Lactic acid-forming bacteria, acetic acid-forming bacteria, and butyric acid-forming bacteria play important roles in food microbiology. Lactic acid-forming bacteria are involved in the production of sauerkraut, cheese, and wine spoilage. Acetic acid-forming bacteria oxidize ethanol to acetic acid and are used to make vinegar and can spoil alcoholic beverages. Butyric acid-forming bacteria, like Clostridium, are spore forming anaerobes.

1. MICROBIOLOGY QUICK LEARN
FOOD MICROBIOLOGY
Saajida Sultaana Mahusook

2. Groups of Bacteria important in Food Bacteriology
Groups of Bacteria Role in Food microbiology
Lactic acid-forming Bacteria
or Lactics
These bacteria ferment sugar to lactose.
Involved in the production of sauerkraut, cheese and spoilage
of wine.
Major genera: Leuconostoc, Lactobacillus, Streptococcus,
Pediococcus.
Acetic acid-forming Bacteria
or Acetics
Oxidize ethanol to acetic acid.
Manufacture of vinegar and spoilage of alcoholic beverages.
Major genera: Acetobacter and Gluconobacter.
Butyric acid-forming Bacteria
or Butyrics
Spore forming anaerobes.
Genus: Clostridium.
Propionic acid-forming Bacteria
or Propionics
Genus: Propionibacterium.
Proteolytic Bacteria Produce extracellular proteinases.
Eg: Bacillus cereus, Pseudomonas fluorescens.
Major genera: Clostridium, Bacillus, Pseudomonas.
Some are acid- proteolytic and cause putrefaction.

3. Groups of Bacteria Role in Food microbiology
Lipolytic Bacteria Produce lipase enzymes that catalyze the hydrolysis of fats to
fatty acids and glycerol.
Major genera: Pseudomonas, Alcaligenes, Staphylococcus,
Serratia and Micrococcus.
Saccharolytic Bacteria Hydrolyze disaccharides or polysaccharides to simple sugars.
Eg: Bacillus subtilis and Clostridium butyricum.
Gas-forming Bacteria Produce small amount of gas and yield it very slowly that is not
ordinarily detected.
Major genera: Leuconostoc, Lactobacillus, Escherichia,
Bacillus.
Osmophilic or
Saccharophilic Bacteria
Grow in high concentration of sugar.
Eg: Species of Leuconostoc.
Pigmented Bacteria Capable of producing pigments.
Serratia- red, Flavibacterium-yellow to orange pigments.
Other groups
Pectinolytic Bacteria
Thermophiles
Psychrophiles
Halophiles
Slime or Rope-forming Bacteria
Coliforms and Fecal Coliforms

4. Importance of Bacteria in Food Microbiology
• Bacteria are important members of Food Microbiology as
they are involved in
• Production of various food and dairy products. Strains of
Streptococcus, Lactobacillus, Bifidobacterium are used in
the production of fermented food and dairy products.
• Pathogenic bacteria cause food intoxications. Example:
C. boltulinum and B. cereus.
• Cause food spoilage. Example: Serratia, Pseudomonas.

5. Reference
• Food Microbiology by Martin R. Adams and Maurice O.
Moss, 3rd e.
• Food Microbiology by William C. Frazier and Dannis C.
Westhoff, 5th e.