Civil Engineering 1 ppt Semina Presentation by 282REF


MAY 10 ,2011
Microbial biofilms and their
impact in the water industry
     College of Science, Engineering and
Civil and Chemical Engineering Department
          University of South Africa
 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
 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
 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
 EPS is made up of carbohydrates, proteins,
  amino acid, lipids including humic
 Biofilms produce different EPS structures
  (depending on growth conditions)
   What is the role of EPS during
       biofilm formation?
 Facilitates attachment (protects biofilm
 Maintains micro colonies (structural
 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

Pseudomonas fluorescens and Staphylococcus lentus biofilms
    Biofilm developmental cycle
 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)
 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
 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                           Tested biofilms
        Individually Combination                 Single    multi species

            Mechanism of removal -
               Degradation of EPS           Individually       Combination
         single        multi species

        Savinase >80%       >80%            Single Species        multi species
        Evelase >80%        >80%           Highly effective    Highly effective
        Esperase >80%       >80%
        Combination >90%    >80
    Amylases (Amyloglucosidase (AMG), Bacterial Amylase Novo (BAN)

        Tested enzymes                          Tested biofilms
Individually Combination                 Single    multi species

   Mechanism of removal -            Individually           Combination
      Degradation of EPS
single         multi species
AMG >50%           >50%              Single Species          multi species
BAN <50%           <40%              Partially effective    Not effective
Combination >50%   >50%
Combination of protease and amylase enzymes

        Tested biofilms              Combination
 Single    multi species
                            Single Species      multi species
                             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
 Study the nature of the biofilm EPS
 Study the type of microbes within a
 Thorough study on the impcat of
  parameters influencing biofilm formation
  and structures
 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
 Collaborative research on biofilm study
  (involvement of expertise – different
         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
 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!!!!!!!!

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