Soil microbial carbon metabolism reveals a disease suppression pattern in continuous ginger mono-cropping fields

Microbial competition for carbon sources is associated with disease suppression, and continuous mono-cropping stimulates certain patterns of carbon deposits. In this study, we investigated five fields from three ginger mono-cropping durations (over 35 years, approximately 15 years and 3 years) and two disease conditions (wilt-suppressive and wilt-conducive) at two collection time points (fallow and harvest). We measured the bacterial community and overall microbial carbon metabolism ability using high-throughput sequencing and Biolog EcoPlates. The results showed that the metabolic capabilities of soil microbes at harvest time were higher than at fallow time. The distribution of the bacterial community and the soil microbial metabolic diversity were significantly affected by both factors of cropping years and disease conditions at harvest time. Moreover, potentially beneficial microbes more enriched in wilt-suppressive soils than in wilt-conducive soils and l-arginine and 4-hydroxybenzoic acid were significantly metabolized in suppressive samples. We further confirmed that l-arginine and 4-hydroxybenzoic acid were only slightly metabolized by the pathogen. Taken together, these results suggest that the addition of l-arginine could enrich the beneficial microbes, while metabolism of 4-hydroxybenzoic acid could indicate the disease conditions of soil.