Information for Researchers, No. 40 | May 3, 2024

Priority Programme “Productive Biofilm Systems” (SPP 2494)

In March 2024, the Senate of the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) established the Priority Programme “Productive Biofilm Systems” (SPP 2494). The programme is designed to run for six years. The present call invites proposals for the first three-year funding period.

Research Topic of the Priority Programme

Most microorganisms that we know grow in the form of biofilms, and everybody is familiar with this ubiquitously distributed life form. Although most known microbial biocatalysts on Earth grow in the form of biofilms presenting a high cell density, industrial bioprocesses use suspended cells in stirred tank reactors. As a result, the natural advantages such as high cell density and robustness against process fluctuations are lost. There is a lack of knowledge, experience and novel reactor technology that hampers the successful implementation of these systems as new biocatalytic tools in a bio-based economy. Consequently, there is an urgent need in fundamental research to understand biofilms in a productive technical context, to harness their full potential by metabolic and genetic engineering and to apply them in reactor environments that allow competitive space-time yields in future applications.

Focus of Projects within the Priority Programme

Overall, we envisage the submission of joint projects in which at least two groups with complementary expertise work together and simultaneously offer at least one specialised technology or area of knowledge to the other partners.

In the best case, the partners design a project that covers two of the following five focus areas:

1) Steering biofilm architecture towards high productivity

Biofilms are immobile biocatalysts with superior characteristics regarding continuous processes. Nevertheless, until now, we have only insufficient control over (I) biofilm architecture, (II) chemistry and density of extracellular polymeric substances, (III) cellular activity as well as (IV) cell-cell and cell-substrate interaction to harness their full potential and render them more predictable. Within this objective, we aim to establish how process conditions and substrate interactions can be used to tailor biofilms towards specific process goals. Accordingly, among others, the following research questions are supposed to be answered within the projects focusing on this objective:

  • Is the steadily growing biofilm thickness a process parameter that can be controlled for an optimum turnover rate?
  • How can we engineer the biofilm matrix to optimise the biocatalyst performance?
  • Can we predict and engineer the three-dimensional architecture of biofilms using process parameters as well as molecular mechanisms and synthetic engineering?

2) Understanding biocatalyst adaptation resulting from spatiotemporal location

Continuous bioprocesses develop their full potential when they run in a stable manner over longer periods without losing activity. Ideally, biocatalytic activity even improves during the process. As biofilms are natural retentostats, they are consequently naturally suited in this respect. Still, we need to understand the role and kinetics of the genetic drift, which drives biofilm adaptation and selection, to predict and tune stability of biofilm-processes. Also, we will have to establish the regulatory routines with which the cells adapt to process conditions and to the stabile but often steep gradients within the biofilms. We expect that the following research questions will be in the focus of this research objective:

  • What are factors that interfere with long-time activity in biofilms and how can these factors be steered to adjust biofilm activity and reactivity?
  • How can we steer the uncoupling of growth and catalysis in biofilm systems?
  • What are the molecular routines that run at different depths of biofilms and can we use these adaptation mechanisms in applied processes?

3) Construction of scalable biofilm reactors

Most bioprocesses are conducted using traditional stirred tank reactor systems, and there is a general shortage of new reactor technologies. In fact, we hypothesise that a majority of processes are designed for stirred tank reactors because these systems are well characterised and not because they are the most suitable reactor technology. At least in the productive biofilm field, inefficient reactor technologies are a key bottleneck to advancing technology readiness levels. We expect that innovations will be made within this objective that merge state-of-the-art additive manufacturing, 3D printing, material manufacturing and 3D modelling of fluid mechanics at interfaces. Consequently, the following research questions should be reflected in projects addressing this objective:

  • What are the blueprints of suitable biofilm reactors that support competitive turnover rates and allow for full process control?
  • How can we integrate sufficient sensor systems to implement effective process control?
  • How can we upscale these systems?

