BACKGROUND MICROBIAL GENOMICS FROM MAJOR GROUNDWATER PRODUCTION AQUIFERS IN CENTRAL LOS ANGELES BASIN - A BASELINE STUDY

As part of hydrogeological assessment conducted during the expansion of a pre-existing production well field in the Central Groundwater Basin of Los Angeles, genetic analysis was performed on microbes within groundwater samples collected from discrete depth intervals in the well field. A total of six samples were collected from five distinct water-bearing units at approximate depths of 240 feet, 345 feet, 600 feet, 765 feet, 1,000 feet, and 1,400 feet below ground surface, generally representing the upper Gage, lower Gage aquifers (Upper Pleistocene), and the Lower Pleistocene hydrostratigarphic units within the San Pedro Formation (including the lower Lynwood, lower Silverado, and Sunnyside aquifers). Samples were analyzed by the Microbial Insights Inc. laboratory located in Knoxville, Tennessee, for total genetic materials using conventional high-throughput DNA sequencing techniques. Analytical results included phylogenetic classes identified from each sample, and the aerobic and/or anaerobic genera identified within those classes. This study was unique in identifying baseline microbial community structures within these important high-yield potable aquifers, as well as understanding the microbial inter-community relationships which exist in light of natural aquifer geochemistry, and identifying the potential for natural or enhanced biodegradation of anthropogenic contaminants known to occur within this portion of the groundwater basin.