Fig. 4

Potential activity of brine vOTUs by metatranscriptomic read recruitment. A Coverage of active vOTUs based on metatranscriptomic read mapping to virome-generated vOTUs from CB and SB samples. The metatranscriptomic reads were mapped (90% read identity + 90% read coverage + 50% contig coverage) to brine vOTUs to identify potentially active viruses. The potential active vOTUs that contained the AMG FAD genes and that were among the top 20 abundant viruses (compared to the whole community that comprised both active and inactive viruses) were marked in blue and purple, respectively. The two vOTUs containing the AMG FAD genes did not belong to the top 20 abundant viruses. B Network analysis shows the genus-level taxonomy of the two vOTUs containing the AMG FAD genes. These two vOTUs belonged to the same VC (i.e., approximate to a viral genus) and are indicated in blue triangles. C The genome composition and the coverages of mapped metatranscriptomic reads for the two vOTUs encoding the AMG FAD genes. The vOTU vOTU43_CB18_222366 was recovered with a complete (circular) genome, while vOTU105_CB18_230153 had 85% completeness based on checkV assessment. The AMG FAD genes are indicated in red, while the phage structural genes, including head, tail, and capsid genes, are indicated in blue. All other genes are colored in gray. Genes with high activity (i.e., interpreted by high reads coverage; top panel) included phage structural genes (i.e., head and capsid), signal transduction gene, and some unknown genes. The FAD genes were active at a low level