Insecticidal Cyclodepsitetrapeptides from Mortierella alpina.

Early diverging fungi, such as Mortierella alpina, are an emerging source of bioactive peptides. By screening 22 fungal isolates together with precursor-directed biosynthesis, a family of threonine-linked cyclotetradepsipeptides, the cycloacetamides A-F (1-6), was identified. The structure elucidation was conducted using NMR and HR-ESI-MS/MS analyses, and the absolute configuration was determined by Marfey's analysis and total synthesis. Cycloacetamides are not cytotoxic to human cells, while being highly selectively insecticidal against fruit fly larvae.

Potential of Mortierellaceae for polyunsaturated fatty acids production: mini review.

The health benefits of polyunsaturated fatty acids (PUFAs) have encouraged the search for rich sources of these compounds. However, the supply chain of PUFAs from animals and plants presents environmental concerns, such as water pollution, deforestation, animal exploitation and interference in the trophic chain. In this way, a viable alternative has been found in microbial sources, mainly in single cell oil (SCO) production by yeast and filamentous fungi. Mortierellaceae is a filamentous fungal family world-renowned for PUFA-producing strains. For example, Mortierella alpina can be highlighted due to be industrially applied to produce arachidonic acid (20:4 n6), an important component of infant supplement formulas. Thus, the state of the art of strategies to increase PUFAs production by Mortierellaceae strains is presented in this review. Firstly, we have discussed main phylogenetic and biochemical characteristics of these strains for lipid production. Next, strategies based on physiological manipulation, using different carbon and nitrogen sources, temperature, pH and cultivation methods, which can increase PUFA production by optimizing process parameters are presented. Furthermore, it is possible to use metabolic engineering tools, controlling the supply of NADPH and co-factors, and directing the activity of desaturases and elongase to the target PUFA. Thus, this review aims to discuss the functionality and applicability of each of these strategies, in order to support future research for PUFA production by Mortierellaceae species.

Soil fungal communities affect the chemical quality of flue-cured tobacco leaves in Bijie, Southwest China.

Soil microorganisms could affect the quality of tobacco leaves, however, little is known about the association of tobacco chemical components and soil fungal communities. In the present study, the relationship between soil fungi and tobacco quality based on chemical components in Bijie was investigated. The results showed that the total harmony scores (THS) of the analyzed tobacco leaves ranged from 46.55 ± 3.5 to 91.55 ± 2.25. Analyses of chemical components revealed that high contents of nicotine (≥ 1.06%) and sugar (total sugar: ≥ 22.96%, reducing sugar: ≥ 19.62%), as well as low potassium level (≤ 2.68%) were the main factors limiting the quality of flue-cured tobacco leaves. Pearson correlation analysis indicated that soil nitrate, available potassium/phosphorous, and organic matter significantly correlated with tobacco nicotine, potassium, and chloride levels (p < 0.05). Besides, the analysis of alpha- and beta-diversity of soil fungal communities implied that fungal structure rather than the richness affected the chemical quality of tobacco. In detail, the relative abundance of Humicola olivacea species in soils was positively correlated with the THS of tobaccos (r = 0.52, p < 0.05). Moreover, the species including Mortierella alpina, Mortierella hyalina, Tausonia pullulan, and Humicola olivacea were negatively correlated with tobacco sugar (r ≤ - 0.45, p < 0.05) while, Codinaea acaciae and Saitozyma podzolica species were negatively correlated with tobacco nicotine (r ≤ - 0.51, p < 0.05). The present study provides a preliminary basis for utilizing fungal species in soils to improve the chemical quality of tobacco in the studied area.

Three New Hydroxyphenylacetic Acid Derivatives and A New Alkaloid from Endophytic Fungus Mortierella sp. in Epimedium acuminatum Franch. and Their Antibacterial Activity.

Three new hydroxyphenylacetic acid derivatives, stachylines E-G (1-3), and a new alkaloid, mortieridinone (4), along with six known compounds (5-10), were isolated from endophytic fungus Mortierella sp. in Epimedium acuminatum Franch. Their structures were determined by their spectroscopic analyses and by comparison with the literature data. Compounds 7 and 10 showed selective antibacterial activity against tested multidrug-resistant bacteria with minimum inhibitory concentration (MIC) values ranging from 25 to 3.13 µg/mL.

