Presentation from Sloan Symposium at Indoor Air 2011 in Austin, Texas.

1. EHEC serotype O104 E. coli
-- 93 percent sequence
similarity with the EAEC
55989 E. coli strain
Building Ecology: Linking Microbial
Ecology with Indoor Environment
and Building Science
Hal Levin
Building Ecology Research Group
Santa Cruz, California
hal.levin@buildingecology.com

2. Purpose of Presentation
• Summarize preliminary findings and
questions re: IE factors relevant to
microbial ecology of the indoor
environment
• Stimulate discussion: what matters
and why?
• Ask better questions for future
research
• Stimulate potential collaboration
between IE scientists and microbial
ecologists
• Identify subjects for microBEnet
workshops, valuable pilot studies This is Bacillus subtilis, a ubiquitous bacterium whose
spores are commonly found in house dust! On the
left, the image of a colony grown on semi solid (agar)
medium. On the right, a floating biofilm we call
pellicle. Notice the complex architecture, wrinkles,
ridges, aerial projections, etc.

3. Implications
• A preliminary review of the
scientific literature related to
environmental factors that
affect the indoor microbial
ecology suggests the existence
of an extremely complex
system.
• Future research will more
comprehensively address
indoor environmental microbial
ecology with advanced gene-
based tools.
• This review identifies important
factors determining the The pellicles are remarkably
microbial species present in the robust… a penny thrown in does
indoor environment. not break them…..

4. What is Building Ecology?
• Buildings = more than inanimate physical entities, masses of inert material that
remain relatively stable over time.
• The building, what’s in it (occupants and contents), and what’s around it (the larger
environment) – a interactive triad , all elements affect each other.
• Buildings = dynamic combination of physical, chemical, and biological dimensions.
• Buildings can (must?) be described and understood as complex systems.
• Microbial ecology of the indoor environment illustrates the complexity.
• Models, methods, and tools similar to those used by ecologists to understand
ecosystems can help us understand the processes occurring out of sight, within the
walls, and how those processes affect the durability and function of the building

5. The field of “microbial ecology” …
• Seeks to understand how microbes
interact with other organisms
(including both macroorganisms and
other microbes) and with the
environment.
• Like any other environment, buildings
and other man-made objects provide
rich habitats for microbes.
• Buildings provide space and nutrients
for microbes, and the people (and
various animals and plants) passing
through continually carry new species
to the community.

6. What is Microbial Ecology?
• Highly diverse activities from genetics to evolution to ecology
• Ecologists looking at microbial communities in a wide range of
locations, from deep ocean to tropical forests to
• Microbiologists using new genomic methods
• Metagenomics: (who’s there and what are they doing?)
– Built environment:
• Buildings houses (Moschandreas et al)
• Urban environment
– Diverse “natural” locations
• Tropical forests
• Oceans: surface, deep vents, etc.

7. What can microbial ecologists do in
the indoor environment?
• Identify the organisms or groups
from which the organisms come
• Identify the conditions that give
rise to the organisms found
• Identify the relationships or
connections among the
organisms or between organisms
and environmental factors
• Help us predict what microbes
will be found based on IEQ
factors

8. What can building scientists do to help the
microbial ecologists?
Carefully and thoroughly
characterize the indoor
environmental factors
thought to be relevant to
the microbes that are
present.
Identify mechanisms of
interactions between
environmental factors
and microbial ecology

9. Purpose and Summary
• Microbial ecologists characterizing indoor microbial ecology.
• Sloan Foundation funding microbiologists, bioinformaticians,
microbial ecologists, and indoor and building scientists to advance
understanding of the indoor microbial ecology.
• Simultaneous characterization of microbial ecology and associated
indoor environmental factors will enable advances in both fields.
• Challenging to identify all relevant factors before more extensive,
collaborative research.
• This presentation reviews preliminary efforts to identify the
significant IE factors.
• Purpose: inform and stimulate discussions and collaboration among
scientists working in the relevant fields.

