718 Modern Food Microbiology
STERIGMATOCYSTIN
This mycotoxin is structurally and biologically related to the aflatoxins, and like the latter, it causes
hepatocarcinogenic activity in animals. At least eight derivatives are known. Among the producing
organisms are Aspergillus versicolor, A. nidulans, A. rugulosus, and others. The LD 50 for rats by
intraperitoneal injection is 60–65 mg/kg. Under UV light, the toxin fluoresces dark brick-red. Although
not often found in natural products, they have been found in wheat, oats, Dutch cheese, and coffee
beans. Although related to the aflatoxins, they are not as potent. They act by inhibiting DNA synthesis.
FUMONISINS
The fumonisins are produced by Fusarium spp. on corn and other grains, and certain diseases of
humans and animals are associated with the consumption of grains and grain products that contain
high levels of these molds.
The species demonstrated to produce fumonisins include F. sacchari, F. subglutinans, F. thapsinum,
F. globosum, F. anthophilum, F. dlamini, F. napiforme, F. nygami, F. moniliforme, and F. proliferatum.
60
The latter species produces large quantities. F. moniliforme (formerly F. verticilliodes; Gibberella
fujikuroi) was the first to be associated with the mycotoxin and it is the best studied of the three. The
prevalence of F. moniliforme is significantly higher in corn from areas where a high rate of human
esophageal cancer occurred than in low esophageal cancer rate areas.
54
There are at least 15 fumonisins, with the best known being FB 1 , FB 2 , FB 3 , FB 4 , FA 1 , FA 2 , and FA 3 .
The major ones are FB 1 –FB 3 , and the others are considered to be minor and less well characterized.
Of the three major toxins, FB 1 (also designated macrofusine) is produced in the largest quantities by
producing strains. For example, among nine strains of F. moniliforme, the range of FB 1 produced on
autoclaved corn was 960 –2350 µg/g while for FB 2 the range was 120–320 µg/g.
72
Fusarin C is produced by F. moniliforme but apparently is not involved in hepatocarcinogenic
activity.
35 It is mutagenic in the Ames test but only after liver fraction activation.
98 In a culture
medium, more was produced at pH <6.0 than above, and the highest yields were achieved between
days 2 and 6 at around 28
◦ C.
33 Corn isolates were shown to produce about 19–332 µg/g when grown
on corn.
33
Growth and Production
In regard to optimum growth temperature and pH, the maximum yield of FB 1 by a strain of F.
moniliforme in a corn culture occurred in 13 weeks at 20
◦ C with a yield of 17.9 g/kg dry weight.
2
The higher growth rate of the fungus occurred at 25
◦ C, not at 20
◦ C, and the stationary phase was
reached in 4–6 weeks at either temperature.
2 In the same study, FB 1 production commenced after 2
weeks of active growth and decreased after 13 weeks. Overall, the optimum time and temperature
for FB 1 production was 7 weeks at 25
◦ C. Good growth by an F. moniliforme strain at 25 and 30
◦ C
over the pH range of 3–9.5 has been demonstrated.
97 Little growth occurred at 37
◦ C over the same
pH range. Culture media were used with acidic pH values adjusted with phosphoric acid.
97 Neither
F. moniliforme nor F. proliferatum produces much toxin at a w 0.925.
57 For one strain of the former
grown on sterile corn for 6 weeks at 25
◦ C, the ppm of FB 1 produced were 6.8, 14.4, 93.6, and 102.6 at
the respective a w values of 0.925, 0.944, 0.956, and 0.968.
57 The level of FB 1 was ca. 5 times higher in
degermed maize kernals than in germ tissue. The pH of the degermed decreased from 6.4 to 4.7 after
10 days while that of colonized germ tissue increased to pH 8.5.
79 Acidic conditions were conducive
to FB 1 production while alkaline conditions were repressive. When F. moniliforme and F. proliferatum
STERIGMATOCYSTIN
This mycotoxin is structurally and biologically related to the aflatoxins, and like the latter, it causes
hepatocarcinogenic activity in animals. At least eight derivatives are known. Among the producing
organisms are Aspergillus versicolor, A. nidulans, A. rugulosus, and others. The LD 50 for rats by
intraperitoneal injection is 60–65 mg/kg. Under UV light, the toxin fluoresces dark brick-red. Although
not often found in natural products, they have been found in wheat, oats, Dutch cheese, and coffee
beans. Although related to the aflatoxins, they are not as potent. They act by inhibiting DNA synthesis.
FUMONISINS
The fumonisins are produced by Fusarium spp. on corn and other grains, and certain diseases of
humans and animals are associated with the consumption of grains and grain products that contain
high levels of these molds.
The species demonstrated to produce fumonisins include F. sacchari, F. subglutinans, F. thapsinum,
F. globosum, F. anthophilum, F. dlamini, F. napiforme, F. nygami, F. moniliforme, and F. proliferatum.
60
The latter species produces large quantities. F. moniliforme (formerly F. verticilliodes; Gibberella
fujikuroi) was the first to be associated with the mycotoxin and it is the best studied of the three. The
prevalence of F. moniliforme is significantly higher in corn from areas where a high rate of human
esophageal cancer occurred than in low esophageal cancer rate areas.
54
There are at least 15 fumonisins, with the best known being FB 1 , FB 2 , FB 3 , FB 4 , FA 1 , FA 2 , and FA 3 .
The major ones are FB 1 –FB 3 , and the others are considered to be minor and less well characterized.
Of the three major toxins, FB 1 (also designated macrofusine) is produced in the largest quantities by
producing strains. For example, among nine strains of F. moniliforme, the range of FB 1 produced on
autoclaved corn was 960 –2350 µg/g while for FB 2 the range was 120–320 µg/g.
72
Fusarin C is produced by F. moniliforme but apparently is not involved in hepatocarcinogenic
activity.
35 It is mutagenic in the Ames test but only after liver fraction activation.
98 In a culture
medium, more was produced at pH <6.0 than above, and the highest yields were achieved between
days 2 and 6 at around 28
◦ C.
33 Corn isolates were shown to produce about 19–332 µg/g when grown
on corn.
33
Growth and Production
In regard to optimum growth temperature and pH, the maximum yield of FB 1 by a strain of F.
moniliforme in a corn culture occurred in 13 weeks at 20
◦ C with a yield of 17.9 g/kg dry weight.
2
The higher growth rate of the fungus occurred at 25
◦ C, not at 20
◦ C, and the stationary phase was
reached in 4–6 weeks at either temperature.
2 In the same study, FB 1 production commenced after 2
weeks of active growth and decreased after 13 weeks. Overall, the optimum time and temperature
for FB 1 production was 7 weeks at 25
◦ C. Good growth by an F. moniliforme strain at 25 and 30
◦ C
over the pH range of 3–9.5 has been demonstrated.
97 Little growth occurred at 37
◦ C over the same
pH range. Culture media were used with acidic pH values adjusted with phosphoric acid.
97 Neither
F. moniliforme nor F. proliferatum produces much toxin at a w 0.925.
57 For one strain of the former
grown on sterile corn for 6 weeks at 25
◦ C, the ppm of FB 1 produced were 6.8, 14.4, 93.6, and 102.6 at
the respective a w values of 0.925, 0.944, 0.956, and 0.968.
57 The level of FB 1 was ca. 5 times higher in
degermed maize kernals than in germ tissue. The pH of the degermed decreased from 6.4 to 4.7 after
10 days while that of colonized germ tissue increased to pH 8.5.
79 Acidic conditions were conducive
to FB 1 production while alkaline conditions were repressive. When F. moniliforme and F. proliferatum