The tendency for certain single- and mixed-strain lactic
starter cultures to develop a fruity and/or fermented off-flavor
in ripening Cheddar cheese was traced to certain strains of
Streptococcus lactis in the starter. A very intense fruity and/or
fermented flavor developed in experimental cheeses when one particular
S. lactis strain was...
Streptococcus gordonii (S. gordonii) is being developed as a Gram-positive
expression vector for the expression of heterologous proteins. This bacterial
expression system takes advantage of the natural pathway of protein export and
anchoring on the surface of the bacterium. The expression of heterologous proteins
relies on the homologous recombination of...
A method for rapid isolation of plasmid DNA from group N
streptococci was developed. Chief advantages of the method were
simplicity, the utilization of microliter quantities of reagents,
and the obtainment of preparations highly enriched for covalently
closed circular plasmid DNA. The method was also applied to over
15 Leuconostoc...
Fast acid-producing streptomycin-resistant mutants for several
strains of lactic streptococci currently used in commercial Cheddar
cheese manufacture were isolated. Their isolation involved use of a
recently developed differential plating medium that allows identification
of fast acid-producing colonies. Both parents and mutants were characterized
with regard to growth, acid production, proteolytic...
Trypticase-Soy Broth (TSB) was inoculated with Streptococcus
diacetilactis, incubated at 21C for 24 hours and centrifuged to remove
the cells. When the spent TSB was inoculated with Staphylococcus
aureus, it allowed 99.8% less growth than fresh TSB. If the spent
TSB were supplemented with 0.08 μg/ml of niacinamide, this inhibition...
Factors influencing diacetyl production by the aroma bacteria
Leuconostoc citrovorum and Streptococcus diacetilactis were investigated.
When grown in association with lactic streptococci, L. citrovorum
strain 91404 decreased in cell numbers from 10⁸ to 10⁶ over
two weeks of daily subculturing in sterile non-fat milk incubated at
21°C. The ability to...
Experiments were carried out to purify and characterize the
galactosidase of the Streptococcus lactis 7962. Purification was
accomplished using standard procedures; however the lability of
the enzyme to numerous treatments limited the techniques that could
be used and the amount of active enzyme recovered. Gel filtration
revealed that the enzyme...
A report in the literature suggesting that the use of cottage
cheese dressing cultured with S. diacetilactis would afford enhanced
flavor and shelf life in the finished product prompted this study to
examine reasons for its effectiveness. The method used involved
addition of a culture of S. diacetilactis 18-16 to...
The enzymes and pathways involved in the catabolism of
glucose by several strains of Streptococcus diacetilactis, Streptococcus
cremoris, and Streptococcus lactis, commonly called the
lactic streptococci, were studied. The presence of aldolase,
triosephosphate isomerase and alcohol dehydrogenase in these
organisms provided evidence for the operation of the Embden-Meyerhof-Parnas (EMP) pathway...