10. Microbial ecology is diverse
• Genomes to human systems to ecosystems
• Human microbiomes to global environmental
systems
• Characterizing abundance, diversity, evolution
• Potential for prediction from indoor environmental
characteristics
• Is reverse prediction possible?: microbes to indoor
environmental conditions

11. Focus of work to date
• Attempt to find literature connecting environmental
conditions, especially indoors, and the microbes found
there
• Sort through the diverse and abundant literature to
identify prominent environmental factors as
determinants of the microbial ecology of the indoor
environment
Biofilm of a fluorecently tagged Bacillus
subtilis on the root of a tomato plant, keeping
it growing well and keeping pathogens at bay.

12. Level 1 – strong connection hypothesized based on
abundant evidence in the scientific literature:
• Humidity:
– Air: relative and absolute: for viruses, possibly as it contributes to
vapor pressure
– Surfaces: water activity as a function of air and material moisture
content and temperatures.
• Temperature: surface and air
• Ventilation (outdoor air change rate and room air distribution or air
flow patterns)
• Surfaces of building materials (and furnishings) facing the enclosed
space and in the structure
• Chemicals and materials found primarily on surfaces but also in air
(dust, organic matter, nutrients, biocides, others)
• pH of moisture on surfaces: contribution of airborne chemicals
(including CO2) to surface moisture Ph
• People (age, size/activity/metabolic rate, culture)

13. Level 2–Important building components or processes w/ plausible
connections, but either not strong or not well-established
• Filtration
• Cleaning practices
• HVAC system
– System type
– Humidity in HVAC systems (Water blowing off coils, accumulated in drip pans, etc.)
– Air conditioning (yes or no)
– Humidifiers
– UVc on wetted surfaces
– Extent of drainage of water from HVAC surfaces
• Envelope design and construction quality
• Maintenance (building and HVAC) including frequency, materials and processes
used
• Type of materials used (e.g., plaster, vs. gypsum board, vs. the new mold-
resistant gypsum board)
• Flat vs pitched roofs – important as a function of prevalence of precipitation
• Roof overhangs versus none
• Operable windows vs. sealed and occupant window- opening behaviors.
• Toilets as a source of microbial agents
• Organic compounds comprising the dust in duct work (or on building surfaces)

14. Level 3 – Additional factors that may affect the
microbial ecology of the indoor environment
• Building location:
– Biogeographical, e.g., latitudes, climates, historical factors (changes over time, past
microbial populations and their evolution)
– Climate factors: latitude: some fungi only appear to occur at certain latitudes, effects of
severe storms, floods, weather cycles
– Locality (as in adjacency to parks/natural areas/water bodies affecting what gets brought
into a building - indoor/outdoor transport factors)
• Building type (e.g. hospitals different from residences - this relates to human
activities/building program)
• Building design (overhangs, roofs, windows, etc. - and what about insulation?
made a big difference in the condensation in my apartment!)
• Building materials/furnishings: I came across the terms 'substrates' and
'nutrients'
• Room types/activities (kitchens, bathrooms different from office, bedroom) - the
word 'eco-niche' was in one of the articles relating to bathrooms, I think
• Light / darkness, Ultraviolet light
• Potential effects of interactions of other air pollutants
• Pets, house plants
• Smoking behavior

15. Examples of dynamic, interactive and
independent processes
• Symbiosis between humans
and gut flora
• Temperature and humidity and
emissions of chemicals from
building materials, furnishings,
and consumer products
I give you this as a reminder of the fact that in a very healthy pastoral state, a
foundational aspect (keystone) is the colonization of all surfaces by microbes: the root
of the grass, the grass leaves, the fur on the sheep, their teeth, tongues and of course,
the entrie surface of the intestinal tract. Same with us….

16. Endosymbiotic origin of eukaryotes
Creg Darby: Micro 202, June 4, 2007

17. All microbes are not bad!
Animal- microbe mutualisms
Source: Creg Darby: Micro 202, June 4, 2007

18. Identify the “Patterns that Connect”
Bateson, Mind and Nature: A Necessary Unity
ENVIRONMENT
MICROBES
PEOPLE
BUILDINGS

19. Think you very much!
www.microBE.net
SLOAN SYMPOSIUM – THURSDAY: 9:55 – 12:00, 1:00 – 3:00