganisms with demonstrated health benefits when administered in sufficient quantities, have a rich history as dietary supplements to benefit human health. Recently, understanding of their mechanisms in the gastrointestinal tract has prompted exploration of probiotics in treating human diseases. However, the effective and precise delivery of probiotics remains a significant challenge in therapeutic applications. Here, we review the mechanisms of action of probiotics in human health and the most advanced strategies for efficient probiotic delivery. We also discuss the potential applications of engineered probiotics in disease treatment. This review contributes insights into the evolving landscape of probiotic research for therapeutic applications.

Biotechnology offers unique opportunities for mitigating and upcycling plastic waste with low-intensity bioprocesses. Synthetic biology can further enhance bioprocesses for sustainably dealing with plastic waste and supporting a circular plastics economy. We provide an overview of current strategies for leveraging synthetic biology and microbial community engineering to degrade and upcycle plastic waste, with application to both industrial and environmental settings. We further discuss complementary strategies for pre-treating plastic materials and altering recalcitrant vinyl polymers to enhance bioprocessing efficiency. Additionally, we provide commentary on future research directions that would propel biotechnological solutions toward application in a circular plastics economy.