On water and indoor fungi Fungal workshop Berkeley USA September 23 - - PowerPoint PPT Presentation

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On water and indoor fungi Fungal workshop Berkeley USA September 23 - - PowerPoint PPT Presentation

Sep 26, 2023 211 likes •577 views

On water and indoor fungi Fungal workshop Berkeley USA September 23 2014 Olaf Adan Tranport in Permeable Media-Applied Physics Karel van Laarhoven Mirjam Bekker 17 PhD students+ 3 Post-docs 2-4 Master students Staff: 1 Professor, 1

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On water and indoor fungi

Fungal workshop Berkeley USA September 23 2014 Olaf Adan

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Tranport in Permeable Media-Applied Physics

  • 17 PhD students+ 3 Post-docs
  • 2-4 Master students
  • Staff: 1 Professor, 1 Associate professor, 1 Assistant professor

3 Industrial Research fellows (AkzoNobel, Canon-Oce, TNO)

  • 2 Technical assistents
  • 1 Secretary

Karel van Laarhoven Mirjam Bekker

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Unique infrastructure Darcy Lab

PAGE 3 9/24/14

  • Homebuilt
  • Spatial resolution: 5 µm
  • Additional info from relaxation
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Outline

  • Water in the air: introducing humidity dynamics
  • Water in the substrate
  • Humidity dynamics revisited
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Outline

  • Water in the air: introducing humidity dynamics
  • Water in the substrate
  • Humidity dynamics revisited
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Time-Of-Wetness (TOW)

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80% RH thresshold RH growth no growth time

indoor air RH

‘Time-Of-Wetness’ TOW

surface RH

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TOW as function of RH

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10 minutes vapor production… (=TOW <0.02) wet surface > 6 hours! (=TOW >0.5)

gypsum plaster

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Growth as function of TOW

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20 40 60 80 100 0.0 0.2 0.4 0.6 0.8 1.0 relative growth rate (-) TOW (%)

prediction by standard model

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Growth as function of TOW

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20 40 60 80 100 0.0 0.2 0.4 0.6 0.8 1.0

bare gypsum

coated gypsum

relative growth rate (-) TOW (%)

prediction by standard model

Penicillium rubens

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Growth as function of TOW

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20 40 60 80 100 0.0 0.2 0.4 0.6 0.8 1.0

bare gypsum

coated gypsum

relative growth rate (-) TOW (%)

prediction by standard model

model : underestimated growth model :

  • verestimated growth

Penicillium rubens

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Growth as function of TOW

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20 40 60 80 100 0.0 0.2 0.4 0.6 0.8 1.0

bare gypsum

coated gypsum

relative growth rate (-) TOW (%)

prediction by standard model

Penicillium rubens

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Outline

  • Water in the air: introducing humidity dynamics
  • Water in the substrate
  • Humidity dynamics revisited
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Complexity of the water-fungus relation

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indoor air RH porous material aw & θ

evaporation condensation

RH = relative humidity aw = water activity θ = moisture content in different phases aw, nutrients aw hyphae

diffusion

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Unraveling the aw - θ effect

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aw RH

equilibrium

θ aqueous glycerol solution (controlled aw)

maximum

θ experiment: same aw, different θ

equilibrium sorption equilibrium saturation

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Growth on gypsum equilibrated with RH=97%

Hyphae extension as a measure for growth

!!!!!!!!!!USB!Microscope!recordings:!op1cal!resolu1on!~1.5µm!(pixel~0.6µm)!

!

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0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 2 4 6 8 10 12 14 16 18 20

Equilibrated

Growth rate (µm/h) Water activity

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0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 2 4 6 8 10 12 14 16 18 20

Equilibrated

Growth rate (µm/h) Water activity

θ~8% θ~3% θ~2% θ~2% θ~1%

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0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 2 4 6 8 10 12 14 16 18 20

Equilibrated Soaked Glycerol

Growth rate (µm/h) Water activity

θ~35%

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0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 2 4 6 8 10 12 14 16 18 20

Equilibrated Soaked Glycerol Soaked water

Growth rate (µm/h) Water activity

Pure water

saturated sample

θ ~ 35%

equilibrated sample

θ ~ 10%

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0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 2 4 6 8 10 12 14 16 18 20

Soaked Glycerol Equilibrated Soaked KCl Soaked NaCl Soaked PEG Soaked water

Growth rate (µm/h) Water activity

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Conclusion

The effect of the moisture content θ on hyphal growth

  • Strong indication: θ affects growth rate,

apart from aw or compatible solutes.

  • This effect is inherent to the material(-geometry):

not relevant on agar, highly relevant on porous media

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Summary (Penicillium rubens)

  • Indoor climate dynamics matter

Growth and TOW are non-linearly related

  • Both water activity&substrate water content

play a role in growth Porous media ≠ culture media: less water, inertia

Culture media data cannot be extrapolated to porous substrates

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Outline

  • Water in the air: introducing humidity dynamics
  • Water in the substrate
  • Humidity dynamics revisited
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Our FOCUS

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Fungal Observatory Climate controlled aUtomized Set-up

Response monitoring: quantified macroscopic surface discoloration (digital analysis)

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0! 0.05! 0.1! 0.15! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! Penicillium rubens

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0! 0.05! 0.1! 0.15! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!!

a

Penicillium rubens

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0! 0.05! 0.1! 0.15! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!!

a b

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0! 0.05! 0.1! 0.15! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!!

a b c

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C0.02! 0.03! 0.08! 0.13! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! !!!!!!!!!!0! 0!! Penicillium rubens

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C0.02! 0.03! 0.08! 0.13! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! period!of!desicca1on! !!!!!!!!!!0! 0!! Penicillium rubens

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C0.02! 0.03! 0.08! 0.13! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! period!of!desicca1on! !!!!!!!!!!0! 0!! ‘reset’ ‘germination’ time of conidia Penicillium rubens

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C0.02! 0.03! 0.08! 0.13! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! !!!!!!!!!!!!0! !!!!!!!!!!0! period!of!desicca1on! Penicillium rubens

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C0.02! 0.03! 0.08! 0.13! 0! 40! 80! 120! 160! 200! 240! 280! discolora1on!(C)! 1me!(hours)!! !!!!!!!!!!!!0! !!!!!!!!!!0! period!of!desicca1on! No ‘reset’ Penicillium rubens

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Conclusion

Colony recovery (P. rubens) after first desiccation

  • “full reset” after a 48 h desiccation in initial stages

recovery: conidia, and (not) more?

  • “ignores” a 6 h desiccation in initial stages

recovery: more than conidia

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ungerminated spores ungerminated spores + ECM Extra Cellular Matrix (ECM)

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