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

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 Associate professor, 1 Assistant professor 3 Industrial Research fellows (AkzoNobel, Canon-Oce, TNO) • 2 Technical assistents • 1 Secretary

Unique infrastructure Darcy Lab • Homebuilt • Spatial resolution: 5 µ m • Additional info from relaxation 9/24/14 PAGE 3

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

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

Time-Of-Wetness (TOW) RH ‘Time-Of-Wetness’ TOW growth surface RH 80% RH thresshold no growth indoor air RH time 9/24/14 PAGE 6

TOW as function of RH gypsum plaster wet surface > 6 hours! (=TOW >0.5) 10 minutes vapor production … (=TOW <0.02) 9/24/14 PAGE 7

Growth as function of TOW 1.0 prediction by relative growth rate (-) standard model 0.8 0.6 0.4 0.2 0.0 0 20 40 60 80 100 TOW (%) 9/24/14 PAGE 8

Growth as function of TOW Penicillium rubens 1.0 prediction by bare gypsum relative growth rate (-) standard model coated gypsum 0.8 0.6 0.4 0.2 0.0 0 20 40 60 80 100 TOW (%) 9/24/14 PAGE 9

Growth as function of TOW Penicillium rubens 1.0 prediction by bare gypsum relative growth rate (-) standard model coated gypsum 0.8 model : underestimated growth 0.6 0.4 model : 0.2 overestimated growth 0.0 0 20 40 60 80 100 TOW (%) 9/24/14 PAGE 10

Growth as function of TOW Penicillium rubens 1.0 prediction by bare gypsum relative growth rate (-) standard model coated gypsum 0.8 0.6 0.4 0.2 0.0 0 20 40 60 80 100 TOW (%) 9/24/14 PAGE 11

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

Complexity of the water-fungus relation indoor air RH evaporation a w hyphae condensation diffusion a w & θ a w , nutrients porous material RH = relative humidity a w = water activity θ = moisture content in different phases 9/24/14 PAGE 13

Unraveling the a w - θ effect experiment: same a w , different θ equilibrium sorption equilibrium saturation maximum equilibrium θ θ RH a w aqueous glycerol solution (controlled a w ) 9/24/14 PAGE 14

Hyphae extension as a measure for growth Growth on gypsum equilibrated with RH=97% !!!!!!!!!!USB! Microscope!recordings:!op1cal!resolu1on!~1.5µm!(pixel~0.6µm)! ! 9/24/14 PAGE 15

20 Equilibrated 18 16 Growth rate ( µ m/h) 14 12 10 8 6 4 2 0 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 Water activity 9/24/14 PAGE 16

20 Equilibrated 18 16 Growth rate ( µ m/h) 14 12 θ ~8% 10 8 6 θ ~3% 4 θ ~2% 2 θ ~2% θ ~1% 0 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 Water activity 9/24/14 PAGE 17

20 Equilibrated Soaked Glycerol 18 16 Growth rate ( µ m/h) 14 θ ~35% 12 10 8 6 4 2 0 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 Water activity 9/24/14 PAGE 18

20 Equilibrated Soaked Glycerol 18 Soaked water 16 Growth rate ( µ m/h) 14 12 saturated sample θ ~ 35% 10 Pure water 8 6 equilibrated sample θ ~ 10% 4 2 0 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 Water activity 9/24/14 PAGE 19

20 Soaked Glycerol Equilibrated 18 Soaked KCl 16 Soaked NaCl Soaked PEG Growth rate ( µ m/h) 14 Soaked water 12 10 8 6 4 2 0 0.78 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 Water activity 9/24/14 PAGE 20

Conclusion The effect of the moisture content θ on hyphal growth • Strong indication: θ affects growth rate, apart from a w or compatible solutes. • This effect is inherent to the material(-geometry): not relevant on agar , highly relevant on porous media 9/24/14 PAGE 21

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

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

Our FOCUS Fungal Observatory Climate controlled aUtomized Set-up Response monitoring: quantified macroscopic surface discoloration (digital analysis) 9/24/14 PAGE 24

Penicillium rubens 0.15! discolora1on!(C)! 0.1! 0.05! 0! 0! 40! 80! 120! 160! 200! 240! 280! 1me ! (hours)!! 9/24/14 PAGE 25

Penicillium rubens a 0.15! discolora1on!(C)! 0.1! 0.05! 0! 0! 40! 80! 120! 160! 200! 240! 280! 1me ! (hours)!! 9/24/14 PAGE 26

a 0.15! b discolora1on!(C)! 0.1! 0.05! 0! 0! 40! 80! 120! 160! 200! 240! 280! 1me ! (hours)!! 9/24/14 PAGE 27

a 0.15! b c discolora1on!(C)! 0.1! 0.05! 0! 0! 40! 80! 120! 160! 200! 240! 280! 1me ! (hours)!! 9/24/14 PAGE 28

Penicillium rubens discolora1on!(C)! 0.13! 0.08! 0.03! 0! ! 0! 40! 80! 120! 160! 200! 240! 280! !!!!!!!!!!0 ! C0.02! 1me ! (hours)!! 9/24/14 PAGE 29

Penicillium rubens discolora1on!(C)! 0.13! period!of!desicca1on! 0.08! 0.03! 0! ! 0! 40! 80! 120! 160! 200! 240! 280! !!!!!!!!!!0 ! C0.02! 1me ! (hours)!! 9/24/14 PAGE 30

Penicillium rubens discolora1on!(C)! 0.13! period!of!desicca1on! 0.08! 0.03! ‘reset’ � ‘germination’ time of conidia 0! ! 0! 40! 80! 120! 160! 200! 240! 280! !!!!!!!!!!0 ! C0.02! 1me ! (hours)!! 9/24/14 PAGE 31

Penicillium rubens discolora1on!(C)! 0.13! period!of!desicca1on! 0.08! 0.03! !!!!!!!!!!0 ! !!!!!!!!!!!!0 ! 0! 40! 80! 120! 160! 200! 240! 280! C0.02! 1me ! (hours)!! 9/24/14 PAGE 32

Penicillium rubens discolora1on!(C)! 0.13! period!of!desicca1on! 0.08! 0.03! No ‘reset’ !!!!!!!!!!0 ! !!!!!!!!!!!!0 ! 0! 40! 80! 120! 160! 200! 240! 280! C0.02! 1me ! (hours)!! 9/24/14 PAGE 33

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 9/24/14 PAGE 34

Extra Cellular Matrix (ECM) ungerminated spores ungerminated spores + ECM 9/24/14 PAGE 35

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