Process optimization and characterization of arachidonic acid oil degumming using ultrasound-assisted enzymatic method.

Ultrasound assisted enzymatic method was applied to the degumming of arachidonic acid (ARA) oil produced by Mortierella alpina. The conditions of degumming process were optimized by response surface methodology with Box- Behnken design. A dephosphorization rate of 98.82% was achieved under optimum conditions of a 500 U/kg of Phospholipase A1 (PLA1) dosage, 2.8 mL/100 g of water volume, 120 min of ultrasonic time, and 135 W of ultrasonic power. The phosphorus content of ultrasonic assisted enzymatic degumming oil (UAEDO) was 4.79 mg/kg, which was significantly lower than that of enzymatic degumming oil (EDO, 17.98 mg/kg). Crude Oil (CO), EDO and UAEDO revealed the similar fatty acid compositions, and ARA was dominated (50.97 ~ 52.40%). The oxidation stability of UAEDO was equivalent to EDO and weaker than CO, while UAEDO presented the strongest thermal stability, followed by EDO and CO. Furthermore, aldehydes, acids and alcohols were identified the main volatile flavor components for the three oils. The proportions of major contributing components such as hexanal, nonanal, (E)-2-nonanal, (E, E)-2,4-decadienal, (E)-2-nonenal and aldehydes in UAEDO and EDO were all lower than CO. Overall, Ultrasound assisted enzymatic degumming proved to be an efficient and superior method for degumming of ARA oil.

Carbohydrate analysis of Mortierella alpina by colorimetry and HPLC-ELSD to reveal accumulation differences of sugar and lipid.

OBJECTIVES: To establish reliable methods for the extraction and quantification of the total carbohydrate and intracellular saccharides from Mortierella alpina and study the changes between carbohydrate and lipid in fermentation process. RESULTS: The extraction of mycelia with HCl following a photometric phenol-sulphuric acid reaction was identified as an optimal method for total carbohydrate analysis in Mortierella alpina, which the extraction efficiency performed 1.1-3.6 fold than other five methods. The total carbohydrate content increased from initial 19.26 to 25.86% during early fermentation process and declined gradually thereafter, while the fatty acid was increasing from 8.47 to 31.03%. For separation and qualitative estimation of intracellular saccharides, the acetonitrile/water freeze-thaw method for extraction and Sugar-Pak I column for separation proved to be possible. With the glucose rapidly decreasing at the beginning of growth, the trehalose accumulated rapidly from 1.63 to 5.04% and then decreased slightly but maintain above 4% of dry biomass. CONCLUSIONS: This work established comprehensive carbohydrate extraction and analysis methods of Mortierella alpina and identified the main saccharide in fermentation process which indicated that the accumulation of fatty acids was related to the change of intracellular carbohydrate content.

In vitro cytotoxic effect of a chitin-like polysaccharide produced by Mortierella alpina on adrenocortical carcinoma cells H295R, and its use as mitotane adjuvant.

This study presents an in vitro evaluation of the antitumor potential of a chitin-like exopolysaccharide (EPS, produced by Mortierella alpina) on Adrenocortical carcinoma cells (ACC) compared to mitotane, a commercial drug commonly used in ACC treatment, and known for its side effects. Techniques of cellular viability determination such as MTT and fluorescence were used to measure the cytotoxic effects of the EPS and mitotane in tumoral cells (H295R) and non-tumoral cells (VERO), observing high cytotoxicity of mitotane and a 10% superior pro-apoptotic effect of the EPS compared to mitotane (p < 0.05). The cytotoxic effect of the EPS was similar to the effect of 50 µM mitotane on tumoral cells (p < 0.05). A decrement of the lysosomal volume was also noted in tumoral cells treated with the EPS. To enhance the antitumor effect, a combination of mitotane at a lower dosage and the EPS (as adjuvant) was also tested, showing a slight improvement of the cytotoxicity effect on tumoral cells. Therefore, the results indicate a cytotoxic effect of the EPS produced by Mortierella alpina on adrenocortical carcinoma, and a possible application in biomedical formulations or additional treatments.

