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FS HN 420


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Kate Jaros


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Primary sources of microorganisms
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- soil and water - plants and plant products - food utensils - intestinal tract of humans and animals - food handlers - animal feeds and hides - air and dust - food ingredients - equipment

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FS HN 420 - Marcador

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FS HN 420 - Detalles

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Primary sources of microorganisms
- soil and water - plants and plant products - food utensils - intestinal tract of humans and animals - food handlers - animal feeds and hides - air and dust - food ingredients - equipment
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Cell Wall (structure)
- peptidoglycan - encloses cells of most prokaryotes (except for mycoplasma)
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
NA
NA
NA
NA
Cell Wall (function)
- provides shape and protection from bursting - determines cell shape - protection from lysis and harmful chemicals
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Gram Stain
- differential stain - one of the first steps in ID of bacteria 1) crystal violet, 2) iodine, 3) alcohol, 4) safranin
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Gram-negative bacteria
- thin peptidoglycan layer - do NOT retain CV - iodine stain when washed with alcohol - stains pink - dual cytoplasmic membrane
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Gram positive bacteria
- thick peptidoglycan layer - retain CV - iodine stain, not easily removed by acetone/alcohol - stain blue
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Cytoplasmic membrane (structure)
- lipid bilayer - mainly phospholipids, membrane proteins - fluid structure - hydrophobic barrier - severe damage can cause cell death
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Cytoplasmic membrane (function)
- enzymes present: ATPase, dehydrogenase - impermeable to protons - facilitates nutrient transport - hydrophobic barrier
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Ribosomes (structure)
- give granular appearance to cytoplasm - made up of protein and RNA
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Ribosomes (function)
- synthesize cell protein - 10k per cell
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Nucleoid
- diffuse nucleus (no nuclear membrane) - single circular DNA molecule - major genetic material of the cell
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Flagella (structure)
- helical filaments - protein (flagellin) - polar flagellum to 10s, 100s - 3 parts: filament, hooks, basal body
Flagella (function)
- rotate to propel the cell - help cell respond to chemical attractants and repellants (chemotaxis)
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Pilli (structure)
- aka fimbriae - ptrotein (pilin) - straight rods
Pili (function)
- no rotation - used for cell attachment - bind to specific receptors - special pili used for conjugation
Fungi
Yeasts and molds
Yeasts
- oval, spherical, or elongated cells - cell wall contains polysaccharides (glycan), protein, and lipids; some chitin - cell membrane - organelles in cytoplasm - well defined nucleus - nuclear membrane - far larger than molds
Molds
- filamentous fungi - cell wall of chitin, cellulose, or both! - hyphae: filaments - mycelium: numerous branches of hyphae
Hyphae
- filaments of molds - can be vegetative or reproductive - reproductive hyphae: form exospores - aerial hyphae: bear conidia or sporangia - subsurface hyphae: produce enzymes to digest substrate
Classifying microorganisms
- species: basic taxonomic group for yeasts/molds/bacteria - genus: several species with similar characteristics - family: several genera with similar characteristics
Microbes in food: bioprocessing
- use of food grade microorganisms as a starter culture - different types of fermented foods made - microbial enzymes also used
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms - antimicrobial metabolites: lactic acid, acetic acid, propionic acid
Probiotics
- viable bacteria that seem to produce health benefits when consumed in foods - specific strains (of Lactobacillus, Bifidobacterium, Lactococcus, Enterococcus) are important
Food spoilage
- growth of microbes in foods and/or action of their enzymes - lead to undesirable changes in food texture, taste, flavor, color - discoloration, softening, increased exudate, off-odors, bad taste - causes substantial economic loss
Foodborne disease
- pathogenic microorganisms (bacteria, mold, viruses, parasites) - caused by under-processing, cross-contamination, and mishandling of foods - large-scale production of food & increase in foreign importation of food: increase chances of disease outbreaks and new pathogens - most caused by foods of animal origin - common causes: under processing, cross contamination, and mishandling of food
Bacterial spores
- endospores: formed inside vegetative cells - exospores: vegetative cells change to cysts
Microbes in food: biopreservation
- using antimicrobial metabolites from desirable microorganisms to preserve food - control pathogens and spoilage organisms
Endospores
- one endospore per vegetative cell - produced by some Gram-positive bacteria - highly stress-resistant, dormant structure - resistant to heat, chemical disinfectants, radiation, and desiccation
Destruction of endospores
- destroyed by very harsh chemical or physical treatments - 121 deg C at 15psi for 20 minutes in an autoclave - irradiation at 30-40 kGy - Not killed by high pressure practically attainable by current technology ex 600-8800 MPa
