The invasive golden apple snail (Pomacea canaliculata) threatens rice agroecosystems, yet its direct density-dependent effects on flooded paddy soil biogeochemistry and bacterial communities remain unclear. We established flooded soil microcosms with four snail densities (0, 2, 4, and 6 snails/box) for 20 days, without external food inputs. Soil dissolved organic carbon (DOC), ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃⁻-N), and the activities of β-glucosidase, N-acetyl-β-D-glucosaminidase, urease, and dehydrogenase were measured, and bacterial communities were characterized by full-length 16S rRNA gene amplicon sequencing. Snail density was significantly and positively related to all three nutrient variables and all four enzyme activities. The dominant bacterial phyla and genera remained stable, and bacterial α-diversity changed little among treatments, despite a small but significant increase in Simpson diversity in the high-density treatment. PERMANOVA detected significant differences in overall bacterial community structure among density treatments, while environmental fitting identified DOC, urease, and dehydrogenase as variables significantly associated with community variation. These findings indicate that living golden apple snails can alter nutrient availability, soil biochemical activity, and bacterial community organization in flooded paddy soil, revealing a belowground pathway through which this invader may influence paddy ecosystem functioning.

Microorganism–semiconductor biohybrids integrate biological metabolism with inorganic light-harvesting materials to enable solar-driven chemical transformations; however, how incident light wavelength regulates extracellular metabolic states remains largely unexplored. Unlike previous hybrid systems that have generally employed fixed-wavelength illumination and bacteria without plant-growth-promoting properties, we investigated wavelength-dependent reprogramming of extracellular metabolism in a CdS biohybrid based on the plant-growth-promoting bacterium Priestia sp. ZJT-3. Sucrose supported the highest bacterial growth, while L-cysteine alleviated Cd²⁺ stress through H₂S-mediated CdS biomineralization, with maximal Cd removal at a cysteine/Cd²⁺ molar ratio of 2:1. Morphological analyses confirmed the formation of surface-associated CdS nanoparticles with an average size of 6.41 nm and a cubic crystal structure. Wavelength-dependent illumination markedly altered the extracellular metabolome, with the number of upregulated metabolites relative to the dark control decreasing in the order of 400, 450, and 520 nm. This pattern suggests that wavelength-dependent CdS excitation modulates photochemical interactions at the biohybrid interface and is associated with distinct bacterial metabolic responses. The 450 nm treatment produced a comparatively moderate metabolic response and was associated with increased levels of plant growth-promoting hormones, whereas 400 nm induced the strongest metabolic remodeling but also greater CdS photocorrosion and cellular morphological perturbation. These findings demonstrate that illumination wavelength can serve as a tunable parameter for regulating extracellular metabolism in bacteria–semiconductor biohybrids, highlighting the potential of such biohybrids for practical applications in areas such as light-controlled metabolite production and bioengineering.