Impact of Triclosan on Genetic Diversity in Artificial Green Roof Microbial Communities

Open Access
Mehalik, Lauren Kay
Graduate Program:
Environmental Pollution Control
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 01, 2015
Committee Members:
  • Katherine H Baker, Thesis Advisor
  • Shirley Elizabeth Clark, Thesis Advisor
  • Daniel M Borsch, Thesis Advisor
  • Green roof
  • Triclosan
  • Genomic
  • Micro
  • Diversity
Low-impact development (LID) is a cost effective engineering strategy using natural features to manage stormwater runoff. Green roofs, vegetated rooftops, are an emerging LID strategy that not only manage stormwater runoff, but also minimize energy costs, improve aesthetics, provide wildlife habitats, and reduce the urban heat index. Recycled and reused materials offer additional improvements to LID techniques by repurposing waste diverted from landfills. Waste tires can be shredded to provide an artificial growth medium on green roofs. LID strategies can be further enhanced by reusing greywater (GW) to irrigate an artificial growth medium of recycled rubber supplemented with compost (RM). Artificial soils are less expensive and more lightweight than commercially available soils, better accommodating the weight bearing limit of buildings. Additionally, GW reuse helps to conserve potable water, reducing water scarcity. GW often contains triclosan, an antimicrobial found in personal care products that can select for resistant organisms. Previous studies support the use of RM, but the impact of greywater and triclosan on microbial communities in RM has yet to be investigated. In this study, the effects of greywater irrigation on microbial community genomic and phenotypic diversity were compared in RM and commercially available green roof media (CM). A mixture of ryegrass and Kentucky bluegrass were grown in each medium and watered with either GW or greywater with triclosan (GWT). Biolog EcoPlates™ and soil microbial DNA, characterized through pyrosequencing, were used to analyze microbial diversity. The Biolog EcoPlates™ suggest that the medium, independent of triclosan, has some effect on microbial physiological diversity. Pyrosequencing results agree with the Biolog plates, showing little change in genomic diversity after GWT irrigation.