PRESENTER: IP MOLOBELAMAY 10 ,2011

Microbial biofilms and their impact in the water industry

College of Science, Engineering and Technology

Civil and Chemical Engineering DepartmentUniversity of South Africa

Objectives To introduce you to the concept of biofilms To let you know why the study of biofilms is

important in the water industry To help you see how biofilms are radically

changing the way we understand and deal with them as they change

To excite you about the prospects of the continued study of biofilms and the technologies on biofilm control and removal

Outline Biofilms What are biofilms? What are the parameters contributing to

their formation and development? Why is it important to study biofilms in

the water industry – is it really necessary?

What are the disadvantages of chemical, physical and mechanical strategies in controlling but most importantly removing microbial biofilm?

Are the above mentioned strategies successful in removing microbial biofilms? The answer is “............”

“Enzyme Technology”- An emerged technology for microbial biofilm control and removal. Is this technology effective? The answer is “..........”

What are biofilms? Prof Flemming simply defines biofilms

city of microbes; EPS houseof microbes Group of microorganisms (bacteria, fungi

etc) (attached to biotic or abiotic surfaces immersed in an aqueous environment) Embedded in extracellular polymeric

substances (EPS). Biofilms have complex social structures

that scientists and engineers are still trying to unravel

Cont

EPS is made up of carbohydrates, proteins, amino acid, lipids including humic substances

Biofilms produce different EPS structures (depending on growth conditions)

What is the role of EPS during biofilm formation?

Facilitates attachment (protects biofilm cells)

Maintains micro colonies (structural integrity)

Protects the biofilm cells from harsh conditions and predation

Enables the biofilms to capture nutrients (surrounding fluid medium)

Enhances biofilm resistance to environmental stress, antimicrobial agents (bactericidal, fungicidal etc)

Pseudomonas fluorescens biofilms (Picture, Molobela IP, PhD studies )

EPS structures

Pseudomonas fluorescens and Staphylococcus lentus biofilms (Pictures, www.informaworld.com)

threat like structures EPS

Biofilm developmental cycle (stages)

Attachment (Protein molecules, flagella, fimbria etc) (conditioned surface)Primary stage (reversible) Secondary stage (irreversible)

Formation of micro colonies Biofilm maturation Detachment and dispersal of biofilm cells

Picture of Liang Research group (LL)

What are parameters influencing biofilm attachment and formation? Nutrients Temperature effects Surface condition Hydrodynamics Quorum sensing (QS) (Gene expression

and regulation)

Why is it important to study biofilms in the water industry?

They are the mainly reason water infrastructures and pipe materials are corroded (causative agent of biofouling and biocorrosion

Corrosion is the mainly problem in the water industry

Biofilms are also the biological contaminants of drinking water

Developed methods for biofilm control and removal

1. Chemical method (Bactericidal, Fungicidal, antimicrobials etc)

Disadvantages Partially effective Fails to penetrate the EPS Cannot destroy the biofilm cells Some toxic to the surface materials

Environmental unfriendly (produce odour) (their use-regulated by the EPA)

2. Mechanical method (machines for cleaning)

Disadvantages Cannot penetrate to biofilm

contaminated sites/ areas Costly - involves equipments down

site - also labour expenditure

Enzyme Technology for microbial biofilm removal

Effective and robustingEnzymes are specific

- target specific componentsTherefore: Enzyme can also target biofilm

EPS (EPS - proteins, carbohydrates, lipid, amino acid)

Note: It is important to understand the nature of EPS so that relevant enzymes are used

Enzymatic degradation of biofilm EPS (Molobela et al., 2010)

Proteases (Savinase, Evelase, Esperase, polarzyme )

Single Species multi species

Mechanism of removal -Degradation of EPS

single multi species

Savinase >80% >80%Evelase >80% >80%Esperase >80% >80%Combination >90% >80

Tested biofilmsSingle multi species

Tested enzymes Individually Combination

Highly effective Highly effective

Individually Combination

Amylases (Amyloglucosidase (AMG), Bacterial Amylase Novo (BAN)

Tested enzymes Individually Combination

Tested biofilmsSingle multi species

Single Species multi species

Mechanism of removal -Degradation of EPS

single multi speciesAMG >50% >50%BAN <50% <40%Combination >50% >50%

Individually Combination

Partially effective Not effective

Combination of protease and amylase enzymes

Tested biofilmsSingle multi species

Single Species multi species

Combination

Highly effective effective

Mechanism of removal -Degradation of EPS

single multi species>80% <80%

Methods used to study biofilm EPS

Protein assay- Froelund et al., 1996 Carbohydrate assay - Gaudy’s, 1962 Biofilm growth Assay – Molobela et al., 2010 Enzymatic degradation of biofilm EPS –

Molobela et al., 2010

Conclusion Study the nature of the biofilm EPS Study the type of microbes within a

biofilm Thorough study on the impcat of

parameters influencing biofilm formation and structures

Cont

Design of models for monitoring of biofilm attachment, formation and development and study the structures of biofilm EPS

Enzymatic technology seems promising on biofilm removal. However, more research still need to be done on this study

Collaborative research on biofilm study (involvement of expertise – different disciplines

Note to take home! We have talked about biofilms being

bad! Yes many of them are quite harmful and must be controlled and most importantly removed.

However Other biofilms are beneficial, and can be used to help fix serious problems (such as ground contamination from an oil spill, bioremediation, nitrogen fixers, rhizobial biofilms etc)

I thank you!!!!!!!!!

I am a strong biofilm, I destroy and destroy and destroy!!!!!!!! Hahahahahaha!!!!!!!!!!!!!!!!!!!