Developments in Fatty Acid-Derived Insect Pheromone Production Using Engineered Yeasts

The use of traditional chemical insecticides for pest control often leads to environmental pollution and a decrease in biodiversity. Recently, insect sex pheromones were applied for sustainable biocontrol of pests in fields, due to their limited adverse impacts on biodiversity and food safety compared to that of other conventional insecticides. However, the structures of insect pheromones are complex, and their chemical synthesis is not commercially feasible. As yeasts have been widely used for fatty acid-derived pheromone production in the past few years, using engineered yeasts may be promising and sustainable for the low-cost production of fatty acid-derived pheromones. The primary fatty acids produced by Saccharomyces cerevisiae and other yeasts are C16 and C18, and it is also possible to rewire/reprogram the metabolic flux for other fatty acids or fatty acid derivatives. This review summarizes the fatty acid biosynthetic pathway in S. cerevisiae and recent progress in yeast engineering in terms of metabolic engineering and synthetic biology strategies to produce insect pheromones. In the future, insect pheromones produced by yeasts might provide an eco-friendly pest control method in agricultural fields.

Fatty Acids Derivatives From Eukaryotic Microalgae, Pathways and Potential Applications

The exploitation of petrochemical hydrocarbons is compromising ecosystem and human health and biotechnological research is increasingly focusing on sustainable materials from plants and, to a lesser extent, microalgae. Fatty acid derivatives include, among others, oxylipins, hydroxy fatty acids, diols, alkenones, and wax esters. They can occur as storage lipids or cell wall components and possess, in some cases, striking cosmeceutical, pharmaceutical, and nutraceutical properties. In addition, long chain (>20) fatty acid derivatives mostly contain highly reduced methylenic carbons and exhibit a combustion enthalpy higher than that of C14–20 fatty acids, being potentially suitable as biofuel candidates. Finally, being the building blocks of cell wall components, some fatty acid derivatives might also be used as starters for the industrial synthesis of different polymers. Within this context, microalgae can be a promising source of fatty acid derivatives and, in contrast with terrestrial plants, do not require arable land neither clean water for their growth. Microalgal mass culturing for the extraction and the exploitation of fatty acid derivatives, along with products that are relevant in nutraceutics (e.g., polyunsaturated fatty acids), might contribute in increasing the viability of microalgal biotechnologies. This review explores fatty acids derivatives from microalgae with applications in the field of renewable energies, biomaterials and pharmaceuticals. Nannochloropsis spp. (Eustigmatophyceae, Heterokontophyta) are particularly interesting for biotechnological applications since they grow at faster rates than many other species and possess hydroxy fatty acids and aliphatic cell wall polymers.

Metabolomics affirms traditional alcoholic beverage raksi as a remedy for high-altitude sickness

Raksi, a fermented distilled alcoholic beverage, is an ethnic drink consumed in high altitude regions of Singalila Ridge of the Himalayas and in adjoining high altitude places in Nepal, northern and north eastern part of India and Tibetan plateau. Like jaanr, tongba, nigar, chhyang, and other fermented ethnic beverages, raksi is considered as an element of ethnopharmacology of high altitude with claims of medicinal properties. An ethnobiological survey was done in the study area prior to collection and identification of raksi samples. In this research, two raksi samples (khokim raksi and chimphing raksi) of Singalila Ridge of the Himalayas were investigated by metabolite profiling using gas chromatography-mass spectrometry analysis. Results of the experiment showed presence of several respiratory protective, cardioprotective, neuroprotective, anti-inflammatory, and antioxidant components which have properties to prevent various high altitude illnesses. Moreover, large quantities of bioactive terpenoids, fatty acid derivatives, coumarins, and peptides were detected whose chemotaxonomy and biosynthesis pathways were further studied. This metabolomics investigation not only affirmed Raksi as a remedy for high-altitude sickness but also helped in understanding the importance of this type of ethnic foods in high altitude ethnoecology. This research on raksi in the fields of ethnobiology and metabolomics is a cumulative approach which has opened the door for in-depth investigations on similar ethnic foods. However, further experiments on raksi are surely needed in ethnobiology, microbiology, biochemistry, and food technology.

Chemical constituents from Piper betle L. Var Nigra (Piperaceae)

Two fatty acid derivatives, 2-octenoic acid and 2-hexenoic acid were isolated from the extract of n-hexane of the Piper betle L. Var. Nigra (Piperaceae). The chemical structures were identified on the basis of spectroscopic evidence and compared to previously reported spectra. These isolated compounds appear for the first time in the plant.

Rehydration Process in Rustyback Fern (Aspleniumceterach L.): Profiling of Volatile Organic Compounds

When exposed to stressful conditions, plants produce numerous volatile organic compounds (VOCs) that have different biological and environmental functions. VOCs emitted during the rehydration process by the fronds of desiccation tolerant fern Aspleniumceterach L. were investigated. Headspace GC–MS analysis revealed that the volatiles profile of rustyback fern is mainly composed of fatty acid derivatives: isomeric heptadienals (over 25%) and decadienals (over 20%), other linear aldehydes, alcohols, and related compounds. Aerial parts of the rustyback fern do not contain monoterpene-type, sesquiterpene-type, and diterpene-type hydrocarbons or corresponding terpenoids. Online detection of VOCs using proton-transfer reaction mass spectrometry (PTR–MS) showed a significant increase in emission intensity of dominant volatiles during the first hours of the rehydration process. Twelve hours after re-watering, emission of detected volatiles had returned to the basal levels that corresponded to hydrated plants. During the early phase of rehydration malondialdehyde (MDA) content in fronds, as an indicator of membrane damage, decreased rapidly which implies that lipoxygenase activity is not stimulated during the recovery process of rustyback fern.

Mycorrhizal symbiosis primes the accumulation of antiherbivore compounds and enhances herbivore mortality in tomato

Plant association with arbuscular mycorrhizal fungi (AMF) can increase their ability to overcome multiple stresses, but their impact on plant interactions with herbivorous insects is controversial. Here we show higher mortality of the leaf-chewer Spodoptera exigua when fed on tomato plants colonized by the AMF Funneliformis mosseae, evidencing Mycorrhiza-Induced Resistance (MIR). In search of the underlying mechanisms, an untargeted metabolomic analysis through UPLC-MS was performed. The results showed that the mycorrhizal symbiosis had a very limited impact on the leaf metabolome in the absence of stress, but significantly modulated the response to herbivory in the damaged area. A cluster of overaccumulated metabolites was identified in those leaflets damaged by S. exigua feeding in mycorrhizal plants, while unwounded distal leaflets responded similarly to those from non-mycorrhizal plants. These primed-compounds were mostly related to alkaloids, fatty acid derivatives and phenylpropanoid-polyamine conjugates. The deleterious effect on larval survival of some of these compounds, including the alkaloid physostigmine, the fatty acid derivatives 4-oxododecanedioic acid and azelaic acid, was confirmed. Thus, our results evidence the AM impact on metabolic reprograming upon herbivory that leads to a primed accumulation of defensive compounds.