Stormwater and greywater are increasingly recognized as freshwater resources, and the effective separation and reutilization of nitrogen (N) and phosphorus (P) from these streams is vital for water quality improvement and urbanization sustainability. In this study, we constructed a pilot-scale hydroponic green roof wetland system planted with two economically important Chinese herbal plant species (Mentha spicata L. (ML) and Basella alba L. (BL)) to separate and reutilize N and P from synthetic stormwater/greywater. The results reveal that the highest plant biomass was obtained at an ML:BL ratio of 1:3, indicating their superior adaptation to rooftop hydroponics with synthetic stormwater/greywater. This configuration also achieved the strongest water purification, with substantial separation and reutilization efficiency of N (82.09%) and P (81.90%). Furthermore, the lowest microbial richness in the ML roots at this specific plant ratio suggested that increasing BL may enhance ML’s allelopathic effects. An increase in the BL proportion was further associated with a gradual shift in the dominant ML root-associated microorganisms toward microeukaryotic taxa. The green vegetation of the two plant species also effectively suppressed algal blooms (especially diatoms) in the hydroponic rooftop system. This study demonstrates that a Chinese herb-based green roof wetland system can effectively separate and reuse N and P from stormwater/greywater while concurrently purifying water and producing economic crops.

As a pivotal chiral precursor for the synthesis of the antituberculosis drug ethambutol and antiepileptic drugs such as levetiracetam, Chiral (S)-2-aminobutanol requires high optical purity for clinical safety. This review systematically summarizes the evolution and recent advances in its synthetic routes. Traditional chemical methods, including the 1-nitropropane and 1-butene epoxidation routes, suffer from severe safety hazards and heavily rely on downstream chiral resolution. However, both chemical crystallization and enzymatic kinetic resolution are constrained by a 50% theoretical yield ceiling and incur heavy environmental burdens. To break this bottleneck, in vitro multienzyme cascades utilizing amine dehydrogenases (AmDHs) and ω-transaminases (ω-TAs) have emerged, achieving 100% theoretical yield from prochiral precursors and >99% enantiomeric excess (ee) driven by a distinct dual-pocket active site model. Furthermore, synthetic biology has enabled de novo biosynthesis via whole-cell cell factories. It should be noted that the recently reported 45.3 g·L⁻¹ titer refers to the upstream amino acid precursor L-2-aminobutyric acid (L-2-ABA), not to the final (S)-2-aminobutanol product. To overcome bottlenecks like the intracellular toxicity of the intermediate 2-ketobutyrate (2-OBA), strategies including efflux pump engineering (e.g., rhtA) and quorum sensing-based dynamic regulation have successfully boosted the fermentation titer to 45.3 g·L⁻¹. Finally, the industrialization potential of these generations of technologies is evaluated, highlighting that the transition toward in vitro continuous-flow microreactors and a hybrid whole-cell + cell-free architecture, combined with the integration of AI into whole-cell factories, represents a future trend for green and low-carbon manufacturing.