# Unveiling Valuable Secondary Metabolites from the Bioconversion of Banana (Musa balbisiana) Peel-Derived Biomass with Aspergillus niger. Metabolomic Insights into the Chemical Profiles

## TL;DR

This study explores how Aspergillus niger can convert banana peels into valuable secondary metabolites, offering a low-cost way to repurpose agricultural waste.

## Contribution

The study identifies optimal conditions and key metabolites from fungal bioconversion of banana peel biomass using metabolomic analysis.

## Key findings

- BP media yielded 76 secondary metabolites, 66 of which were produced by A. niger.
- BPS media produced 99 metabolites, including 22 previously identified A. niger-derived compounds.
- 21-day BP and 28-day BPS fermentations were optimal for secondary metabolite production.

## Abstract

Santa Catarina is
Brazil’s fourth-largest banana
producer,
generating a significant amount of waste. Banana peel conversion into
useful products is uncommon. However, it produces natural products
that possess benefits for human health or can serve as biomass to
produce fungi-derived metabolites. Therefore, Aspergillus
niger was isolated from banana peels and then cultured on
three distinct media composed of starch, banana peels (BP), and starch-enriched
banana peels (BPS) for 14, 21, and 28 days at 28 °C. Their chemical
profiles were established using liquid chromatography coupled to mass
spectrometry data assisted by the GNPS database and MS-FINDER software.
In BP media, 76 secondary metabolites were detected; among them, 66
were produced by the fungus. Twenty-seven compounds, such as nigragillin
and pyranonigrin A, are A. niger chemomarkers, while
other substances, except for the 13 unidentified, were previously
found in other organisms. Among the 99 metabolites detected in BPS
media, 22 were previously identified as A. niger-derived
compounds. BPS media also yielded 26 unidentified compounds, while
12 annotated ones were also found in BP. The remaining metabolites
were previously reported in other organisms. Principal component 1
of 44.8% and principal component 2 of 22.2% indicated that 21-day
fermentation for BP medium and 28-day fermentation for BPS medium
were the optimal conditions to produce secondary metabolites. Variable
importance plots reveal nonadecan-2-amine (score >3) and an alkylaryl
amine derivative (m/z 304.3005)
as the most concentrated compounds. The present results showed a cheap
process to turn food residues and waste into valuable molecules.