Yeasts Occurring in Souring Figs

Mrak, E. M.; Phaff, H. J.; Vaughn, Reese H.; Hansen, H. N.

doi:10.1128/jb.44.4.441-450.1942

Cited by 30 publications

(13 citation statements)

References 9 publications

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“…Since these yeasts compete poorly with other microorganisms in nonselective environments, these parameters become important in favoring the growth of osmotolerant yeasts. Osmotolerant yeasts are the main spoilage organisms in foods such as honey, maple syrup, raw sugar cane, fruit syrups, candy, jams, jellies (37), soy mashes (24), fondants (28), fruit juice concentrates (30), dried fruits (21,22), and chocolate syrup (unpublished data). Contamination of these food products could originate from highly contaminated raw ingredients, inadequate sanitation due to the difficulty of cleaning a highsugar commodity from equipment, improper packaging and storage facilities, and insects during all phases of production.…”

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Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup

Restaino¹,

Bills²,

Tscherneff³

et al. 1983

Appl Environ Microbiol

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We investigated the growth parameters of Saccharomyces rouxii isolated from spoiled chocolate syrup. The optimum pH range for S. rouxii was 3.5 to 5.5, whereas the minimum and maximum pH values that permitted growth were 1.5 and 10.5, respectively. For cells grown in 0 and 60% sucrose the optimum water activity (a,) values were 0.97 and 0.96, respectively. The optimum temperature for S. rouxii increased with a decreasing a, regardless of whether glucose or sucrose was used as the humectant. The optimum temperatures for S. rouxii were 28°C at an a. of >0.995 and 35°C at an a, of 0.96 to 0.90 in 2x potato dextrose broth with sucrose. Increasing the sorbate concentration (from 0.03 to 0.10%) caused the growth of S. rouxii to become more inhibited between a,s of >0.995 and 0.82. S. rouxii did not grow when the sorbate level was 0.12% (wt/vol). At lower sorbate levels, the effect of sorbate on the growth of S. rouxii depended on

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mentioning

confidence: 99%

Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup

Restaino¹,

Bills²,

Tscherneff³

et al. 1983

Appl Environ Microbiol

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“…Yeast taxonomists in North America have not generally used nitrogen or carbon assimilation tests, exceptions being Graham and Hastings (1941), Mrak and McClung (1940), Hansen (1942), and Bedford (1942). Mrak and Bedford used a synthetic liquid medium rather than auxanographic plates because the liquid method expedited the determinations and gave results comparable to those obtained by the auxanographic method.…”

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A Critical Evaluation of the Nitrogen Assimilation Tests Commonly Used in the Classification of Yeasts

1946

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The ability of some groups of closely related yeasts to use potassium nitrate as a source of nitrogen was applied successfully by Stelling-Dekker (1931) to the classification of the sporogenous yeasts. Later, Lodder (1934) added other nitrogen compounds, namely, ammonium sulfate, urea, asparagine, and peptone, in diagnostic tests for her classification of the nonsporogenous, nonfilamentous yeasts. She employed a modification of Beijerinck's (1889) auxanographic technique in the following manner: About 2 ml of a dense suspension of the yeast to be tested were placed in a petri dish. It was assumed on the basis of Wildiers' (1901) work that the use of such a heavy inoculation of cells would provide adequate growth factors. An agar medium consisting of 2 per cent glucose, 0.1 per cent potassium dihydrogen phosphate, 0.05 per cent magnesium sulfate, and 2.0 per cent washed agar was cooled to 40 C and poured into the dish. The medium and yeast were quickly mixed. After the medium had solidified, the plate was placed in an incubator to dry for a few hours at 30 C. Then small portions of the nitrogen-containing compounds were placed on the solid surface of the inoculated agar. On incubation at 25 C, an area of growth was produced around those compounds that were assimilated. Lodder's study disclosed that a majority of the yeasts with which she worked were capable of utilizing all the compounds that she had introduced. However, some species of Torulopsis and all species of Kloeckera failed to assimilate ammonium sulfate, urea, and asparagine. These facts were subsequently incorporated in her descriptions of species and genera. These nitrogen compounds, as well as the use of the auxanographic plate method, were generally adopted for diagnostic purposes by succeeding workers in Europe and South America. Langeron and Guerra (1938) used Lodder's medium and technique for their study of filamentous yeasts belonging to the genus Candida. Because they found that urea diffused through the medium so rapidly that it sometimes overlapped the diffusion zones of other nitrogen sources, only one other test substance was placed in the same plate. Langeron and Guerra found that 2 of their 16 species of Candida, C. pelliculosa and C. zeylanoides, utilized peptone only, but 6 assimilated urea. At variance with these results were the findings of Diddens and Lodder (1942) with respect to the assimilation reactions of the Candida species. They found that C. pelliculosa and C. zeylanoides utilized ammonium sulfate, urea, and asparagine in addition to peptone, and that the species C. tropicalis, C. guil-1 One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.

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“…(a) General ; the origin of osmophilic contamination. Osmophilic yertsts are in the minority among the normal microflora on fresh fruit; thus Mrak & McClung (1940) found that on the surface of grapes on the vine the proportion of normal to osmophilic strains is 15 : 1, whereas Mrak, Phaff, Vaughn & Hansen (1942) showed that on dried grapes and dates the proportion W M 1 : 7. Similarly, the present author has isolated occasional osmophiles from sugar cane, which carries many normal yeasts, while in molasses (a strictly osmophilic habitat) there are few normal yeasts present but many osmophiles.…”

Section: The Industrial Microbiology Of Osmophilesmentioning

confidence: 99%

The Microbiology of Sugar‐preserved Foods

Scarr

1953

Proceedings of the Society for Applied Bacteriology

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Yeasts Occurring in Souring Figs

Cited by 30 publications

References 9 publications

Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup

Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup

A Critical Evaluation of the Nitrogen Assimilation Tests Commonly Used in the Classification of Yeasts

The Microbiology of Sugar‐preserved Foods

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