Applied Microbiology and Biotechnology

, Volume 68, Issue 1, pp 117–123

The mechanism of bacterial indigo reduction

Applied Microbial and Cell Physiology

DOI: 10.1007/s00253-004-1839-4

Cite this article as:
Nicholson, S.K. & John, P. Appl Microbiol Biotechnol (2005) 68: 117. doi:10.1007/s00253-004-1839-4


The reduction of water-insoluble indigo by the recently isolated moderate thermophile, Clostridium isatidis, has been studied with the aim of developing a sustainable technology for industrial indigo reduction. The ability to reduce indigo was not shared with C. aurantibutyricum, C. celatum and C. papyrosolvens, but C. papyrosolvens could reduce indigo carmine (5,5′-indigosulfonic acid), a soluble indigo derivative. The supernatant from cultures of C. isatidis, but not from cultures of the other bacteria tested, decreased indigo particle size to one-tenth diameter. Addition of madder powder, anthraquinone-2,6-disulfonic acid, and humic acid all stimulated indigo reduction by C. isatidis. Redox potentials of cultures of C. isatidis were about 100 mV more negative than those of C. aurantibutyricum, C. celatum and C. papyrosolvens, and reached −600 mV versus the SCE in the presence of indigo, but potentials were not consistently affected by the addition of the quinone compounds, which probably act by modifying the surface of the bacteria or indigo particles. It is concluded that C. isatidis can reduce indigo because (1) it produces an extracellular factor that decreases indigo particle size, and (2) it generates a sufficiently reducing potential.

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  1. 1.Plant Science Laboratories, School of Plant Sciences,The University of ReadingReadingUK