Fig. 6: Metabolic potential for IHT-driven denitrification at the global scale CA.
From: Interspecies hydrogen transfer between cyanobacteria and symbiotic bacteria drives nitrogen loss
a World map of the sample distributions of different types of CA or free-living TARA ocean samples in this study. The point color shows whether the genomes of H2-evolving Cyanobacteria (encoding hydrogenase or nitrogenase) and hydrogenotrophic denitrifier consumers (encoding both H2-uptake hydrogenase and narG/napA) were isolated at that location. The number of presented samples is noted if a site has multiple samples without all being present. b Gene abundance of H2-uptake hydrogenases in different samples. ES, engineered system (n = 13); lakes (n = 13); marine (n = 9); HS, hot spring (n = 12); glacier (n = 16); SRF, surface (n = 12); DCM, deep chlorophyll maximum (n = 12). Boxplot: center line, median; box limits, upper and lower quartiles; whiskers, 1.5× interquartile range. Gene abundance was present in percentage of sequence reads identified within 1 million random metagenome reads. c Linear correlation between gene abundance of H2-evolving hydrogenase and H2-uptake hydrogenase in global CA. Black lines indicate the fitted linear models with confidence intervals of 0.95 (grey area). Pearson correlation coefficients are shown, two-sided tests are used for alternative hypothesis testing (n = 63 biologically independent samples). d Linear correlation between gene abundance of H2-uptake hydrogenase and nitrate reductase (sum of narG and napA) in the global CA sample. Black lines indicate the fitted linear models with confidence intervals of 0.95 (grey area). Pearson correlation coefficients are shown, two-sided tests are used for alternative hypothesis testing (n = 63 biologically independent samples). e Abundance of metabolic marker genes based on the metagenomic short reads across the global cyanobacterial aggregates. Homology-based searches are used to calculate the relative abundance of marker genes as average gene copies per organism for the metagenomes (abundance relative to a set of universal single-copy genes). Source data are provided with this paper.
