Genomic and Transcriptomic Insights into Calcium Carbonate Biomineralization by Marine Actinobacterium Brevibacterium linens BS258

Calcium carbonate (CaCO(3)) biomineralization has been investigated due to its wide range of scientific and technological implications, however, the molecular mechanisms of this important geomicrobiological process are largely unknown. Here, a urease-positive marine actinobacterium Brevibacterium linens BS258 was demonstrated to effectively form CaCO(3) precipitates. Surprisingly, this bacterium could also dissolve the formed CaCO(3) with the increase of the Ca(2+) concentration. To disclose the mechanisms of biomineralization, the genome of B. linens BS258 was further completely sequenced. Interestingly, the expression of three carbonic anhydrases was significantly up-regulated along with the increase of Ca(2+) concentration and the extent of calcite dissolution. Moreover, transcriptome analyses revealed that increasing concentration of Ca(2+) induced KEGG pathways including quorum sensing (QS) in B. linens BS258. Notably, most up-regulated genes related to QS were found to encode peptide/nickel ABC transporters, which suggested that nickel uptake and its associated urease stimulation were essential to boost CaCO(3) biomineralization. Within the genome of B. linens BS258, there are both cadmium and lead resistance gene clusters. Therefore, the sequestration abilities of Cd(2+) and Pb(2+) by B. linens BS258 were checked. Consistently, Pb(2+) and Cd(2+) could be effectively sequestered with the precipitation of calcite by B. linens BS258. To our knowledge, this is the first study investigating the microbial CaCO(3) biomineralization from both genomic and transcriptomic insights, which paves the way to disclose the relationships among bacterial metabolisms and the biomineralization.