pH Antimicrobial

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pH Antimicrobial

• Ms. Sunisa Thongdee 4518996
• Ms.Janjira Sillapee 4518999

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Antimicrobial

• The basis for an Antimicrobial finish is to
  prevent the adhesion, activity, or multiplication
  of bacteria.
• Antimicrobial agents are substances or mixtures
  of substances used to destroy or suppress the
  growth of harmful microorganisms whether
  bacteria, viruses, or fungi on inanimate objects
  and surfaces.

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Antimicrobial (con.)

• Antimicrobial is a term given to any type of
  chemical compound that can aid in the death or
  suppress the growth of microorganisms (bacteria,
  yeast, mycoplasma), etc

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Antimicrobial

• An antimicrobial drug is a chemical substance
  that destroys pathogenic microorganisms with
  minimal damage to host tissues.
• Bacteriocidal kill microbes directly
• Bacteriostatic prevent microbes from growing

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What is the Difference Between an Antimicrobial
and an Antibiotic?

• Although these two terms are often used
  interchangeably, technically there is a
  difference.
• -Antibiotics are natural substances produced
  by microorganisms that, at low concentrations,
  are able to inhibit or kill other
  micro-organisms.
• - Antimicrobials are any natural,
  semi-synthetic or synthetic substances, including
  antibiotics, which inhibit or kill microorganisms
  without harming the host.

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Two groups of antimicrobial agents used in the
treatment of infectious disease

• antibiotics, which are natural substances
  produced by certain groups of microorganisms.
• chemotherapeutic agents, which are chemically
  synthesized.

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How do antimicrobial agents work?

• Damage cell wall
• Lysozyme and penicillin
• Damage cell membrane
• Surfactants
• Affect protein and nucleic acid
• synthesis
• Chloramphenicol, radiation
• Alter protein function
• Heat, alcohol, pH

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Example of antimicrobial
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Food have been categorized according to their pH
as follows

• High acid foods pH below 3.7
• Acid foods pH 3.7-4.6
• Medium acid foods pH 4.6 5.3
• Low or non acid food pH over 5.3

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Bacteriocin

• Bacteriocins are only one category of substances
  produced by bacteria that are inhibitory to other
  bacteria.
• These potent inhibitors offer potential
  alternatives to antibiotics and may also replace
  chemical preservatives in food.

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Bacteriocin (con.)

• Bacteriocins differ greatly with respect to
  sensitivity to pH. Many of them are considerably
  more tolerant of acid than alkaline pH values.
  Bacteriocin produced by LC-09 exhibited the same
  profile and was active at pH values between 3-7.
  Maximum inhibitory activity was demonstrated at
  pH 4 and 5.

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Nicin

• An antibacterial polypeptide produced by some
  strains of Lactococcus lactis subsp. Lactis.
• Not only Gram-negative organisms and molds
  insensitive to nisin but its effectiveness
  against even sensitive Gram-positive organisms
  depends on the bacterial load.

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Nicin

• As the number of organisms increases so the
  inhibitory effectiveness of nicin decreases.
• At neutral and alkaline pH values, nicin is
  practically insoluble and irreversible
  inactivation occurs even at room temperature.
• Large molecules from milk or broth protect nisin
  from heat inactivation.

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Nicin

• The effect of processing temperature and pH on
  the stability of nicin in different foods
• Low-acid foods at pH 6.1-6.9 heating for 3 min.
  at 250oF destroyed 25-50 of the added nisin.
• A similar degree of destruction for highly acid
  foods having pH values of 3.3-4.5.

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Lysozyme

• Lysozyme is found abundantly in nature and is
  produced by bacteria, fungi, plants, birds, and
  mammals
• The antibacterial properties action against
  gram-positive and gram-negative bacteria.
• Lysozyme activity is highest from pH 3.5 to 7.0,
  although lysozyme is active over a pH range of
  2.010.0.

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Lactoperoxidase

• The oxidation of important thiol groups will
  destroy the proton pump, which is essential to
  the bacterium as a source of energy for the
  transport of ions and low molecular weight
  substances through the cell membrane.

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Lactoperoxidase (con.)

• The first direct effect of a lactoperoxidase
  attack is cell membrane damage leading to a
  dominished pH gradient, increase K leakage and
  inhibition of the transport of amino acids and
  glucose. It has also been shown to inhibit
  lipoprotein lipase in brovine milk.

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