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A microscopy study of hyphal growth of Penicillium rubens on gypsum under dynamic humidity conditions.

van Laarhoven KA, Huinink HP, Adan OC - Microb Biotechnol (2016)

Bottom Line: It was found that hyphal tips ceased to extend when exposed to any tested decrease in RH.However, new hyphal growth always emerges, seemingly from the old mycelium, suggesting that this indoor fungus does not rely only on conidia to survive the humidity patterns considered.These findings are a fundamental step in unravelling the effect of RH on indoor fungal growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of the setup for growth experiments. (A) An inoculated sample is stored in the incubation chamber above a glycerol solution that controls the chamber's RH. Growth on the substrate is recorded with video microscopy through the transparent lid of the chamber. The RH in the container is controlled by replacing one glycerol solution with another with pumps connected to the inlet and outlet. The setup is placed in a constant temperature room; the temperature in the incubation chamber is 23.3 ± 0.1°C. The temperature difference between sample and solution is at most 0.05°C. (B) Schematic representation of the sequence of humidity steps during experiments. Directly after inoculation at t = 0, samples are stored at RH = 97% for 96 h. Then, samples are exposed to a period of lower RH with value RHmin with duration Δt. The RH returns to 97% after the period of low RH, and the experiment continues until conidiation is observed on the sample.
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mbt212357-fig-0001: Schematic representation of the setup for growth experiments. (A) An inoculated sample is stored in the incubation chamber above a glycerol solution that controls the chamber's RH. Growth on the substrate is recorded with video microscopy through the transparent lid of the chamber. The RH in the container is controlled by replacing one glycerol solution with another with pumps connected to the inlet and outlet. The setup is placed in a constant temperature room; the temperature in the incubation chamber is 23.3 ± 0.1°C. The temperature difference between sample and solution is at most 0.05°C. (B) Schematic representation of the sequence of humidity steps during experiments. Directly after inoculation at t = 0, samples are stored at RH = 97% for 96 h. Then, samples are exposed to a period of lower RH with value RHmin with duration Δt. The RH returns to 97% after the period of low RH, and the experiment continues until conidiation is observed on the sample.

Mentions: The inoculated samples were stored in small incubation chambers (Fig. 1). The RH inside these chambers was controlled with an aqueous glycerol solution of defined concentration and aw on the bottom of the container, below the samples (Forney and Brandl, 1992). An aw‐meter (Labtouch‐aw Basic, Novasina, Lachen, Switzerland) was used to verify the aw of the solutions with an accuracy of ± 0.01 (equivalent to ± 1% RH in the incubation chambers). Syringe pumps (NE‐1600; New Era, Farmingdale, New York, United States of America) were used to replace one glycerol solution with another, thereby dynamically controlling the RH. The containers were airtight to prevent the development of inhomogeneous RH profiles and to prevent evaporation‐induced changes in the concentration and aw of the glycerol solutions. Moreover, verification of the aw of solutions before and after experiments confirmed that their aw did not change noticeably during the experiments. The setups were kept in a constant temperature room and cameras were water cooled so that the setups had a uniform, constant temperature (23.3 ± 0.1°C), as verified with 4 thermocouples (NI USB‐9213; National Instruments, Austin, Texas, United States) distributed across the incubation chamber. This again ensured that homogeneous RH profiles developed throughout the whole container after each change of glycerol solution.


A microscopy study of hyphal growth of Penicillium rubens on gypsum under dynamic humidity conditions.

van Laarhoven KA, Huinink HP, Adan OC - Microb Biotechnol (2016)

Schematic representation of the setup for growth experiments. (A) An inoculated sample is stored in the incubation chamber above a glycerol solution that controls the chamber's RH. Growth on the substrate is recorded with video microscopy through the transparent lid of the chamber. The RH in the container is controlled by replacing one glycerol solution with another with pumps connected to the inlet and outlet. The setup is placed in a constant temperature room; the temperature in the incubation chamber is 23.3 ± 0.1°C. The temperature difference between sample and solution is at most 0.05°C. (B) Schematic representation of the sequence of humidity steps during experiments. Directly after inoculation at t = 0, samples are stored at RH = 97% for 96 h. Then, samples are exposed to a period of lower RH with value RHmin with duration Δt. The RH returns to 97% after the period of low RH, and the experiment continues until conidiation is observed on the sample.
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Related In: Results  -  Collection

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Show All Figures
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mbt212357-fig-0001: Schematic representation of the setup for growth experiments. (A) An inoculated sample is stored in the incubation chamber above a glycerol solution that controls the chamber's RH. Growth on the substrate is recorded with video microscopy through the transparent lid of the chamber. The RH in the container is controlled by replacing one glycerol solution with another with pumps connected to the inlet and outlet. The setup is placed in a constant temperature room; the temperature in the incubation chamber is 23.3 ± 0.1°C. The temperature difference between sample and solution is at most 0.05°C. (B) Schematic representation of the sequence of humidity steps during experiments. Directly after inoculation at t = 0, samples are stored at RH = 97% for 96 h. Then, samples are exposed to a period of lower RH with value RHmin with duration Δt. The RH returns to 97% after the period of low RH, and the experiment continues until conidiation is observed on the sample.
Mentions: The inoculated samples were stored in small incubation chambers (Fig. 1). The RH inside these chambers was controlled with an aqueous glycerol solution of defined concentration and aw on the bottom of the container, below the samples (Forney and Brandl, 1992). An aw‐meter (Labtouch‐aw Basic, Novasina, Lachen, Switzerland) was used to verify the aw of the solutions with an accuracy of ± 0.01 (equivalent to ± 1% RH in the incubation chambers). Syringe pumps (NE‐1600; New Era, Farmingdale, New York, United States of America) were used to replace one glycerol solution with another, thereby dynamically controlling the RH. The containers were airtight to prevent the development of inhomogeneous RH profiles and to prevent evaporation‐induced changes in the concentration and aw of the glycerol solutions. Moreover, verification of the aw of solutions before and after experiments confirmed that their aw did not change noticeably during the experiments. The setups were kept in a constant temperature room and cameras were water cooled so that the setups had a uniform, constant temperature (23.3 ± 0.1°C), as verified with 4 thermocouples (NI USB‐9213; National Instruments, Austin, Texas, United States) distributed across the incubation chamber. This again ensured that homogeneous RH profiles developed throughout the whole container after each change of glycerol solution.

Bottom Line: It was found that hyphal tips ceased to extend when exposed to any tested decrease in RH.However, new hyphal growth always emerges, seemingly from the old mycelium, suggesting that this indoor fungus does not rely only on conidia to survive the humidity patterns considered.These findings are a fundamental step in unravelling the effect of RH on indoor fungal growth.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands.

No MeSH data available.


Related in: MedlinePlus