Modeling the respiration of Pseudomonas fluorescens on solid-state lettuce-juice agar |
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| Affiliation: | 1. Department of Microbiology, College of Natural Sciences, Pusan National University, Pusan 46241, South Korea;2. Soil and Land Resources Division, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Moscow ID 83844-2339, USA;1. Centre for Agricultural Technology Augustenberg (LTZ), Kutschenweg 20, 76287 Rheinstetten-Forchheim, Germany;2. Institute of Crop Science, University of Hohenheim, 70599 Stuttgart, Germany;1. Department of Global Ecology, Graduate School of Global Environmental Studies, Kyoto University, Kyoto Daigaku-Katsura CI-2-233, Nishikyo-ku, Kyoto, 615-8540, Japan;2. Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto Daigaku-Katsura CI-2-233, Nishikyo-ku, Kyoto, 615-8540, Japan;1. United States Department of Agriculture, Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, 538 Tower Road, Ithaca, NY 14853, USA;2. Soil and Crop Sciences Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA;1. Institute of Environmental Sciences (CML), Leiden University, 2300 RA Leiden, The Netherlands;2. National Institute of Public Health and the Environment (RIVM), Center for Safety of Substances and Products, 3720 BA Bilthoven, The Netherlands;1. Aarhus University, Department of Agroecology, Forsøgsvej 1, DK-4200 Slagelse, Denmark;2. Aarhus University, Department of Agroecology, Blichers Allé 20, DK-8830 Tjele, Denmark |
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| Abstract: | When modeling gas atmospheres within equilibrium-modified atmosphere packaging it is vital to cover all influences on the atmosphere inside. It is necessary to take the microbial respiration into account when considering an extensive growth of microorganisms on fresh-cut vegetables during shelf life. Therefore the respiration of Pseudomonas fluorescens (due to its frequent occurrence on vegetables) was determined under solid-state conditions. A lettuce-juice agar was chosen to provide similar conditions for the microorganisms. Incubated agar plates were stored in air-tight glass jars at 7 °C for 8 days. The change in gas composition was measured and the data were examined by fitting them to Michaelis–Menten equations. All glass jars were filled with air initially; some of them additionally contained sodium hydroxide to bind the carbon dioxide. In other jars, 26.3% carbon dioxide was added after 4 days of storage whereas the rest of the glass jars were used without any modification. The data were successfully fitted to the Michaelis–Menten equation for substrate limitation (neglecting the influence of CO2) for the three different experiments. The fit with the Michaelis–Menten equation for competitive inhibition was only successful for the respiration experiments with carbon dioxide added. The order of magnitude of the maximum respiration rate (rmax = 0.289–0.305 mL/(incubated plate (1.7 × 107 cfu) · h)) shows by comparing it with reported respiration rates for fresh-cut vegetables, that the influence of microbial respiration should not be neglected, particularly at the end of the shelf life, where the amount of microorganisms may increase to 107 cfu/g. |
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