Analysis of the Bacterial Community of Metal Scrap Using an Enrichment Culture Approach

Microbiologically influenced corrosion (MIC) of metal alloys is promoted by biofilms formed on metal surfaces. In the marine environment, MIC causes serious metal infrastructure problems, which lead to significant economic losses. In this study, we used an enrichment culture approach to examine the bacterial community that grows on metal surface at levels below the detection limit as a preliminary study for developing guidelines to prevent biofilm formation. An enrichment culture approach was employed to analyze the bacterial community on metal surface without biofilms and corrosion. Genomic DNA was extracted from culture sample after incubation in the enrichment culture with a metal piece, and then the V3–V4 variable regions of the bacterial 16S rRNA gene were amplified using the extracted genomic DNA as the template. Subsequently, using a next-generation sequencing approach, the amplified V3–V4 regions were sequenced, and the bacterial community was analyzed using the QIIME 2 microbiome bioinformatics platform. Using this enrichment culture approach, more than 80 bacterial genera were detected with Sphingomonas bacteria exhibiting the highest relative abundance (44%). These results demonstrated that this method could be useful for bacterial community analysis for bacteria below detection limits, and will serve as a basis for the development of the guidelines.