Abstract
Summary High‐affinity hydrogen ( H 2 )‐oxidizing bacteria possessing group 5 [ NiFe ]‐hydrogenase genes are important contributors to atmospheric H 2 uptake in soil environments. Although previous studies reported the occurrence of a significant H 2 uptake activity in vegetation, there has been no report on the identification and diversity of the responsible microorganisms. Here, we show the existence of plant‐associated bacteria with the ability to consume atmospheric H 2 that may be a potential energy source required for their persistence in plants. Detection of the gene hhyL – encoding the large subunit of group 5 [ NiFe ]‐hydrogenase – in plant tissues showed that plant‐associated high‐affinity H 2 ‐oxidizing bacteria are widely distributed in herbaceous plants. Among a collection of 145 endophytic isolates, seven S treptomyces strains were shown to possess hhyL gene and exhibit high‐ or intermediate‐affinity H 2 uptake activity. Inoculation of A rabidopsis thaliana (thale cress) and O ryza sativa (rice) seedlings with selected isolates resulted in an internalization of the bacteria in plant tissues. H 2 uptake activity per bacterial cells was comparable between plant and soil, demonstrating that both environments are favourable for the H 2 uptake activity of streptomycetes. This study first demonstrated the occurrence of plant‐associated high‐affinity H 2 ‐oxidizing bacteria and proposed their potential contribution as atmospheric H 2 sink.