BACILLUS
• Gram Positive Bacilli
• Arranged in chains
• Motile - peritrichous flagella
• Capsulated - polypeptide in nature
• Ubiquitous
• Common contaminants of bacteriological culture media
• The Bacillus genus encompasses 70 species
• Highly pathogenic in this genus are:
Bacillus anthracis: Causative agent of anthrax
Bacillus cereus: causes food poisoning and leads to foodborne gastroenteritis
Bacillus subtilis
Bacillus thuringiensis
Bacillus stearothermophilus
• Bacillus spp are used as sterilization control
• B. stearothermophilus and B. subtilis both are used as biological controls for
autoclave sterilization
• B. Pumilus is used as a biological control for ethylene oxide
Bacillus Morphology
• Large (3-10 µm X 1-1.6 µm)
• Bacilli are arranged end to end in long chains
• Bamboo-stick appearance
• Spores are oval and central in position
• Forms non bulging spores
• Spores are formed in culture and soil but never in host
Cultural Characteristics
, • Aerobes and facultative anaerobes
• Includes psychrophiles, mesophiles and thermophiles
• Temperature: 5°C to 75 °C
• Salt tolerance: 2 - 25 % NaCl
• Colonies: round, 2-3mm in diameter, raised, opaque and greyish white
• Non haemolytic colonies on blood agar
BIOCHEMICAL REACTIONS
• Glucose, maltose and sucrose are fermented with acid
• Catalase: positive
• Indole: Negative
• Nitrate reduction test: positive
RESISTANCE
• Vegetative forms are destroyed at 600C in 30min
• Spore form is viable for years in soil
• Autoclaving kills spores
• 4% KMNO4 for 15 mts kills spores
• Susceptible to many antibiotics
Bacillus cereus
• Foodborne pathogen
• Produce toxins
• Ubiquitous in nature
• Commonly found in soil
• Foods: Vegetables, milk, cereals, spices, meat and poultry
• Common cause of gastroenteritis
• Common in improperly handled and stored food especially after cooking
• Produce heat and desiccation resistant spores
• Uncommon in cooked foods
• Spores germinate and grow if the food is held under favorable conditions of pH
(>4.8) and temperature (8 and 55°C) for a sufficient time
• Presence of vegetative form in food is necessary to cause foodborne disease
TYPES OF FOOD POISOINING
• B.cereus produce toxins, causing 2 types of GI illness:
• 1) Emetic (vomiting) syndrome
• Gram Positive Bacilli
• Arranged in chains
• Motile - peritrichous flagella
• Capsulated - polypeptide in nature
• Ubiquitous
• Common contaminants of bacteriological culture media
• The Bacillus genus encompasses 70 species
• Highly pathogenic in this genus are:
Bacillus anthracis: Causative agent of anthrax
Bacillus cereus: causes food poisoning and leads to foodborne gastroenteritis
Bacillus subtilis
Bacillus thuringiensis
Bacillus stearothermophilus
• Bacillus spp are used as sterilization control
• B. stearothermophilus and B. subtilis both are used as biological controls for
autoclave sterilization
• B. Pumilus is used as a biological control for ethylene oxide
Bacillus Morphology
• Large (3-10 µm X 1-1.6 µm)
• Bacilli are arranged end to end in long chains
• Bamboo-stick appearance
• Spores are oval and central in position
• Forms non bulging spores
• Spores are formed in culture and soil but never in host
Cultural Characteristics
, • Aerobes and facultative anaerobes
• Includes psychrophiles, mesophiles and thermophiles
• Temperature: 5°C to 75 °C
• Salt tolerance: 2 - 25 % NaCl
• Colonies: round, 2-3mm in diameter, raised, opaque and greyish white
• Non haemolytic colonies on blood agar
BIOCHEMICAL REACTIONS
• Glucose, maltose and sucrose are fermented with acid
• Catalase: positive
• Indole: Negative
• Nitrate reduction test: positive
RESISTANCE
• Vegetative forms are destroyed at 600C in 30min
• Spore form is viable for years in soil
• Autoclaving kills spores
• 4% KMNO4 for 15 mts kills spores
• Susceptible to many antibiotics
Bacillus cereus
• Foodborne pathogen
• Produce toxins
• Ubiquitous in nature
• Commonly found in soil
• Foods: Vegetables, milk, cereals, spices, meat and poultry
• Common cause of gastroenteritis
• Common in improperly handled and stored food especially after cooking
• Produce heat and desiccation resistant spores
• Uncommon in cooked foods
• Spores germinate and grow if the food is held under favorable conditions of pH
(>4.8) and temperature (8 and 55°C) for a sufficient time
• Presence of vegetative form in food is necessary to cause foodborne disease
TYPES OF FOOD POISOINING
• B.cereus produce toxins, causing 2 types of GI illness:
• 1) Emetic (vomiting) syndrome
