Food and Industrial Microbiology

Vocabulary flashcards generated from the Food and Industrial Microbiology lecture covering key microorganisms, bacterial groups, growth measurement techniques, growth curve phases, and culture systems.

Aspergillus

A widely distributed mold genus with septate hyphae that produces black-colored asexual spores on conidia, causes food spoilage in jams, ham, nuts, fruits, and vegetables, and includes strains that produce mycotoxins.

Alternaria

A mold genus with septate members forming dark-colored spores or conidia that cause rot in tomatoes, rancid flavor in dairy products, and mycotoxin production in some species.

Fusarium

A mold genus characterized by cottony growth and septate, sickle-shaped conidia that causes rot in citrus fruits, potatoes, and grains, and produces mycotoxins.

Geotrichum

A mold genus with septate hyphae forming rectangular arthrospores and yeast-like cottony, creamy colonies; known as dairy mold because it establishes easily in equipment and grows on dairy products.

Mucor

A widely distributed mold genus with nonseptate hyphae that produces sporangiophores with cottony colonies.

Penicillium

A widely distributed mold genus with septate hyphae forming conidiophores on a blue-green, brush-like conidia head; used in cheese production ($Penicillium\,roquefortii$) and causes rot or spoilage in fruits, vegetables, grains, breads, and meat.

Rhizopus

A mold genus with aseptate hyphae forming sporangiophores in sporangium that cause spoilage of many fruits and vegetables.

Rhizopus stolonifer

The mold species commonly known as the black bread mold.

Saccharomyces

The most important yeast genus containing round, oval, or elongated cells; variants such as $Saccharomyces\,cerevisiae$ are used in baking and alcoholic fermentation, but can also spoil food by producing alcohol and $CO_2$.

Pichia

A yeast genus with oval to cylindrical cells that forms pellicles in beer, wine, and brine to cause spoilage, with species like $Pichia\,membranaefaciens$.

Rhodotorula

A genus of pigment-forming yeasts, such as $Rhodotorula\,glutinis$, that cause discoloration of foods like meat, fish, and sauerkraut.

Torulopsis

A yeast genus with spherical to oval cells (e.g., $Torulopsis\,versatilis$) that ferment lactose to spoil milk, as well as fruit juice concentrates and acid foods.

Candida

A yeast genus with species that spoil foods high in acid, salt, and sugar, form pellicles on liquid surfaces, and cause rancidity in butter and dairy products (e.g., $Candida\,lipolyticum$).

Zygosaccharomyces

A yeast genus (e.g., $Zygosaccharomyces\,bailii$) that causes spoilage of high-acid foods such as sauces, ketchups, pickles, mustards, mayonnaise, and salad dressings.

Lactic Acid Bacteria

Bacteria that produce relatively large quantities of lactic acid from carbohydrates, including species from $Lactococcus$, $Leuconostoc$, $Pediococcus$, $Lactobacillus$, and $Streptococcus\,thermophilus$.

Acetic Acid Bacteria

Bacteria that produce acetic acid, such as $Acetobacter\,aceti$.

Propionic Acid Bacteria

Bacteria used in dairy fermentation that produce propionic acid, such as $Propionibacterium\,freudenreichii$.

Butyric Acid Bacteria

Bacteria that produce butyric acid in relatively large amounts, such as $Clostridium\,butyricum$.

Proteolytic bacteria

Bacteria that hydrolyze proteins because they produce extracellular proteinases.

Lipolytic bacteria

Bacteria that hydrolyze triglycerides because they produce extracellular lipases.

Saccharolytic bacteria

Bacteria that are able to hydrolyze complex carbohydrates.

Thermophilic bacteria

Bacteria able to grow at temperatures of $50\,^{\circ}\text{C}$ and above.

Spore Formers

Bacteria possessing the ability to produce spores, including species from $Bacillus$, $Clostridium$, and $Desulfotomaculum$.

Aerobes

Bacteria that require oxygen for growth and multiplication, including species from $Pseudomonas$, $Bacillus$, and $Flavobacterium$.

Anaerobes

Bacteria that cannot grow in the presence of oxygen, such as species from $Clostridium$.

Facultative Anaerobes

Bacteria able to grow in both the presence and absence of oxygen, including $Lactobacillus$, $Pediococcus$, $Leuconostoc$, enteric pathogens, and coliforms.

Coliforms

Bacterial species from $Escherichia$, $Enterobacter$, $Citrobacter$, and $Klebsiella$ that are used as an index of sanitation.

Binary Fission

An asexual process of reproduction where unicellular growth involves an increase in cell constituents leading to cell division.

Hemocytometer

Special slides known as counting chambers used for direct microscopic counts of cells.

Lag Phase

The growth phase occurring immediately after inoculation during which no apparent cell division occurs.

Exponential (log) Phase

The pattern of balanced growth wherein all cells divide regularly at a constant rate.

Generation Time ($G$)

The time interval required for a bacterial population to double, calculated using the formula $G = \frac{t}{n}$ or $G = \frac{t}{3.3 \log\left(\frac{b}{B}\right)}$.

Stationary Phase

The bacterial growth phase characterized by the production of secondary metabolites where the cell population is not quiescent but net growth ceases.

Death Phase

The phase of the bacterial growth curve during which the viable cell population declines.

Continuous Culture

A culture system utilizing a chemostat or turbidostat to maintain a bacterial population at a constant density by adding fresh medium at the same rate that spent medium and cells are removed.

Synchronous Growth

A condition in which all cells in a culture are at the exact same stage of the bacterial cell cycle.