Morphogenesis and heterogeneity in liquid-grown streptomyces cultures
The filamentous bacteria Streptomyces are widespread inhabitants of terrestrial soils.
- Zacchetti, B.
- 14 November 2018
- Thesis in Leiden Repository
The filamentous bacteria Streptomyces are widespread inhabitants of terrestrial soils. Streptomycetes are not only among the most potent producers of valuable secondary metabolites (e.g. antibiotics), but also the source of various industrially relevant hydrolytic enzymes. The mode-of-growth of streptomycetes under industrial conditions is markedly different to that observed in their natural habitat. Most species form dense particles called pellets. Pellets are heterogeneous in size; more specifically at least two populations of differently-sized pellets exist in submerged cultures. Importantly, pellet size and production have been shown to be to be tightly correlated in streptomycetes. The study and control of pellet size heterogeneity in streptomycetes is the subject of the research presented in this thesis. Here, the various phenomena occurring throughout growth are characterized with the aim of understanding the factors underlying this phenomenon. Subsequently, the obtained knowledge is applied to obtain homogeneously-sized pellets of the industrial workhorse Streptomyces lividans. The work described in this thesis also addresses the fate of pellets at late stages of growth and a growth strategy representing a valuable alternative to conventional liquid cultures.