UM achieves breakthrough in bacteria-assisted biosynthesis

The research team led by Zhang Xuanjun, professor in the Faculty of Health Sciences (FHS) at the University of Macau (UM), has made a breakthrough in bacteria-assisted chemical synthesis. By utilising the fermentation of Acetobacter xylinum, the team incorporated glycosylated fluorescent molecules into chiral bacterial cellulose through in situ glycosylation reactions. This innovative approach represents a new strategy for the biosynthesis of circularly polarised luminescent materials. The research, titled ‘Microbe-assisted fabrication of circularly polarised luminescent bacterial cellulosic hybrids’, has been published in the prestigious journal Nature Communications.

Chirality is ubiquitous in nature, observable in phenomena ranging from cosmic nebulae and atmospheric vortices to the snail shells and morning glory vines, and even in the core molecules that make up living organisms. Circularly polarised light (CPL), as an expression of optical chirality, has applications in fields such as information encryption, data storage, 3D displays, and biomedical imaging. However, unlike fluorescence signals, the intensity of CPL signals is proportional to the difference between the left- and right-handed luminescence of molecules, leading to very weak CPL signals for most luminescent molecules. Enhancing the luminescence dissymmetry factor is thus crucial for developing effective CPL materials.

Currently, these materials are mainly prepared through two approaches: organic chemical synthesis and molecular assembly. The chemical synthesis route involves complex and lengthy synthesis steps, including chiral separation, while the molecular assembly route places luminescent molecules in a chiral environment through weak intermolecular interactions. However, the latter method often results in poor product stability. Biosynthesis, catalysed by various enzymes, is spontaneous, green, and efficient. The abundance of chiral molecules such as L-amino acids and D-glucose in organisms provides distinct advantages for biosynthesis in preparing CPL materials. Nevertheless, challenges remain in the controlled biosynthesis of CPL materials due to the lack of bioactive luminescent precursors and suitable bioreactors, as well as the need for improved methods to confirm the covalent embedding of bioactive luminescent precursors.

Qimin Yaoshu (literally: Essential Techniques for the Welfare of the People), an ancient book on Chinese agriculture, documents the formation of a gel-like bacterial membrane (i.e. bacterial cellulose) on the surface of the fermentation liquid during the vinegar brewing process. Inspired by this, the research team designed a series of glycosylated molecules with different luminescent colours. Using the bacterial fermentation of Acetobacter xylinum, the glycosylated molecules were incorporated into chiral bacterial cellulose through in situ glycosylation reactions within the bacteria. This strategy achieved a breakthrough in the circularly polarised luminescence of glycosylated molecules, increasing the luminescence dissymmetry factor by up to 39 times. In addition, the research team developed a method for the enzymatic hydrolysis of bacterial cellulose, confirming the occurrence of this biosynthesis and providing a reliable characterisation method for verifying the biological polymerisation of glycosylated fluorescent molecules. More importantly, this strategy demonstrates strong universality and has been successfully extended to the development of a series of circularly polarised luminescent materials, which have been effectively utilised for information storage and dual-mode detection of metal ions using both fluorescence and circularly polarised luminescence.

The corresponding authors of this study are Prof Zhang, Chris Wong Koon Ho, associate professor in UM FHS, and Wu Changfeng, professor in the Department of Biomedical Engineering at Southern University of Science and Technology. The first author is Sun Yongjie, a PhD student from UM FHS. The project was funded by the Science and Technology Development Fund of the Macao SAR (File No.: 0085/2020/A2, 0047/2023/RIB2, 0099/2022/A2, 0142/2024/AFJ), UM (File No.: MYRG2024-00162-FHS, MYRG2022-00036-FHS), and the Guangdong Basic and Applied Basic Research Foundation (File No.: 2022A1515010616, 2023A1515012524). The full text of the research article is available at: https://www.nature.com/articles/s41467-025-56253-7.

Bacteria-assisted biosynthesis of circularly polarised light-active cellulose membranes and their applications in information encryption and chiral detection

Zhang Xuanjun (centre) and Sun Yongjie (1st row, 2nd from right)