Study Sub-Membrane Structure and Corresponding Functions of Conductive Bacteria Cable by SPMs

Abstract

As a kind of surface characterization tool, traditional scanning probe microscopy (SPM), especially atomic force microscopy (AFM), is hard to explore the structures underneath sample surface and correlate them with the corresponding functions. With the development of advanced AFMs, this obstacle has been overcome gradually, for example, with the application of quantitative dynamic AFM mapping, the hollow helical amyloid self-assembly fibrils have been identified;[1] and the protein structure flexibility on inner/outer sides of membrane is also possible to determine[2]. However, distinguishing the sub-surface features and corresponding function of macro-size biological samples, such as bacteria and cells, is still challenging to SPM. In this presentation, we combined quantitative dynamic AFM, AFM based manipulation, electrostatics force microscopy and scanning ion conductance microscopy to illustrate the inside membrane feature of recently identified conductive bacteria cable[3]. Basing on the SPM results, we proposed the model to explain the reason of the bacterial function to transport electrons over centimeter distance along cable direction. On one hand, this work will help biologists to understand the bacterial cable and promote the future application in nano-conductive cable field; on the other hand, it will inspire the further applications of SPM to beyond surface limitation on macro-size bio-systems.1. Zhang, S., et al., Coexistence of ribbon and helical fibrils originating from hIAPP20-29 revealed by quantitative nanomechanical atomic force microscopy. PNAS, 2013.2. Dong, M.D., S. Husale, and O. Sahin, Determination of protein structural flexibility by microsecond force spectroscopy. Nat. Nano., 2009. 4(8): p. 514-517.3. Pfeffer, C., et al., Filamentous bacteria transport electrons over centimetre distances. Nature, 2012. 491(7432).