Microbial Attachments and Biofilm Formation ◾ 77
Control and Removal of Biofilms
To control and remove biofilm in the food industry different strategies may be needed, including physical, chemical, and biological approaches. 8 Microbial biofilm formation on equipment
surfaces and attachment to solid food surfaces can resist their removal and killing by using some
of the traditional methods designed to remove or kill unattached microbial cells from a culture
broth. Therefore, modified as well as novel methods must be applied because biofilms are difficult
to remove if they are left to grow. They should be removed when the biofilms are young. The
planktonic cells at the early stage of biofilm formation are more sensitive to cleaning and sanitizers
than the sessile cells in the matured biofilms. In a food-processing operation, cleaning, rinsing,
and sanitation, in that order, have to be done every few hours. Cleaning is essential to remove
food residues, which interfere with sanitization. Removal and control of biofilms also depend on
sanitizer exposure time, temperature, and mechanical action to break down the matrix to facilitate
sanitizer penetration.
Several sanitization methods have been used such as enzyme-based detergents to break down
the glycocalyx. EDTA, along with treatment by quaternary ammonium compounds following
enzyme treatment, can be helpful. However, this may prove to be expensive because of the high
price of enzymes compared to other chemical sanitizers. Some oxidizing agents, including chlorine and hydrogen peroxide, are useful and are effective against a broad range of microorganisms.
Bacteriocins, such as those used as biopreservatives, including nisin, pediocin, reuterin, etc., are
considered effective against microorganisms, including Listeria monocytogenes in a dairy processing plant. The antagonistic effects can be enhanced by acidic environment. Bacteriophages are
viruses that infect bacteria, are considered natural and highly specific, and have great potential
in controlling biofilms. A bacteriophage binds to the bacterial host irreversibly, and infects and
lyses the bacteria. A bacteriophage engineered to express a biofilm-degrading enzyme can also
be effective against both bacterial cells and the EPS. Use of quorum sensing antagonists, such as
Furanones, Azithromycin, garlic extract, and 4-NPO (4-nitro-pyridine-N-oxide), is an intriguing
approach to control biofilms. 9 In addition, processing equipment needs to be designed in such a
way that would prevent formation of biofilm or have access to sanitizers to control and remove
biofilms.
To reduce attachment of microorganisms to solid food surfaces, suitable control measures need
to be adopted. Use of suitable preservatives, low A W , low pH, and low storage temperature can be
used judiciously in combination to reduce the rate of biofilm formation in food. Furthermore, to
reduce pathogen loads on fruits and vegetables, thorough washing with sanitizers (Chapter 31) is
effective. In addition, care should be taken to prevent the formation of a pathogen colonization
niche on tissues by avoiding the induction of injury to fruits and vegetables during handling, processing, transportation, or storage. 6
Conclusion
Microbial attachment and biofilm formation are important strategies for microbial survival on
food or food-contact surfaces under adverse conditions, such as limited nutrients, moisture, and
oxygen. In the biofilm, quorum sensing facilitates bacterial cell-to-cell communication and persistence through production of EPS, which becomes the source of nutrients and helps resist sanitizers
and physical removal from the surface.
Control and Removal of Biofilms
To control and remove biofilm in the food industry different strategies may be needed, including physical, chemical, and biological approaches. 8 Microbial biofilm formation on equipment
surfaces and attachment to solid food surfaces can resist their removal and killing by using some
of the traditional methods designed to remove or kill unattached microbial cells from a culture
broth. Therefore, modified as well as novel methods must be applied because biofilms are difficult
to remove if they are left to grow. They should be removed when the biofilms are young. The
planktonic cells at the early stage of biofilm formation are more sensitive to cleaning and sanitizers
than the sessile cells in the matured biofilms. In a food-processing operation, cleaning, rinsing,
and sanitation, in that order, have to be done every few hours. Cleaning is essential to remove
food residues, which interfere with sanitization. Removal and control of biofilms also depend on
sanitizer exposure time, temperature, and mechanical action to break down the matrix to facilitate
sanitizer penetration.
Several sanitization methods have been used such as enzyme-based detergents to break down
the glycocalyx. EDTA, along with treatment by quaternary ammonium compounds following
enzyme treatment, can be helpful. However, this may prove to be expensive because of the high
price of enzymes compared to other chemical sanitizers. Some oxidizing agents, including chlorine and hydrogen peroxide, are useful and are effective against a broad range of microorganisms.
Bacteriocins, such as those used as biopreservatives, including nisin, pediocin, reuterin, etc., are
considered effective against microorganisms, including Listeria monocytogenes in a dairy processing plant. The antagonistic effects can be enhanced by acidic environment. Bacteriophages are
viruses that infect bacteria, are considered natural and highly specific, and have great potential
in controlling biofilms. A bacteriophage binds to the bacterial host irreversibly, and infects and
lyses the bacteria. A bacteriophage engineered to express a biofilm-degrading enzyme can also
be effective against both bacterial cells and the EPS. Use of quorum sensing antagonists, such as
Furanones, Azithromycin, garlic extract, and 4-NPO (4-nitro-pyridine-N-oxide), is an intriguing
approach to control biofilms. 9 In addition, processing equipment needs to be designed in such a
way that would prevent formation of biofilm or have access to sanitizers to control and remove
biofilms.
To reduce attachment of microorganisms to solid food surfaces, suitable control measures need
to be adopted. Use of suitable preservatives, low A W , low pH, and low storage temperature can be
used judiciously in combination to reduce the rate of biofilm formation in food. Furthermore, to
reduce pathogen loads on fruits and vegetables, thorough washing with sanitizers (Chapter 31) is
effective. In addition, care should be taken to prevent the formation of a pathogen colonization
niche on tissues by avoiding the induction of injury to fruits and vegetables during handling, processing, transportation, or storage. 6
Conclusion
Microbial attachment and biofilm formation are important strategies for microbial survival on
food or food-contact surfaces under adverse conditions, such as limited nutrients, moisture, and
oxygen. In the biofilm, quorum sensing facilitates bacterial cell-to-cell communication and persistence through production of EPS, which becomes the source of nutrients and helps resist sanitizers
and physical removal from the surface.