title: Production of thermotolerant entomopathogenic fungal conidia on millet grain.
abstract: Thermotolerance of entomopathogenic (insect-killing) fungi should be seriously considered before industrialization. This work describes the feasibility of millet grain as a substrate for production of thermotolerant Beauveria bassiana (Bb) GHA and ERL1170 and Metarhizium anisopliae (Ma) ERL1171 and ERL1540 conidia. First, conidial suspensions of the Bb isolates, produced on millet grain in polyethylene bags, were exposed to five temperatures (43-47 °C) at 15-min intervals for up to 120 min (experiment I). Agar-based quarter-strength (¼) Sabouraud dextrose agar supplemented with yeast extract (SDAY) and whey permeate media served as controls. Millet-grain-based culture was superior in producing the most thermotolerant Bb conidia, followed by whey permeate agar and ¼SDAY-based cultures. Secondly, to compare the thermotolerance of conidia produced at the same conditions, the Bb isolates were then produced on agar-based millet powder medium, with ¼SDAY and whey permeate agar media as controls, and the two Ma isolates were added (experiment II). They were then exposed to the same temperatures as above. More thermotolerant Bb and Ma conidia were produced on millet powder agar than on whey permeate agar and ¼SDAY overall. These results suggest that millet grain can be used as a substrate to produce thermotolerant conidia in a mass production system.
authors.affiliation: Entomology Research Laboratory, Plant and Soil Science, University of Vermont, 661 Spear Street, Burlington, Vermont 05405-0105, USA.
authors.forename: Jae Su
authors.initials: JS
authors.lastname: Kim
authors.forename: Adane
authors.initials: A
authors.lastname: Kassa
authors.forename: Margaret
authors.initials: M
authors.lastname: Skinner
authors.forename: Teri
authors.initials: T
authors.lastname: Hata
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Parker
mesh_terms: D000362:Agar; D052982:Beauveria / Q000502:physiology*; D003470:Culture Media; D002523:Edible Grain / Q000382:microbiology; D052981:Metarhizium / Q000502:physiology*; D050296:Microbial Viability; D008897:Panicum / Q000382:microbiology*; D013172:Spores, Fungal / Q000254:growth & development; D013696:Temperature
chemical_list: D003470:Culture Media; D000362:Agar
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