FM lesson 1

• Microorganisms are organisms and acellular biological entities too small to be seen clearly by the unaided eye
• Microorganisms are 1 millimeter or less in diameter, often colonial, consisting of small aggregations of cells, and some are multicellular
• In glacial environments, the 2 main forms of erosion are abrasion and plucking
• Abrasion is a sandpapering effect caused by small rocks embedded within the glacier rubbing on bedrock, usually leaving a smooth surface with scratches called striations
• Plucking is when meltwater from glaciers freeze around broken or cracked parts of rock, breaking it off from the bedrock or sides as the ice moves down the slope, most prominent when there are many joints in the rock
• Bacteria are single-celled organisms, most have cell walls containing peptidoglycan, abundant in various environments including soil, water, air, extreme temperatures, pH, or salinity, major inhabitants of skin, mouth, and intestines
• Bacteria contribute to the development of the body’s immune system, help maintain the health and well-being of their human hosts, some cause diseases like the plague, while most play beneficial roles like breaking down dead plant and animal material
• Archaea have distinctive rRNA sequences, lack peptidoglycan in their cell wall, unique membrane lipids, and some have unusual metabolic characteristics like generating methane gas, found in extreme environments with high temperatures and salt concentrations
• Eukarya include microorganisms classified as protists or fungi, along with animals and plants
• Protists are generally unicellular but larger than most bacteria and archaea, including major groups like algae, protozoa, slime molds, and water molds
• Fungi range from unicellular forms like yeast to molds and mushrooms, with beneficial roles like bread rising, producing antibiotics, decomposing dead organisms, and forming mycorrhizae with plant roots
• Viruses are the smallest of all microbes, require a host cell to replicate, composed of proteins and nucleic acid, causing diseases like smallpox, rabies, influenza, AIDS, and some cancers
• Viroids and satellites are composed of ribonucleic acid (RNA), causing plant and animal diseases, while prions are infectious agents composed of only protein, responsible for spongiform encephalopathies
• Microorganisms are named according to Latinized binomial nomenclature, with a genus and species name, italicized and capitalized respectively, for example, Saccharomyces cerevisiae
• Microorganisms can be found in a wide range of habitats, from cold brine ponds in polar regions to hot springs, present in soil, water, plants, gastrointestinal tracts, air, dust, and everywhere
• The atmosphere is a hostile environment for many microorganisms, with airborne bacteria dominated by Gram-positive rods and cocci, and airborne fungi evolving mechanisms for air dispersal of reproductive propagules
• The soil environment is complex, with diverse flora of bacteria, fungi, protozoa, and algae, providing many strains used for industrial production of antibiotics, enzymes, amino acids, vitamins, and other pharmaceutical products
• Different soils have their own diverse flora of bacteria, fungi, protozoa, and algae
• The soil is a rich reservoir of micro-organisms, providing strains used for industrial production of antibiotics, enzymes, amino acids, vitamins, and other products in pharmaceutical and food industries
• The aquatic environment contains many species of micro-organisms adapted to fresh water and the sea, with bacteria from open oceans often having a physiological requirement for salt and growing best at low ocean temperatures
• Marine bacteria are usually described as oligotrophic psychrophiles with a requirement for sodium chloride for optimum growth
• Fish caught from cold water in the open sea will have a bacterial flora reflecting their environment, containing predominantly psychrophilic and psychotropic species
• Many marine organisms can break down macromolecules like proteins, polysaccharides, and lipids, with doubling times as short as ten hours at refrigeration temperatures of 0–7°C
• The seas around coasts are influenced by inputs of terrestrial and freshwater micro-organisms and human activities, with shellfish from polluted coastal waters posing health risks due to contamination
• All plant surfaces have a natural flora of micro-organisms specialized for their environment, with leaf surfaces having a phylloplane flora and root surfaces having a rhizoplane flora
• The gut is considered part of the external surface of an animal, with different specialized environments like the skin, nose, and throat being colonized by various micro-organisms
• General roles of microorganisms include being ubiquitous, harmless or beneficial, causing spoilage, and breaking down food components
• Bacteria can be classified according to shape: round (cocci), elongated/rods (bacillus), spiral (e.g., spirulina), and in colonies
• Spore-forming bacteria have a dormant stage in their life cycle, surviving a wide range of environmental extremes, with notable spore formers like Clostridium botulinum
• Bacteria can be classified based on temperature requirements: psychrophiles (1-20°C), psychrotrophic (grow at refrigeration temperatures), mesophiles (20-40°C), and thermophiles (>45°C)
• Factors affecting microbial growth include food content, acidity, temperature, time, oxygen, and moisture
• Water Activity (Aw) measures the "free" water available to microorganisms for growth, with lower Aw reducing the ability for microorganisms to grow
• Moisture in a food system affects microbial growth and chemical reactions, with relative humidity ranging from 0.98 to 0.995 for most foods
• Controlling growth of microorganisms on food involves factors like food, acidity, temperature, time, oxygen, and moisture
• Important Mold Genera in food:

