Inactivation of bacteria and yeasts on agar surfaces with high power Nd: YAG laser light

Ward, G D, Wastson, I A, Stewart-Tull, D E S, Wardlaw, A C and Chatwin, C R (1996) Inactivation of bacteria and yeasts on agar surfaces with high power Nd: YAG laser light. Letters In Applied Microbiology, 23 (3). pp. 136-140. ISSN 0266-8254

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Near infrared light from a high-powered, 1064 nm, Neodymium : Yttrium Aluminium Garnet (Nd : YAG) laser killed a variety of Gram-positive and Gramnegative bacteria and two yeasts, lawned on nutrient agar plates. A beam (crosssectional area, 1.65 cm2) of laser light was delivered in 10 J, 8 ms pulses at 10 Hz, in a series of exposure times. For each microbial species, a dose/response curve was obtained of area of inactivation vs energy density (J cm−2). The energy density that gave an inactivation area (IA) equal to 50% of the beam area was designated the IA50-value and was plotted together with its 95% confidence limits. Average IA50-values were all within a threefold range and varied from 1768 J cm−2 for Serratia marcescens to 4489 J cm−2 for vegetative cells of Bacillus stearothermophilus. There were no systematic differences in sensitivity attributable to cell shape, size, pigmentation or Gram reaction. At the lowest energy densities where inactivation was achieved for the majority of organisms (around 2000 J cm−2), no effect was observed on the nutrient agar surface, but as the energy density was increased, a depression in the agar surface was formed, followed by localized melting of the agar.

Item Type: Article
Keywords: Inactivation of bacteria, Nd YAG laser,Inactivation of yeasts, high power lasers
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: Q Science
Q Science > QR Microbiology
Q Science > QR Microbiology > QR0075 Bacteria
T Technology
Depositing User: Chris Chatwin
Date Deposited: 19 Jun 2015 11:41
Last Modified: 08 Mar 2017 08:21

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