Download View/Open

PRESENTER: IP MOLOBELA
MAY 10 ,2011
Microbial biofilms and their
impact in the water industry
College of Science, Engineering and
Technology
Civil and Chemical Engineering Department
University 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)
EPS structures
Pseudomonas fluorescens biofilms (Picture, Molobela IP, PhD
studies )
threat like structures
EPS
Pseudomonas fluorescens and Staphylococcus lentus biofilms
(Pictures, www.informaworld.com)
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 robusting
Enzymes are specific
- target specific components
Therefore: 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 )
Tested enzymes
Individually Combination
Mechanism of removal Degradation of EPS
single
multi species
Savinase >80%
Evelase >80%
Esperase >80%
Combination >90%
>80%
>80%
>80%
>80
Tested biofilms
Single
multi species
Individually
Single Species
Highly effective
Combination
multi species
Highly effective
Amylases (Amyloglucosidase (AMG), Bacterial Amylase Novo (BAN)
Tested enzymes
Individually Combination
Mechanism of removal Degradation of EPS
single
multi species
AMG >50%
BAN <50%
Combination >50%
>50%
<40%
>50%
Tested biofilms
Single
multi species
Individually
Combination
Single Species
multi species
Partially effective
Not effective
Combination of protease and amylase enzymes
Tested biofilms
Single
multi species
Mechanism of removal Degradation of EPS
single
multi species
>80%
<80%
Combination
Single Species
multi species
Highly effective
effective
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!!!!!!!!!!!!!!!!!!!