Synthesis of queuine by colonic gut microbiome via cross‐feeding

Queuine (Que) is an essential micronutrient, and its deficiency will lead to errors in tRNA modification and protein misfold, further to diseases. Meanwhile, the content of Que in food will be further reduced due to the modern planting pattern and processing. In this study, an idea, synthetic biology of gut microbiome, was introduced to meet people's demand for Que. Further, various food can be used as a media for promoting the growth of synthetic biology of flora and the concentrations of Que. Through this research, gut bacteria (Escherichia coli K12, Bacteroides fragilis ATCC25285, and Lactobacillus reuteri DSM20058) with abilities of Que independent synthesis in vitro were selected, and higher productivity of Que was fulfilled through the above three strains cocultivation via cross‐feeding. Moreover, the effect of Que on the structure of microbiome was also studied, in order to figure out the continuous synthesis of Que by this coculture system in colonic situation. Que could enhance bacterial α‐diversity, increase the abundance of Limosilactobacillus, Pediococcus, and Lactobacillus, while decrease the abundance of Eschi‐Shigella. Three bacteria combination intervention changed intestinal microbial composition, and distribution of enzymes transglycozyme, QueA, and QueG that involved in last three steps of Que synthesis in microorganisms was significantly changed. These results provide an experimental basis for colonic synthesis of Que via food intervention to solve the deficiency Que in human body. Here, we regard gut microbes as a fermentation system in human body, providing a constant supply of tiny but important substance that humans need. Escherichia coli, Bacteroides fragilis, and Lactobacillus reuteri could independently synthesize Que in vitro. Abundance of Limosilactobacillus, Pediococcus, and Lactobacillus was increased by Que. Distribution of TGT, QueA, and QueG in microorganisms was changed by Que and bacteria.