FS HN 420
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FS HN 420 - Marcador
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 |