Microbial characterization of a natural biofilm associated with Peruvian scallop (Argopecten purpuratus) larvae settlement on artificial collector by confocal imaging, microbiology, and metagenomic analysis

Biofilms strongly influence bivalve settlement patterns on artificial substrates; however, their structure and taxonomic composition remains a black box. We characterized a natural biofilm composition that exhibits a large settlement of larvae of the Peruvian scallop Argopecten purpuratus by culture-dependent and culture-independent methods. Thirty-two different strains, representing six genera (10 strains of Bacillus, 9 of Vibrio, 6 Acinetobacter, 4 Staphylococcus, 2 Photobacterium, and 1 Exiguobacterium) were isolated. Those strains represented only 1.09% of the relative abundance compared with the total microbiota obtained by 16S rRNA high-throughput sequencing. The metagenomic analysis identified 441 species. Prokaryotes were predominant (93.4%) over eukaryotes (6.6%), with Pelobacter (13.4%), Lewinella (5.6%), Marinobacter (5.4%), Hoeflea (4.2%), and Microcystis (3.1%) being the most representative genera. Laser scanning confocal microscopy (LSCM) imaging evidenced an irregular and heterogeneous biofilm with an average thickness of 35 mu m, where the heterotrophic prokaryotic community (3.4 x 10(6) cell cm(-2)) dominate the photoautotrophic communities (2.3 x 10(5) cell cm(-2)). For the first time, an A. purpuratus settlement-related biofilm was described by the next generation sequencing tool (NGS) and compared with traditional methodologies.