Characterization of bacterial diversity in contaminated groundwater using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Groundwater is a major source for drinkingwater in the United States, and therefore, its quality and quantity is of extreme importance. One major concern that has emerged is the possible contamination of groundwater due to the unconventional oil and gas extraction activities. As such, the impacts of exogenous contaminants onmicrobial ecology is an area to be explored to understandwhat are the chemical and physical conditions that allowthe proliferation of pathogenic bacteria and to find alternatives for water treatment by identifying organic-degrading bacteria. In thiswork, weassess the interplay between groundwater quality and themicrobiome in contaminated groundwaters rich in hydrocarbon gases, volatile organic and inorganic compounds, and various metals. Opportunistic pathogenic bacteria, such as Aeromonas hydrophila, Bacillus cereus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia, were identified, increasing the risk for consumption of and exposure to these contaminated groundwaters. Additionally, antimicrobial tests revealed thatmany of the identified bacteria were resistant to different antibiotics. The MALDI-TOF MS results were successfully confirmed with 16S rRNA gene sequencing, proving the accuracy of this high-throughput method. Collectively, these data provide a seminal understanding of the microbial populations in contaminated groundwater overlying anthropogenic activities like unconventional oil and gas development. (c) 2017 Elsevier B.V. All rights reserved.