Ultra Performance Liquid Chromatography-Q Exactive Orbitrap/Mass Spectrometry-Based Lipidomics Reveals the Influence of Nitrogen Sources on Lipid Biosynthesis of Mortierella alpina.

The objective of the present study was to reveal the effects of four types of nitrogen sources (soymeal, yeast extract, KNO3, and ammonium tartrate) on the lipid metabolism of the oleaginous fungus Mortierella alpina using untargeted lipidomics, targeted fatty acid, and reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis. Our results showed clear differences in the contents and compositions of lipids between four types of nitrogen sources. Soymeal and ammonium tartrate supplementation favored the accumulation of triglycerides with arachidonic acid (ARA) and C16-18 fatty acids, respectively. These results were further validated by our targeted fatty acid analysis. RT-qPCR analysis of related genes in M. alpina between the four nitrogen source conditions found that soymeal supplementation dramatically increased the expression of GPAT, ELOVL, and Δ12/Δ6 desaturase. Our findings provided new insights into the regulation of lipid biosynthesis in M. alpina and potential avenues for genetic manipulation and highlighted the importance of an optimal nitrogen source for ARA-rich oil production.

Fungal Biosurfactants from Mortierella alpina.

The zygomycete Mortierella alpina is a well-known producer of polyunsaturated fatty acids in the food industry. Two series of its secondary metabolites are reported: Malpinins, a family of amphiphilic acetylated hexapeptides, were chemically characterized and serve as natural emulsifiers during lipid secretion. Additionally, hydrophobic cyclopentapeptides, malpibaldins, were structurally elucidated by NMR experiments, and their absolute stereochemistry was elucidated through chemical derivatization and synthesis. This work highlights lower fungi as a novel reservoir for natural products.

Molecular mechanism of substrate preference for ω-3 fatty acid desaturase from Mortierella alpina by mutational analysis and molecular docking.

The ω-3 fatty acid desaturase (ω3Des) is a key enzyme in the biosynthesis of polyunsaturated fatty acids (PUFAs). However, the enzyme exhibits a significant preference towards different fatty acid substrates. To examine the molecular mechanism of its substrate specificity, a series of site-directed mutants were constructed based on the membrane topology model and functionally characterised by heterologous expression in Saccharomyces cerevisiae. Our results revealed that the W106F and V137T mutations markedly decreased the enzyme activity which indicated that these two residues were associated with substrate recognition. In contrast, the A44S, M156I and W291M mutations showed significant increments (30 to 40%) of the conversion rate for AA substrate desaturation, which suggests that these residues play a pivotal role in desaturation of longer chain-length substrates. Through homology modelling of 3-dimensional structures and molecular docking of FADS15, we propose that the critical residues that bind to the CoA groups may affect substrate localisation and govern substrate preference and chain-length specificity. Our work increases the understanding of the structure-function relationships of the microbial membrane-bound desaturases. The growing knowledge of the molecular mechanism will also aid in the efficient production of value-added fatty acids.

Mortiamides A-D, Cyclic Heptapeptides from a Novel Mortierella sp. Obtained from Frobisher Bay.

Four new cyclic heptapeptides, mortiamides A-D (1-4), were obtained from a novel Mortierella sp. isolate obtained from marine sediment collected from the intertidal zone of Frobisher Bay, Nunavut, Canada. The structures of the compounds were elucidated by NMR spectroscopy and tandem mass spectrometry. The absolute configurations of the amino acids were determined using Marfey's method. Localization of l and d amino acids within each compound was ascertained by retention time comparison of the partial hydrosylate products of each compound to synthesized dipeptide standards using LC-HRMS. Compounds 1-4 did not exhibit any significant antimicrobial or cytotoxic activity.

Influence of Supplementation of Vegetable Oil Blends on Omega-3 Fatty Acid Production in Mortierella alpina CFR-GV15.

