Bacteriology for Engineersfor the 21st Century
Tom CurtisNewcastle University
Mara, D. D. (1974) Bacteriology for Sanitary Engineers, Churchill Livingstone, Edinburgh
and London, 209 p
“Bacteriology for Engineers [17] is an excellent reference on the bacteriology of wastewater ”
– Metcalf and Eddy 1979
– 1974!
• Duncan was 29!
Mara, D. D. (1974) Bacteriology for Sanitary Engineers, Churchill Livingstone, Edinburgh
and London, 209 p
“Engineers put bacteria to work sewage treatment systems”
Urbanization
Chapter 14: Waste Treatment 1974
Waste StabilisationPonds
Attached Growth
ActivatedSludge
Anaerobic
Waste Treatment 2011
1910
1899
1914
1930/74
"European and North American practices do not represent the zenith of scientific treatment, nor are they the product of a logical and rational and design process.”
“Rather, treatment practices are the products of history, a history that started about a 100 years ago when little was known about the fundamental physics and chemistry of the subject and when practically no applicable microbiology had been discovered."
Feachem, Bradely, Garelick and Mara (1983)
Evolution: 1974
Chapter 2!
Evolution: 2010
Stylised Representation of Carl Woese’s 3 Domain Tree of Life
An Explosion in methods
PCR TTG
E
TGGE
FISH
T-RFLP
STARFISH
MAR-FISH
RT-PCR
MICRO-FISH
Real Time-PCR
DGGECARD-FISH
Clone libraries
Microarrays
RNA-SIP
SIP
MacroarraysRSGP
Pyrosequencing
Arrays
LH-PCR
ARISA
LAMP
IS-PCR
Explosion in data
• Cost falling
• Efficiency growth now exceeding Moore’s law
• Moore’s law vs sequencing
Economist June 2010
An explosion in hubris
“The ability to routinely write the software of life will usher in a new era in science, and with it, new products and applications such as advanced biofuels, clean water technology... “
http://www.jcvi.org/cms/research/projects/first-self-replicating-synthetic-bacterial-cell/overview/
The scale of the microbial world
• ~1021 stars in Universe
• ~1030 bacteria in the world• ~1029 bacteria in the sea
• ~4x1011 Stars in the galaxy
• ~1018 bacteria in a modest activated sludge plant
• >2.8 billion years of evolution
• Untutored observation is futile
Sample of a map of the million brightest galaxies within 109 light-years from earth
Species diversity in Activated Sludge
• 30,000 sequences from UK AS plants– Sequencing noise
removed
• 1000s of species in AS plants!
• Just to sequence 90% of diversity in 0.25 ml requires– 2-8 MILLION
sequencesLognormal Inverse
Gaussian
0
1000
2000
3000
4000
5000
6000
7000
8000Derby Wanlip
Nu
mb
er
of
Sp
eci
es
Davenport et al., in prep
The largest railway bridge:1725
Causey Arch, Built 1725
The second largest bridge in the Roman World
Severan Bridge, Turkey ~200 AD
The Forth railway bridge:1885
• Designed 1882 • Rationally designed and new materials• Classical structural theory
Engineering without theory is possible
W M Rankine 1853: The Harmony of Theory and Practice
in Mechanics Prof. Civil Engineering Glasgow 1853-
82
“avoids risks, but stops the progress of all improvement”
“Lavish expenditure of material and labour”
“Failure within a limited number of years”
“Misdirected ingenuity….vain pursuit of unworkable innovations
Vain pursuit of the unworkable
What kind of theory do we need?
• Parsimony,
• Generality,
• Consilience,
• Predictiveness. – Calibration
Wilson, E.O (1998) Consilience, The unity of knowledge Random House, New York.
Photo by J Harrison /ASU
Good Company
“KISS: Keep it simple stupid”
– Clarence Johnson, Lockheed
"Simplicity is the ultimate sophistication"
– Leonardo Da Vinci
"Very good Tom.....
