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Lactic streptococci : the use of defined strains and bacteriophage-insensitive mutants in commercial manufacture of cheddar and cottage cheesesThunell, Randall Kirk 04 November 1982 (has links)
Phage-insensitive Streptococcus cremoris starter strains were
selected by assaying cheese whey against potential starter
strains. Six strains were selected and characterized for continual
use in cheesemaking. Upon phage-infection, strains were removed
from the blend. Cheesemaking continued with remaining strains. A
phage-insensitive, fast-acid-producing mutant of the infected
strain was isolated and characterized. This mutant, similar to the
parent, was returned to the strain mixture. Multiple-blend
starters were also used in cottage cheese and cultured buttermilk
manufacture.
Individual strains were used as antigens for a rapid detection
test for lactic-streptococcal agglutinins in cheese milk. When
sedimentation was encountered, agglutinin-sensitive strains were
identified and replaced instead of an entire culture blend.
Phage-insensitive mutants were compared to their respective
parent strains. Traits examined included acid-producing activity,
optimum temperature, generation time, proteolysis, phosphate and
NaCl tolerance, phage adsorption, agglutination, morphology, and
induction. Mutant strains showed variations in individual characteristics,
but no general pattern of variation was observed.
Bulk starters, prepared by growing then freezing individual
strains in a commercial internal-pH-control medium (PHASE 4), were
stored for 3 mo with and without glycerol. Strains varied in
storage survival at -20 C. Glycerol enhanced cell viability and
activity at -20 C. Storage in PHASE 4 at -40 C and -80 C preserved
activity and viability without glycerol. Unfrozen PHASE 4 cultures
retained original activity and viability after 1 mo refrigerated
storage. Frozen and refrigerated PHASE 4 starters have been used
in Cheddar and cottage cheese manufacture for more than 1 yr.
Exclusive use of defined-strain cultures resulted in significant
manufacturing and economic improvements including elimination
of culture rotations and starter failure from phage infection, no
ripening period, greater cheese uniformity, predictable starter
activity, standardized manufacture, and improved cheese quality.
Grade-A cheese production was increased by almost 10%. This
technology enabled some factories to increase cheese yields by
adding whey cream to cheese milk. The combined improvements, based
on defined-strain technology, have enabled factories to increase
production—some by nearly 50%. To date, more than 150 million lb
of Cheddar cheese have been manufactured with defined-strain
cultures. / Graduation date: 1983
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Dimethyl disulfide produced in sterile fish muscle by Pseudomonas putrefaciensRhee, Kie Ho 12 April 1974 (has links)
Sterile fish muscle homogenate was prepared from the individually
line caught black rockfish (Sebastes melanops) and inoculated
with the pure culture of Pseudomonas putrefaciens strain 17. The
inoculated homogenate was incubated at 5°C and the growth and production
of volatile sulfur compounds determined by a combined gas-liquid
chromatography and mass spectrometry.
A column containing 90-100 mesh diatomaceous earth coated
with 10% Carbowax 20M was developed and tested for the quantitative
determination of dimethyl sulfide (DMS), dimethyl disulfide (DMDS)
and dimethyl trisulfide (DMTS).
The DMDS levels in fish homogenate closely paralleled that of
P. putrefaciens growth. The maximum DMDS level of 2.00 μg per
100 g fish homogenate was obtained after 10 days at 5°C in samples
treated with 1.5% NaCl.
NaCl was not required by P. putrefaciens but both the growth
and DMDS production were stimulated by 1-2% of NaCl.
The DMDS production and the growth of P. putrefaciens were
reduced when the homogenate was treated with sodium benzoate (SB)
or ethylenediaminetetraacetic acid (EDTA). The maximum levels of
DMDS in 0.05% SB treated fish were 0.75 μg per 100 g and 0.85 μg
for 0.05% EDTA treatment, respectively.
The SB inhibited the growth rate as well as the maximum
growth of P. putrefaciens, while EDTA had no effect on the maximum
growth but extended the lag period and reduced the rate of growth.
Potassium sorbate (PS) had little effect on DMDS production or the
growth of P. putrefaciens. The maximum level of DMDS in fish
homogenate, treated with 0.1% PS, was 1.80 μg per 100 g and the
growth curve was similar to that of the control. / Graduation date: 1974
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Drug resistance, source, and environmental factors that influence fecal coliform levels of Tillamook BayKelch, William James 15 February 1977 (has links)
In order to determine the source of bacteria in Tillamook Bay,
Oregon, water samples were collected monthly for six months during
the rainy season from October 1975 through March 1976 from the bay
and its tributaries, the Kilchis, Trask, Tillamook, and Wilson
Rivers.
Fecal coliform levels of these samples were determined and the
1,917 bacteria isolated were tested for their resistance patterns
to chloramphenicol (Cm), streptomycin (Sm), ampicillin (Am), tetracycline
(Tc), chlortetracycline (Ct), oxytetracycline (Ot), neomycin
(Nm), nitrofurazone (Ni), nalidixic acid (Na), sulfathiazole (Su),
kanamycin (Km), and procaine penicillin G (Pe).
The fecal coliform count per 100 ml of bay water ranged from
3.6 to 42.0. The counts for Tillamook River ranged from 13.5 to
112.0, Trask River from 0.0 to 132.0, Wilson River from 8.5 to 105.0,
and Kilchis River from 0.5 to 13.9. The rise and fall of fecal
coliform levels were characteristic of the sampling date and each sampling station showed its characteristic maximum and minimum levels.
The 1,917 fecal coliform isolates showed 176 different resistance
patterns to the 12 antibiotics tested. None of the patterns, however,
was characteristic of any specific sampling site.
The fecal coliform counts of the bay were statistically compared to
135 independent variables that included the fecal coliform counts of
tributaries, temperature, river flow data, tide information, antibiotic
use data, and the antibiotic resistance patterns.
Bay fecal coliform levels were highly correlated with the fecal
coliform counts of tributaries especially those of the Trask and Wilson
Rivers, degree of resistance to antibiotics, recreational activities,
and precipitation. Negative correlation existed between bay fecal
coliform count and the ambient temperature.
two potentially useful linear regression models to predict bay
fecal coliform level were developed using a computerized stepwise multiple
linear regression program. / Graduation date: 1977
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Expression of SIV antigens in live Salmonella vaccinesStrahan, Karen M. January 1992 (has links)
No description available.
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Biochemistry and genetics of Bacillus thuringiensis insecticidal delta-endotoxinsHaider, Muhammad Zafaryab January 1987 (has links)
No description available.
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Immunity to salmonellae and their use as recombinant antigen carriersIzhar, Mateen January 1992 (has links)
No description available.
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The interaction of the complement membrane attack complex with surface of gram-negative bacteriaTomlinson, Stephen January 1989 (has links)
No description available.
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Isolation and analysis of the vaccinia virus P4B gene promotorKent, Richard Keith January 1988 (has links)
No description available.
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The production of influenza virus spliced mRNAsSmith, D. B. January 1985 (has links)
No description available.
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Bacterial resistance ot glycopeptide antibioticsMesser, Janet Mariam January 1991 (has links)
No description available.
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