Kuliah 2 kmk
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Transcript of Kuliah 2 kmk
Dept. Kesehatam Lingkungan
FKM UI
Microorganisms classified, growth,Microorganisms classified, growth,and ecologyand ecology
pathogenic organisms
spoilage organisms
useful organisms
Microorganisms classifiedMicroorganisms classifiedby their significanceby their significance
Dangerous microorganismsDangerous microorganismsand parasitesand parasites
Foodborne diseases
bacteria
moulds
viruses
parasites
Major bacteria causing Major bacteria causing foodborne diseasefoodborne disease
Aeromonas spp.
Bacillus cereus
Brucella spp.
Campylobacter jejuni
Clostridium botulinum
Clostridium perfringens
Escherichia coli
Listeria monocytogenes
Mycobacterium bovis
Salmonella spp.
Shigella spp.
Staphylococcus aureus
Vibrio cholerae
Vibrio parahaemolyticus
Vibrio vulnificus
Yersinia enterocolitica
Spoilage Spoilage microorganismsmicroorganisms
bacteria
yeasts
moulds
Food products madeFood products madewith useful microorganismswith useful microorganisms
fermented meats yoghurt cheese beer leavened bread soy sauce fermented soybean (tofu)
Useful microorganismsUseful microorganisms
Lactic acid bacteria (LAB) These ferment carbohydrates into organic acids which inhibit
Salmonella Staphylococcus Listeria Clostridium E. coli
LAB are found in Plants Soil Animals Human Gut
World population is
5.9 BILLION
i.e. 5 900 000 000
1 cup
of yoghurt contains
20 X this number!
i.e. 120 000 000 000
separate living
organisms.
Microorganisms are very smallMicroorganisms are very small
YOGHURT
Microorganisms are very smallMicroorganisms are very small
Cell wall
Ribosomes
Cytoplasmicmembrane
CytoplasmNuclear
body
Bacterial divisionBacterial division
1
2
3
4
5
Bacterial growth curveBacterial growth curve
Toxic
+_
+ +_ _ _ _ _ _ _ _ _ __ _ _ _ _ _
- - - - - - - - - - - -+++++++++++
Time to spoilage
Spoils
Time0
1
2
3
4
5
6
7
8
9
Lag phase Log phase Stationary phase
Lag phase(short) period of adjustment to environment
Logarithmic Growth phasegrowth begins and accelerates to a phase of rapid, constant exponential growth
Stationary phase
depletion of nutrients and accumulation of toxic
metabolic products growth is slowed to a point
where cell division and cell death are in balance Death phase
population decreases due to death of cells
Phases of bacterial growthPhases of bacterial growth
Factors affecting growth of Factors affecting growth of bacteria in foodbacteria in food
Temperature
Time
pH
Water activity (aw)
Oxygen tension
Preservatives
Microbial interactions
0°
10°
36.5°
60°
72°
100°
Boilingpoint
Pasteurisingtemperature
Freezer
Fridge
Bodytemperature
TemperatureTemperature
SAFETY SAFETY
SAFETY SAFETY
DANGERDANGER
TemperatureHotCold
How temperature affects How temperature affects growth rate of a bacterial populationgrowth rate of a bacterial population
C (Minimum)
B (Optimum)
A (Maximum)
Growth of Growth of S. typhimuriumS. typhimuriumat different temperaturesat different temperatures
Time (Days)
Lo
g N
um
ber
s
0123456789
0 1 2 3 4 5
25°20°15°10°
Temperature rangeTemperature rangefor growth of pathogensfor growth of pathogens
Temperature°CMin. Opt. Max.
Salmonella 5 35 - 37 47Campylobacter 30 42 47E. coli 10 37 48S. aureus 6.5 37 - 40 48C. botulinum (proteolytic) 10 50C. botulinum (non-proteolytic) 3.3 25 - 37B. cereus 4 30 - 35 48 - 501
432
Temperature °CMin. Opt. Max.
