Mycobacteria are unicellular, aerobic, Gram-positive bacteria with high G+C DNA.  They are taxonomically related to the antibiotic-producing streptomycetes which are studied intensively at the John Innes Centre. The mycobacteria are unusual among bacteria in that they have an enormously thick, hydrophobic cell wall that prevents desiccation. Many mycobacteria are harmless and useful because they degrade organic matter in soil.  Some are used industrially to help convert cheap plant sterols (sitosterol) into useful steroid hormones.  Better known are, however, the few pathogenic mycobacteria which cause the ancient diseases tuberculosis (M. tuberculosis, M. africanum, M. bovis) or leprosy (M. leprae).

Leprosy is gradually becoming less important, but tuberculosis is currently the bacterial disease that kills the largest number of people world-wide.  The emergence of difficult-to-cure multi drug-resistant tuberculosis is of great concern.

The entire genome of one M. tuberculosis strain has been sequenced, and the M. leprae genome sequence will soon be completed.

These dangerous, very slow growing mycobacterial pathogens are difficult to manipulate.  Mycobacterium genes are poorly expressed from their own promoters in E. coli.  Therefore the relatively fast growing, non-pathogenic M. smegmatis is often used as a host strain for gene cloning.

At the John Innes Centre, we study the functioning of Streptomyces transposable elements in M. smegmatis, and the mechanism of the newly discovered inter-specific conjugation from Streptomyces to M. smegmatis.
 
 

Group leaders
 

Dr. Tobias Kieser