Sporulation
- formation of spores in vegetative cells - endospores appear as clear areas in vegetative cells
Germination
- formation of vegetative cells from spores - only one veg. cell produced from one spore
Gram positive spore formers
- Bacillus spp - Clostridium spp - Alicyclobacillus spp - Sporosarcinia spp (cocci)
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Psychrophile (T)
- organism that can grow at 0 C, optimum 15 C or lower, max 20 C - commonly isolated from Arctic and Antarctic environments - enzymes, transport systems, and protein synthesis mechanisms of psychrophiles work well at cold temperatures - cytoplasmic membrane remains fluid at cold temps due to high levels of unsaturated fatty acids - many psychrophiles suffer from membrane disruption & leak cytoplasmic constituents
Psychrotroph (T)
- an organism that can grow from from 0-7 C, optimum temperature between 20-30 C- maximum growth temperature 35 C- major spoilage organisms of refrigerated foods- Pseudomonas spp.
Mesophile (T)
- an organism that grows optimally between 30-40 C - minimum growth at 15-20 C, maximum is 45 C - many human enteric pathogens that grow rapidly at human body temp - ex: Salmonella, Escheria coli, Shigella dysenteriae
Thermophile (T)
- an organism that can grow at 55 C or higher, optimum temp between 55 - 65 C - minimum temp 45 C - ex: Bacillus stearothermophilus
Metabolism
- sum total of all chemical rxns in living cells - catabolism and anabolism
Catabolism
- break down - energy (ATP) generated by breaking bonds (stripping electrons from large molecules) - e- pass along an electron transport chain (ETC) in cytoplasmic membrane - ATP produced by special enzymes (ATPases) located in cytoplasmic membrane - some energy stored as ATP, remainder given off as heat
Anabolism
- build up - microorganisms use simple molecules and ATP to synthesize complex molecules - ex: protein, DNA
ETC in microbes
- if electron transport stops, microbial cell will stop growing and eventually die bc of its inability to make energy (ATP) - microorganisms must use a terminal e- acceptor at end of chain to remove electrons and maintain electron transport
TEA
- terminal electron acceptor - aerobes: oxygen - anaerobes: nitrite, nitrate, sulfate
Aerobe
- organism that uses oxygen in metabolic reactions - requires oxygen for growth - Pseudomonas spp.
Strict aerobe
- grows only in the presence of air (21% oxygen) - Alteromonas putrefaciens
Anaerobe
- cannot grow in the presence of air - can't use oxygen in metabolic reactions - oxygen is toxic - Clostridium botulinum, Bifidobacterium spp.
Microaerophile
- requires a small amout of oxygen (5%) for growth - larger amounts of oxygen are toxic to this organism - anaerobic environment inhibits growth - Campylobacter jejuni
Facultative anaerobe
- oxygen not req. but may use it if available - metabolically versatile organsim - can use oxygen or other compounds as a TEA - Salmonella spp, Listeria monocytogenes, Escherichia coli, Shigella spp, Vibrio spp
Aerotolerant anaerobe
- organsim that doesn't use oxygen in metabolic rxns but can grow in its presence - an anaerobe that tolerates air (21% oxygen) - can detoify or excrete toxic oxygen products - some Lactobacillus spp, Enterococcus faecalis, Enterococcus faecium
Pseudomonas
- gram-negative aerobes - motile rods; polar flagella - psychrotrophic - found widely in environment - spoil refrigerated fresh meats and vegetables
Alteromonas
- motile rods - strict
Pseudomonas examples
Pseudomonas fluorescens, P. aeruginosa, P. putida
Xanthomonas
- gram-negative aerobes - motile rods, polar flagellum - plant pathogens - spoil fruits and vegetables - pseudoplastic
Brucella example
- Brucella abortus: disease in cows - Brucella melitensis: disease in sheep - Brucella suis: disease in pigs
Xanthomonas examples
- Xanthomonas campestris produce xanthan gum - Xanthomonas axonopus: black spots on mangoes - Xanthomonas spp
Acetobacter
- gram-negative aerobes - motile or non-motile rods - mesophilic - widely distributed in plants - spoil alcoholic beverages and fruit juices
Acetobacter examples
- Acetobacter aceti oxidizes ethanol to acetic acid
Alcaligenes
- gram-negative aerobes - motile; 4 to 8 peritrichous flagella - rods or coccobacilli - mesophilic; optimum growth at 20-37 C - present in water, soil, fecal material - spoil protein rich foods (milk, poultry, red meats)
Alcaligenes examples
- Alcaligenes faecalis
Alteromonas
- gram-negative aerobes - motile rods - strict aerobe - psychrotrophic - found in marine and coastal waters - need 100mM NaCl for growth - spoil fish and other meats
Alteromonas example
- Alteromonas putrefaciens - recently classified as Shewanella putrefaciens
Flavobacterium
- gram-negative aerobes - nonmotile rods - yellow to red pigments on agar medi - some mesotrophs, other are psychrotrophs - spoil refrigerated meats, milk, other protein foods
Acinetobacter
- gram-negative aerobes - motile rods - spoilage - strict aerobes - twitching motility - widely distributed in soils and water - psychrotrophic
Flavobacterium examples
Flavobacterium aquatile
Psychrobacter
- gram-negative aerobes - non-motile coccobacilli, usually in pairs - psychrotrophic - growth at 5 C, optimal 20 C, no growth at 35 C - spoil fish, red meats, and poultry products
Acinetobacter example
Acinetobacter calcoaceticus
Psychrobacter example
Psychrobacter immobilis
Brucella
- gram-negative aerobes - non motile coccobacilli - mostly single - mesophilic, optimal growth at 37 C - different species cause disease in animals and human pathogens - implicated in foodborne brucellosis
Brucella example
- Brucella abortus: disease in cows - Brucella melitensis: disease in sheep - Brucella suis: disease in pigs