# Study of the antagonistic relationship between gene expression biofilm of Aspergillus niger and Staphylococcus aureus that cause otomycosis

## TL;DR

This study shows how Staphylococcus aureus inhibits the biofilm formation and gene expression of Aspergillus niger, which are both involved in causing ear infections.

## Contribution

The study reveals a novel antagonistic interaction between S. aureus and A. niger during biofilm formation related to otomycosis.

## Key findings

- Co-culturing S. aureus with A. niger significantly reduced A. niger biofilm formation.
- S. aureus inhibited the expression of A. niger biofilm-related genes like eng1, xynB, and eglA.
- The antagonistic relationship was observed in both 24 and 48-hour in vitro experiments.

## Abstract

Various species of microorganisms interact in a variety of ecological niches and can lead to infection. A biofilm of one or more species may form during the infectious process.
Otomycosis can be brought on by etiologic agents, such as Staphylococcus aureus and Aspergillus niger. This study aimed to survey the antagonistic
relationship between the gene expression biofilms of A. niger and S. aureus in the context of otomycosis-related biofilm formation.

This study examined single-species biofilms of A. niger and S. aureus, as well as mixed-species biofilms of A. niger-S. aureus,
over 24 and 48 h. Expression of A. niger biofilm-related genes (eng1, xynB, exo, eglA, eglB, and eglC) was analyzed using real-time polymerase chain reaction (PCR).
Impact of S. aureus on the gene expression of A. niger was evaluated and compared to the gene expression of A. niger alone, which served as the control.

Biofilm formation assays showed that A. niger biofilm formation was significantly inhibited when co-cultured with S. aureus, with optical density values
dropping from 0.56 (alone) to 0.15 at 24 h and 0.05 at 48 h. Real-time PCR analysis revealed that the expression of A. niger biofilm-related genes,
namely eng1, xynB, exo, eglA, eglB, and eglC, increased significantly in single-species biofilms,
reaching 2.5, 3, 1.5, 3.5, 2, and 1.7, respectively, at 24 h and 3.5, 4, 2, 4.2, 3, and 2, respectively at 48 h. However, in co-culture with S. aureus,
their gene expression was markedly reduced to 0.8, 0.5, 0.4, 0.9, 0.6, 0.5, respectively, at 24 h and 0.5, 1, 0.2, 0.8, 0.6. , and 0.3, respectively, at 48 h, demonstrating a strong
inhibitory effect of S. aureus on A. niger biofilm formation and gene expression.

This study described the antagonistic relationship between S. aureus and A. niger on the gene expression biofilm that causes otomycosis, as well as the antibiosis relationship between the
two during in vitro biofilm formation. These findings provide new insights into the complex interactions between these microorganisms during infection and may have
implications for understanding and managing otomycosis.