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Biomedical subjects

L A Lindenfelser

Publications and source records attributed to L A Lindenfelser.

8 recordsLinked to original sources
PubMed1978

Wild rice as fermentation substrate for mycotoxin production.

Many cereal grains have been studied for their suitability as substrates for the fermentative production of mycotoxins. However, except for aflatoxin, wild rice has not been investigated. Hence, five mold cultures known to produce the mycotoxins ochratoxin-A, penicillic acid, patulin, vomitoxin, and zearalenone were grown on wild rice under varying conditions of moisture and temperature to determine whether this grain would serve as a suitable substrate for toxin production. Under appropriate fermentation conditions, good yields of ochratoxin-A and moderate amounts of patulin were obtained, but only small amounts of penicillic acid, vomitoxin, and zearalenone were elaborated. An extract from a sample of naturally molded wild rice contained 0.8 microgram of patulin per g of rice. The predominating mold was identified as Aspergillus clavatus. Under identical cultural conditions, this isolate and a known patulin-producing strain of A. clavatus yielded approximately equivalent amounts of the mycotoxin.

Aspergillus↗
PubMed1977

Penicillic acid production in submerged culture.

Twenty known penicillic acid (PA)-producing Aspergillus and Penicillium cultures were grown under various conditions in shaken flasks to determine the highest yielding strains and their requirements for maximum toxin production. Abilities of the cultures to utilize eight different carbon sources in Raulin-Thom medium for mycotoxin synthesis were determined at four different incubation temperatures: 15, 20, 25, and 28 degrees C. Of the 20 cultures, P. cyclopium NRRL 1888 was superior, yielding up to 4 mg of PG per ml, with mannitol as the carbon source and 25 degrees C as the incubation temperature. Fifteen of the cultures elaborated lesser amounts of PA, whereas four strains yielded none under the test conditions. Whey from the manufacture of cottage cheese by the cultured process was also a satisfactory medium for PA production. In whey medium, yields up to 3 mg/ml were obtained with P. cyclopium NRRL 1888.

Aspergillus↗
PubMed1975

Solid-substrate fermentor for ochratoxin A production.

A laboratory-scale fermentor designed for solid-substrate fermentation was constructed and tested. Its capacity to produce ochratoxin under varied conditions was determined with wheat as substrate. Ochratoxin yields of 2,000 to 2,500 mug/g of wheat were regularly obtained, and occasionally yields as high as 4,000 mug/g were obtained. The most critical factor in the fermentation was initial substrate moisture content; wheat tempered at 30 to 31% moisture produced the highest yields. Other variables tested were agitation and aeration rates, initial static culture time, and inoculum types and volumes.

Air↗
PubMed1971

Microbial transformation of flavonoids.

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.

Aluminum↗
PubMed1964

Antibiotics Against Plant Disease: VIII. Screening for Nonpolyenic Antifungal Antibiotics Produced by Streptomycetes.

In a survey of Streptomyces species, methods were designed and followed that would specifically select strains capable of producing heat-stable, nonpolyenic, antifungal antibiotics. Of 500 strains grown in shaken flasks, 240 of the culture liquors contained active factors as demonstrated by paper-disc assay against Mucor ramannianus. Culture filtrates and mycelial extracts of the active strains were examined by ultraviolet spectrophotometry; 166 were nonpolyenic as determined by absorption spectra. Heat-stability tests of the nonpolyenic antibiotics over a broad pH range revealed that 15 were stable under all test conditions, 70 moderately stable, and 81 unstable. Culture liquors containing stable, nonpolyenic antifungal agents were chromatographed with eight solvent systems in an attempt to identify the antibiotics. The producing cultures were studied by cross-antagonism tests to discover similarities with producers of known antibacterial antibiotics. Two of the antibiotics produced by promising strains were identified as cycloheximide and musarin. Six antibiotics, presumably new, were detected.

Journal Article↗