2024 Volume 39 Issue 3 Article ID: ME24027
Nitrite-oxidizing bacteria (NOB), which perform the second step of aerobic nitrification, play an important role in soil. In the present study, we report a novel isolate from agricultural soil affiliated with the genus Nitrobacter and its physiological characteristics. We sampled the surface soil of a vegetable field and obtained mixed culture A31 using the most probable number (MPN) method with inorganic medium containing 0.75 mM urea (pH 5.5). The dilution–extinction procedure on culture A31 led to the isolation of a strain that was designated as Nitrobacter sp. A67. The nxrB1 gene sequence of Nitrobacter sp. A67 (302 bp) was classified into Cluster 5, and the highest sequence identity was 96.10% with Nitrobacter sp. BS5/19. The NO2– oxidation activity of Nitrobacter sp. A67 was investigated at various pH. The optimum pH for NO2– oxidation was 5.8–6.4. This result indicates that Nitrobacter sp. A67 is a moderately acidophilic nitrite-oxidizing bacterium.
