# Diversity, antibacterial and antioxidant activities of fungi associated with Apis cerana

## TL;DR

This study explores the fungal diversity in the gut and honeycomb of Apis cerana and finds that some fungi have antibacterial and antioxidant properties.

## Contribution

The study provides the first in-depth analysis of fungal diversity and biological activities in Apis cerana.

## Key findings

- Fungal communities in the gut and honeycomb of Apis cerana showed significant differences in dominant genera.
- Extracts from A. subramanianii ZFCZ33 showed strong antibacterial activity against multiple pathogens.
- P. adametzioides ZFCZ03 and strain ZFT07 exhibited high antioxidant activity in free radical scavenging assays.

## Abstract

Insect-associated fungi are a treasure trove of natural active compounds. Nevertheless, the diversity and biological activities of fungi associated with Apis cerana have not been studied in depth. Here, we investigated fungal diversity in the A. cerana gut and honeycomb using a combination of culture-dependent and -independent methods. A total of 652 fungal operational taxonomic units belonging to five phyla and 334 genera were detected in the samples. Significant differences were found in the fungal communities of the honeybee gut and honeycomb—the genera Fusarium, Stenocarpella, and Botrytis were dominant in the gut, whereas Botrytis, Periconia, and Aspergillus were dominant in honeycomb. A total of 28 fungal strains were isolated from honeybee gut, head, and honeycomb, belonging to two phyla, four classes, and 10 genera. Most of these isolates were identified as Aspergillus, Penicillium, and Cladosporium spp. The antibacterial and antioxidant activities of crude extracts of their fermentation broths were investigated. Extract from A. subramanianii ZFCZ33 exhibited the best antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and P. syringae pv. Actinidiae with the disc diameter of inhibition zone diameter (IZD) of 24.33, 15.33, 17.00, and 25.33 mm, respectively. Extract from P. adametzioides ZFCZ03 had a free radical scavenging rate of 89.71% in assay with 2,2-diphenyl-1-picrylhydrazyl, and that from strain ZFT07 had a free radical scavenging rate of 97.13% in assay with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). Our results preliminarily elucidate the fungal diversity of A. cerana gut and honeycomb and indicate that honeybee-associated fungi have antibacterial and antioxidant activities. This study provides a basis for further development and use of honeybee-associated fungi.