Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2012
Publication Date: 8/5/2012
Citation: Jackson, M.A., Jaronski, S. 2012. Comparison of microsclerotia production by various Metarhizium species [abstract]. Society for Invertebrate Pathology. p. 49-50.
Technical Abstract: Microsclerotia (MS) production by various species and strains of Metarhizium was evaluated by growing cultures in liquid media with 36 g L-1 carbon and carbon-to-nitrogen ratios (CN) of 10:1. 30:1, or 50:1. Species evaluated included M. anisopliae, M. brunneum, M. pingshaense, and M. robertsii. Biomass accumulation and MS concentrations were measured after 4 and 7 days growth.Microsclerotia-containing biomass was harvested from 7 day-old cultures, mixed with diatomaceous earth (3% w/v), and air-dried to less than 4% moisture. Air-dried MS granules were vacuum packaged and stored at 4 °C for 12 months with viability and conidia production measured over time. All the Metarhizium species tested produced MS, although the yield varied by species, isolate, C:N ratio, and fermentation time. Yields of MS ranged from 0.2 - 17 x 106 MS L-1 after 4 days growth and 0.6 - 62 x 106 MS L-1 after 7 days growth. Conidia production by air-dried MS granules rehydrated on water agar and incubation at 28 °C for 8 days varied by Metarhizium species and isolate, culture medium, and storage age. Highest conidial yields were obtained by M. pingshaense cultures (9.0 x 109 conidia g-1 MS granules after drying and 9.8 x 109 conidia g-1 MS granules after 12 months’ storage). Our studies have shown that numerous Metarhizium species produced MS under appropriate culture conditions and that conidia production by MS granules was dependent on the isolate selected and culture conditions employed.