Biofilms – Avoid, use and control

Figure 1. Scanning electron microscopic image of a Candida albicans biofilm.

Microorganisms on surfaces occur widely in nature. Bacteria, fungi and algae have adapted to growth on various surfaces and benefit considerably from this way of life, which is adapted to each particular location, for example on stones in a stream, and also in various kinds of piping. Their growth becomes visible to the human eye when biofilms develop excessively. Frequently the microbial growth causes damage to the material or impairs the functioning of technical equipment.

Interactions between microbial cells and surfaces

At Fraunhofer IGB, we have been working on questions in which the interactions between microbial cells and surfaces or the formation of biofilms play a role for several years. On the one hand, we use biofilms by targeted immobilization of microorganisms on a carrier material, for the production of valuable substances or for waste water purification.

On the other hand, we also consider the prevention and control of biofilms – where they are undesirable and cause damage – through our research. For example, we have developed test methods for the investigation of biofilms and are investigating surfaces and components in medical technology, construction, wastewater treatment and hygiene for microbiological contamination.

Examples of damage caused by biofilms are the deterioration of the efficiency of heat exchangers or air-conditioning systems. In the healthcare sector enormous efforts are being made to prevent the growth of biofilms on natural surfaces such as dental material as well as synthetic materials such as implants, catheters or medical devices – also due to high consequential costs in the event of human injury.

What are biofilms?

Biofilms are communities of bacteria, fungi or algae that attach themselves to surfaces and grow on them. They can be composed of individuals of a single species or of mixed populations of different species of organisms. In this case, they are adapted to the respective environment and have a higher resistance to environmental conditions. Characteristically, the cells are surrounded by a microbially induced matrix – the extracellular polymeric substance EPS – consisting of polysaccharides, a variety of proteins, lipids and often extracellular DNA. They provide protection to the population from chemical and physical environmental agents such as disinfectant solutions, biocides, antibiotics or radiation. This structure cannot be removed from the surface even by vigorous rinsing. Individual cells are released from the biofilm, which can re-colonize at another site and form a new biofilm.

Wherever biofilms concern you, we support you!

Today, we take a holistic approach to biofilm control. To sustainably and effectively remove unwanted biofilms from the process, we rely on a strategy combining individual concepts and methods:

Reduce the number of microorganisms in the process stream
Reduce nutrient flows
Antimicrobial surface modification
- Prevent adhesion of microorganisms
- Release of biocidal substances
Selection of surfaces that are easy to clean (easy-to-clean properties)
Continuous monitoring (permanently installed sensors as early warning systems and for cleaning control)

Application examples

Controlling the adhesion of microorganisms on surfaces by specific coatings

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Antimicrobial surfaces by the application of natural active substances

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Biofilms – Consultancy and range of services

Studies and scientific monitoring for the prevention and control of biofilms
Development, optimization and verification of desired biofilms with a positive effect on the process or system (e.g. biofilters, bioscrubbers, wastewater treatment)
Localization of biofilms or coatings in the process stream
Characterization and species identification (FISH, DNA barcoding)

Broad range of methods and infrastructure

Microbiological laboratories with modern equipment and an especially qualified team allow the handling of microorganisms of risk groups 1 and 2
Culture-based and molecular biological methods
Methods for evaluating adhesion properties and biofilm formation under static and dynamic conditions
- Flow cells
- Microfluidics
Biofilm reactors (e.g. CDC, Drip flow, Ribbons Device, …)
Raman spectroscope with 532 nm, 785 nm laser and CARS technology
Imaging techniques
- Scanning electron microscopy (SEM)
- Fluorescence microscopy (FISH, Zeiss LSM 710)
Quantitative real time PCR (qRT-PCR LightCycler 480)
Real time impedance analysis (ACEA xCELLigence) for the investigation of active substances on biofilms
Qualitative and quantitative measurement methods with the possibility to test different materials or products for industrial use (pilot scale)

Reference projects

BIOCLEAN –

BIOfilm management and CLEANing by leveraging fundamental understanding of biological, chemical and physical combined approaches

BIOCLEAN addresses the urgent need to create a sustainable training network across academia, industry and the healthcare sector which will fill the gap in Europe and beyond to produce highly skilled multi‑disciplinary young scientists competent in chemistry, engineering and experimental wet lab biology.

Duration: October 2016 – September 2020

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Demo-medVer – Decentralized mobile medical care with autonomous test platforms

The risk of further rapid spread of COVID-19 is particularly high in many developing and emerging countries due to inadequate hygienic conditions. Fraunhofer researchers are developing autonomous, fully and partially mobile platforms for testing for SARS-CoV-2 suitable for slums, refugee camps, urban and rural areas.

Duration: September 2020 – August 2021

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BioCapabili – Antibacterial bone implants to prevent local infections

In the binational project BioCapabili, Fraunhofer IGB and the French Carnot Institute CIRIMAT collaborate to equip bioactive, biomimetic CaP apatites with various antimicrobial compounds and to investigate them comprehensively. CaP apatites were prepared at CIRIMAT, focusing on synthesis, characterization and surface activity. Alternative surface modifications as well as the biological characterization of the modified CaP apatites were performed at Fraunhofer IGB.

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FoAM-BUILD – Functional Adaptive Nano-Materials and Technologies for Energy Efficient Buildings

The FoAM-BUILD project will develop a next generation External Thermal Insulation Composite System (ETICS). A new, lightweight and high insulating nano-cellular foam including a non-halogenated nano-based flame retardant will be developed. Also a moisture control system, based on a sensor network which measures moisture and liquid water on the façade will be developed to prevent microbiological growth on the façade.

Duration: September 2013 – August 2017