Probiotics with auxin producing bacteria: emerging benefits for human health

Title : Probiotics with auxin producing bacteria: emerging benefits for human health

Abstract:

We eat vegetables that contain bacteria (1) many of which are capable of producing plant hormones such as auxins. Thus, we eat bacteria that produce auxins. Will bacteria produce auxins in our guts?  If so, what are the effects of auxins in human health?  Indole-acetic acid (3-IAA) is an auxin, known for a long time, that has significant effects in root proliferation in plants, enhances plant growth and is produced from the essential amino acid tryptophan, which is also precursor of other bioactive molecules such as serotonin, kynurenine, melatonin and others. In intestines, other sources of 3-IAA are the vegetables themselves because some may contain high levels of auxins that could be readily absorbed in the small intestine. Seemingly the proportion of 3-IAA that derives directly from plants or produced by bacteria in the colon will vary depending on diet and the gut microbiota. It appears that we should favor consuming probiotics with 3-IAA-producing bacteria as this metabolite looks beneficial for human health. Nevertheless, there was a report on the toxic effects of 3-IAA at high concentrations.  We recently reported a review on the benefits of IAA in human health (2). It is outstanding that 3-IAA is anti-inflammatory, may alleviate colitis, activates the aryl hydrocarbon receptor that would support the integrity of gut epithelial cells. 3-IAA-producing bacteria improve the response to chemotherapy in patients with cancer (3,4).  Even if we consume probiotics with auxin producing bacteria this is no warrant that this metabolite will be produced in guts.  Bacterial genes must be expressed and enzymes must have the needed substrate. In addition, 3-IAA may be catabolized by other gut bacteria before reaching the gut epithelium for its uptake. Thus, more studies are needed to understand the ecology and roles of probiotics to produce bioactive metabolites in the gut.

Biography:

Professor Esperanza Martínez-Romero is a professor and head of the Genomic Ecology Program at the Genomic Sciences Center at UNAM. She studies the mutualistic symbioses of bacteria with plants and animals native to Mexico using metagenomic and functional genomics approaches. She was a pioneer in the molecular study of the nitrogen-fixing symbioses of beans and endophytes of corn and beans. She has given workshops and advice to agricultural producers. She described new species of bacteria from plants and insects from Mexico, some of them nitrogen-fixing bacteria. The strains that she obtained have been deposited in official bacterial collections and some of them are used as inoculants or biofertilizers in agriculture. She has received awards and prizes such as the National University Award, the Mexican Academy of Sciences Award and recently, the National Science Award of Mexico in December of 2019 and the UNESCO Prize for Women in Science in March 2020. She has been recognized as a highly cited Mexican scientist. She has published 216 articles in international journals, 23 book chapters and 11 genome announcements. She has received more than 20,400 citations to her published work, with an H-index of 80.