Owing to its capability to be biosynthetic and biodegradable, polylactic acid (PLA) is considered as the most promising biopolymer among all plastic materials, which will play a crucial role as a potentially environmentally friendly material for a sustainable bioeconomy. However, its long life cycle indicates that it cannot be easily degraded in nature. Therefore, understanding the biodegradation mechanism of PLA is important to reduce impacts of waste plastic, waste disposal and alleviate the energy crisis. With the recent development of molecular biological techniques, some studies have confirmed that specific groups of microorganisms may aid the biodegradation process of PLA. Here, recent advances in the biodegradation of PLA (i.e., microbial and enzymatic degradation) and key factors affecting the degradation efficiency were reviewed. In addition, compared to complete degradation through mineralization, upcycling is also proposed as a more recyclable strategy for disposing the waste plastics.

Living materials bring together material science and biology to allow the engineering and augmenting of living systems with novel functionalities. Bioprinting promises accurate control over the formation of such complex materials through programmable deposition of cells in soft materials, but current approaches had limited success in fine-tuning cell microenvironments while generating robust macroscopic morphologies. Here, we address this challenge through the use of core-shell microgel ink to decouple cell microenvironments from the structural shell for further processing. Cells are microfluidically immobilized in the viscous core that can promote the formation of both microbial populations and mammalian cellular spheroids, followed by interparticle annealing to give covalently stabilized functional scaffolds with controlled microporosity. The results show that the core-shell strategy mitigates cell leakage while affording a favorable environment for cell culture. Furthermore, we demonstrate that different microbial consortia can be printed into scaffolds for a range of applications. By compartmentalizing microbial consortia in separate microgels, the collective bioprocessing capability of the scaffold is significantly enhanced, shedding light on strategies to augment living materials with bioprocessing capabilities.

Infectious diseases caused by pathogenic microbes have posed a major health issue for the public, such as the ongoing COVID-19 global pandemic. In recent years, wastewater-based epidemiology (WBE) is emerging as an effective and unbiased method for monitoring public health. Despite its increasing importance, the advancement of WBE requires more competent and streamlined analytical platforms. Herein we discuss the interactions between WBE and droplet microfluidics, focusing on the analysis of pathogens in droplets, which is hard to be tackled by traditional analytical tools. We highlight research works from three aspects, namely, quantitation of pathogen biomarkers in droplets, single-cell analysis in droplets, and living cell biosensors in droplets, as well as providing future perspectives on the synergy between WBE and droplet microfluidics.

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Application of polyester‐degrading microorganisms or enzymes should be considered as an eco‐friendly alternative to chemical recycling due to the huge plastic waste disposal nowadays. However, current impranil DLN‐based screening of polyester‐degrading microorganisms is time‐consuming, labour‐intensive and unable to distinguish polyesterases from other protease‐ or amidase‐like enzymes. Herein, we present an approach that combined a novel synthetic fluorescent polyurethane analogue probe (FPAP), along with the droplet‐based microfluidics to screen polyurethane‐degrading microorganisms through fluorescence‐activated droplet sorting (FADS) pipeline. The fluorescent probe FPAP exhibited a fluorescence enhancement effect once hydrolysed by polyesterases, along with a strong specificity in discriminating polyesterases from other non‐active enzymes. Application of FPAP in a microfluidic droplet system demonstrated that this probe exhibited high sensitivity and efficiency in selecting positive droplets containing leaf‐branch compost cutinase (LCC) enzymes. This novel fluorogenic probe, FPAP, combined with the droplet microfluidic system has the potential to be used in the exploitation of novel PUR‐biocatalysts for biotechnological and environmental applications.

Living materials have emerged as systems bringing together material science and biology to allow the engineering and augmenting of living systems with novel functionalities. Bioprinting promises accurate control over the formation of such complex materials through programmable deposition of cells in soft materials, but current approaches had limited success on fine-tunning cell microenvironments while generating robust macroscopic morphologies. Here, we address this challenge through the use of microgel ink to bioprint functional living materials. Jammed core-shell microgels are microfluidically functionalized with cells in the aqueous cores which can promote the growth of both microbial communities and mammalian cellular spheroids, followed by an interparticle annealing to give covalently stabilized functional scaffolds with controlled microporosity that enhances the mass transfer of nutrients and metabolites. Different microbial consortia are immobilized in scaffolds towards versatile applications; more importantly, by compartmentalizing microbial consortia at microscale, the collective bioactivities of both consortia are significantly enhanced, shedding light on strategies to augment living materials with bioprocessing capabilities.

Rhamnolipids (RLs) are biosurfactants with great economic significance that have been used extensively in multiple industries. Pseudomonas aeruginosa is a promising microorganism for sustainable RL production. However, current CTAB-MB based screening of RL-producing strains is time-consuming, labor-intensive, and unable to distinguish monoand di-RL. In this study, we developed a novel transcription-associated fluorescence-activated droplet sorting (FADS) method to specifically target the di-RL hyperproducers. We first investigated critical factors associated with this method, including the specificity and sensitivity for discriminating di-RL overproducers from other communities. Validation of genotype−phenotype linkage between the GFP intensity, rhlC transcription, and di-RL production showed that rhlC transcription is closely correlated with di-RL production, and the GFP intensity is responsive to rhlC transcription, respectively. Using this platform, we screened out ten higher di-RL producing microorganisms, which produced 54−208% more di-RL than the model P. aeruginosa PAO1. In summary, the droplet-based microfluidic platform not only facilitates a more specific, reliable, and rapid screening of P. aeruginosa colonies with desired phenotypes, but also shows that intracellular transcription-associated GFP intensity can be used to measure the yield of di-RL between populations of droplets containing different environmental colonies. This method also can be integrated with transposon mutation libraries to target P. aeruginosa mutants.