Stress responses and sugar metabolism in Bacillus subtilis. A transcriptomic portrait

PhD ceremony: Mr. A.T. Lulko, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Title: Stress responses and sugar metabolism in Bacillus subtilis. A transcriptomic portrait

Promotor(s): prof. O.P. Kuipers

Faculty: Mathematics and Natural Sciences

The work presented in Andrzej Lulko’s thesis focuses on the regulation of gene expression of Bacillus subtilis in response to stress conditions by using the DNA microarrays. There were two major goals of the project described in his thesis: the development of the DNA microarrays technology and the implementation of this technology to investigate the effects of various stress conditions encountered for example under industrial food fermentation processes.

In natural environments as well as during industrial processes, microorganisms are often challenged with a variety of unfavourable conditions. To increase their chance of survival, bacteria evolved various mechanisms to confront and adapt to encountered stresses. In general, they achieve that by a concerted reprogramming of gene expression coordinated by transcription factors and leading to a rapid and optimal adjustment to a particular stress. Such a reprogramming of gene expression can be monitored and quantified by DNA microarrays, the technology which allows measuring changes in expression levels of thousands of genes in a single experiment.

The effects of three different types of stress conditions were investigated by Lulko: (i) overproduction and secretion of a heterologous protein, (ii) exposure to lactic acid and (iii) disturbance of carbon-metabolism caused by the point mutations or absence of the CcpA protein, the most important transcription factor in catabolite control regulation.