Objectives of this study were designed for improved production of mycelial omega-3 fatty acids with particular reference to EPA and DHA from the oleaginous fungus Mortierella alpina CFR-GV15 under submerged low temperatures fermentation supplemented with linseed oil and garden cress oil as an additional energy source. The fungus was grown at 20°C temperature for four days initially followed by 12°C temperature for next five days. The basal medium contained starch, yeast extract, and a blend of linseed oil (LSO) and garden cress oil (GCO) in the ratio 1 : 1. Results of the study revealed that, after nine days of total incubation period, the enhancement of biomass was up to 16.7 g/L dry weight with a total lipid content of 55.4% (v/w). Enrichment of omega-3 fatty acids indicated a significant increase in fatty acid bioconversion (ALA 32.2 ± 0.42%, EPA 7.9 ± 0.1%, and DHA 4.09 ± 0.2%) by 2.5-fold. The two-stage temperature cultivation alters the fatty acid profile due to activation of the desaturase enzyme in the cellular levels due to which arachidonic acid (AA) content reduced significantly. It can be concluded that Mortierella alpina CFR-GV15 is a fungal culture suitable for commercial production of PUFAs with enriched EPA and DHA.

The Role of Lipid Droplets in Mortierella alpina Aging Revealed by Integrative Subcellular and Whole-Cell Proteome Analysis.

Lipid droplets (LDs) participate in many cellular processes in oleaginous microorganisms. However, the exact function of LDs in the Mortierella alpina aging process remains elusive. Herein, subcellular proteomics was employed to unveil the composition and dynamics of the LD proteome in the aging M. alpina for the first time. More than 400 proteins were detected in LDs and 62 of them changed expression significantly during aging. By combining the LD proteomic data with whole-cell data, we found that the carbohydrate metabolism and de novo lipid biosynthesis were all inhibited during aging of M. alpina mycelia. The up-regulation of fructose metabolism-related enzymes in LDs might imply that LDs facilitated the fructose metabolism, which in turn might cause pyruvate to accumulate and enter malate-pyruvate cycle, and ultimately, provide additional NADPH for the synthesis of arachidonic acid (ARA). Lysophospholipase and lecithinase were up-regulated in LDs during the aging process, suggesting that the phospholipids and lecithin were starting to be hydrolyzed, in order to release fatty acids for the cells. The impairment of the anti-oxidant system might lead to the accumulation of ROS and consequently cause the up-regulation of autophagy-related proteins in LDs, which further induces the M. alpina mycelia to activate the autophagy process.

Developmental and reproductive toxicological evaluation of arachidonic acid (ARA)-Rich oil and docosahexaenoic acid (DHA)-Rich oil.

The purpose of this study was to investigate the reproductive and developmental toxicity of dietary exposure to DHA-rich oil from Schizochytrium sp. and ARA-rich oil from Mortierella alpina. In a developmental toxicity study, pregnant Wistar rats were untreated (control) or administered corn oil (vehicle control), 1000, 2500, or 5000 mg/kg bw/day of DHA-rich oil or ARA-rich oil via gavage from gestation days 6 through 20. In the reproductive toxicity study, male and female Wistar rats were administered vehicle control (corn oil), or 1000, 2500, or 5000 mg/kg bw/day of DHA- or ARA-rich oil via gavage throughout the mating period, pregnancy, and the nursing and lactation period. Differences in the number of fetuses, fetal skeletal malformations, and external and visceral anomalies in the developmental study and mortality, clinical signs, fertility indices, physical observations, gross necropsy findings, and gestation period length in the reproductive toxicity study were not dose-related or significantly different from control groups, and were not considered to be treatment related. The no observed adverse effect level (NOAEL) for maternal toxicity and embryo/fetal development and for paternal or maternal treatment-related reproductive toxicity for the DHA-rich oil and ARA-rich oil administered by gavage, was 5000 mg/kg bw/day.

FTIR Spectroscopy for Evaluation and Monitoring of Lipid Extraction Efficiency for Oleaginous Fungi.

