Spatial heterogeneity of high-affinity H2 oxidation activity in agricultural soil profile

Abstract

Soil H₂ oxidizing bacteria metabolize H₂ from the atmosphere, but soil carbon substrates and environmental factors influence their distribution in the soil profile. We conducted a field survey of the spatial distribution of H₂ content and high-affinity H₂ oxidation activity in the soil profile (5 cm, 15 cm, and 35 cm) and between the soybean rhizosphere and bulk soil. We found the H₂ content declined exponentially with soil depth, but potential H₂ oxidation activity was consistent at all soil depths. The rhizosphere soil had 66% more high-affinity H₂ oxidation activity than bulk soil. Simultaneous presence of H₂ and carbon likely facilitates mixotrophic growth of H₂ oxidizing bacteria in the rhizosphere.