Potential mycotoxin productivity of Alternaria alternata isolated from leaves of Mube (Stauntonia hexaphylla), Hanamizuki (Cornus florida), and Kobushi (Magnolia praecocissima) was investigated with cultures growing on rice medium. By thin-layer chromatography and high-performance liquid chromatography, the presence of alternariol (AOH), alternariol monomethyl ether (AME), and altenuene (ALT) was confirmed in the rice culture extract. A. alternata isolate from Mube leaves produced AOH, AME, and ALT at concentrations of 22.99 mg/kg, 9.13 mg/kg, and 2.53 mg/kg, respectively. A. alternata isolate from Hanamizuki leaves produced AOH, AME, and ALT at concentrations of 1.50 mg/kg, 0.59 mg/kg, and 3.42 mg/kg, respectively. A. alternata isolate from Kobushi leaves produced AOH, AME, and ALT at concentrations of 20.37 mg/kg, 0.95 mg/kg, and 7.25 mg/kg, respectively. These results suggested that A. alternata on garden trees contaminate food and feed with the mycotoxins.
We conducted a survey of fumonisin B1, B2 and B3 contaminations in feed ingredients and formula feeds (109 samples) distributed in Japan in 2004-2005. Fumonisins were determined with LC/MS after purification with ion-exchange cartridge column. Fumonisins were detected in all samples of corn and it's by product, milo (grain sorghum), rye and formula feed. No contamination was observed in dehulled rice, cotton seed and alfalfa. The mean values of fumonisin B1 concentration in corn and formula feed were 350 and 340 μg/kg, respectively, the highest value was 1,900 μg/kg in corn.
In nature, a microbe tries an invasion to a plant by using every opportunity, but many plants can prevent an invasion as a non-host plant. However, in the case of plant disease, a plant is unable to prevent an infection causing growth inhibitions, then a relation of plant-plant pathogen occur, and various interactions are performed. Various chemical substances such as microbe-producing phytotoxins and plant-producing phytoalexins, incorporated in their interactions, have been elucidated. Investigation of quantitative/qualitative biological activities against man/animal of these chemical substances, and of accumulation situation are necessary, to circumvent the danger of becoming mycotoxin or mycotoxin mimic. If phytotoxins such as host-specific-toxins showed an important activity, their accumulation amount in resistance varieties/non-host plants/post-harvests should be investigated. Similar investigations are also required in the case of plant-protecting substances.
Ochratoxin A is a nephrotoxic mycotoxin known to contaminate a variety food and beverages. The current studies indicate the possibility of ochratoxin A -related carcinogenicity in human. The fungi producing ochratoxin A exist two genera, Aspergillus in tropical areas and Penicillium in cooler climates areas including Japan. Occurrence of ochratoxin A in retail food in Japan has been investigated from 2004 to 2005. The result shows that ochratoxin A contaminates several kinds of food and beverages even though a low level in Japan. The total diet study of ochratoxin A has been performed in 2000-2002, indicating that the exposure level to ochratoxin A was quite low in Japan. However, the efforts to mitigate the risk of carcinogenicity induced by ochratoxin A, such as monitoring system and setting the standard would be needed.
Ochratoxin A, B and citrinin were simultaneously determined in foods and food stuffs for over 20 years. Ochratoxin A was found in cereals such as wheat, barley, rye, coix seed, buckwheat and corn, and coffee bean, cacao, bean for bean-paste. Ochratoxin B was found in samples containing high level of ochratoxin A at the level of 1/3 to 1/10 of ochratoxin A. Co-occurrence of ochratoxin A and citrinin was frequently found in buckwheat and coix seed. It was not possible to confirm these toxins less than 1 μg/kg in samples because of the low sensitivity of the TLC method or HPLC analysis of ochratoxin esters until a few years ago. But now, it is possible to confirm these toxins less than 1 μg/kg with LC/MS/MS analysis. This revealed the contamination of these toxins at low level in food in Japan. Recently, Aspergillus carbonarius come to the fore as ochratoxin A-producing fungi, causing natural occurrence of ochratoxins in grapes in European counties. Four strains out of 6 strains examined produced ochratoxin A.
Cigarette beetle (Lasioderma serricorne) and Indian meal moth (Plodia interpunctella) are notorious insects because they eat a variety of dried plant materials much. We showed that these two insects inhabited so frequently in human living environments, and that fungi and bacteria causing public health problems were isolated from their body surfaces and digestive tracts. Aspergillus ochraceus, A. versicolor, and A. fumigatus, which are known to produce a mycotoxin, have been isolated from their body surfaces. A study on the potency of A. ochraceus strains to produce ochratoxin A revealed that 18 of 20 of A. ochraceus isolates from cigarette beetle highly produced ochratoxin A on moistened barley culture and 11 of 13 isolates form Indian meal moth did as well. In addition, myclogical study on lesser grain borer (Rhizopertha dominica) captured at an ordinary house also showed that A. ochraceus isolates produced the mycotoxin extensively on the culture medium as well as those from the others of two insects described before.
Confusion in defining the species producing OTA arose when P. viricatum was included to the toxigenic species by Walbeek et al. (1969) and then later by Ciegler et al. (1973). Pitt (1979, 1987) and Frisvad (1983,1986) determined only P. verrucosum was the OTA-producing species in Penicillium because P. viricatum and P. verrucosum were separated based on growth rate and profile of mycotoxin production profile. Recently, P. verrucosum from cheese and meats has been proposed as a new species P. nordicum because almost all P. verrucosum is derived from plants. P. verrucosum grows in the range of 0-31 °C with an optimum at 20 °C OTA production correlated well with the temperature range of growth being greater at optimum temperature. The minimum aw for growth and mycotoxin production is 0.86. Growth and the mycotoxin production are affected by the nature of substrates and the isolate. Cycling of temperature gradient causes moving of moisture in the grains stored in warehouse and allows fungal growth and the mycotoxin production when moisture content increase. Processing facilities for drying and storage of crops or foods should be cleaned to reduce the contamination potential because soil, residual grains, or old product may be the source of the P. verrucosum infection.