Researchers have discovered a new method to enhance the flavor of tea by adjusting the microbial communities within the plant’s roots. Published on February 15, 2024, in *Current Biology*, the study demonstrates that inoculating tea plant roots with nitrogen-metabolizing bacteria can significantly increase the synthesis of theanine, an amino acid that not only contributes to tea’s soothing effects but also enhances its umami flavor.
The research was led by Zhenbiao Yang, a plant cell biologist at the Shenzhen Institute of Advanced Technology in China. Yang and his team focused their study on two oolong tea plant varieties: maoxie, which is naturally sweet but low in theanine, and rougui, known for its cinnamony flavor and higher theanine levels. Their analysis revealed that the rougui variety’s roots harbored a greater number of microbes capable of metabolizing nitrogen, which is crucial for theanine production.
To exploit this discovery, the researchers created a blend of 21 bacterial strains isolated from the rougui roots, dubbed SynCom. They then treated several tea plant varieties with this microbial concoction. The plants were first grown in sterilized soil to ensure no initial microbial influence and then inoculated with either live or dead SynCom along with a nutrient solution varying in nitrogen levels.
The results were significant. Within 20 days, tea plants treated with live SynCom, especially under low nitrogen conditions, showed a marked increase in theanine levels. For example, maoxie plants treated with live SynCom contained nearly 0.007 milligrams of theanine per gram of leaf—0.005 mg/g more than those treated with dead SynCom.
This breakthrough suggests a promising future for tea cultivation, where flavor can be enhanced naturally through microbial management. The team plans to further refine SynCom to simplify its production and distribution, aiming to make it accessible to tea growers worldwide. This could not only improve the quality of tea but also contribute to more sustainable agricultural practices by optimizing the use of natural resources.
Source: ScienceNews
