Simultaneous interferometric measurement of corrosive or demineralizing bacteria and their mineral interfaces.

Here, we report simultaneous surface profile measurements of several bacterial species involved in microbially influenced corrosion and their solid-surface interfaces by using vertical scanning interferometry. The capacity to nondestructively quantify microscale topographic changes beneath a single bacterium without its removal offers a unique opportunity to examine in vivo microbe-surface interactions.

In search of the microbe/mineral interface: quantitative analysis of bacteria on metal surfaces using vertical scanning interferometry.

To understand the development of biofilms on metal surfaces, analysis of initial bacterial attachment to surfaces is crucial. Here we present the results of a study, using Shewanella oneidensis MR-1 as a model organism, in which vertical scanning interferometry (VSI) was used to investigate the initial stages of cell attachment to glass, steel and aluminium surfaces. It was found that while VSI gave unambiguous results with opaque surfaces, when reflective surfaces were used, an artifact sometimes appeared, with the bacteria appearing as rod-shaped pits rather than as cells on the surface. When the bacteria were altered to increase opacity, this artifact disappeared, and upon further investigation, it was found that the observational artifact was the result of a conflict between light reflected from the bacteria and the light reflected from the bacteria-metal interface. These results suggest that not only can bacteria be measured on surfaces using VSI, but with some modifications to the analytical software, there may be a unique window for studying the bacterial/substrate interface that can be used for quantitative observations. Imaging and characterization of the bacteria-substrate interface in vivo (previously invisible) will provide new insights into the interactions that occur at this important juncture.

Microorganisms, mineral surfaces, and aquatic environments: learning from the past for future progress.

The interactions between the geosphere and the biosphere are central questions in environmental and geological research. The relationship between bacteria and their environment is an important example of these interactions. By studying microbial communities in modern environments, it is possible to understand the underlying mechanisms that shape these environments and apply this knowledge to the rock record. Recently, new experimental and theoretical methods, ranging from nano- and biotechnology to mathematical and conceptual modelling, have come into play. Thus, new opportunities for interdisciplinary research in the field of geobiology have emerged. In this paper, we review aspects of state-of-the-art imaging and modelling techniques and propose a research concept linking the experimental and the theoretical approaches.

Variation of crystal dissolution rate based on a dissolution stepwave model.

A formulation based on defect-generated dissolution stepwaves of the variation of dissolution rate with the degree of undersaturation is validated by near-atomic-scale observations of surfaces, Monte Carlo simulations, and experimental bulk dissolution rates. The dissolution stepwaves emanating from etch pits provide a train of steps similar to those of a spiral but with different behavior. Their role in accounting for the bulk dissolution rate of crystals provides a conceptual framework for mineral dissolution far from equilibrium. Furthermore, the law extends research to conditions closer to equilibrium and predicts a nonlinear decrease in the rate of dissolution as equilibrium is approached, which has implications for understanding artificial and natural processes involving solid-fluid reactions.