Mould contamination and the influence of water activity and temperature on mycotoxin production by two aspergilli in melon seed.
Both the moisture levels and the incidence of mould contamination recorded for shelled water melon seed samples (22) obtained from 9 markets were generally higher as those recorded for the unshelled seed samples. 16 fungi, mostly toxigenic, were isolated from the surface-disinfected mouldy seeds. Of these isolates, 7, 3 and 2 species belonged to Aspergillus, Penicillum and Fusarium genera, respectively, while Botryodiplodia, Rhizopus, Sclerotium and Syncephalastrum had one representative each. Production of aflatoxins (B1, B2) by 5 toxigenic strains of Aspergillus flavus and of ochratoxin A by 4 toxigenic strains of A. ochraceus in melon seed at varying water activity (aw) and temperature levels were investigated. Of the aw levels (0.65, 0.70, 0.80, 0.90 and 0.98) provided, toxins were detected only at and above 0.80 with the peak production recorded at either 0.90 or 0.98 aw level. Whereas aflatoxins were produced and detected under all the test temperatures (15, 20, 25, 30, 35, and 40 degrees C), the elaboration of ochratoxin A was detected only as from 25 to 40 degrees C. Optimum temperature for toxin production by all the strains of the two fungi used was 30 degrees C.
Adebajo
L O
LO
Department of Biological Sciences, Ogu State University, Ago-Iwoye, Nigeria.
Bamgbelu
O A
OA
Olowu
R A
RA
D016604:Aflatoxin B1 / Q000096:biosynthesis; D000348:Aflatoxins / Q000096:biosynthesis; D001231:Aspergillus flavus / Q000378:metabolism*; D001235:Aspergillus ochraceus / Q000378:metabolism*; D005516:Food Microbiology; D005658:Fungi / Q000737:chemistry; D009183:Mycotoxins / Q000096:biosynthesis*; D009793:Ochratoxins / Q000096:biosynthesis; D012639:Seeds / Q000737:chemistry*; D013172:Spores, Fungal / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000032:analysis
D000348:Aflatoxins; D009183:Mycotoxins; D009793:Ochratoxins; D014867:Water; C025589:ochratoxin A; C029753:aflatoxin B2; D016604:Aflatoxin B1