Microbiology

What do the following acronyms stand for wrt food safety? DAEC, ETEC, EAEC, EHEC, EPEC, EIEC

Diffuse-adhering E. coli(DAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), Enteroinvasive (EIEC), Enterohemorrhagic (EHEC), Enteroaggregative (EAEC)

Determine whether the following characteristics are of eukaryotic or prokaryotic cells: Does not have membrane bound organelles; true nucleus; Size 10-100 um; does not have membrane bound organelles; unicellular

Does not have membrane bound organelles (Pro) True nucleus (Eu) Size 10-100 um (Eu) Does not have membrane bound organelles (Pro) Unicellular (Pro)

Sauerkraut fermentation can be broken down into 3 different phases, early, middle and late. What bacteria is responsible for fermentation in each stage and what is their major fermentation products?

Early: Leuconostoc mesenteroides (Produces CO2 and acetic acid, lowers pH) Intermediate: Lactobacillus plantarum (Homofermentative, produces high levels of lactic acid) Late: Lactobacillus brevis (Further acidifies, final flavor development)

What are the four main stages in the life cycle of the Drosophila fruit fly?

Egg, Larva, Pupa, Adult Fly.

Name extrinsic factor in foods which affect microbial growth.

Environmental conditions where the food is stored

Name the microorganism associated w/ the following: Ergot poisoning, Zearalenones in corn, Patulin, Aflatoxin

Ergot poisoning= Claviceps purpurea; Zearalenones in corn= Fusarium graminarium; Patulin= Penicillium eseparsum; Aflatoxin= Aspergillus flavus

Name 3 of the 16 gram negative, facultative anaerobic rods.

Escherichia (e.g., E. coli), Salmonella (Food poisoning, Typhoid), Shigella (Dysentery), Klebsiella (Pneumonia), Enterobacter (Opportunistic infections), Serratia (Produces red pigment), Proteus (Highly motile/swarming), Morganella, Providencia, Citrobacter, Edwardsiella, Yersinia (The Plague, Y. enterocolitica), Erwinia (Plant pathogens), Hafnia, Kluyvera, Cedecea

Name six of the dirty dozen foods.

EWG 2025 list-Strawberries, spinach, (kale, collard and mustard greens), grapes, peaches, pears, nectarines, apples, cherries, blueberries, blackberries, potato

Define fecal coliforms and indicate the reason that they are often evaluated in foods.

Facultative anaerobes (organisms which can survive in the absence of oxygen), gram-negative, non-spore forming, rod-shaped bacteria that ferment lactose (a type of sugar), producing gas and acid within 48 hours when cultured at 44.5 C. Their lack of ability to form spores makes them more susceptible to destruction by environmental conditions.they are used as indicators of fecal contamination

Name three thermal calculation parameters that can be ascertained from a TDT curve.

Fo, F, Z, and D

Name the four key conditions or intrinsic factors often represented by the acronym FATTOM that influence the growth of most foodborne bacteria.

Food (nutrients); Acidity (pH); Time; Temperature; Oxygen (or lack thereof); Moisture or Water Activity).

What are the 5 main types of botulism?

Foodborne, infant, wound, Adult intestinal toxemia, Iatrogenic botulism

Name one example of each of the following used in food and beverages industry: Fungi Yeast Mold Bacteria Single-cell food

Fungi: Actinomucor, Amylomyces, Mucor, Rhizopus, Monascus, Neurospora, Aspergillus, Penicillium, Candida, Endomyces, Hansenula, Saccharomyces, Torulopsis, Trichosporon, Zygosaccharomyces/ Just say mushrooms Yeast: Saccharomyces, Kluyveromyces Mold: Aspergillus, Penicillium, Rhizopus, Neurospora Bacteria: Lactobacillus, Lactococcus, thousands of names Single-cell foods: eggs, microalgae such as spirulina, chlorella

How is the cell wall structure of a Gram+ and Gram - cell responsible for the cell's Gram-stain reaction?

G+ bacteria have a very thick cell wall consisting of peptidoglycan or murein. These are dehydrated by the alcohol, causing the pores to close, thus preventing the Crystal Violet-Iodine complex from leaving the cell. In Gram -, cells have a thin peptidoglycan layer surrounded by an outer membrane. The alcohol dissolves the Outer Membrane and the thin peptidoglycan layer cannot retain the dye.

Name 5 spices that have antimicrobial activity.

Garlic, cinnamon, cloves, onion, horseradish, and mustard

Name three methods for the calculation of lethality.

General, formula (ball) method, and numerical

Give the traits necessary to completely define a microorganism as a fecal coliform.

Gram negative rod, facultative anaerobe, ferments lactose at 44.5 degrees Celsius

Name three characteristics of Salmonella.

Gram negative, facultative anaerobe, catalase positive, oxidase negative, ubiquitous, lactose non-fermenting, H2S positive and cause foodborne illness

Give the genus and species of one microorganism for each of the following categories: gram negative, strict anaerobe, foodborne pathogen, sulfide spoiler

Gram negative= Salmonella typhimerium or E. coli; strict anaerobe= C. botulinum; foodborne pathogen= S. aureus, Listeria monocytogenes, Sulfide spoiler= Desulfotomaculum nigrificans

How are bacteria grouped according to Bergey’s Manual?

Gram reaction, morphology (rod or cocci), based on phylogeny (evolutionary relationships) using 16S rRNA sequencing