Metagenomic sequencing analysis of cinnamon soil with high urease activity and identification of urease genes from microbe

To investigate the source of urease-producing microbes in cinnamon soil, the urease activity of cinnamon soil samples collected from Zhengzhou, Luoyang, Xuchang, Pingdingshan and Anyang in Henan Province were measured. Five samples with the highest urease activity in each city were cultured in liquid medium containing high concentration urea to enrich urease-producing microbes. The DNA in a mixture of the five samples was extracted and used to construct a metagenomic library, and the urease-producing microbes in cinnamon soil were analyzed with metagenome sequencing technology. The results showed that the urease activity of cinnamon soil ranged from 8.34 to 67.18 μg·d^-1·g^-1, and the highest urease activities were 46.98, 67.18, 57.68, 45.97 and 64.15 μg·d^-1·g^-1 at the five sampling points. Via sequence assembly with metagenome sequencing data, 406 urease structural proteins and 437 urease accessory proteins were identified. Species annotation indicated that the urease-producing microbes in cinnamon soil were mainly bacteria, plus a few types of fungi and archaeas. The urease-producing bacteria closely related to Streptomyces, Arthrobacter and Acinetobacter. The urease-producing fungi had close relationships with Madurella mycetomatis, Neofusicoccum parvum and Chaetomium thermophilum. The urease-producing archaeas were closely related to Nitrososphaera and Nitrosopumilus, which suggested that archaeas might be involved in urea degradation in cinnamon soil as well.