4) Developing biofilm analytical tools to quantitatively follow biocatalyst activity and interaction with substrate over time and position

Biofilms benefit from their heterogeneity that is foremost the result of spontaneous mutations and an adaptation to prevailing gradients. Online imaging of biofilm structure and productivity as well as analysis of local process conditions are necessary to establish predictable processes and process control. Moreover, establishing new strains with altered biofilm characteristics necessitates ways to quantify their behaviour at the individual stages of biofilm formation and maturation. For the biotechnological realisation, we will depend on ways to integrate these imaging and sensory tools in scalable biofilm reactor infrastructures. We envisage research projects being established that address the following questions, among others:

  • Are we able to observe the activity and structure of biocatalysts in biofilm systems both at micro and meso scales?
  • Can we predict future biofilm architecture based on molecular characteristics of production strains?
  • Can multiparallel biofilm analytical tools be informative with regard to industrial upscaling?

5) Building instructive models for biofilm processes and reactors

While we have rather complex models for stirred tank reactor-based bioprocesses that even allow the setup of digital twins for these systems, modelling is comparably less established for biofilm-based processes. Productive biofilm models will necessarily be rather complex as they have to include not only the three-dimensional architecture of the biofilms and the prevailing gradients of substrates and products but also cellular activity as well as the interactivity and cooperativity of the cells. The following research questions might act as guidelines for possible research projects addressing this objective:

  • Can we model biofilm processes in a way that allows us to optimise space-time yields and predict productivity over longer periods of time?
  • Can we establish digital twins for complex biofilm processes?
  • Can we integrate process heterogeneity as well as adaptations of genetic information metabolism (e.g. genetic drift and regulatory adaptations) in advanced models?

Although biofilms are suited for many process concepts employing a variety of microbial workhorses, we will focus the research conducted within the priority programme using the following guidelines: 

  1. Only biofilms consisting of genetically tractable and defined organisms can be considered.
  2. All biofilm systems under consideration have to be applicable in white biotechnology. Hence, all projects should aim to produce important bulk and fine chemicals. Medical as well as wastewater applications are excluded from the envisioned Priority Programme. 
  3. We consider the interface between biofilm substrates and microorganisms (biohybrid material) to be particularly interesting and encourage projects in which the substrate employs a specific long-lasting function for the process (hydrogen or light source for chemolithoautotrophic organisms, responsiveness towards process conditions, e.g. by surface increase, decrease or hydrophobicity variation). 

Research projects aiming to study direct interaction between electrodes and biological systems or to develop biofilms as materials without biocatalytic focus cannot be considered as this could potentially be covered by another Priority Programme. 

On 21 June 2024, there will be an online coordination meeting (Rundgespräch) to enhance the coherence of the Priority Programme. This meeting will also allow to discuss (bilaterally) potential collaborations or joint proposals. If you are interested, please contact the coordinator of the Priority Programme in advance.

Proposal Instructions

Proposals must be written in English and submitted to the DFG by 1 October 2024. Please note that proposals can only be submitted via elan, the DFG’s electronic proposal processing system. To enter a new project within the existing Priority Programme, go to Proposal Submission – New Project/Draft Proposal – Priority Programmes and select “SPP 2494” from the current list of calls. 

In preparing your proposal, please review the programme guidelines (DFG form 50.05, section B) and follow the proposal preparation instructions (DFG form 54.01). These forms can either be downloaded from our website or accessed through the elan portal.

Applicants must be registered in elan prior to submitting a proposal to the DFG. If you have not yet registered, please note that you must do so by 17 September 2024 to submit a proposal under this call; registration requests received after this time cannot be considered. You will normally receive confirmation of your registration by the next working day. Note that you will be asked to select the appropriate Priority Programme call during both the registration and the proposal process.

The DFG strongly welcomes proposals from researchers of all genders and sexual identities, from different ethnic, cultural, religious, ideological or social backgrounds, from different career stages, types of universities and research institutions, and with disabilities or chronic illness. With regard to the subject-specific focus of this call, the DFG encourages female researchers in particular to submit proposals.

The reviewing process will include a colloquium with presentations and discussions between applicants and reviewers, scheduled to take place in January 2025. The date and location of the colloquium as well as all other relevant updates will be published in due course. 

Further Information

The elan system can be accessed at:

DFG forms 50.05 and 54.01 can be downloaded at:

For scientific enquiries, please contact the Priority Programme coordinator:

  • Professor Dr. Johannes Gescher
    Technische Universität Hamburg
    Institut für Technische Mikrobiologie
    Kasernenstraße 12
    21073 Hamburg
    phone +49 40 42878-3634

Questions on the DFG proposal process can be directed to:

Programme contact:

Administrative contact: