Factors Influencing the Thermal Death Time of Microorganisms

While it has been shown that the time required to destroy a bacterial suspension lengthens with increase in the number of organisms present no detailed study of the relationship has been made. The present paper details the results of such a study made on Staphylococcus aureus with methyl mercuric nitrate

Bacteriological studies on sulfid spoilage of canned vegetables

Sulfid spoilage of canned vegetables is characterized by the marked blackening of the contents and the production of hydrogen sulfid by the organism responsible. Externally the can manifests no characteristics of spoilage; it does not swell or spring. The condition constitutes a new type of thermophilic spoilage due to insufficient processing. It has caused losses in both the sweet corn and pea canning industries of the middle western states. The general characteristics of the spoilage have led to the designation of sulfid spoilage for this type. Sulfid spoilage in canned sweet corn has been shown to be caused by a thermophilic sporulating heat resistant anaerobe. Study of the cultural and physiological characters of the organism indicates that it is an undescribed species, for which the name Clostridium nigrificans has been proposed. Processing at 118°C. (245 °F.) for 70 minutes has not proved effective in destroying the spores of Clostridium nigrificans in No. 2 cans of sweet corn. In the-light of experimental evidence now available, it seems desirable in the control of Clostridium nigrificans to elminate the foci of infection in the cannery and prevent the presence of spores in the product. Prevention of contamination in the plant by avoiding\u27 the use of raw materials harboring the organism may offer a way of control if it can be shown that the organism is carried into the cannery on certain raw materials. The effect of Clostridium nigrificans on different canned vegetables has been pointed out. It would seem that there is little possibility of the organism causing spoilage in vegetables other than peas and sweet corn. In a large number of cases the acidity of the canned product is sufficient to prevent growth of the organism. Clostridium nigrificans occurs in the soil, in manure and on sugar and probably finds its way into the cannery in these materials, where it may set up a focus of infection

Dimethyl-Alpha-Naphthylamine for the Determination of Bacterial Reduction of Nitrates

The alpha-naphthylamine-sulphanilic acid test is widely employed for the detection of reduction of nitrates to nitrites by bacteria. The test has the disadvantage that the reel coloration produced in the presence of the nitrite ion appears for only a few seconds and then fades in cultures of organisms in which a relatively high concentration of nitrite occurs. Frequently in our work it is necessary to test considerable numbers of cultures at one time. Fading makes the results unreliable and cultures having a relatively high concentration of nitrite may be recorded as negative. A second difficulty experienced with the test is the instability of the alpha-naphthylamine solution, resulting in its marked discoloration. When added to the culture, the discolored solution imparts a pink color which may prove confusing when testing cultures having relatively little nitrite present

The Synthesis of Vitamins by Microorganisms

The synthesis of vitamin B is of general occurrence among microorganisms. Negative results of some investigators may be accounted for by inadequate amounts fed or too limited feeding periods. Our experiments showed the following organisms to elaborate vitamin B when tested by the rat weight test: Saccharomyces cerevisiae, Torula rosea, Oospora lactis, Bacillus adhaerens, Bacterium coli (three strains), Bacillus subtilis and Bacillus mycoides

Fermentation of Artichokes

The application of fermentative processes to the problem of the industrial utilization of agricultural products and by-products for the production of organic acids and \u27solvents\u27 has been approached from a number of angles. During the course of related studies the possibility of the fermentative utilization of artichoke tubers was considered. In many ways this plant would provide an agricultural product highly suited to such purposes. The artichoke is indigenous to North America and grows freely in all parts of the country. It can be machine cultivated in the same manner as corn and can be stored in the ground until needed. It is extremely hardy, adapts itself to great variations in soil and climate and is resistant to frost, while the foliage is very resistant to the ravages of insects and fungous diseases. Yields have been reported of from seven tons up to twenty tons per acre

Notes on the Bacterial Flora of the Snake

A study was made of the bacterial flora of diseased and normal snakes. The material was furnished by the Museum of the Minnesota Academy of Science, Minneapolis Public Library. Two types of disease were reported as being the cause of the death of their snakes. One, a typhoid-like disease; the other, a pneumonia. Scrapings from the intestines of the typhoid-like cases and the lungs from the snakes which had died of pneumonia were sent to this laboratory for bacteriological examination. The species from which isolations were made are as follows: Western Diamond Rattlesnake (Crotalus atrox), Timber Rattlesnake (Crotalus horridus), California Red Rattlesnake (Crotalus exsul), and Coachwhip Racer (Coluber flagellum)

A New Species of Actinomyces Pathogenic in Man

The organism which proved fatal to a boy of 14 was isolated under the direction of Dr. John Gammel of the Lakeside Hospital, Cleveland, Ohio, from a lesion measuring approximately 9 by 13 cm. located on the back. This large granulomatous process persisted for months; the central portion was ulcerated and freely exuded a tenacious, mucopurulent, sometimes blood streaked discharge. In the periphery there were several open and closed sinuses. Two biopsies revealed no actinomycotic granules although the organism was observed in sections of the granulomatous tissue. No granules were present in the morning discharge after washing with saline solution. The clinical diagnosis was paramycetoma

Bacterial Blackening of Canned Vegetables

Sulfur stinker is the trade name given to canned sweet corn which has undergone an anaerobic decomposition resulting in a blackened condition of the germ, and the evolution of hydrogen sulfid gas. The condition is caused by an anaerobic, gram positive, sporulating, hydrogen sulfid producing thermophile whose spores resist boiling temperature for five hours. Vegetative cells are destroyed by 10 min. at 100°C. Optimum temperature for multiplication is 55°C.; the upper limit is 65°C. Growth and blackening of corn occur at room temperature if incubation is sufficiently long - 6-8 weeks. The organism occurs singly or in chains of as many as eight bacilli. Twenty-four sugars, glucosids and alcohols were tested, but none has been attacked with acid production. Nitrates are reduced with no liberation of gas; blood agar is hemolyzed

Comparative Dissimilation of Xylose and Glucose by Escherichia coli and Citrobacter anindolicum

The dissimilative action of Escherichia coli, Citrobacter anindolicum and various organisms of the intermediate groups on xylose and on dextrose was studied under comparable conditions with the aim of postulating a mechanism of the breakdown of the xylose molecule. It was found in many cases that there were significant differences in the ratios of the end products obtained from the two sugars. The products found were H2, CO2, formic, acetic, lactic, and succinic acids, and ethyl alcohol. Acetaldehyde could be isolated by means of sodium bisulphite during the fermentative process