Validation of respirometry as a short-term method to assess the efficacy of biocides.
This study shows that a short-term respirometric measurement based on the rate of oxygen uptake needed to oxidize glucose is a reliable and fast method to assess biocide efficacy against P. fluorescens cells. Respiratory activity using oxygen consumption rate, the determination of viable and nonviable cells using Live/Dead BacLight kit and colony formation units (CFU), were compared as indicators of the biocidal efficacy of ortho-phthalaldehyde (OPA). The results showed that determining the effect of OPA against P. fluorescens using the different methods leads to different conclusions. The minimum bactericidal concentration (MBC) was 80 mgl(-1), 100 mgl(-1) and 65 mgl(-1) respectively, using respiratory activity, viability using BacLight counts and culturability. The plate count method was shown to underestimate the biocidal action of OPA, whilst data from respirometry and viability using Live/Dead BacLight kit correlated strongly and were not statistically different when yellow cells were considered nonviable. Respirometry therefore represents an expeditious, non-destructive and accurate method to determine the antimicrobial action of biocides against aerobic heterotrophic bacteria.
Simões
M
M
Centro de Engenharia Biológica, Universidade do Minho, Braga, Portugal.
Pereira
M O
MO
Vieira
M J
MJ
D001431:Bacteriological Techniques; D015169:Colony Count, Microbial; D003470:Culture Media; D004202:Disinfectants / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects*; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D009764:o-Phthalaldehyde / Q000494:pharmacology*
D003470:Culture Media; D004202:Disinfectants; D009764:o-Phthalaldehyde; D005947:Glucose