  • Aspergillus: widely distributed, xerophilic, involved in spoilage of foods like jams, cured ham, nuts, and fruits, some produce mycotoxins
  • Alternaria: causes rot in tomatoes and rancid flavor in dairy products
  • Fusarium: associated with rot in citrus fruits, potatoes, and grains
  • Geotrichum: grows on dairy products, forms yeastlike cottony, creamy colony
  • Mucor: used in food fermentation, causes spoilage of vegetables
  • Penicillium: many species, used in food production like cheese, causes fungal rot in fruits and vegetables
• Important Yeast Genera in food:

  • Saccharomyces: used in baking and alcoholic fermentation, causes spoilage producing alcohol & CO2
  • Pichia: forms pellicles in beer, wine, and brine to cause spoilage
  • Rhodotorula: pigment-forming, causes discoloration of foods like meat, fish, and sauerkraut
  • Torulopsis: causes spoilage of milk and fruit juice concentrates
  • Candida: causes rancidity in butter and dairy products
  • Zygosaccharomyces: causes spoilage of high-acid foods like sauces, ketchups, pickles, mustards, mayonnaise, salad dressings
• Important Viruses in food:

  • Some viruses like Hepatitis A and Noroviruses can cause enteric disease
  • Bacteriophages are used to identify some pathogens like Salmonella spp., Staphylococcus aureus strains
• Important Bacterial Genera in food:

  • Gram-Negative Aerobes: Campylobacter, Pseudomonas, Xanthomonas, Acetobacter, Gluconobacter
  • Gram-Negative Facultative Anaerobes: Citrobacter, Escherichia, Enterobacter, Edwardsiella, Erwinia, Hafnia, Klebsiella
• • Lactobacillus delbrueckii subsp. bulgaricus, Lab. helveticus, Lab. plantarum, Lab. acidophilus, Lab. reuteri, Lab. casei subsp. casei, Lab. sake, Lab. curvatus
  • Carnobacterium piscicola
  • Brochothrix thermosphacta
  • Listeria monocytogenes
  • Corynebacterium glutamicum
  • Brevibacterium linens and Bre. casei
  • Propionibacterium freudenreichii
  • Bifidobacterium bifidum, Bif. infantis, Bif. adolescentis
• Important bacteria in food include:

  • Erwinia amylovora
  • Hafnia alvei
  • Klebsiella pneumoniae
  • Morganella morganii
  • Proteus vulgaris
  • Salmonella enterica ssp. enterica
  • Shigella dysenteriae
  • Serratia liquefaciens
  • Yersinia enterocolitica
  • Vibrio cholerae, Vib. parahaemolyticus, Vib. vulnificus
  • Aeromonas hydrophila
  • Plesiomonas shigelloides
  • Coxiella burnetii
  • Micrococcus luteus
  • Staphylococcus aureus
  • Streptococcus pyogenes
  • Enterococcus faecalis
  • Lactococcus lactis subsp. lactis and subsp. cremoris
  • Leuconostoc mesenteroides subsp. mesenteroides, Leu. lactis, Leu. carnosum
  • Pediococcus acidilactici and Ped. pentosaceus
  • Sarcina maxima
  • Bacillus cereus, Bac. coagulans, Bac. stearothermophilus
  • Sporolactobacillus inulinus
  • Clostridium botulinum, Clo. perfringens, Clo. tyrobutyricum, Clo. saccharolyticum, Clo. laramie