Biofilms – Ancient life in breweries

Research Institute for Beer and Beverage Production of VLB Berlin (FiBGP) – Dr.‐Ing. R. Pahl

Biofilms – ancient life in breweries

Dr. Roland Pahl


• A biofilm is an assemblage of microbial cells that is irreversibly associated (not removed by gentle rinsing) with a surface and enclosed in a matrix of primarily polysaccharide material.Biofilms: Microbial Life on Surfaces, R. M. Donlan

• Oldest fossils ever found: Biofilms 3.2 billion years of agehttps://de.wikipedia.org/wiki/Biofilm


Biofilm growth

1. Initial attachment2. Irreversible attachment

3. Maturation I4. Maturation II5. Dispersion


„who“ lives in a biofilm?

• Formation of a biofilm begins with the attachment of free-floating (airborne) microorganisms to a surface (“Pioneer” organisms)

• Biofilms can contain many different types ofmicroorganisms, e.g. bacteria, archaea, protozoa, fungi(yeast and mold) and algae

• The majority of microorganisms forms biofilms as a symbiotic community, each group performs specializedmetabolic functions

• Biofilm covers itself in slime


Example for Biofilm: dental plaque

Source: google picture search „dental plaque“


Example for Biofilm: cellar area


Example for Biofilm: product line


Example for Biofilm: bottling line


Can Biofilms harm the brewer?

Surface

Anaerobic germs

EPS and random MO

O2

H+

Matrix

Yes.


Beer spoilage is not harmful for health

but…


Important questions

• What grows where• What grows when• After what time occur changes• How is the influence of

– Climate– Product being filled– Cleaning system– Cleaning agents– Cleaning frequency– matrix effects


General Idea of Biofilm breeding:


Simulating an uncleaned area (a blind spot of cleaning)


Ergebnisse


Biofilms – Only a hygienic Issue?• Microbial influenced corrosion (MIC) or biocorrosion:• It is estimated, that 20 % of all corrosion damages of metals

and other materials are influenced by microorganisms and cause costs of several billions per year [2]

• MIC is not a “new” mechanism of corrosion, but a factor which influences corrosion together with abiotic processes [2]

• MIC mostly results through the adhesion of a biofilm on a metal surface [3]


Mechanisms of MIC (examples)• Biofilm on a surface: Altering of the electrochemical conditions between

surface and fluid. In a biofilm the diffusion of O2 , nutrients and salts is decreased, which leads to the formation of gradients and changes in the redox potential [3].

• Aerobic MO are consuming oxygen and therefore forming areas of low‐oxygen which are acting anodic and lead to corrosion [2]

• Sulfate reducing bacteria are forming H2S which is highly corrosive [2]• Production of acids (e.g. acetic acid) [2]• The EPS layers of biofilms are containing uronic acids which are able to

bond metallic cations and therefore change the electrochemical potential [3]

• Examples of MO involved in MIC: Thiobacillus thiooxidans, Gallionella, Clostridium, Disulvovibrio thermophilus, Pseudomonas, Lactobacillus delbrueckii [4]


MIC Trials

Massive biofilm growth on a metal surface ( example: zinc coated low‐quality steel – not state of the art in breweries)


MIC Trials

• Material removal: up to 40 % (plate thickness)

• Roughness: Ra 0,13 μm (before); Ra 1,22 μm (after)


MIC Trials – SEM / EDX Analysis

EDX Analysis:

Before growth: Zn was theelement detected the most / no Fe detected

After growth: Fe was theelement detected the most / no Zn detected

Thanks for your attention!!

VLB BerlinResearch Institute for Beer & Beverage ProductionSeestrasse 1313353 BerlinGermany

pahl@vlb‐berlin.orgwww.vlb‐berlin.org

Biofilms – Ancient life in breweries

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