Metabolomics-Guided Analysis of the Biocatalytic Conversion of Sclareol to Ambradiol by Hyphozyma roseoniger

Weather parameters and biotic factors synergistically shape the phyllosphere microbiome of pomelo (Citrus maxima (Burm.) Merr.) across annual cycle

Phyllosphere microbiome plays important roles in crop adaptation to the changing environments. Perennial woody crops undergo annual cycles with the changing weather parameters and the biological factors, which might shape the phyllosphere microbial community. In this study, we aimed to investigate the dynamics of phyllosphere microbiome of pomelo (Citrus maxima (Burm.) Merr.), an economically important horticultural crops worldwide, and to compare the respective contribution of the weather parameters and the biotic factors to the microbial community assembly, with special focus on the amino acids in leaves. Hi-Seq analysis revealed that both bacterial and fungal communities showed annual cycle dynamics, and the bacterial community in summer was much different from those in other seasons probably due to high temperature and precipitation. However, contribution of the biotic factors (e.g., leaf traits) (12%-29%) to microbial community assembly was higher than that of the weather parameters (4%-15%). Redundancy analysis indicated that the leaf amino acids significantly affected bacterial community while sugars significantly affected fungal community, highlighting the differential patterns of bacterial and fungal community as affected by the biotic factors. Finally, structure equation model showed that the weather parameters influenced microbial community colonizing pomelo leaves both in a direct way and in an indirect way via leaf traits (mainly amino acids). These results demonstrate the primary role of weather parameters and the key role of leaf amino acids in shaping phyllosphere microbiome.

Sniffing Out the Sustainable Future: The Renewability Revolution in Fragrance Chemistry

In this review, the impact of the transition from today's resource-wasting petrochemical economy towards a 100/100 renewable and biodegradable future is discussed with respect to the fragrance families: "citrus", "green", "fruity", "floral", "floriental", "oriental", "woody", "chypre" and "fougère". After benchmark data on ingredients usage, definitions on biodegradation and sustainability are given. Celebrating the 150th anniversary of synthetic vanillin, its historic synthesis from renewable starting materials serves as introduction. In the grand scheme of things, citrus scents upcycled from the beverages industry, are already an ideal case for 100/100 with new opportunities for artificial essential oils. In the fruity domain, transparent and lactonic ingredients are available in a sustainable manner. However, in the domain of green odorants, there is a lack of green chemistry for important key materials. In the floral family, renewability is more critical than biodegradability, but cost is an issue. Thanks to Ambrox and maltol, florientals and orientals will persist, while woody notes severely lack an Iso E Super replacer. In the chypre genre, patchouli became the new moss, but more musks are increasingly in demand. With their high percentage of linalool and dihydromyrcenol, the construction of fougères could well become a precedent for other families, despite challenges in vetiver and salicylates. Still, the challenges exemplified here create immense opportunities for new perfumery materials.

Efforts toward Ambergris Biosynthesis

Ambergris is a very rare and highly valued fauna natural perfume. Its main component, ambrein, undergoes oxidative degradation to produce ambroxide, forming the unique ambergris fragrance. To meet the market demand while not offending the law of protecting sperm whales, ambrein and ambroxide are chemically synthesized. Recently, the biosynthesis of these compounds has been explored as a green and sustainable production route to ensure the safety of use. The ambrein biosynthesis pathway has been successfully constructed in model microorganisms, leading to de novo biosynthesis of ambrein from glucose and glycerol. In addition, partial biosynthesis of ambroxide has been achieved by modular co-culture of engineered sclareol-producing yeast and a natural fungus converting sclareol to ambradiol, which can be further converted to ambroxide by zeolite. Alternatively, ambroxide can be produced by the chemical transformation of biosynthesized farnesene, followed by enzymatic cyclization. In this paper, the efforts toward biosynthesis of ambrein and ambroxide as representative compounds to substitute the natural ambergris are reviewed, and the challenges and prospects are discussed.

Biotechnologies in Perfume Manufacturing: Metabolic Engineering of Terpenoid Biosynthesis

The fragrance industry is increasingly turning to biotechnology to produce sustainable and high-quality fragrance ingredients. Microbial-based approaches have been found to be particularly promising, as they offer a more practical, economical and sustainable alternative to plant-based biotechnological methods for producing terpene derivatives of perfumery interest. Among the evaluated works, the heterologous expression of both terpene synthase and mevalonate pathway into Escherichia coli has shown the highest yields. Biotechnology solutions have the potential to help address the growing demand for sustainable and high-quality fragrance ingredients in an economically viable and responsible manner. These approaches can help compensate for supply issues of rare or impermanent raw materials, while also meeting the increasing demand for sustainable ingredients and processes. Although scaling up biotransformation processes can present challenges, they also offer advantages in terms of safety and energy savings. Exploring microbial cell factories for the production of natural fragrance compounds is a promising solution to both supply difficulties and the demand for sustainable ingredients and processes in the fragrance industry.

Untargeted Metabolomics Exploration of the Growth Stage-Dependent Chemical Space of the Sclareol-Converting Biocatalyst Hyphozyma roseonigra

Hyphozyma roseonigra is a dimorphic yeast used as a biocatalyst to convert sclareol, a plant diterpenoid to ambradiol. The latter is an intermediate in the synthesis of ambrafuran, a high-value chemical in the fragrance industry. Unfortunately, little is known about the underlying biochemistry of this microorganism. In this study, the integration of multi-platform-based metabolomics was used to better comprehend H. roseonigra from a biochemical perspective. The focus on metabolomic changes during growth and development was accomplished using untargeted LC–MS and NMR analyses. Cell suspensions were grown in batch culture over a 14-day period, and cells from the early-, log-, and stationary phases were harvested every second day using platform-compatible extraction procedures. Following chemometric analysis of LC–MS and NMR data acquired from both intra- and extracellular extracts, the identified discriminatory ions annotated from the endo- and exometabolomes (metabo-fingerprinting and metabo-footprinting) were found to fall predominantly in the primary metabolism class. Pathway mapping and feature-based network correlation analysis assisted in gaining insights into the active metabolic pathways during growth and development and did not flag terpene synthesis. This study provides novel insights into the basic metabolic capabilities of H. roseonigra and suggests that sclareol is metabolized as the detoxification of a hydrophobic xenobiotic compound.

Probing the Biotransformation Process of Sclareol by Resting Cells of Hyphozyma roseonigra

Sclareol glycol is a key starting material with significant market interest for synthesizing high-value ambroxide, a sustainable substitute for ambergris in high-end fragrances. Sclareol glycol can be obtained by biotransformation of sclareol, a labdane-type diterpene, using Hyphozyma roseonigra. However, the pathway and mechanism of sclareol glycol biosynthesis remain unclear. In this study, the dynamic time course of sclareol biotransformation was explored by resting cell assays and several intermediates produced during biotransformation were detected. The results show that (1) sclareol glycol and sclareolide are not interconverted and are potentially synthesized via different metabolic pathways and (2) several putative intermediates resulting from biotransformation are featured with a labdane carbon backbone, including isomerized and oxidized analogues. A plausible transformation pathway of sclareol in H. roseonigra was proposed based on detected metabolites. This study sheds light on the biosynthetic mechanism of sclareol glycol and paves a way for the future biotechnological production of this promising compound.