Penicillium verrucosum 0 20 31
Aspergillus ochraceus 8 28 37
Aspergillus flavus 10 32 42
Fusarium moniliforme 3 25 37
Temperature range for growthTemperature range for growthof toxigenic mouldsof toxigenic moulds
Growth of different bacteria at 25°CGrowth of different bacteria at 25°C
Time (Days)
0
1
2
3
4
5
6
7
8
9
0 1 2 3 4
S. typhimuriumL. monocytogenesPs. fluorescensB. cereusC. bot-ProteolyticG+ve Spoilers
Log CFU
Temperature affects bacteriaTemperature affects bacteria
Lag phase Growth rate Final cell numbers
Enzymatic and chemical composition of cells Nutritional requirements Limits for other factors influencing growth
through the change in
Effect of salt concentration on time to botulinum toxin production
Salt Concentration (%)
0
2
4
6
8
10
12
14
16
0 0.5 1 1.5 2
10°C14°C18°C24°C
Limits of pH for growth of pathogens
pHMin Max.
Escherichia coli 4.4 8.5Salmonella typhi 4 - 4.5 8 - 9.6Bacillus cereus 4.9 9.3Clostridium botulinum 4.6 8.5Staphylococcus aureus 4 9.8Saccharomyces cerevisiae 2.3 8.6Aspergillus flavus 2.0 11.2Fusarium moniliforme 2.5 10.7Penicillium verrucosum 2.0 10.0
Definition of water activity (aDefinition of water activity (aww))
aw is the ratio of the water vapour pressure of the food (p) to that of pure water (po) at the same temperature.
aW = p / po
NaCl and glucose concentrations andcorresponding aw values at 25°C
1.00 0.00 0.00 0.99 1.74 8.90 0.98 3.43 15.74 0.96 6.57 28.51
0.94 9.38 37.83 0.92 11.90 43.72 0.90 14.18 48.54 0.88 16.28 53.05 0.86 18.18 58.45
aW % w/w % w/w NaCl Glucose
Range of aW in foodsand their microbial flora
aw range foods microbial flora
> 0.98
Fresh meatsFresh fishFresh fruitsFresh vegetablesCanned vegetables in brine Canned fruit in light syrup (<3.5% salt, 26% sugar)
(C. perfringens, Salmonella)
(Pseudomonas)
0.93 - 0.98 Fermented sausagesProcessed cheeseBreadEvaporated milkTomato paste(10% salt, 50% sugar)
(B. cereus,C. botulinum,Salmonella)lactobacilli, bacilli andmicrococci
Range of aW in foodsand their microbial flora
aw range foods microbial flora
0.85 - 0.93 S. aureus
Mycotoxin producing mouldsSpoilage yeasts and moulds
Dry fermented sausagesRaw ham (17% salt, saturated sucrose)
0.6 - 0.85Xerophilic fungi
HalophilesOsmophilic yeasts
Dried fruitFlourCerealsSalted fishNuts
< 0.6 No growth but may remain viable
ConfectioneryHoneyNoodlesDried egg, milk
Key messages
Temperature, pH, water activity and oxygen tension are the principal factors affecting microbial growth
There are optimum ranges for these parameters
These optima are interdependent
They can be selected to inhibit the growth of certain organisms within limits related to the palatability of food
Certain foods are suited for the growth of certain flora
Some toxigenic mouldsSome toxigenic mouldscausing foodborne diseasecausing foodborne disease
Aspergillus spp.
Fusarium spp.
Penicillium spp.
