Microbial community characterization in Red Sea-derived samples using a field-deployable DNA extraction system and nanopore sequencing

Background In this study, xTitan, a field-deployable, automated, and versatile nucleic acid extraction system was employed to characterize microbial communities in Red Sea-derived samples, including coral colonies, mangrove sediments, and seawater. The use of the xTitan in the field was intended to minimize sample transport bias, obtaining data that may be closer to “ground truth” for microbial diversity. The observed microbial communities from DNA extracted in the field using the xTitan system were compared to DNA extractions performed in a laboratory setting using both xTitan and a commercial Qiagen kit after approximately 24 h of samples transfer and storage. Results Microbial community analyses conducted on DNA extracted using the xTitan system and the Qiagen kit yielded similar alpha diversity metric values, with a trend toward higher diversity observed in most samples extracted with the xTitan. The microbial community structure in samples from a Pocillopora verrucosa colony, mangrove sediments, and seawater was affected by the DNA extraction system. In the P. verrucosa colony, an amplicon sequence variant (ASV) identified as Endozoicomonas acroporae was preferentially abundant when DNA was extracted in the field with the xTitan system rather than in the lab. In mangrove sediments, significant differences ( P -value < 0.05) in beta diversity and functional gene profiles were observed when comparing in-field to in-lab xTitan DNA extracts. In seawater, a pronounced decrease in the relative abundance of cyanobacterial populations was observed when DNA was extracted with both methods after samples were transported to the lab on ice. In addition, hundreds of ASVs from mangrove-associated samples were differentially abundant when DNA was extracted on-site with xTitan system compared to in-lab extractions. Balneolaceae was one of the most abundant taxa in mangrove sediments and several genera from this family were detected in all replicates across all DNA extraction systems. Conclusions The usability of different field-deployable instruments for microbial community characterization in marine-derived samples was demonstrated. Moreover, differences in beta diversity were observed when DNA was extracted in-field versus in-lab using the xTitan system, particularly for mangrove-associated samples. These results highlight the value of on-site nucleic acid extraction for enhancing the detection of microbial taxa that can be sensitive to cold storage. This study enabled the testing of the xTitan on Red Sea-derived samples, generating comprehensive information on the effects of DNA extraction systems and transportation of samples on coral and mangrove-associated microbiomes.