1. What are the physical, biochemical and metabolic characteristics of
Bacillus mensentericus present in canned fish?
It is a mesophilic bacterium, develops optimally in temperature from 30°C to 40°C.
can survive in environments whose pH is between 4.9 and 9.3. easily adapts to
slightly acidic and slightly alkaline environments. At a neutral pH they are
effectively maintained. Its minimum water activity of 0.93. It is optional anaerobic,
but it develops better in oxygen environments. It has a varied metabolism
depending on environmental conditions and the availability of nutrients, can
ferment various types of compounds such as glucose, glycerol and sucrose, can
metabolize nitrates by transforming them into nitrites. It is catalase positive, that
is the enzyme.
2. What are the microscopic and macroscopic morphological
characteristics of Bacillus coagulans in blood Agar present in canned
fish?
They are Gram-positive bacteria, have the form of 1 x 3-4 microns bacilli and
have peritric flagella, have rounded edges, form short chains. Cylindrical spores
are observed. In the cultures can be seen as straight or slightly curved bars.
Macroscopically in Blood Agar round colonies of 3-8 mm of diameter are
observed, hemolytic beta with complete hemolysis, with transparent halo around
gray to yellow, has bright appearance and wavy margins, the colonies extend in
the middle.
3. What microscopic and macroscopic morphological characteristics does
bacillus subtilis grow in TSA Soybean Tripticase Agar?
Bacillus subtillis are bar-shaped with rounded edges. They are about 1 micron
wide by 2-3 microns long. They are found individually or form small chains. In
TSA agar cultures form off-white colonies, are characterized by bulging folds as
blisters and with irregular edges because the medium contains enzyme
compounds of casein and soy food that provides amino acids and other
nitrogenous substances and Dextrose acts as an energy source.
4. What physical and metabolic characteristics does Streptococcus
thermophilus present in canned fish?
, S. thermophilus grows best in mesophilic temperatures around 42 to 45 ° with an
acid pH of 4-6.5, it is facultatively anaerobic and metabolically fermentative, it is
catalase negative because it does not possess the enzyme catalase and does
not decompose hydrogen peroxide into water and oxygen. it is heterotrophic and
generally fastidious, requiring simple carbohydrates as a source of energy and
preformed amino acids as a source of nitrogen, and is generally not hemolytic.
5. Where does it live and how do Bacillus mesentericus spores get into
canned fish?
It is a common inhabitant of soil, thermal waters, arctic waters, ocean sediments.
The presence of its spores in canned foods is of particular interest as the spores
enter canneries in the canning process. spores enter canneries in soil, in raw
foods and in ingredients such as spices or starch and flour. The presence of
spores in some containers of any given batch of canned food is of particular
interest.
6. What is the metabolism of Clostridium nigrificans and what does it cause
in canned fish?
Clostridium nigrificans is associated with sulfur spoilage of canned products
because it is a thermophilic member of the sulfate-reducing bacteria, besides
being strict anaerobes, it can adapt to use glucose as an energy source by
metabolizing glucose into acetate, CO 2 and ethanol.
7. What kind of alterations do Gr Bacillus bacteria cause in canned fish?
Gr Bacillus bacteria can cause alterations such as simple fermentation, gas
production and acid and gas production. Simple fermentation is the most common
and is due to the attack of carbohydrates with acid production and without gas
production. For example, Bacillus stearothermophilus and B. coagulans are the
main thermophiles causing simple fermentation. Gas production by sporulated
aerobes is due to denitrification of nitrate in canned meat or seafood products,
e.g. B. cereus.
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