( Main sources - fruits, nuts and grains )
Major virusesMajor virusescausing foodborne diseasecausing foodborne disease
Hepatitis A and E viruses
Small Round Structured Viruses (e.g. Norwalk agent)
Rotavirus
Polio virus
Virus structureVirus structure
Protein Capsule
Nucleic acid(DNA or RNA)
Poliovirus
Hepatitis-A virus
RotavirusNorwalk-like or
SRSV
Virus levels required forVirus levels required forinfection and detectioninfection and detection
infection10 -100 particles / ml
detection105 - 106 particles / g(by electron microscopy)
104 - 105 particles / g(by radioimmunoassay)
Major parasitesMajor parasitescausing foodborne diseasecausing foodborne disease
• Cryptosporidium
• Entamoeba histolytica
• Giardia
• Toxoplasma
• Fasciola
• Fasciolopsis
• Haplorchis
• Opisthorchis
• Paragonimus
• Cysticercus cellulosae
Protozoa
Helmints• Angiostrongylus
• Anisakis
• Ascaris
• Capillaria
• Gnathostoma
• Trichinella
Nature of bacteria, moulds, virusesNature of bacteria, moulds, virusesand parasites - Key messages (1)and parasites - Key messages (1)
foodborne diseases are caused by bacteria, moulds, viruses, and parasites
certain microorganisms are of greater significance than others for humans
bacteria and moulds multiply on foods andmay produce toxins
understanding the factors controlling growthof microorganisms allows us to control themin food
bacteria may be harmful or useful
bacteria, yeasts and moulds can be usedto preserve foods
lactic acid bacteria secrete lactic and other organic acids
organic acids inhibit pathogens in food andin the gut
viruses and parasites do not grow in food
Nature of bacteria, moulds, virusesNature of bacteria, moulds, virusesand parasites - Key messages (2)and parasites - Key messages (2)
Microbiological ecologyMicrobiological ecology
Microbiological ecologyMicrobiological ecology
Microbes are everywhere air water food soil humans (e.g. gut, nose,
skin) surfaces
The The SalmonellaSalmonella (non typhi) cycle (non typhi) cycle
Effluent, slurry and sludge
Imported animal /
vegetable protein
Slaughter houses
Human food
Wildlife reservoirs
Animal importation ManPets
Farm
animals
Imported food
Animal feedsMeat / bone meal, dried
poultry waste, etc.
Offal
Transmission of Transmission of CampylobacterCampylobacter
Raw materials Raw materials will have a normal florawill have a normal flora
meat poultry fish and shellfish cereals milk egg products vegetables, fruits and nuts spices oils and fats water
Meat and meat products hazardsMeat and meat products hazards
Salmonella S. aureus Yersinia enterocolitica C. perfringens C. botulinum Pathogenic E. coli Listeria
monocytogenes Parasites
The contamination chain for meatThe contamination chain for meat
Cross contamination
Cross contamination
Infected portion
Butcher
Jointed meat
Blood and tissue drip
Pass
Slaughter
Cross contamination
Cross contamination
Cross contamination
Fail --diseased or
contaminated
Hazards in milkHazards in milk
Mycobacterium Brucella Salmonella L.
monocytogenes E. coli S. aureus Bacillus Clostridium Campylobacter
Poultry and poultry productsPoultry and poultry products
Salmonella
Campylobacter
C. perfringens
S. aureus
Y. enterocolitica
L.
monocytogenes
Eggs and egg products - hazardsEggs and egg products - hazards
Salmonella!
Fish and shellfish - hazardsFish and shellfish - hazards
Bacteria C. botulinum type E Vibrio parahaemolyticus Vibrio vulnificus Vibrio cholerae L. monocytogenes
Parasites Viruses
Hepatitis A virus Norwalk virus
Vegetables, fruits and nuts - hazardsVegetables, fruits and nuts - hazards
Bacteria Salmonella Shigella V. cholerae L. monocytogenes Enterotoxigenic E.coli Clostridium botulinum
Hepatitis A and other enteric viruses
Parasites
Moulds
Moulds
Salmonella
B. cereus
Cereals -Cereals - hazards hazards
C. perfringens
B. cereus
Salmonella
Moulds
Spices - hazardsSpices - hazards
Ecology of foodborne pathogensEcology of foodborne pathogensKey MessagesKey Messages
Some originate from animals Salmonella Campylobacter E. coli
Some come from plants and soil Moulds B. cereus C. botulinum
Ecology of foodborne pathogensEcology of foodborne pathogensKey MessagesKey Messages
Some originate in the sea V. parahaemolyticus C. botulinum Type E V. cholerae
Some originate from man Viruses S. typhi S. aureus Shigella