# From Isolation to Genomics: Characterization of Aspergillus uvarum HT4 as a Novel Producer of Extracellular Tannase

## TL;DR

A new strain of Aspergillus uvarum is found to produce high levels of tannase, an enzyme useful in industry for breaking down tannins into valuable compounds.

## Contribution

Identification of Aspergillus uvarum HT4 as a novel high-yield extracellular tannase producer with a safe genomic profile.

## Key findings

- A. uvarum HT4 produced the highest extracellular tannase activity (182 U/mL) among tested isolates.
- Genome analysis revealed 15 putative tannase genes, including two acquired via horizontal gene transfer.
- Secretome analysis confirmed tannase expression and absence of major mycotoxin gene clusters, indicating biosafety.

## Abstract

Tannases (tannin acyl hydrolases, EC 3.1.1.20) are enzymes of industrial interest due to their ability to hydrolyze hydrolyzable tannins into bioactive compounds like gallic acid. In this study fungal strains capable of producing extracellular tannase were isolated and identified. From tannin-rich substrates, 24 fungal isolates were obtained, of which 17 showed tannase activity. Molecular identification based on calmodulin gene sequencing identified three species of tannase-producing black aspergilli: Aspergillus luchuensis, A. niger (formerly A. welwitschiae), and A. uvarum. The isolate A. uvarum HT4 exhibited the highest extracellular tannase activity (182 U/mL) and was selected for further study. Whole-genome sequencing of HT4 revealed 15 putative tannase genes, most sharing high identity with A. uvarum CBS 121591. Two divergent genes appeared to be acquired via horizontal gene transfer from Aspergillus brunneoviolaceus and Penicillium angulare. Proteomic analysis of the secretome confirmed the expression of two extracellular tannases. The enzyme showed optimal activity at pH 5.0–6.0 and 40–50 °C. Secretome analysis revealed hydrolytic enzymes typical of saprophytic fungi in lignocellulose-rich environments. Importantly, no biosynthetic gene clusters of major mycotoxins were detected, supporting the biosafety of HT4 for industrial applications.