Effect of pH on growth and sporulation of Hirsutella minnesotensis and Hirsutella rhossiliensis in vitro

• Author(s): Chen, S.; Liu, S.;
• Abstract: The fungi Hirsutella minnesotensis and Hirsutella rhossiliensis occur naturally in agricultural fields and parasitize a wide range of nematodes. The objective of this study was to determine the effect of pH on their growth and sporulation. Cornmeal agar plates were prepared and their pH was adjusted to 4, 5, 6, 7, 8, 9, and 10 by adding 1N HCl or 1N NaOH. The fungi H. minnesotensis isolate WA23-1 and H. rhossiliensis isolate OWVT-1 were transferred to the culture media and incubated at room temperature (22-24degreeC). Colony diameters were recorded at days 3, 7, 14, 21, 28, 35, 42, 49, and 56 after transferring, and the number of spores produced per cm2 colony was measured at day 35. The two species grew very well on the media at pH 5 to 8. The optimum pH was approximately 5.5 for H. minnesotensis growth and approximately 6 for H. rhossiliensis. The growth of both species was reduced drastically when pH was reduced to 4. Optimum pH for H. minnesotensis and H. rhossiliensis sporulation was between 6 and 7, and the sporulation was greatly inhibited by either low pH at 4 or high pH at 9 and 10. This data shows that the growth and sporulation of the two fungi are not limited between pH 5 and 8, which encompasses the normal range of soil pH for Minnesota soybean production.
• Publication Date: Jun 2002
• Journal: Phytopathology