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Microcycle Conidia Production in an Entomopathogenic Fungus Beauveria bassiana: The Role of Chitin Deacetylase in the Conidiation and the Contribution of Nanocoating in Conidial Stability

Summary

This study explores how to produce more fungal spores from Beauveria bassiana, a natural pest control organism, through a process called microcycle conidiation. Scientists found that a specific enzyme, chitin deacetylase, plays a crucial role in this process. They also discovered that coating these spores with nanoparticles made them more resistant to heat and UV light, making them more effective for field application against insect pests like leaf caterpillars. The nanocoated spores maintained their ability to kill pests while being more stable in harsh environmental conditions.

Background

Aerial conidia of entomopathogenic fungi are used extensively for pest control, requiring application of large quantities (5 × 10¹² /ha) for field effectiveness. Microcycle conidiation, where conidia germinate directly into secondary conidia bypassing normal vegetative growth, offers potential for higher yields. The role of chitin deacetylase and nanocoatings in enhancing microcycle conidia production and stability has not been fully characterized.

Objective

To investigate the role of chitin deacetylase in microcycle conidia production of Beauveria bassiana and evaluate the effectiveness of chitosan and alginate-chitosan nanocoatings in enhancing conidial stability against temperature and UV stress.

Results

SYB-grown inoculum enhanced microcycle conidia production approximately 5-fold compared to aerial conidia within 10 days in solid-state fermentation on rice. A higher chitin deacetylase to chitosanase activity ratio (>30) correlated with increased microcycle conidiation. Nanocoatings increased temperature and UV stability; ACNP-coated microcycle conidia showed mycelial growth after 8 days of UV exposure versus 12 days for uncoated conidia. Cumulative mortalities at day 10 were 83-90% across all treatments, with LT₅₀ values of 5.8-7.5 days.

Conclusion

Chitin deacetylase plays a significant role in microcycle conidiation, with the CDA to chitosanase activity ratio being a key biochemical correlate. Nanocoatings significantly enhance environmental stability of microcycle conidia while maintaining virulence, offering a viable approach for mass production and field application of this entomopathogenic fungus for pest biocontrol.
  • Published in:Microorganisms,
  • Study Type:Experimental Research,
  • Source: 10.3390/microorganisms13040900, PMID: 40284736
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