Machined silicon traps for capturing novel bacterial communities and strains in-situ

We tested the feasibility of a novel machined silicon nanopore enrichment device to recover individual microbial taxa from anaerobic sediments. Unlike other environmental isolation devices that have multiple entry points for bacteria or require the sample to be manually placed inside of a culturing chamber, our silicon device contains 24 precisely sized and spaced nanopores, each of which is connected to one culturing well, thereby providing only one entry point for bacteria. The culturing wells allow nutrient transport, so the bacteria that enter continue to experience their natural chemical environment, allowing collection of microbes without manipulating the environment. The device was deployed in marsh sediment and subsequently returned to the laboratory for bacterial culturing and analysis. 16S rRNA marker gene and metagenomic sequencing was used to quantify the number of different microbial taxa cultured from the device. The 16S rRNA sequencing results indicate that each well of the device contained between 1 and 62 different organisms from several taxonomic groups, including likely novel taxa. We also sequenced the metagenome from 8 of the 24 wells, enabling the reconstruction of 56 metagenomic assembled genomes (MAGs), and 44 of these MAGs represented non-redundant genome reconstructions. These results demonstrate that our novel silicon nanofluidic device can be used for isolating and culturing consortia containing a small number of microbial taxa from anaerobic sediments, which can be very valuable in determining their physiological potential. Importance There are very few methods that can remove a few bacterial cells from a complex environment and keep the cells alive so that they can propagate sufficiently to be analyzed in a laboratory. Such methods are important to develop because the physiological functions of individual species of bacteria are often unknown, cannot be determined directly in the complex sample, and many bacterial cells cannot be grown outside of their natural environment. A novel bacterial isolation device has been made tested in a salt marsh. The results show that the device successfully isolated small groups of bacterial species from the incredibly diverse surroundings. The communities of bacteria were easily removed from the device in the laboratory and analyzed.