Bacteria are highly complex and diverse organisms that have adapted to survive in ecological niches ranging from the most extreme to the most heterogeneous environments. Actinobacteria, with their... Show moreBacteria are highly complex and diverse organisms that have adapted to survive in ecological niches ranging from the most extreme to the most heterogeneous environments. Actinobacteria, with their beautiful morphologies and complex multicellular life cycle, are a striking example. These filamentous bacteria produce many enzymes and natural products, including two-thirds of all known antibiotics, which makes them highly relevant for medical, biotechnological and industrial applications. In Streptomyces, complex and intertwining regulatory networks, consisting of pathway-specific and global regulators, control development and antibiotic production in response to environmental stimuli and stresses. This thesis explores how the model organism Streptomyces coelicolor senses environmental signals, related to oxygen stress and the availability of aminosugars, and how the bacterium translates these into appropriate responses. Show less
The soil is a thriving ecosystem, composed of both living and non-living matter with a multitude of interactions between them. It is considered as the most diverse microbial habitat on earth. Soil... Show moreThe soil is a thriving ecosystem, composed of both living and non-living matter with a multitude of interactions between them. It is considered as the most diverse microbial habitat on earth. Soil microorganisms perform important functions in recycling nutrients. They act as nutrient scavengers, obtaining nutrition from dead, decaying matter of plants and animals. Actinomycetes (including Streptomyces) are a large group of filamentous bacteria and may account even 30% of the total microorganisms in the soil rhizosphere, depending on nutrient availability (Barreto et al., 2008; Kennedy, 1999).They are able to utilize broad range of naturally occurring polymers, including starch, cellulose, chitin and xylan. A sufficiency of utilisable organic material promotes the vegetative growth of these bacteria, thereby delaying morphological development and associated antibiotic production. My thesis focuses on understanding the molecular mechanisms by which Streptomyces link nutrient availability with antibiotic production and development. Show less
