Microbial Aggregates in Human Saliva Build the Oral Biofilm Raw sequence reads. Microbial Aggregates in Human Saliva Build the Oral Biofilm

Microbes in biological fluids can be found as aggregates. Yet how these multicellular structures bind to surfaces and initiate biofilm lifecycle remains understudied. Here, we investigate the structural organization of microbial aggregates in human saliva and its role in biofilm formation. We found diverse mixture of aggregates with different sizes, structures, and composition in addition to free-living cells. When individually tracked during binding and growth on tooth-like surfaces, most aggregates developed into structured biofilm communities, whereas most single-cells remain static or were engulfed by the growing aggregates. Our results suggest an alternative to classical models of orderly succession of single-cells attachment, whereby microbes collectively adhere as initiators of biofilm growth leading to heterogenous populations at various spatial and taxonomic scales.