Fig. 2: Distribution of metabolic genes encoded by photogranules’ communities.
From: Interspecies hydrogen transfer between cyanobacteria and symbiotic bacteria drives nitrogen loss
a Functional classification and abundance of hydrogenase from the 9 metagenomic samples (S1–S9) collected in different time points (on Days 0, 20, 40, 60, 80, 150, 220, 300, 400, respectively) during reactor operation. No [Fe]-hydrogenases were detected in these metagenomes. Gene abundance was present in percentage of sequence reads for each hydrogenase type identified within one million random metagenome reads. b Spearman’s correlation heatmap between hydrogenase gene abundance and denitrification gene abundance. Spearman’s correlation coefficients are shown (n = 9 biologically independent samples). The asterisk indicates two-tailed test of Spearman’s statistical significance adjusted. The significant correlations are indicated as follows: *, P < 0.05; **, P < 0.01. ***, P < 0.001. c Maximum-likelihood phylogenetic tree of the hydrogenase sequences retrieved from the high-quality MAGs (completeness > 90%, contamination < 10%) retrieved from the metagenomic samples of photogranules. Black circles indicate bootstrap support values over 70%. The transcriptional abundance of each hydrogenase sequence in the metatranscriptomic sample of photogranules (2–5 mm) harvested on day 400 was represented with log10(RPKM + 1). d Bubble plot showing the metabolic potential of the 42 MAGs. Each MAG is noted as family level, and the right bar plot represents the relative abundance of MAGs in the phototgranules harvested on the last operational day. The maximum likelihood phylogenetic tree of MAGs was constructed based on 37 marker gene families in the genome. The size of the circle corresponds to the number of functional genes in the specific MAGs, and marker genes that were not detected in any MAG are omitted. MAGs marked with red name represent the MAGs with hydrogenotrophic denitrification potential. Source data are provided with this paper.
