Lipid-Like Biofilm from a Clinical Brain Isolate of Aspergillus terreus: Quantification, Structural Characterization and Stages of the Formation Cycle

Abstract

Invasive infections caused by lamentous fungi have increased considerably due to the alteration of the host's immune response. Recently, Aspergillus terreus is considered an emerging pathogen and has shown resistance to amphotericin B treatment, resulting in high mortality. The development of fungal bio lm is a virulence factor, and it has been described in some cases of invasive aspergillosis. In addition, although the general composition of fungal bio lms is known, ndings related to bio lms of a lipid nature are rarely reported. In this study, we present the identi cation of a clinical strain of A. terreus by microbiological and molecular tools, also its in vitro bio lm development capacity: i) Bio lm formation was quanti ed by Crystal Violet (CV) and reduction of tetrazolium salts assays (MTT), and simultaneously the stages of bio lm development were described by Scanning Electron Microscopy in High Resolution (SEM-HR). ii) Characterization of the organizational structure of the bio lm was performed by SEM-HR. The hyphal networks developed on the surface, the abundant air channels created between the ECM (extracellular matrix) and the hyphae fused in anastomosis were described. Also, the presence of microhyphae is reported.iii) The chemical composition of the ECM was analyzed by SEM-HR and CLSM (Confocal Laser Scanning Microscopy). Proteins, carbohydrates, nucleic acids and a relevant presence of lipid components were identi ed. Some structures of apparent waxy appearance were highlighted by SEM-HR and backscatterelectron diffraction, for which CLSM was previously performed. To our knowledge, this work is the rst description of a lipid-type bio lm in lamentous fungi, speci cally of the species A. terreus from a clinical isolate.

Exploring Non-Thermal Plasma and UV Radiation as Biofilm Control Strategies against Foodborne Filamentous Fungal Contaminants

“…Our findings unequivocally reveal that exposure to UV radiation significantly induced the production of an extracellular matrix (ECM) compared to the control group. In particular, for A. alternata and A. niger, we observed the formation of ECMs and film-like ECMs with deeply embedded hyphae, consistent with the descriptions in Rayon-Lopez's research [65]. Additionally, Rayon-Lopez describes the occurrence of vesicular ECMs in A. terreus, a phenomenon which we observed in the F. culmorum and F. graminearum fungi post-UV radiation, accompanied by abundant mycelia embedded into the ECM.…”

Accelerating the understanding of Aspergillus terreus: Epidemiology, physiology, immunology and advances

“…Another study on A. terreus conducted by Rayón-López et al on-biofilm formation showed the presence of nucleic acid, carbohydrates, proteins, and different lipid components. It has been observed that the lipid-like biofilm may be associated with increased AmB resistance in some A. terreus isolates ( Rayon-Lopez et al., 2023 ). Similarly, Sonia et al demonstrated biofilm formation in Amb-resistant isolate of A. terreus , suggesting secretory proteins play important role in induction or establishment of biofilms in A. terreus ( Shishodia et al., 2020b ).…”