AUTHOR=Zhu Yuying , Ma Ning , Jin Weihua , Wu Shimei , Sun Chaomin 

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

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00602

DOI=10.3389/fmicb.2017.00602

ISSN=1664-302X

ABSTRACT=<p>Calcium carbonate (CaCO<sub>3</sub>) 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 <italic>Brevibacterium linens</italic> BS258 was demonstrated to effectively form CaCO<sub>3</sub> precipitates. Surprisingly, this bacterium could also dissolve the formed CaCO<sub>3</sub> with the increase of the Ca<sup>2+</sup> concentration. To disclose the mechanisms of biomineralization, the genome of <italic>B. linens</italic> BS258 was further completely sequenced. Interestingly, the expression of three carbonic anhydrases was significantly up-regulated along with the increase of Ca<sup>2+</sup> concentration and the extent of calcite dissolution. Moreover, transcriptome analyses revealed that increasing concentration of Ca<sup>2+</sup> induced KEGG pathways including quorum sensing (QS) in <italic>B. linens</italic> 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<sub>3</sub> biomineralization. Within the genome of <italic>B. linens</italic> BS258, there are both cadmium and lead resistance gene clusters. Therefore, the sequestration abilities of Cd<sup>2+</sup> and Pb<sup>2+</sup> by <italic>B. linens</italic> BS258 were checked. Consistently, Pb<sup>2+</sup> and Cd<sup>2+</sup> could be effectively sequestered with the precipitation of calcite by <italic>B. linens</italic> BS258. To our knowledge, this is the first study investigating the microbial CaCO<sub>3</sub> biomineralization from both genomic and transcriptomic insights, which paves the way to disclose the relationships among bacterial metabolisms and the biomineralization.</p>