AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Distinct Reaction of Bacterial Culturability and Viability on Antimicrobial Air Filters Coated with Sophora Flavescens Nanoparticles
GI BYOUNG HWANG, Kyoung Mi Sim, Jae Hee Jung, Gwi Nam Bae, Korea Institute of Science and Technology
Abstract Number: 228 Working Group: Health Related Aerosols
Abstract Most studies evaluated the performance of antimicrobial filters by means of measuring the loss of culturability of bacteria, and some estimated the antimicrobial effect on viability using the plate count method. However, recent studies related have indicated that this method may produce overestimations or partial results because bacterial culturability is susceptible to natural decay and environmental stimuli such as acidic water, low temperature, and etc. Additionally, the plate count method cannot demonstrate bacterial viability and the presence of VBNC bacteria, which have low metabolic activity but may be able to reproduce at favorable conditions. Therefore, to investigate the more precise antimicrobial effect of filters on bacteria, their effects on the culturability and viability of bacteria must be investigated, particularly in terms of the VBNC state. This study was performed to investigate effects of antimicrobial air filter on culturability and viability of E. coli and B. subtilis bacteria. At the antimicrobial test with various exposure time, after 60 min, >80% of both bacteria species lost culturability on control filter due to natural decay whereas >86% kept their viability and the number of VBNC bacteria increased as residence time of bacteria on control filter increased. For antimicrobial filter, culturability reduction trends of both bacterial species were similar, but viability reduction differed with it. E. coli viability reduced gradually from 77% to 66% over 60 min, while that of B. subtilis decreased dramatically from 70% to 22% over the same period. As residence time increased, the proportion of E. coli cells that entered the VBNC state also increased; however, the proportion of B. subtilis cells that entered the VBNC state decreased.