To assess whether Fourier Transform Infrared (FTIR) spectroscopy could be used to evaluate and monitor lipid extraction processes, the extraction methods of Folch, Bligh and Lewis were used. Biomass of the oleaginous fungi Mucor circinelloides and Mortierella alpina were employed as lipid-rich material for the lipid extraction. The presence of lipids was determined by recording infrared spectra of all components in the lipid extraction procedure, such as the biomass before and after extraction, the water and extract phases. Infrared spectra revealed the incomplete extraction after all three extraction methods applied to M.circinelloides and it was shown that mechanical disruption using bead beating and HCl treatment were necessary to complete the extraction in this species. FTIR spectroscopy was used to identify components, such as polyphosphates, that may have negatively affected the extraction process and resulted in differences in extraction efficiency between M.circinelloides and M.alpina. Residual lipids could not be detected in the infrared spectra of M.alpina biomass after extraction using the Folch and Lewis methods, indicating their complete lipid extraction in this species. Bligh extraction underestimated the fatty acid content of both M.circinelloides and M.alpina biomass and an increase in the initial solvent-to-sample ratio (from 3:1 to 20:1) was needed to achieve complete extraction and a lipid-free IR spectrum. In accordance with previous studies, the gravimetric lipid yield was shown to overestimate the potential of the SCO producers and FAME quantification in GC-FID was found to be the best-suited method for lipid quantification. We conclude that FTIR spectroscopy can serve as a tool for evaluating the lipid extraction efficiency, in addition to identifying components that may affect lipid extraction processes.

Differential expression of desaturase genes and changes in fatty acid composition of Mortierella sp. AGED in response to environmental factors.

BACKGROUND: Some oleaginous fungi can produce large amounts of polyunsaturated fatty acids (PUFAs) which serve many physiological functions. Numerous desaturases are critical for the synthesis of PUFAs. This study aimed to investigate the regulation of lipid production and desaturase gene expression in Mortierella sp. AGED in response to different environmental factors, and the relationships between lipid production and desaturase gene expression. RESULTS: The fatty acid composition and mRNA levels of desaturase genes were significantly changed under low temperatures. With the exception of Δ5-desaturase, the transcript levels of all desaturase genes increased at a temperature of 20 °C. Changes in content of lipid and PUFAs responding to low temperature were consistent with desaturase gene expression. Time course studies on gene expression showed that mRNA levels of four desaturase genes increased rapidly after transferring the cells to low temperature. Ethanol (1.5% v/v) increased the transcript levels of Δ9-, Δ6- and Δ5-desaturase genes significantly and of Δ12-desaturase gene slightly. Different metal ions such as Ca2+ , Zn2+ and Fe3+ could stimulate PUFA synthesis and up-regulate desaturase gene transcription, while Cu2+ inhibited desaturase gene expression and lipid accumulation. CONCLUSION: This study should enable us to understand the regulatory mechanism of desaturase gene expression and lipid synthesis. It is helpful to improve PUFA productivity in Mortierella sp. AGED. © 2016 Society of Chemical Industry.

Application of a delta-6 desaturase with α-linolenic acid preference on eicosapentaenoic acid production in Mortierella alpina.

