Microbiology
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what are the three outcomes of microbes in food?
pathogenesis, spoilage, preservation
What are characteristics of colony morphology? (macroscopic)
form, margin, elevation, size, pigment, optical characteristics, texture
what are the major cell morphologies? (microscopic)
cocci, rod (bacillus), spirillum, spirochetes, appendaged, filamentous
gram positive stains ___, gram negative stains ___
purple; pink
this traps the stain
peptidoglycan
what are the 4 phases of bacterial growth?
lag, exponential, stationary, death
what is the lag phase?
interval between when culture is inoculated and when growth begins
what is the most desirable stage for study of bacteria for enzymes?
exponential phase
which phase is associated with waste production?
stationary phase
these are highly resistant to heat, easily dispersed, hard to destroy
endospores
what are 4 parts of spore?
core, cortex, coat, exosporium
outermost layer of spore, thin protein covering
exosporium
loosely cross-linked peptidoglycan
cortex
contains core wall, cyto membrane, cyto, nucleoid, ribo
core
core is high in ____ acid, and ____ proteins
dipicolinic; small acid soluble
cytoplasm in endospore core contains ___% of water found in vegetative cell, pH is __ unit lower
10-25; 1
examples of bacteria that don’t form spores
e coli and s. aureus
molds multiply by spores known as ___
conidia
these can’t be cultured on plates and must be detected directly; single celled eukaryotes
protozoan parasites
obligate parasites that are host specific, transmitted fecal/orally
food borne virus
sources of microbes in food?
soil/water, plants, food utensils, GI, mamary tissue, food handlers, animal feed, animal hide, air/dust
biggest source of microbes in foods?
soil and water
fresh cut meats have ___ cells/gram microbes, comminuted (ground up) meats have ____ cells/gram
10^3; 10^6
contamination occurs primarily during ___
harvesting