Q-202. Colonization of Tire Shreds by Bacteria and the Effect of Tire Shred Leachate on Bacterial Growth

R. Vukanti, M. Crissman, A. A. Leff, L. G. Leff;
Kent State Univ., Kent, OH.

Annually, vast amounts of used tires require disposal and a variety of different methods are employed for disposing and recycling tire waste. One disposal method involves shredding tires before landfilling; this process potentially has impacts on environmental health. Little is known about bacterial communities of tire shred monofill sites and their potential role in degradation of tire shreds. In this study, we isolated and identified culturable aerobic and anaerobic bacteria associated with buried shredded tires from a dedicated tire monofill site in Northeast Ohio and tested their ability to colonize (or attach to) recently shredded tire fragments and grow in water surrounding tire shreds. In addition, we tested the effect of aqueous tire leachate on the growth of two tire shred isolates. Two different types of colonization experiments were conducted: one used shreds without steel belts and the other used shreds with steel belts. The bacteria used in the former experiment were: Bacillus megatarium, Bacillus cereus, Hydrogenophaga flava, and Janthinobacterium lividum (originally isolated from the tire shreds or leachate at the study site) and Escherichia coli (a standard laboratory strain). The bacteria used in latter colonization experiment were Celluosimicrobium sp. , Arthrobacter globiformis (tire shred surface isolates) and Acidothiobacillus ferroxidans (an iron oxidizer). In colonization experiments, both attached and planktonic bacterial numbers increased over time and different bacteria responded differently. Of the bacteria tested, J. lividum, H. flava, E. coli, C. cellulans and A. globiformis exhibited the most extensive colonization of the tire shreds. Responses to leachate from tire shreds was also examined using B. cereus and J. lividum. In the leachate experiment, both bacteria responded positively to the addition of leachate. The ability of some bacterial isolates to readily colonize and grow under these laboratory conditions suggests their potential importance in the microbial ecology of tire monofills and prompts us to further explore the link between colonization and biodegradation of waste tires.