Pablo Bravo
PhD Candidate in Quantitative Biosciences at GeorgiaTech. I am interested in biofilms, and how their topography evolves and what we could learn about their development by looking at them
A. veronii
E. coli
S. cerevisiae (wt)
S. cerevisiae (aa)
V. cholerae (wt)
V. cholerae (EPS-)
K. pneumoniae
B. cereus
S. aureus
Hall-Stoodley, L., et al., Nat Rev Microbiol (2012)
Lacy, D. E., et al. Journal of Infection (1993).
McConoughey, S., et al. F. Microbiology (2014)
Enning, D., et al. Appl. and env. microbiology (2014).
Biomedical
Industry
Ecological
Biofilms are complex surface-attached 3D structures
Extracellular matrix formed of polysaccharides, DNA, and proteins
Surface
Interface
Cells
Horizontal Growth
Vertical
Growth
Understanding vertical growth could provide insight in the developmental process
Visualizing Bacterial Colony Morphologies Using
Time-Lapse Imaging Chamber MOCHA
Peñil Cobo et al. 2017
The geometry of the colony is setting a limit in growth, not nutrient availability in the environment!
Growth rate
Decay rate
Diffusion length
Describes the height \(h\) of a microbe colony
Tested against multiple microbes, and up to two weeks of growth!
In press at PNAS
From nutrient dynamics:
We approximate the total amount of nutrients \(N\) inside a colony:
Growth rate
Decay rate
Diffusion length
And build a heuristic model that describes vertical growth dynamics
Additional measurements for 14 days. Showing that different growth dynamics in the 48h period, can lead to large changes in longer timescales
And long-time agreement does not mean lower accuracy in the shorter timescales!
Maximum height can be obtained from the model easily:
Adkins, Kolvin, and You, et al. 2022
Profiles are flat. A few cells in amplitude, over thousands of micrometers!
\(500 \mu m\)
Staphylococcus aureus
Bacillus cereus
Eschericia coli
\(2 mm\)
\(8 \mu m\)
Time since inoculation [hours]
\(0\)
\(24\)
\(48\)
A. veronii
E. coli
S. cerevisiae (aa)
S. cerevisiae (wt)
V. cholerae (wt)
V. cholerae (EPS-)
K. pnerumoniae
B. cereus
S. aureus
Aeromonas veronii
Eschericia coli
On growth and form of Bacillus subtilis biofilms
Dervaux, et al. 2014
Fluctuations in:
Height differences
Different rates \( (\alpha, \beta, h^*) \)
Paper | N_x | N_y | Roughness |
---|---|---|---|
On growth and form of Bacillus subtilis biofilms | 2 | 1.5 | 0.5-0.7 |
Roughening instability of growing 3D bacterial colonies | 1.2 | 1 | 0.67 |
Yunkerlab-Interferometry | 3.2 | 3.6 | 0.74-0.84 |
Morphological instability and roughening of growing 3D bacterial colonies
Martinez-Calvo and Bhattacharjee, et al. 2022
\(w_l(t) \propto l^{H} \)
Dervaux, et al. 2014
Martinez-Calvo and Bhattacharjee, et al. 2022
\(H\)
\(l_{\text{sat}}\)
\(w_{\text{sat}}\)
Crystal growth
Biofilms
Roughness \(H\), after a period of time, stabilizes at \(H_{\text{steady}} \sim 0.8\)
Paper | Roughness | ||
---|---|---|---|
On growth and form of Bacillus subtilis biofilms | ~2 | ~1.5 | 0.5-0.7 |
Morphological instability and roughening of growing 3D bacterial colonies | ~1.5 | ~1 | 0.67 |
Yunkerlab-Interferometry | ~3 | ~2.5 | 0.74-0.84 |
\(N_x\)
\(N_y\)
There is high variability between microbes
And an apparent correlation between vertical growth dynamics and the topography!
Colonies reach nutrient depletion length \(L\)
Knowing the moment when the colony is growing the fastest, just by looking at
fluctuations
\(S(k) [\mu m^4]\)
\(k [\mu m^{-1}]\)
\(10^4\)
\(10^3\)
\(10^2\)
\(10^1\)
Dynamic scaling, a test for self-similarity requires:
\(\nu = 1+2H\)
We do not see observe dynamic scaling.
It is close but not the same!
Dynamic scaling
(Family-Vicsek)
\( \nu = 1 + 2\alpha\)
Two regimes:
*What about biofilm-liquid interface?
Biofilm composition and properties
Memory
Flat
Patterned
Wells, et al. 2014
NIH-NIMS
NSF BMAT
Biolocity
Dr. Peter Yunker
Dr. Brian Hammer
Dr. Siu Ling Ng
Dr. Thomas Day
Aawaz Pokhrel
Emma Bingham
Adam Krueger
Raymond Copeland
Maryam Hejri
Lin Zhao
Chris Zhang
Universal bulk vertical growth dynamics, but fluctuations do not appear to be!
Can we establish a link between topographies and biofilm development?
By Pablo Bravo
Presentation for PoLS Lunch and Learn at GT
PhD Candidate in Quantitative Biosciences at GeorgiaTech. I am interested in biofilms, and how their topography evolves and what we could learn about their development by looking at them