but it is too f@*%ing complicated”
– Duncan Mara
Ecological Theory
McArthur and Wilson 1965
Tools to predict diversityTheory of Island Biogeography
McArthur and Wilson 1965
Still too f@%ing complicated
• Island biogeography theory– Cannot be parameterised
– We do not know • How many species there are on an island
(S)• How many species in the “source” (ie P)• Immigration rates• Extinction rates
Stochastic assembly of a functional group Sloan (2006) theory (after
Bell/Hubbell)
Sloan’s Stochastic Model
A. Source community q
B. Local community NT (NT predicted by ASMx)
C. Sampling from q into NT
NT
m
m
m
q
Sloan et al., 2006
Immigration rate affects relationship between frequency and abundance
0 0.1 0.2 0.3 0.4 0.5 0.60
0.10.20.30.40.50.60.70.80.9
1
Ntm = 1 Ntm = 2 Ntm = 10Mean abundance of a species
Fre
quen
cy
0
0.2
0.4
0.6
0.8
1
1.2
0 0.2 0.4 0.6 0.8 1
Mean Abundance (Pi)
Freq
uenc
y
99%
97%
Model Ntm=11.6
NT = 47.2
Ammonia oxidising bacteria in activated sludge
0
0.2
0.4
0.6
0.8
1
1.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Mean abundance
Fre
qu
en
cy
Observed
Model Ntm = 32.7, m =0.1
The Sea
With thanks to Ake Hagstrom
0
0.2
0.4
0.6
0.8
1
0 0.1 0.2 0.3 0.4
Mean Relative abundance (p i)
Fre
qu
ency
Neutral Model Ntm = 14.65
Detection frequency inthe lungs of 24 people
Lungs
We can find m
• m emerges from NTm
• But a sort of fitted parameter
• It has a biological reality..
• The number of immigration events for each birth
Immigration Scales
0.000000001
0.00000001
0.0000001
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
1 100 10000 1000000 1000000001000000000
0
Individuals
Imm
igra
tion
(pe
r de
ath/
birt
h)
Clone
FISH
DGGE
TRFLP
What Scaling Means• If 1016 individuals, NTm = 10
• Probability of a death being replaced – from outside 10-15
– by growth 1-10-15
• Immigration – very rare in mature community– Very very high in new community
Implications
Engineers• Dynamics might be
slower than we think– Even “unsuitable”
microbes may disappear slowly
• Start up crucial– Practitioners have always
known this
• We should “design” the seeding process– Design is not always
intuitive
Ecology and Evolution
• Explains the founder effects– (qv babies and teeth)
• Rates of Immigration & Evolution can be compared
Dynamics will be crucial
• Neutral dynamics are slow
• We know that taxa vary
• Selective pressure could wipe out neutral dynamics
Incorporating biological effects
• The Sloan model has an advantage parameter– ai
• Can confer advantage or disadvantage– Over time – Over community– Advantage sums to zero
• Σ a = 0
Criddle/Well’s dataset in Palo Alto WWTP
0
0.1
0.2
0.3
0.4
0.5
0.6
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51
week number
rela
tive
ab
un
dan
ce amoA
OTU 2 OTU 8 OTU 9
Criddle et al., 2009
NTm = 19
Beta distribution calibration
m = 6.13e-007
Ofiteru et al., PNAS 2010
NTm = 19θ = 4
Gamma distribution calibration
Ofiteru et al., PNAS 2010
' 2 1 2 1i tdX m p X X X dt X X dW
R2 = 0.2
- a = 0 model is totally neutral
Most abundant AOB
' 2 1 2 1i tdX m p X X X dt X X dW
Most abundant AOB
Including environmental factors
2.44 0.06 0.04T Cr
R2 = 0.39
“if a theory can explain 70% of the observed phenomena it will have served its purpose well”
MacArthur and Wilson 1967
Preliminary Application
• Using models to guide seeding and to predict dynamics– EG Low temp
anaerobic digestion
0 2 4 6 8 10 12 140
0.5
1
1.5
2
2.5
3
Methanogenic activity- H2/CO2
4oC_H2/CO2 8oC_H2/CO2 15oC_H2/CO2
The future
Telephony costsEnergy use in the
UK water sector
2003 2004 2005 2006 20070
200400600800
100012001400160018002000
Average BestWorst
Kw
h/M
l of
wast
ew
ate
r 1980 1990 2000 20100
10
20
30
40
50
60
70
Landline long distance
Year
Cen
ts/
min
ute
State of Working America 2006-2007; Federal Communications Commission
• Energy content of wastewater;15-20 Kj/g COD– 0.4-0.5 Kwh/person
• Energy demand of Conventional WWT– 0.2 Kwh/person
Heidrich et al., 2011
ACTIVATED SLUDGE IS
DEAD
Mara, D. D. (1974) Bacteriology for Sanitary Engineers, Churchill Livingstone, Edinburgh
and London, 209 p
“ ‘water bacteriology is really more than just the total count’ ”*
Thank you