Santos, C. N. S. | bioRxiv Science

bioRxiv2026

Genotoxicity and 90-day oral toxicity of a monk fruit (Siraitia grosvenorii) mogroside preparation (>=95% mogrosides) produced by microbial fermentation

Here we report genotoxicity and 90-day oral toxicity evaluations of a high-purity, fermentation-derived mogroside preparation rich in mogroside V, the principal sweetener of monk fruit (Siraitia grosvenorii). The test article ([≥]95% total mogrosides, 70.3% mogroside V) is produced by a modified Escherichia coli from glucose, offering a higher-purity alternative to traditional monk fruit extracts. The test article was non-mutagenic in a bacterial reverse mutation test (OECD TG 471) and non-clastogenic in an in vitro human lymphocyte micronucleus test (OECD TG 487), up to the maximum recommended concentration. In the 90-day study (OECD TG 408), the test article was given by daily oral gavage at 0, 500, 1000, and 2000 mg/kg body weight/day to Sprague-Dawley rats. There were no deaths and no test article-related effects on clinical signs, ophthalmology, functional observational battery, body weight, food consumption, clinical pathology, thyroid hormones, oestrous cyclicity, or sperm parameters. Minor liver-weight increases lacking any clinical chemistry or histopathological correlates were determined to be non-adverse. No effects were seen on testis weight, sperm endpoints, or spermatogenesis. All other statistically significant differences were minor and considered incidental. The no-observed-adverse-effect level (NOAEL) was 2000 mg/kg body weight/day, the highest dose tested, supporting its safety as a food ingredient.

pharmacology and toxicology↗

bioRxiv2025

A Novel Phosphatase Reverses the Leloir Pathway to Promote Tagatose Synthesis from Glucose

D-Tagatose is a natural, low-calorie, rare monosaccharide that has gained substantial interest as an alternative sweetener. It offers numerous benefits, including a low glycemic index, prebiotic properties, and the ability to lower blood sugar levels. Currently, tagatose is primarily produced industrially through the isomerization of galactose, utilizing both chemical and enzymatic catalysis. While these established processes can produce tagatose, they are inefficient and expensive. Recent works have demonstrated alternative biosynthetic routes to produce D-tagatose but suffer from low theoretical yield and/or reliance on expensive feedstocks. This study demonstrates a novel biochemical pathway to produce D-tagatose directly from glucose using a whole-cell process with Escherichia coli. This process is distinct from other biosynthetic schemes and utilizes a newly discovered galactose-1-phosphate-selective phosphatase to drive the native Leloir pathway in reverse and synthesize the substrate D-galactose directly from D-glucose. Our analysis of the phosphatase reveals how an ensemble of intermolecular hydrogen bonds governs substrate specificity. By co-expressing this phosphatase and an L-arabinose isomerase in a modified strain background, we demonstrate production of tagatose directly from glucose. In initial studies, we generated [~]10.5 g/L galactose from 30 g/L glucose (35 % yield) while also producing > 1 g/L tagatose. This demonstrates the feasibility of a novel approach to tagatose production in vivo with a theoretical pathway yield of 94.9 %, which is substantially higher than previously proposed tagatose biosynthetic schemes.

bioengineering↗