Effects of Microbial Fertilizers on the Properties of Simulated Lunar Soil and Lettuce Growth

The lunar surface soil (regolith) represents a potential substrate for crop cultivation in future extraterrestrial bases. However, the absence of indigenous microbial activity severely limits nutrient availability in lunar soil. In this study, the effects of three commercial microbial fertilizers on improving simulated lunar soil and promoting lettuce (Lactuca sativa L.) growth were experimentally evaluated. The results showed that microbial fertilizers significantly increased the contents of available nutrients (N, P, and K) and organic matter in simulated lunar soil, thereby enhancing lettuce growth and biomass accumulation. Compared with the treatment without adding microbial fertilizer application (CK), the aboveground and belowground fresh weights of lettuce increased by up to 91.61% and 89.08%, respectively, under the microbial fertilizer MLQ treatment. In addition, microbial fertilizer treatment increased nutrient accumulation and photosynthetic pigment contents in lettuce, alleviated oxidative stress by improving antioxidant system performance, and consequently enhanced lettuce quality. High-throughput sequencing analysis further revealed that the dominant bacterial genera under these conditions were Bacillus, Glutamicibacter, Acetobacter, Enterococcus, and Microbacterium, while the dominant fungal genera included Saccharomyces, Pichia, and Trigonopsis. These findings provide theoretical support for the development of functional microbial fertilizers tailored for simulating lunar soil.