Fig. 3: Metabolic potential and activity of ‘Ca. A. ciliaticola’.
From: Anaerobic endosymbiont generates energy for ciliate host by denitrification
a, Genome-inferred metabolic potential related to anaerobic respiration via denitrification, ATP generation and exchange, tricarboxylic acid (TCA) cycle, iron–sulfur-cluster (Fe–S) and bis-molybdopterin guanine dinucleotide (bis-MGD) biosynthesis, protein export and other transporters. The presence of a double membrane is presumed by analogy with mitochondria. b, Metatranscriptome coverage of two metatranscriptomic datasets, from samples obtained in 2016 and 2018, of the ‘Ca. A. ciliaticola’ genome. There is a highly consistent transcriptome profile between years and an exceptionally high transcription of genes related to energy conservation, ATP production and transport, chaperones (groE, groS and groL) and denitrification (orange, red, purple and blue shading, respectively). Coverage was corrected for sequencing depth; the higher coverage in the 2018 sample is due to the higher endosymbiont abundance in that year. Genes related to denitrification (blue), electron transport chain (orange), tricarboxylic acid cycle (grey) and ATP generation as well as transport (red) are highlighted. The highlighted genes account for more than 55% of all transcripts. Further information is provided in Supplementary Table 5). c, Correlation of ciliate abundance and denitrification rates (30N2 production) in water from the anoxic hypolimnion (189 m, May 2019) with and without ciliates. Each data point represents a volumetric denitrification rate calculated from the linear regression of six individual time points of an experiment. Error bars represent s.e. from linear regression. Denitrification rates in incubations without ciliates are due to the activity of denitrifying bacteria that are still present in the water.