BACKGROUND: Delta-6 desaturase (FADS6) is a key bifunctional enzyme desaturating linoleic acid (LA) or α-linolenic acid (ALA) in the biosynthesis of polyunsaturated fatty acids (PUFAs). In previous work, we analyzed the substrate specificity of two FADS6 enzymes from Mortierella alpina ATCC 32222 (MaFADS6) and Micromonas pusilla CCMP1545 (MpFADS6), which showed preference for LA and ALA, respectively. We also clarified the PUFA profiles in M. alpina, where these lipids were synthesized mainly via the ω6 pathway and rarely via the ω3 pathway and as a result contained low ALA and eicosapentaenoic acid (EPA) levels. RESULT: To enhance EPA production in M. alpina by favoring the ω3 pathway, a plasmid harboring the MpFADS6 gene was constructed and overexpressed in a uracil-auxotrophic strain of M. alpina using the Agrobacterium tumefaciens-mediated transformation (ATMT) method. Our results revealed that the EPA production reached 80.0 ± 15.0 and 90.4 ± 9.7 mg/L in MpFADS6 transformants grown at 28 and at 12 °C, respectively. To raise the level of ALA, free form fatty acid was used as exogenous substrate, which increased the EPA production up to 114.5 ± 12.4 mg/L. To reduce the cost of EPA production in M. alpina, peony seed oil (PSO) and peony seed meal (PSM) were used as source of ALA, and EPA production was improved to 149.3 ± 7.8 and 515.29 ± 32.66 mg/L by supplementing with 0.1 % PSO and 50 g/L PSM, respectively. The EPA yield was further increased to 588.5 ± 29.6 mg/L in a 5-L bioreactor, which resulted in a 26.2-fold increase compared to EPA production in wild-type M. alpina. In this work, we have significantly enhanced EPA production through overexpression of a FADS6 desaturase with preference for ALA, combined with supplementation of its substrate. CONCLUSION: An ALA-preferring FADS6 from M. pusilla CCMP1545 was applied to enhance EPA production in M. alpina. By exogenous addition of peony seed oil or peony seed meal, EPA production was further increased in flasks and fermenters. This research also highlights the value of peony seed meal which can be converted to a high value-added product containing EPA, and as a way to increase the EPA/AA ratio in M. alpina.

Single cell oil production by Mortierella isabellina from steam exploded corn stover degraded by three-stage enzymatic hydrolysis in the context of on-site enzyme production.

Single cell oil (SCO), promising as alternative oil source, was produced from steam exploded corn stover (SECS) by Mortierella isabellina. Different bioprocesses from SECS to SCO were compared and the bioprocess C using the three-stage enzymatic hydrolysis was found to be the most efficient one. The bioprocess C used the lowest enzyme input 20FPIU cellulase/g glucan and the shortest time 222h, but produced 44.94g dry cell biomass and 25.77g lipid from 327.63g dry SECS. It had the highest lipid content 57.34%, and its productivities and yields were much higher than those of the bioprocess B and comparable to the bioprocess A, indicating that the three-stage enzymatic hydrolysis could greatly improve the efficiency of the bioprocess from high solid loading SECS to SCO by Mortierella isabellina. This work testified the application value of three-stage enzymatic hydrolysis in lignocellulose-based bioprocesses.

Lipid Fraction and Intracellular Metabolite Analysis Reveal the Mechanism of Arachidonic Acid-Rich Oil Accumulation in the Aging Process of Mortierella alpina.

The mechanism of arachidonic acid (ARA) content increase during aging of Mortierella alpina was elucidated. Lipid fraction analysis showed that ARA content increased from 46.9% to 66.4% in the triacylglycerol (TAG) molecule, and ARA residue occupation increased in the majority of TAG molecules during the aging process. For the first time, intracellular metabolite analysis was conducted to reveal the pathways closely associated with ARA biosynthesis during aging. The main reason for the increased ARA content was not only at the expense of other fatty acids degradation but also at the expense of further ARA biosynthesis during aging. Furthermore, translocation played a vital role in ARA redistribution among the glycerol moiety, and mycelium did not die immediately with key pathways activated to maintain a relatively stable intracellular environment. This study lays a foundation for further improvement of ARA content in the oil product obtained from M. alpina.

Separation and Identification of Odd Chain Triacylglycerols of the Protozoan Khawkinea quartana and the Mold Mortierella alpina Using LC-MS.

Liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS/APCI) with reversed- and chiral phases was used for separation of triacylglycerols (TAG) from protozoan and mold. This study describes the separation and identification of odd numbered chains of regioisomers and enantiomers of triacylglycerols from different natural sources, i.e., the protozoan Khawkinea quartana and the mold Mortierella alpina. Using the above-mentioned separation methods and the synthesis of appropriate standards of TAG, we identified regioisomers and enantiomers of both even and odd numbered TAG. The biosynthesis of odd numbered TAG was found to be strictly stereospecific and to depend on the production microorganism, one enantiomer predominating in the protozoan and the other in the mold. It was proved that even numbered TAG are synthesized in a higher optical purity, which can be explained by a higher affinity of acyltransferases to the respective substrate, i.e., to even chain PUFA.