Diversity and Spatial Distribution Patterns of Antioxidant Functional Genes in Prokaryotic Microorganisms: A Case Study of the Lashan Mountain Watershed

[Background] Microbial antioxidant functions hold significant application potential in the development of health resources, yet their spatial distribution patterns across continuous ecological gradients remain poorly understood. [Objective] To elucidate the diversity and spatial distribution characteristics of antioxidant functional genes in prokaryotic microorganisms within the Lashan Mountain watershed. [Methods] A spatially exhaustive nine-grid sampling strategy was employed, establishing 117 sampling points across the watershed and its 12 sub-basins. Functional prediction was performed using PICRUSt2 based on 16S rRNA gene high-throughput sequencing data. [Results] A total of 38 genes associated with antioxidant synthesis were identified, categorised into 12 functional groups. Diversity and total abundance of antioxidant genes were unevenly distributed within the Lashashan watershed, with the downstream region exhibiting higher gene diversity and abundance. Genes associated with non-enzymatic antioxidants dominated both in functional category richness (7 categories, 0.005270–0.007657) and abundance, with glutathione (GSH) and thioredoxin (Trx) genes exhibiting the highest abundances. The overall abundance variation of individual genes (CV = 125.85) primarily originated within sub-basins (CV = 77.23). After classifying antioxidant genes by synthesised compounds, the pattern of variation reversed. [Conclusion] Prokaryotic antioxidant functional genes exhibit spatial distribution differences within the watershed, with the downstream region—characterised by multiple coupled stresses—emerging as a hotspot for antioxidant gene diversity and total abundance. This study provides an ecological basis for the targeted screening of high-quality antioxidant strains.