Figure: Backside of a sheet pile element, showing a clearly visible reduction in wall thickness due to microbially influenced corrosion (MIC), eventually caused by sulfate-reducing bacteria. Typical features are the lamellar corrosion deposits, consisting mainly of iron oxides and hydroxides.
Material-Related Microbiology: Innovative Research and Analytical Services for Sustainable, Forward-Thinking Solutions
Microorganisms such as bacteria, yeasts or molds and their spores are omnipresent in our environment. The Microbiology working group is dedicated to a material-related microbiology, investigating microbial interactions with a broad range of materials. Such materials may be plastics, metals, technical fluids or building materials. The interaction of microorganisms with respective materials can result in colonization, alteration, or even corrosion and structural degradation.
The research content of the working group is influenced by the various disciplines available at Leibniz-IWT, paving the way to interdisciplinary projects. The service sector further facilitates a direct access to analytical questions and problems of industrial customers, resulting in new research topics based on currently relevant issues.
Analytical Services for You: From Standardized Tests as per DIN EN ISO 846:2020 to Customized Corrosion and Inertness Tests
As a service partner, the Microbiology working group offers inertness tests and testing of antimicrobial and biocidal effects of materials in accordance with international standard methods, such as DIN EN ISO 846:2020 – Determination of the effect of microorganisms on plastics; RTCA DO 160 – Environmental conditions and test procedures for airborne equipment – fungus test or the MIL-STD-810 Fungus test.
The working group also offers customized services in the field of microbial influenced corrosion (MIC). MIC can occur under defined environmental conditions on various structures, for example in the form of biogenic sulfuric acid corrosion on concrete buildings or as steel corrosion on sheet pile walls due to the activity of anaerobic microorganisms. For the analysis of MIC, the working group applies a diverse portfolio of both conventional techniques (cultivation, isolation) and advanced methods, including, for example, MALDI-TOF mass spectrometry and next-generation sequencing.
Figure: Analysis according to DIN EN ISO 846:2020, procedure A (determination of inertness of plastics to fungal growth). Extensive growth of test fungi is visible on the test specimen. The material is not inert and provides a nutrient source for fungal growth. The uninoculated, sterile reference sample is shown in the background.
Analytical Services
Standard Tests
The testing laboratory is accredited in accordance with DIN EN ISO/IEC 17025. Specific methods in our portfolio have accreditation from the German Accreditation Body (DAkkS). More detailed information and the certificate can be found here.
DIN EN ISO 846:2020, Procedure A–D
Plastics – Determination of the effect of microorganisms on plastics
A: Fungal growth test, B: Determination of fungistatic efficacy, C: Resistance to bacteria, D: Soil burial test
ISO 22196:2011
Measurement of antibacterial activity on plastic and other non-porous surfaces
JIS Z 2801:2010 (Amendment 1:2012) (= ISO 22196:2011)
Antibacterial products – Test for antibacterial activity and efficacy
DIN EN ISO 20743:2021
Textiles – Determination of the antibacterial effectiveness of textile products
JIS L 1902:2015 (= DIN EN ISO 20743:2021)
Textiles – Determination of antibacterial activity and efficacy on textile products
ISO 13629-2:2014
Textiles – Determination of antifungal activity of textile products – Part 2: Plate count method
DIN EN 14119:2003
Testing of textiles – Determination of the effect of microscopic fungi (microfungi)
RTCA/DO-160G, Section 13RT – Fungus Resistance
Environmental conditions and test procedures for airborne equipment – fungus resistance
ASTM E2149-10
Standard test method for determining the antimicrobial activity of immobilized antimicrobial agents under dynamic contact conditions
ASTM G 21-15
Standard practice for determining resistance of synthetic polymeric materials to fungi
DIN EN 15457:2022
Paints and varnishes – Laboratory method for testing the effectiveness of film preservatives in a coating against fungi
MIL-STD-810H Method 508.8 Fungus
Susceptibility of materials to fungal growth
AITM 3-0026 (Airbus Industry Test Method)
Sealants – Determination of microbiological performance
AITM 7-0011 (Airbus Industry Test Method)
Resistance to fungal growth
Individual Services
The following services are available on request and are adapted to individual customer’s needs:
Analysis of corrosion cases where microbially influenced corrosion (MIC) is suspected
The working group has many years of experience in sampling, analyzing and evaluating microbially influenced corrosion. Practical examples include corroded sheet pile walls in marine and limnic habitats, corrosion on gas pipe lines, biogas plants or wastewater-associated concrete structures. Each corrosion case is addressed individually with each customer on a case-by-case basis.
Detection of bacteria, molds and yeasts
This includes for example the identification and quantification of fecal bacteria in the event of damage or the identification of indoor molds. Analytical requests are addressed on a case-by-case basis.
Development of individual inertness tests
Based on our experience in material-related microbiology, we develop customized material tests using environmentally relevant microorganisms (for example, inertness tests of tank coatings against fuel-utilizing bacteria). The Microbiology working group has its own collection of microorganisms, most of which have been isolated from cases of damage during customer projects. Isolates can be selected from this collection in order to apply realistic test conditions for a specific inertness question.
Teaching and Expert Reviews
The Microbiology working group regularly offers internships as well as bachelor's, master's and doctoral theses as part of national and international projects. In the past, this work has led to various publications in renowned journals. The members of the working group are well connected nationally and internationally and regularly take on reviewing activities for various journals and project sponsors in Germany and abroad.
Projects
Multifunctional RC filter substrates made from masonry rubble for the treatment of stormwater runoff
As part of a joint project, a filter system based on recycled building materials and microorganisms is to be developed to treat surface water contaminated with heavy metals - especially from road runoff - for sustainable urban water use in line with the "sponge city" strategy.
The storage and use of surface water is intended to improve the water supply in cities (keyword: sponge city). Water from road runoff is primarily contaminated by tire abrasion. Typical contaminants here are rubber, heavy metals and plasticizers. The use of this water therefore requires purification using suitable filter systems. In this joint project between the Forschungsvereinigung Kalk-Sand e.V., Biomolab gGmbH, the Federal Institute for Materials Research and Testing and the MPA Bremen, recycled building materials are used as a matrix for special microorganisms. By using sulphate-reducing bacteria, which reduce sulphate to hydrogen sulphide, a quantitative precipitation and removal of the heavy metals present in the water can be achieved.
Funding: IGF project no. 23316 N by the Ministry of Economic Affairs and Climate Protection
Contact:
Dr. Antje Stahl
Tel.: 0421 53708 79
E-Mail: a.stahl@mpa-bremen.de
Figure: Blending of various recycled construction materials used as a matrix for the sulfate-reducing bacteria.
Development of biological filter systems for rainwater treatment using recycled construction debris
Climate change increases extreme rainfall alternating with droughts, challenging urban rainwater management. Instead of rapid drainage, modern concepts focus on local water retention. This project explores microbial treatment of road runoff using recycled construction debris like aerated concrete. Sulfate-reducing bacteria colonize the material and synthesize metabolic products that chemically precipitate dissolved heavy metals for water purification.
Cooperation: BAM Berlin, Forschungsvereinigung Kalk-Sand e. V., Bimolab gGmbH
Funding: BMWK-IGF
Contact:
Dr. Antje Stahl
Tel.: +49 421 53708 79
E-Mail: a.stahl@mpa-bremen.de