Im Rahmen der Jahrestagungen der DECHEMA 2022 (Aachen) hat Roland Ulber die 2. CIT-Lecture mit dem Titel "Life and production on surfaces" gehalten und den CIT-Award verliehen bekommen.
In industrial biotechnological production processes, the term ‘‘biofilm’’ is mainly associated with strong negative effects on process control and product quality in connection with adhering growing micro-organisms. For example, they can block heat exchangers and thus reduce the economic efficiency of the process. Applications of biofilms and microbial communities growing as flocs have a longtradition in wastewater or flue gas treatment, where the organisms reduce the organic load of input streams. A major argument against biofilm processes is the problem of controlling adherent growth of microorganisms, although many recombinant human proteins or monoclonal antibodies, for example, are produced on an industrial scale by adherently growing (mammalian) organisms. However, there is usually no alternative to produce the desired target substances, so that ‘‘films’’ of organisms can be considered well-established in the field of red biotechnology,without the term ‘‘biofilm’’ having been used yet. Harding et al. proposed some criteria that should be fulfilled in order to characterize adherent growing (fungal)cells as biofilms, which can be summarizedas follows [1]:
- surface-associated growth of cells,
- embedding of the cells in a self-produced and secreted matrix of extracellular polymeric substances,
- altered gene expression due to attached growth.
When organisms organize themselves in biofilms, they usually achieve great advantages as a consortium. This is true not only for heterotrophic microbial systems, but also for a variety of autotrophic biofilms. For example, terrestrial cyanobacteria grow in the air on various surfaces such as trees or stones and on the ground. For protection against various environmental influences as well as for adhesion to the surface and cohesion between the cells,the cyanobacteria grow embedded in amatrix of extracellular polymeric substances (EPS). In addition to water, this consists mainly of various polysaccharides, proteins, and fatty acids and makes the biofilm tolerant to sometimes strong temperature fluctuations, dryness or high light irradiation. The release of antimicrobial compounds or toxins also ensures that the biofilm is not overgrown by other micro-organisms and protects against predators. In addition, some strains are able to adjust their pigment composition under different lighting conditions to make optimal use of the available light wavelengths. This combination of interesting components in the biomass with the high adaptability and tolerance to different cultivation conditions makes terrestrial cyanobacteria promising organisms for use in a variety of applications. The lecture takes up Harding’s points and uses heterotrophic and autotrophic biofilms to show the influenceof the surface on gene regulation, metabolomics, and productivity. Different biofilmreactor systems, which also allow scale-up, are described.
[1] M. W. Harding et al., Can filamentous fungi form biofilms? Trends Microbiol.2009,17 (11), 475–480. DOI: 10.1016/j.tim.2009.08.007
R. Ulber; Life and production on surfaces; Chem.-Ing.Tech. (2022) https://doi.org/10.1002/cite.202255338