# Presentation: 363825

## Steven Lower

**Ruchi Yongsunthon**
**Brian Lower**
**Michael Hochella, Jr.**

**MINERAL SPECIFIC PROTEINS**
**SYNTHESIZED BY BACTERIA**

**Ohio State University**
**Virginia Tech**

- ***This research has been published in *Science, Geochimica et Cosmochimica Acta, Advances in Agronomy, Geomicrobiology Journal, *and *Eos.*

## interfacial forces and proteins

**forces control, and are themselves modulated by,       the expression of biopolymers on a bacterium’s surface*

- G. Bowles

## A comparison of two organisms that work in the realm of the nanometer.  

*Consider the following...*

## metal reducing bacteria & oxides

*Shewanella* interactions with Fe oxyhydroxides

- primitive form of respiration using Fe(III) solids
- remediation of organic and inorganic pollutants in 	surface and subsurface environments

*Shewanella*

- Fe(III) mineral

## inside

**inside**

**inner membrane**

**periplasm**

**outer membrane**

**outside**

## Cell-material interface

*discover forces and proteins*

*mimic and utilize information*

**Cell-material interface**

- F~e -*D*

- theory

## biological force microscopy

**biological force microscopy**

- lever

- mineral

- laser

## Force-distance curves                                         using different minerals, bacteria, and solutions

**Force-distance curves                                         *****using different minerals, bacteria, and solutions***

- approach

- retraction

## DLVO Theory

-  = surface charge                                                    R = radius                                                         = dielectric constant o= vacuum permittivity *d *= distance                 = 1 / Debye length

- F(*d*) =

- 4 1 2 R

- o

- e -  *d*

- H* *= Hamaker constant                                                                R = radius                                                       *d*  = distance

- ~(salt concentration) –1/2

## subsurface transport in the environment

- blue – high IS

**subsurface transport in the environment**

***(approach measurements between G- bacterium and a silicate)***

**approach only**

## Force-distance curves                                               (retraction forces between Shewanella and AlOOH vs FeOOH)

**Force-distance curves                                               ****(retraction forces between *****Shewanella and ******AlOOH****** vs ******FeOOH*****)**

- approach

- retraction

**AlOOH**

**FeOOH**

**Shew**

## energy values between Shewanella and mineral (as function of oxygen concentration)

**attoJoules (10****-18**** J)**

***Control experiment with nonviable cells ~6 aJ (did not change with mineral, oxygen concentration, or contact time)***

## Slide 13

## Worm-like Chain Model

- F(*d*) = (*k* T / *b*) [0.25 (1 – *d* / L)–2 – 0.25 + *d* / L]

## OM protein expression patterns Shewanella and AlOOH or FeOOH 

**OM protein expression patterns***** ******Shewanella *****and**** ****AlOOH**** ****or**** ****FeOOH **

*protein signature observed in 80% of the data; only with goethite after some period of “recognition time”*

## 2D Gel Electrophoresis of OM Proteins

- excise proteins
- & fragment   into peptides

- mass spec & database search

**2D Gel Electrophoresis of OM Proteins**

- extract membrane proteins

- culture cells

- separate proteins

- compare with force signature

- force  microscopy

##         pH  4.0        5.0        6.0        7.0        8.0        9.0 

**        ****pH  4.0       **** ****5.0       **** ****6.0       **** ****7.0       **** ****8.0      ****  ****9.0 **

**terminal electron acceptor -**** ****O****2**** ****vs**** ****Fe(III)**

## Cell-material interface

*discover forces and proteins*

*mimic and utilize information*

**Cell-material interface**

- F~e -*D*

- theory

## peptide phage library expose to target mineral

- wash away unbound phage         elute bound phage

- “bio-panning”

- isolate clones, sequence DNA to find mineral-binding motif,

## biological cell lithography

- bacterium as living “pen” that produces and secretes genetically engineered proteins

- T. Beveridge

- S-layer protein

## nanoscale forces and proteins

- quantify natural forces of affinity between inorganic crystalline phases and proteins synthesized by bacteria
- use theoretical models and protein expression patterns to identify putative mineral specific proteins
- mimic natural specificity by attempting to fabricate peptides with unique mineral-binding motifs
- use living microbial cells as a lithographic tool

## Acknowledgements

- Terry Beveridge, John Smit, Courtney Crummett, Graeme Bowles

* **Steven Lower – Ohio State University – Lower.9@osu.edu*

- National Science Foundation (GEO & ENG)
- Department of Energy
- American Chemical Society

- ***This research has been published in *Science, Geochimica et Cosmochimica Acta, Advances in Agronomy, Geomicrobiology Journal, *and *Eos.*