Advances in submerged liquid fermentation and formulation of entomopathogenic fungi.

Entomopathogenic fungi (EPF) can be defined as beneficial multifunctional eukaryotic microorganisms that display pivotal ecological services in pest management, with some species possessing the special ability to establish mutualistic relationships with plants. Mass production of these fungi is critical to support affordable widespread commercialization and worldwide field application. Among the mass production methods explored mainly by industry, submerged liquid fermentation is a robust and versatile technology that allows the formation of different types of propagules designated for various applications in pest control. Many hypocrealean EPF are easily culturable on artificial substrates by producing single-celled structures (hyphal bodies, blastospores, and submerged conidia) or multicellular structures (mycelium and microsclerotia). Less frequently, some EPF may form environmentally resistant chlamydospores, but these structures have almost always been overlooked. A continued research pipeline encompassing screening fungal strains, media optimization, and proper formulation techniques aligned with the understanding of molecular cues involved in the formation and storage stability of these propagules is imperative to unlock the full potential and to fine-tune the development of robust and effective biocontrol agents against arthropod pests and vectors of diseases. Finally, we envision a bright future for the submerged liquid fermentation technology to supplement or replace the traditional solid substrate fermentation method for the mass production of many important EPF. KEY POINTS: • Submerged liquid fermentation (SLF) allows precise control of nutritional and environmental factors • SLF provides a scalable, robust, and cost-effective platform for mycopesticide production • Enhancing formulation, shelf life, and field efficacy of submerged propagules remain crucial • Understanding the molecular mechanisms behind submerged propagule formation is key to advancing SLF technology.

Production of Purpureocillium lilacinum and Pochonia chlamydosporia by Submerged Liquid Fermentation and Bioactivity against Tetranychus urticae and Heterodera glycines through Seed Inoculation.

Pochoniachlamydosporia and Purpureocilliumlilacinum are fungal bioagents used for the sustainable management of plant parasitic nematodes. However, their production through submerged liquid fermentation and their use in seed treatment have been underexplored. Therefore, our goal was to assess the effect of different liquid media on the growth of 40 isolates of P. lilacinum and two of P. chlamydosporia. The most promising isolates tested were assessed for plant growth promotion and the control of the two-spotted spider mite (Tetranychus urticae) and the soybean cyst nematode (Heterodera glycines). Most isolates produced > 108 blastospores mL−1 and some isolates produced more than 104 microsclerotia mL−1. Microsclerotia of selected isolates were used to inoculate common bean (Phaseolus vulgaris L.) seeds in greenhouse trials. All fungal isolates reduced the T. urticae fecundity in inoculated plants through seed treatment, while P. chlamydosporia ESALQ5406 and P. lilacinum ESALQ2593 decreased cyst nematode population. Purpureocillium lilacinum was more frequently detected in soil, whereas P. chlamydosporia colonized all plant parts. Pochonia chlamydosporia ESALQ5406 improved the root development of bean plants. These findings demonstrate the possibility of producing submerged propagules of P. chlamydosporia and P. lilacinum by liquid culture, and greenhouse trials support the applicability of fungal microsclerotia in seed treatment to control P. vulgaris pests.

Compatibility of different Metarhizium spp. propagules with synthetic acaricides for controlling Rhipicephalus microplus / Compatibilidade de diferentes propágulos de Metarhizium spp. com acaricidas sintéticos para o controle de Rhipicephalus microplus

The inappropriate use of synthetic acaricides has selected resistant Rhipicephalus microplus populations. The present study evaluated the compatibility of different Metarhizium spp. propagules (conidia, blastospores, and microsclerotia) by incubating them with synthetic acaricides (amitraz, deltamethrin, and a combination of cypermethrin, chlorpyrifos, and citronellal) for 1 h, 5 h, 10 h, and 24 h. Conidia and microsclerotia of the tested isolates were usually more tolerant to synthetic acaricides than blastospores. Our study also analyzed the in vitro effect of deltamethrin associated with fungal propagules for controlling a population of R. microplus females that were not susceptible to this synthetic acaricide. The use of entomopathogenic fungi in association with deltamethrin in this tick population caused a greater tick control than did the use of the fungus or the synthetic acaricide separately.(AU)

O uso inadequado de acaricidas sintéticos selecionou populações resistentes de Rhipicephalus microplus. O presente estudo avaliou a compatibilidade de diferentes propágulos de Metarhizium spp. (conídios, blastosporos e microscleródios), incubando-os com acaricidas sintéticos (amitraz, deltametrina e uma combinação de cipermetrina, clorpirifós e citronelal) por 1 h, 5 h, 10 h e 24 h. Conídios e microescleródios dos isolados testados foram geralmente mais tolerantes a acaricidas sintéticos do que os blastosporos. Este estudo também analisou o efeito in vitro da deltametrina associada a propágulos fúngicos no controle de uma população de fêmeas de R. microplus não suscetíveis a este acaricida sintético. O uso de fungos entomopatogênicos em associação com deltametrina, nesta população de carrapatos, causou maior controle do carrapato do que o uso do fungo ou acaricida sintético isoladamente.(AU)

Serendipita restingae sp. nov. (Sebacinales): an orchid mycorrhizal agaricomycete with wide host range.

The Serendipitaceae family was erected in 2016 to accommodate the Sebacinales 'group B' clade, which contains peculiar species of cultivable root-associated fungi involved in symbiotic associations with a wide range of plant species. Here we report the isolation of a new Serendipita species which was obtained from protocorms of the terrestrial orchid Epidendrum fulgens cultivated in a greenhouse. This species is described based on phylogenetic analysis and on its microscopic and ultrastructural features in pure culture and in association with the host's protocorms. Its genome size was estimated using flow cytometry, and its capacity to promote the germination of E. fulgens seeds and to associate with roots of Arabidopsis thaliana was also investigated. Serendipita restingae sp. nov. is closely related to Serendipita sp. MAFF305841, isolated from Microtis rara (Orchidaceae), from which it differs by 14.2% in the ITS region and by 6.5% in the LSU region. It produces microsclerotia formed of non-monilioid hyphae, a feature that was not reported for the Sebacinales hitherto. Serendipita restingae promoted the germination of E. fulgens seeds, forming typical mycorrhizal pelotons within protocorm cells. It was also able to colonize the roots of Arabidopsis thaliana under in vitro conditions. Arabidopsis plants grown in association with S. restingae increased their biomass more than fourfold. Serendipita restingae is the first Serendipitaceae species described for the Americas.

Preparation, characterisation and cell viability of encapsulated Trichoderma asperellum in alginate beads.

Aim: The encapsulation of Trichoderma asperellum BRM-29104 using Ca-alginate matrix was evaluated.Methods: Intact and freeze-dried beads containing submerged conidia and microsclerotia (MS) of T. asperellum grown in liquid culture were prepared and characterised. Beads were stored at 8, 25, and 35 °C over 120 days.Results: The mean sizes of beads before and after freeze-drying were 2.5 ± 0.2 mm and 1.5 × 1.1 mm (± 0.1 mm), respectively. Freeze-dried beads stored at 8 °C were more effective in maintaining conidia concentration, while MS concentrations yielded 102 MS/g for both beads at 8 and 25 °C. The concentration of viable cells in freeze-dried beads stored at 8 °C attained 3.0 × 108 CFU/g after 120 days. FIRT analysis showed an interaction between the alginate and the cell wall of the fungus.Conclusion: These findings support the use of alginate beads followed by freeze drying and cold storage for maintenance of viability of T. asperellum.