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Biomedical subjects

V R Bruce

Publications and source records attributed to V R Bruce.

8 recordsLinked to original sources
PubMed1982

Microbial hazards associated with bean sprouting.

The behaviour of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganism were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples show an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increase substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.

Aflatoxins↗
PubMed1979

Mycological survey of selected health foods.

A survey was conducted to compare the total viable fungal content and the number of different mold species encountered in 10 types of health foods labeled organically grown and in the same foods without such a label. The foods were wheat flour, corn meal, brown rice, figs, split peas, pinto beans, soybeans, walnuts, pecans, and peanuts. Results showed no consistent difference in either the total viable fungal content or the number of different mold species encountered between the labeled and unlabeled foods. Two genera of yeasts (Rhodotorula and Saccharomyces) and 22 gener of molds, including more than 65 species, were encountered. The mold flora was dominated by Aspergillus glaucus, Aspergillus niger, Aspergillus flavus, Aspergillus candidus, Penicillium cyclopium, and Penicillium viridicatum. Isolates of the genera Alternaria, Cladosporium, Fusarium, and Helminthosporium also occurred in certain foods. At least 10 toxicogenic species of Aspergillus and Penicillium were encountered. A total of 87 cultures of these species, all isolated from health foods, were screened for laboratory production of their respective toxins. Toxin production potential of these 87 cultures did not differ from that of cultures of the same species isolated from conventional foods.

Aspergillus↗
PubMed1977

Direct plating versus dilution plating in qualitatively determining the mold flora of dried beans and soybeans.

Two methods presently used for examining whole foods and feeds for viable molds were evaluated for their relative effectiveness in the qualitative determination of the total number of mold species present in soybeans and dried beans: the direct plating method and the serial dilution method. Sixty-nine soybean samples and 40 dried bean samples were examined. Although the quantitative results of this study were inconclusive, the qualitative results show that the direct plating method was substantially more effective in detecting individual mold species. An average of 12.9 and 10.9 species was detected by the direct plating method in whole soybean and dried bean samples, respectively. An average of 4.4 and 2.8 species was detected by the dilution method in ground soybean and dried bean samples, respectively. A total of at least 37 mold species were found in the study, including 10 toxicogenic species. With few exceptions, detection rates of the 37 individual species were substantially greater among the samples examined by direct plating than those examined by serial dilution.

Food Microbiology↗
PubMed1976

Comparison of antibiotic-amended potato dextrose agar and acidified potato dextrose agar as growth substrates for fungi.

Fifteen fungal species, all isolated from food, were compared for their growth abilities on potato dextrose agar acidified to pH 3.5, and on nonacidified potato dextrose agar amended with 40 ppm chlortetracycline hydrochloride. Comparisons were made at 16, 21, 26, 32, and 37 degrees C. Of the 15 species, only Penicillium expansum exhibited better growth on the acidified medium than on the nonacidified antibiotic medium, while 9 species grew better on the nonacidified antibiotic medium. Five species grew equally well on either medium.

Agar↗
PubMed1975

Mycotoxin-producing potential of mold flora of dried beans.

To evaluate the potential for mycotoxin production by molds in dried beans, the mold flora of 114 samples was determined both before and after surface disinfection of the beans with 5% NaOCl. Surface disinfection substantially reduced mold incidence, indicating that contamination was mainly on the surface. The flora, both before and after disinfection, was dominated by species of the Aspergillus glaucus group, the toxicogenic species A ochracues, Penicillium cyclopium, and P. viridicatum, and species of Alternaria, Cladosporium, and Fusarium. The toxicogenic species Aspergillus flavis, A. versicolor, Penicillium Citrinum, P. expansum, P. islandicum, and P. urticae were encountered less frequently. Of 209 species of Aspergillus and Penicillium screened for mycotoxin production on sterile rice substrate, 114 produced one or more of the following mycotoxins: A. flavus, aflatoxins; A. ochraceus, ochratoxins; A. nidulans, A. unguis, and A. versicolor, sterigmatocystin; P. cyclopium, penicillic acid; P. citrinum and P. viridicatum, citrinin; P. urticae, patulin and griseofulvin. Sterigmatocystin production by A. unguis is reported for the first time.

Aflatoxins↗
PubMedDate not supplied

Microbiological survey of selected imported spices and associated fecal pellet specimens.

A microbiological survey was performed on 4 selected imported spices: black peppercorns, white peppercorns, coriander, and fennel seed. Aerobic plate count values ranged from 10(4) to 10(7) colony-forming units (CFU)/g for black and white peppercorns and from 10(3) to 10(5) CFU/g for coriander and fennel seed. Combined results of the 3-tube most probable number procedure and the API 20E kit indicated the presence of Escherichia coli in 4 test samples of black peppercorns, 1 test sample of white peppercorns, and 1 test sample of coriander. Two test samples of black peppercorns were positive for Salmonella contamination. Among the various Enterobacteriaceae isolated from the spices, Enterobacter cloacae and Klebsiella pneumoniae were found most frequently in all spice types. Of 18 mammalian and avian fecal pellets removed from the spices and analyzed microbiologically, E. coli was found in only 2 pellet specimens. There was no apparent relationship between the enteric microflora found in spices and those found in the fecal pellets.

Animals↗
PubMedDate not supplied

Cyclopiazonic acid production by cultures of Aspergillus and Penicillium species isolated from dried beans, corn meal, macaroni, and pecans.

Ninety-five isolates of Aspergillus and Penicillium species from selected dried foods were examined for their ability to produce cyclopiazonic acid (CPA). The isolates were grown in sterile synthetic liquid medium at 28 degrees C for 8 days in the dark. The medium and mold mycelia were then extracted with chloroform. CPA was semiquantitatively determined by thin layer chromatography through visual comparison with standards. The cultures of A. flavus were also examined for their ability to produce aflatoxin. One A. tamarii and all 13 P. urticae isolates produced CPA, whereas only 19 of the 31 (61%) A. flavus isolates produced CPA, and 6 (19%) A. flavus produced aflatoxin. All 13 P. urticae isolates also produced patulin and griseofulvin. CPA-producing A. flavus was found in all food types but not in all samples. CPA-producing P. urticae was found only in dried beans and macaroni.

Aflatoxins↗