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Aspergillus niger and Fusarium solani have been reported to show the ability of inducing
agarwood formation in Gyrinops walla. Both these species are also well known for the ability
to produce mycotoxins; products from secondary metabolism of fungi, with varied biochemical
structures and modes of action. Therefore it is worth knowing the characteristics of the toxins
formed by these fungal species before using them as potential inoculants. Since the production
of mycotoxin is limited to certain fungal strains, the present study aimed to identify the
potential of selected strains of A. niger and F. solani for toxin production and its extraction.
Therefore, two strains of A. niger and two strains of F. solani were screened to identify their
ability to produce mycotoxins in Yeast Extract Glucose (YEG) and CzapekDox (CDB) liquid
media. These media were inoculated with three agar plugs from fully grown plate cultures and
incubated at room temperature under normal light and dark regimes. The filtrates were obtained
after incubation periods of 4, 8, 10, 12, 14, 16, 21 and 28 days. Production of toxins was
identified by assessing the damage caused on the surface of Piper nigarum leaves by a known
volume (20µl) of filtrate. Toxicity of culture filtrates were evaluated qualitatively by a graded
scale of Group 1 to Group 5.
According to the results, both strains of A. niger produced positive results for the production
of mycotoxin. However, Asp-MBL1-C strain showed the maximum toxin production in YEG
medium after 4 days of incubation while Asp-U strain showed the maximum toxin production
in the same medium after 12 days of incubation. The maximum toxin production in CDB
medium was observed after 14 days of incubation. More intense leaf damage was observed to
be associated with Asp-U strain in CDB medium. Out of two strains of F. solani tested in two
selected media, only U-Fus strain produced positive results in YEG medium, where maximum
toxicity was observed after 10 days of incubation.
