COMPARISON OF C AND N MINERALIZATION AND METAGENOME ANALYSIS OF RHIZOSPHERE SOILS BELONGING TO DIFFERENT Colchicum L. SPECIES

This study is aimed at determining the characteristics and microbiota of soil upon which some Turkish Colchicum (Colchicaceae) species naturally grows. For this aim the rhizosphere soil samples of Colchicum balansae Planch., Colchicum triphyllum Kunze and Colchicum variegatum L. were analysed in this research. The carbon mineralization rate of C. balansae soil at p<0.05 is significantly different from that of the other two soils. In terms of nitrogen mineralization, significant difference exists between all the three soils (p<0.001). Colchicum variegatum rhizosphere was found to have the highest bacterial diversity. The results revealed that 254 bacterial species were common to the three rhizosphere soils, 35.60% of the bacterial species were unique to C. variegatum soil while 21.89% and 22.67% of the bacterial species were unique to C. balansae and C. triphyllum soil respectively. It was found that C. variegatum and C. balansae collected from areas close to each other had the highest number of common bacterial species, while C. triphyllum from the distant region shared 75 with C. variegatum and 19 with C. balansae. Metagenomics analysis reveals that in the rhizophere of C. variegatum, C. balansae and C. triphyllum, Actinobacteria is dominant at phylum level. Likewise, in C. variegatum soil, Nitrosocosmicus and halophilic Halobacter were found to be the dominant archaea. In the soils of C. triphyllum and C. balansae Saccharomycetales were detected, while Cryptococcus neoformans var. grubii H99 was exclusively detected in C. balansae soil. Significant difference (p<0.05) was observed in C. variegatum rhizosphere soil in terms of organic carbon (C%) and carbon mineralization from the other two soil samples. Significant differences were observed in all three soils in terms of nitrogen content, and the C. triphyllum rhizosphere soil was significantly different from the others in terms of available phosphorus content (p<0.05). This study showed that biological as well as the physico-chemical properties of the rhizosphere soil regulate soil microbial diversity and density and by extension influences their activity which evidently manifests itself in carbon and nitrogen mineralisation.