The planting years of vineyards alters the carbon fixation pathways by soil autotrophic microorganism

Despite previous reports that autotrophic microorganisms have capable of absorbing atmospheric CO₂ and increasing soil organic carbon content, their specific pathways involved in carbon fixation have remained elusive. This study aimed to evaluate the differences of eight known carbon fixation pathways involving soil autotrophic microorganisms in vineyard soils with different planting years, and reveal the effects of soil physicochemical properties on the composition of carbon fixation microorganisms. Thus, we performed metagenomic sequencing on one uncultivated soil and four vineyard soils of different planting years. The results showed that autotrophic microorganisms harboring genes of eight konwn pathways related to carbon fixation were identified at each sampling site. The predominant phyla of autotrophic microorganisms were Actinomycetota, Pseudomonadota, and Acidobacteriota, respectively. The rTCA cycle was the most prominent carbon fixation pathway in this study. The relative abundance of genes related to rTCA cycle were increased by 11 %, 7 %, 4 %, and 8 % in the 5-year-old (C5), the 10-year-old (C10), the 15-year-old (C15), and the 20-year-old (C20) vineyard soils, respectively, compared to that in soil of uncultivated land (UL). The abundance of enzyme encoding genes involved in carbon fixation pathways varied significantly among soil samples, and the variation trend was consistent with the abundances of genes related to carbon fixation pathway, indicating their significant involvement in regulating carbon fixation. Moreover, environmental factors significantly impacted to the composition of autotrophic microbial, in particular, pH was primarily factor impacted on the composition of autotrophic microbial involved in carbon fixation. This study clarified the effects of vineyard planting years on the composition of soil autotrophic microbial and their carbon fixation pathway, which provides basic data for understanding the function of soil autotrophic microbial in orchards.