Bacterial communities of leachate from tire monofill disposal sites

The disposal of used automobile tires is problematic due to the large number generated each year. Newer methods of tire disposal have been developed in which tires are shredded and used for construction materials or buried in dedicated tire monofill sites. In this study, the bacterial assemblage associated with aqueous leachate collected from tire monofill sites was examined and compared to the bacterial assemblage of reference streams. Leachate from two tire monofill sites in Ohio (USA) was collected four times during the course of one year and analyzed for total bacterial number, culturable bacterial number, and number of the bacterium Acinetobacter calcoaceticus. The numbers of culturable bacteria (CFU/ml), total bacteria (cells/ml), and A. calcoaceticus (cells/ml) from the leachate at both monofill sites were generally lower or equal to numbers from the reference streams. Exceptions occurred during February when culturable bacteria at one site and total bacteria at the other site were more abundant in the leachate compared to reference streams; correspondingly the leachate temperature in February was higher than the surface waters. Culturable bacteria, total bacteria, and A. calcoaceticus numbers in the leachate ranged from 5.7 × 102–1.8 × 104, 5.3 × 105–3.8 × 106, and 9.9 × 101–1.8 × 104 respectively. Twenty isolates were selected for species identification using FAME analysis. Nine of the 17 identified isolates belonged to the genus Pseudomonas and two isolates each belonged to the Flavobacterium and Aeromonas genera. The culturable bacterial assemblage of tire leachate was found to be similar to natural surface waters.