Recent studies indicate that N2-fixing endophytic bacteria inside foliage may provide a source of N to high elevation pines on marginal soils in both Colorado and California (Carrel and Frank, 2014; Moyes et al., 2016). In order to identify the bacterial groups responsible for the N-fixation inside pine needles, foliage samples from Pinus contorta murrayana (lodgepole pine) growing in Yosemite National Park, California were collected. Pine needles were surface sterilized and a protocol published by Ikeda et al. (2009) was modified to enrich endophytic bacteria. The enriched bacteria cells were sorted and sequenced at the Joint Genome Institute (JGI).
Results/Conclusions
Single genome sequencing indicated that the bacterial community composition inside pine needles were dominated by Acetobateraceae and Rhizobiaceae, suggesting that these taxa may be responsible for N2-fixation in foliage. Additionally, using different N-free media with diverse carbon sources, several bacteria were isolated from the bacterial enrichments. Their 16S rRNA and nifH genes were analyzed and potential candidates for N-fixation inside of pine needles were identified.