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Production of microsclerotia by Brazilian strains of Metarhizium spp. using submerged liquid culture fermentation
- Mascarin, Gabriel Moura, Kobori, Nilce Naomi, de Jesus Vital, Rayan Carlos, Jackson, Mark Alan, Quintela, Eliane Dias
- World journal of microbiology & biotechnology 2014 v.30 no.5 pp. 1583
- Metarhizium anisopliae, biomass production, carbon, carbon nitrogen ratio, conidia, diatomaceous earth, drought tolerance, fermentation, fungi, germination, granules
- We investigated the potential production and desiccation tolerance of microsclerotia (MS) by Brazilian strains of Metarhizium anisopliae (Ma), M. acridum (Mc) and M. robertsii (Mr). These fungi were grown in a liquid medium containing 16 g carbon l⁻¹with a carbon:nitrogen ratio of 50:1. One hundred milliliters cultures were grown in 250 ml Erlenmeyer flasks in a rotary incubator shaker at 28 °C and 200 rpm for 5 days. Five-day-old MS were harvested, mixed with diatomaceous earth (DE) and air-dried for 2 days at 30 °C. The air-dried MS–DE granular preparations were milled by mortar + pestle and stored in centrifuged tubes at either 26 or −20 °C. Desiccation tolerance and conidia production were assessed for dried MS granules by measuring hyphal germination after incubation for 2 days on water agar plates at 26 °C and for conidia production following 7 days incubation. Yields of MS by all strains of Metarhizium were 6.1–7.3 × 10⁶l⁻¹after 3 days growth with maximum MS yields (0.7–1.1 × 10⁷l⁻¹) after 5 days growth. No differences in biomass accumulation were observed after 3 days growth, whereas Ma-CG168 showed the highest biomass accumulation after 5 days growth. Dried MS–DE preparations of all fungal strains were equally tolerant to desiccation (≥93 % germination) and the highest conidia production was obtained by MS granules of Mc-CG423 (4 × 10⁹conidia g⁻¹). All MS granules showed similar stability after storage at either 26 or −20 °C for 3.5 months.