Additions and corrections

Electroactive biofilms: Current status and future research needs

Abhijeet P. Borole,* Gemma Reguera, Bradley Ringeisen, Zhi-Wu Wang, Yujie Feng and Byung Hong Kim

Energy Environ. Sci., 2011, 4, 4813–4834, DOI: 10.1039/C1EE02511B. Amendment published 22^nd December 2011.

The statements made regarding use of denatured samples in Section 3.4.3 (page 4822) in context of ref. 154 were incorrect. The cytochrome denaturation studies in ref. 154 involved the use of a chemical reagent rather than heat.

Original text:

Mechanically sheared pili and other extracellular components immobilized and dried on electrodes had increased conductivity in comparison to fractions sheared from a pilin-deficient mutant strain¹⁵⁴ Furthermore, the dried pili preparations retained conductivity after the cytochromes were denatured by heat treatment¹⁵⁴ The conductivity of the heatdenatured samples (6 μS cm^-1) was 3-times lower than that measured in peeled biofilm controls (18 μS cm^-1), consistent with cytochromes playing a key role in the conductivity of EABFs. Moreover, conduction across the pili fractions and the biofilms was temperature-dependent and metallic in nature. However, a potential doping of the pili preparations due to the denaturation of the abundant cytochromes was never evaluated in these studies. Although the true contribution of the conductive pili to EABFs and its association with cytochromes remains to be elucidated, a combined role for cytochromes and pili of the biofilm matrix involving a superexchange mechanism seems plausible.¹⁵⁵

Corrected text:

Mechanically sheared pili and other extracellular components, including c-cytochromes, immobilized and dried on electrodes had increased conductivity in comparison to fractions sheared from a pilin-deficient mutant strain,¹⁵⁴ which was also defective in cytochromes such as OmcS.^252,253 The conductivity of the pili preparations (6 μS cm^-1) was comparable to that measured in peeled biofilm controls (18 μS cm^-1). Moreover, conduction across the pili fractions and the biofilms was temperature-dependent and metallic in nature. Chemical treatment with a reducing agent to denature the cytochromes in the pili preparation did not affect the measured conductivity.¹⁵⁴ The treatment is unlikely to release the metal-containing heme, because the prosthetic group remains bound to the cytochromes present in the sample. Although the association of the conductive pili and cytochromes in EABFs remains to be elucidated, a combined rolea combined role for cytochromes and pili of the biofilm matrix involving a superexchange mechanism seems plausible.¹⁵⁵

252 M. Izallalen, R. H. Glaven, T. Mester, K. P. Nevin, A. E. Franks and D. R. Lovley, Going Wireless? Additional Phenotypes of a Pilin-Deficient Mutant Weaken the Genetic Evidence for the Role of Microbial Nanowires in extracellular Electron Transfer. 108th General Meeting of the American Society for Microbiology. Boston, MA, 2008.

253 D. L. Cologgi, S. Lampa-Pastirk, A. M. Speers, S. D. Kelly and G. Reguera, Proc. Natl. Acad. Sci. U. S. A., 2011, 108, 15248–15252.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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