Aflatoxin producers, detection

As in aflatoxin producers, also producers of Fusarium toxins have been detected by PCR assay which were based on primers hybridizing to genes... 

Direct economic losses due to the presence of mycotoxin- (especially aflatoxin-)producing fungi in agricultural crops can be detected in reduced crop yields and lower quality, reduced animal performance and reproductivity... 

The acute bacterial toxins associated with food poisoning episodes are not commonly reported in pharmaceutical products, although aflatoxin-producing aspergilli have been detected in some vegetable ingredients. However, many of the metabolites of microbial deterioration have quite... 

Dichloromethane or methylene chloride is an excellent solvent for oil extraction because of its low boiling point (39.8 °C), which makes desolventization of oil and meal easy. Furthermore, it is non-flammable and has low specific heat, latent heat of vaporization and low solubility of water. Utilization of dichloromethane for oil extraction was first demonstrated in the 1940s but the process was not economically feasible at the time because of the relatively high cost of dichloromethane. In 1986, the feasibility of cottonseed oil extraction by using dichloromethane was demonstrated at a pilot scale study (Johnson et ai, 1986). Residual oil content in the meal was lower than typically achieved with hexane extraction. Cottonseed meal produced during the process was suitable for use in poultry feed formulations, because gossypols present in cottonseed were extracted with oil and removed from meal. No residual aflatoxin was detected in alkali-refined oil. 

A. flavus (ATCC 155A8, NRRL 3251) and A. parasiticus (NRRL 2999), toxigenic isolates, have produced detectable levels of aflatoxin (AFBj ) and aflatoxin (AFG ). A. flavus (ATCC 15548) cultures... 

Natural occurrence in wheat Detection of aflatoxin-producing isolates of Aspergillus flavus from wheat... 

Bedi, P.S., Pal, P., Sing, P.S., and Sohi, H.S. (1981). Detection of aflatoxin-producing isolates of Aspergillus flavus from the wheat grains infected with "Karnal" bunt (Neovossia indica). Indian J. Ecol., 8, 304-305. 

Geisen, R. (1996). Multiplex polymerase chain reaction for the detection of potential aflatoxin and sterigmatocystin producing fungi. Syst. Appl. Microbiol. 19, 388-392. 

Scherm, B., Palomba, M., Serra, D., Marcello, A., and Megheli, Q. (2005). Detection of transcripts of the aflatoxin genes aflD, aflO, and aflP by reverse transcription-polymerase chain reaction allows differentiation of alfatoxin-producing and non-producing isolates of Aspergillus flavus and Aspergillus parasiticus. Int. J. Food Microbiol. 98, 201-210. 

Aflatoxins are potent carcinogenic, mutagenic and teratogenic metabolites produced by molds. The major food affected with aflatoxins are corn, peanuts, rice, cottonseeds, dried fruit and milk from ingestion (103). The US action standards established by FDA are 20 pg/Kg for foods consumed by humans and 0.5 pg/kg for milk. In the case of animal feed, the levels are from 100 to 300 pg/kg. Therefore, assays capable of detecting at these levels have to be developed, (see Table 1 (104,105)). Detection of aflatoxins entails conjugation of these small molecules with carrier proteins like bovine serum albumin to produce antibodies (20). A number of commercial kits for aflatoxins are available (see sections on kits and immunoaflinity purification). 

Aflatoxins are potential carcinogens produced by certain molds that may be found in corn, peanuts, and other food items. They are colorless, odorless, and tasteless. The toxic nature of aflatoxins was made evident by a large turkey kill in England in 1960. One method of detecting... 

Relationship Between Phytoalexin Production and Aflatoxin Contamination. Many samples that had lost the capacity for phytoalexin production had no detectable aflatoxin, while in other similar samples aflatoxin levels ranged as high as 2400 ppb (Table I). Significantly however, no sample of peanuts that had moderate to high phytoalexin-producing capacity contained >5 ppb aflatoxin. Therefore, it can be stated that as long as peanut kernels had the capacity for phytoalexin production, aflatoxin was not formed (Table I). However, the loss of phytoalexin-producing capacity resulted in aflatoxin formation but in only a portion of these susceptible kernels (Domer,... 

E-Z Screen. Manufactured with a proposed use for aflatoxins B1, B2, G1, G2 at 10 ppb, was found to be effective for B1 and G1 in spiked corn at the 10 ppb level. Sample preparation was as prescribed by the kit manufacturer except the sample was shaken for one hour, instead of blending for one minute. A 50 g sample was shaken for one hour with 100 ml 80% methanol and allowed to settle. Then a 100 uL of extract was diluted with 200 uL buffer and 50 uL of this mixture was applied to the sample port of the EZ card. Aflatoxin B2 was detected at the 15 ppb level and G2 at the 20 ppb level. This card test was less sensitive for mixed feeds which contain more pigments- Due to the lack of demand, the manufacturer has stopped producing cards sentitive at the 10 ppb level, but control cards at the 20 ppb are available. In one study 22 samples were tested along with standards and formulated product. No false negatives were encountered and only one false positive. No false positives were encountered on 40 samples tested in another laboratory. Recently cards sensitive to 5 ppb were introduced. Preliminary research indicates the cards will perform to specifications. As the presently used HPIC procedure processes 6 samples in a 2-day period and 99% of the samples were negative, the aflatoxin E-Z Screen could provide the necessary screening capability. 

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