Biomedical subjects
Publications and source records attributed to A Ciegler.
A low temperature (4 C) favors the accumulation of the mycotoxin tremortin when tremortin-producing molds are grown on various agricultural commodities. However, the rate of toxin formation is more rapid at a high temperature (20 C).
Conidia of Aspergillus candidus converted glucose and other sugars to mannitol. Low pH (ca. 3.0) apparently favored the percentage yield but decreased the fermentation rate.
The ability of a number of fungal spores, and in particular of resting vegetative mycelia, to transform naringin and naringenin was studied. In general, only hydrolytic cleavage of the sugar moieties of naringin to produce prunin and naringenin was observed. Two cultures, Penicillium charlesii and Helminthosporium sativum, also produced two unidentified flavonoid compounds but in very low yields. No transformation of aglycone was detected, although the compound was metabolized by some cultures when supplied as the glycoside prunin. A fluorodensitometric method was developed for the quantitative analysis of flavonoid compounds.
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High-moisture yellow dent corn became heavily molded by Penicillium martensii after storage for 6 months at 1 C. Mice ingesting corn molded by P. martensii died within a few days. The toxin was isolated and identified as penicillic acid. Large quantities of the toxin accumulated over a 3-month period on artificially inoculated corn incubated at temperatures between 1 and 15 C. At higher temperatures, the toxin disappeared within 45 days.
Of 10 Penicillium species reported to cause blue-eye disease of corn, four (P. martensii, P. palitans, P. cyclopium, P. puberulum) were found capable of producing the mycotoxin penicillic acid on various agricultural commodities. Commodities with high protein contents did not support toxin synthesis. The extent of toxin production varied with the strain of mold, the commodity, and the temperature; low temperatures (1 to 10 C) favored toxin accumulation.
A technique for biological verification of aflatoxin B(1) was developed based on toxin-mediated induction of lysis in a lysogenic strain of Bacillus megaterium NNRL B-3695. Reduction of culture turbidity was determined at various concentrations of toxin. Incubation of 1.1 x 10(-4) g (dry weight) of cells/ml of growth medium containing 25 mug of B(1) per ml at 37 C reduced initial turbidity 0.20 absorbance units in 4 hr. If the bacterial lysate of the lysogenic strain, after a 2-hr incubation with 25 mug of B(1) per ml, was plated with a sensitive B. megaterium strain (NRRL B-3694), plaque-forming units increased approximately 150 times relative to the control. Comparable testing of the effects of aflatoxin on the nonlysogenic, sensitive strain demonstrated that 75 mug of B(1) per ml neither induced lysis nor plaque-forming units. Although induction is not an exclusive property of aflatoxin B(1), the differential response of the lysogenic and sensitive Bacillus strains to B(1) offers a unique and rapid technique for biological verification of the toxin.
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The toxicity of alfatoxin B(2a) (hydroxydihydro-aflatoxin B(1)) was studied in several biological systems. Aflatoxin B(2a) is the monohydroxylated derivative obtained from addition of water to the double bond of the terminal furan of B(1). Examination of the sensitivity of a group of microorganisms to B(2a) demonstrated that the inhibitory spectrum was similar to aflatoxin B(1). However, the toxicity of B(2a) was markedly lower than B(1), as measured by the initiation of bile duct hyperplasia in ducklings. Binding of aflatoxin to deoxyribonucleic acid (DNA) was determined by measuring the hypochromicity produced by the nucleic acid at 363 nm and the capacity of increasing amounts of DNA to quench the fluorescence of the toxin was also used as a measure of the binding of toxin to nucleic acid. These tests showed that the DNA-binding capacity of B(2a) was lower than B(1).
Of 123 species of bacteria surveyed for L-asparaginase synthesis, Erwinia aroideae NRRL B-138 provided the highest yields.