Cuticular fatty acids of Galleria mellonella (Lepidoptera) inhibit fungal enzymatic activities of pathogenic Conidiobolus coronatus

PLoS One. 2018 Mar 8;13(3):e0192715. doi: 10.1371/journal.pone.0192715. eCollection 2018.

Abstract

The entomopathogenic fungus Conidiobolus coronatus produces enzymes that may hydrolyze the cuticle of Galleria mellonella. Of these enzymes, elastase activity was the highest: this figure being 24 times higher than NAGase activity 553 times higher than chitinase activity and 1844 times higher than lipase activity. The present work examines the differences in the hydrolysis of cuticles taken from larvae, pupae and adults (thorax and wings), by C. coronatus enzymes. The cuticles of the larvae and adult thorax were the most susceptible to digestion by proteases and lipases. Moreover, the maximum concentration of free N-glucosamine was in the hydrolysis of G. mellonella thorax. These differences in the digestion of the various types of cuticle may result from differences in their composition. GC-MS analysis of the cuticular fatty acids isolated from pupae of G. mellonella confirmed the presence of C 8:0, C 9:0, C 12:0, C 14:0, C 15:0, C 16:1, C 16:0, C 17:0, C 18:1, C 18:0, with C 16:0 and C 18:0 being present in the highest concentrations. Additional fatty acids were found in extracts from G. mellonella imagines: C 10:0, C 13:0, C 20:0 and C 20:1, with a considerable dominance of C 16:0 and C 18:1. In larvae, C 16:0 and C 18:1 predominated. Statistically significant differences in concentration (p≤0.05) were found between the larvae, pupae and imago for each fatty acid. The qualitative and quantitative differences in the fatty acid composition of G. mellonella cuticle occurring throughout normal development might be responsible for the varied efficiency of fungal enzymes in degrading larval, pupal and adult cuticles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Conidiobolus / enzymology*
  • Conidiobolus / physiology
  • Fatty Acids / metabolism*
  • Fungal Proteins / metabolism
  • Host-Pathogen Interactions
  • Larva / metabolism
  • Larva / microbiology
  • Lipase / metabolism
  • Moths / metabolism*
  • Moths / microbiology
  • Pancreatic Elastase / metabolism
  • Peptide Hydrolases / metabolism
  • Pupa / metabolism
  • Pupa / microbiology

Substances

  • Fatty Acids
  • Fungal Proteins
  • Lipase
  • Peptide Hydrolases
  • Pancreatic Elastase

Grants and funding

The main source of financing were statutory funds from the resources of the Institute of Parasitology PAS in Warsaw. This work was partly supported by National Centre for Research and Development grant POIG.01.04.00-14-019/12 to the Biomibo company. There was no additional external funding received for this study. Biomibo provided support in the form of salary to KZ, the purchase of chemicals, and made laboratory equipment available for AKW, MK, and AK. The specific roles of these authors are articulated in the ‘author contributions’ section. The funders did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.