The effects of a thermophile metabolite, tryptophol, upon protecting shrimp against white spot syndrome virus

White spot syndrome virus (WSSV) is a shrimp pathogen responsible for significant economic loss in commercial shrimp farms and until now, there has been no effective approach to control this disease. In this study, tryptophol (indole-3-ethanol) was identified as a metabolite involved in bacteriophage-thermophile interactions. The dietary addition of tryptophol reduced the mortality in shrimp Marsupenaeus japonicus when orally challenged with WSSV. Our results revealed that 50 mg/kg tryptophol has a better protective effect in shrimp than 10 or 100 mg/kg tryptophol. WSSV copies in shrimp were reduced significantly (P < 0.01) when supplemented with 50 mg/kg tryptophol, indicating that virus replication was inhibited by tryptophol. Consequently, tryptophol represents an effective antiviral dietary supplement for shrimp, and thus holds significant promise as a novel and efficient therapeutic approach to control WSSV in shrimp aquaculture.

Regulation of Cunninghamella spp. biofilm growth by tryptophol and tyrosol

Fungi belonging to the genus Cunninghamella are often used as microbial models of mammalian metabolism owing to their ability to transform a range of xenobiotic compounds. Furthermore, under specific growth conditions species such as Cunninghamellaelegans and Cunninghamellaechinulata grow as biofilms enabling a convenient semi-continuous production of valuable drug metabolites. However, the molecular mechanism of biofilm regulation is not understood, thus controlling biofilm thickness limits the productive applications of it. In this paper we describe the identification of two molecules, tyrosol and tryptophol, that were identified in C. blakesleeana cultures, but not in C. elegans and C. echinulata. The molecules are known quorum sensing molecules (QSMs) in yeast and their potential role in Cunninghamella biofilm regulation was explored. Both were present in higher concentrations in C. blakesleeana planktonic cultures compared with biofilms; they inhibited the growth of the fungus on agar plates and selectively inhibited biofilm growth in liquid cultures. The molecules had a comparatively minor impact on the biofilm growth of C. elegans and C. echinulata and on the growth of these fungi on agar plates. Finally, when exogenous tyrosol or tryptophol was added to previously grown C. blakesleeana biofilm, detachment was visible and new additional planktonic culture was measured, confirming that these molecules specifically regulate biofilm growth in this fungus.

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Tyrosol and tryptophol were identified in culture supernatants of Cunninghamella blakesleeana.

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Concentrations of the compounds were substantially higher in planktonic cultures compared with biofilms.

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Bioassays revealed that tyrosol and tryptophol inhibited growth of C. blakesleeana on agar plates.

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Biofilm growth was inhibited by exogenous addition of the compounds whereas planktonic growth was unaffected.

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The compounds caused detachment of previously grown biofilms.

Engineering the L-tryptophan metabolism for efficient de novo biosynthesis of tryptophol in Saccharomyces cerevisiae

Tryptophol (IET) is a metabolite derived from L-tryptophan that can be isolated from plants, bacteria, and fungi and has a wide range of biological activities in living systems. Despite the fact that IET biosynthesis pathways exist naturally in living organisms, industrial-scale production of IET and its derivatives is solely based on environmentally unfriendly chemical conversion. With diminishing petroleum reserves and a significant increase in global demand in all major commercial segments, it becomes essential to develop new technologies to produce chemicals from renewable resources and under mild conditions, such as microbial fermentation. Here we characterized and engineered the less-studied L-tryptophan pathway and IET biosynthesis in the baker's yeast Saccharomyces cerevisiae, with the goal of investigating microbial fermentation as an alternative/green strategy to produce IET. In detail, we divided the aromatic amino acids (AAAs) metabolism related to IET synthesis into the shikimate pathway, the L-tryptophan pathway, the competing L-tyrosine/L-phenylalanine pathways, and the Ehrlich pathway based on a modular engineering concept. Through stepwise engineering of these modules, we obtained a yeast mutant capable of producing IET up to 1.04 g/L through fed-batch fermentation, a ~ 650-fold improvement over the wild-type strain. Besides, our engineering process also revealed many insights about the regulation of AAAs metabolism in S. cerevisiae. Finally, during our engineering process, we also discovered yeast mutants that accumulate anthranilate and L-tryptophan, both of which are precursors of various valuable secondary metabolites from fungi and plants. These strains could be developed to the chassis for natural product biosynthesis upon introducing heterologous pathways.

Regulation of ethanol production from anaerobic fermentation of food waste using aromatic alcohol-based quorum-sensing molecules

Quorum-sensing molecules (QSMs) are used to regulate microbial metabolites to effectively improve food waste anaerobic fermentation to produce high-value products of ethanol and lactic acid. In this study, low concentrations (25 and 50 μmol/L) of aromatic alcohol favored the synthesis of ethanol and lactic products. Among the aromatic alcohol QSMs, 50 μmol/L of tyrosol enhanced the yield of products. The correlations between substrate composition indicators confirmed that tyrosol was conducive to the anaerobic fermentation of food waste. The regulation mechanism of tyrosol, such as microbial diversity in anaerobic fermentation, was analyzed from the perspective of microbial ecology. The result revealed that tyrosol increased the microbial diversity in the system. Limosilactobacillus, Weissella, and Pediococcus were the dominant bacterial species in the early stages of fermentation, whereas Clostridiaceae and Bacillus were dominant in the later stages. Meanwhile, the main dominant fungal species were Saccharomyces, Aspergillus, and Pichia. The results of this study show that using QSMs, including tyrosol, to regulate the physiological characteristics of anaerobic fermentation microorganisms, promote the synthesis of cell metabolites, and regulate the diversity and succession of microbial communities is a feasible measure. This approach improves the resource utilization efficiency of anaerobic fermentation technology for food waste, which is significant for promoting sustainable development.

A novel quality-by-design assisted HPLC-DAD method for the simultaneous quantification of tryptophan, tryptophol, and voriconazole for early diagnosis and prognosis of fungal infections decoding quorum sensing phenomenon

For the first time, a comprehensive analytical approach is introduced that simultaneously quantifies a metabolic precursor (tryptophan), a quorum-sensing biomarker for fungal infections (tryptophol), and an antifungal drug (voriconazole) within a single platform using reversed-phase high-performance liquid chromatography coupled with diode array detection (HPLC-DAD). The method utilizes a Pursuit PFP column featuring a unique pentafluorinated structure, with a mobile phase of methanol: water (60:40, v/v), a flow rate of 1.0 mL/min, and a detection wavelength set at 254.0 nm. An Analytical Quality-by-Design (AQbD) methodology was employed, incorporating a full factorial design for optimal method development. Validation was performed in accordance with ICH guidelines, demonstrating exceptional linearity (2.0-60.0 μg/mL) for all target analytes, along with high precision, accuracy, and system suitability. Furthermore, the method proved robust and versatile when applied to complex matrices, including spiked human serum and pharmaceutical tablet formulations. Noteworthy is the integration of green and white chemistry principles for evaluating the method's sustainability, representing a significant advancement in analytical technique development. Assessment of greenness, blueness, and whiteness with AGREE, ComplexGAPI index, BAGI and RGB 12 Tools, respectively. This innovative analytical platform provides a powerful tool for the early detection and real-time therapeutic monitoring of fungal infections. By enabling the simultaneous analysis of a metabolic marker, a quorum-sensing specific biomarker, and an antifungal agent, the method advances personalized medicine. It offers a novel, efficient, and sustainable solution for the personalized management of fungal infections, enhancing both diagnostic and therapeutic strategies.