Use of metabarcoding detects the rapid onset of cultivation bias in the culture-based profiling of marine sediment bacterial communities

When cultivation-based microbiology is used to isolate strains from environmental samples, the cultured populations may not represent ecologically relevant taxa in the source community. To address this, we employed pre-cultivation metabarcoding to establish a baseline community profile and detect cultivation bias. Using time-resolved cultivation of marine sediment bacteria, we demonstrated the need for initial community characterization. Sediment-derived microbiomes were cultured in Marine Broth 2216 and analyzed using 16S rRNA gene metabarcoding at 0, 6, 12, 18, and 24 h. A rapid 10-fold reduction in alpha diversity was observed within the 6 h (from 1029 amplicon sequence variants to 34-106), with the genus Vibrio reaching near-complete dominance (>95%) from 18 to 24 h, while environmentally dominant taxa such as Acinetobacter were quickly excluded. This dramatic shift illustrates that, without baseline characterization, cultivation-induced artifacts cannot be clearly distinguished from ecologically meaningful patterns. Fast-growing generalists can quickly outcompete ecologically significant taxa, distorting isolation outcomes and hindering the recovery of functionally important microorganisms. We show that metabarcoding at 0 h can identify cultivation biases, help interpret isolation results, and suggest targeted strategies for recovering ecologically relevant taxa. This integrated approach facilitates more accurate recovery and analysis of functionally significant microbial diversity.