Community diversity and co-occurrence patterns of keratinophilic microorganisms in hospital garden soils

The hospital area is an important component of the urban ecosystem and a densely populated place. Hospital garden soil may act as a potential pool of keratinophilic taxa, which are the common skin disease-causing microorganisms in humans. However, the community diversity, co-occurrence properties and keratinophilic groups of soil microorganisms in hospital gardens remain poorly understood. Here, Illumina MiSeq high-throughput sequencing after the addition of a keratin-rich substrate (i.e., chicken feathers) to hospital garden soils was used to assess keratinophilic taxa in hospital (i.e., people’s hospital, traditional Chinese medicine hospital, and orthopedic hospital) garden soils from southern China (i.e., Jiangsu Province, Guizhou Province, and Hainan Province). Feather addition significantly decreased the soil microbial diversity, but increased the relative abundance of the dominant phyla. Keratinophilic microorganism such as Paenibacillus, Paenisporosarcina, Sporosarcina, Lysobacter, and Cellulosimicrobium, increased through feather enrichment. The relative abundances of Bacillus and Streptomyces (keratinophilic bacteria) and Chrysosporium (keratinophilic fungi) increased by 51–98 % in feather enrichment compared to control soils. However, Arthrobacter (keratinophilic bacteria) and Trichoderma (keratinophilic fungi) decreased by 76 % and 90 %, respectively. Co-occurrence network analysis revealed that the number of nodes, edges, average degree, and clustering coefficients of bacterial and fungal were decreased after feather enrichment treatment. The feather enrichment significant decreased the pH and C:N rates, but increased the carbon, nitrogen, and phosphorus contents of the hospital garden soil. Linear mixed model and correspondence analyses showed that pH, total nitrogen and soil organic carbon were the main factors responsible for changes in community diversity and structure. We then speculate that the keratinophilic microbial taxa are enriched by exposure to higher concentrations of keratin substrates such as human hair and skin surfaces. We suggest that future research should focus on keratinophilic taxa in some specialized habitats, particularly in hospitals.