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Mannosylerythritol lipids (MELs) are glycolipids possessing unique biosurfactant properties. However, the prices of substrates currently used for MEL formation caused its unsustainable commercial development. Waste cooking oil poses significant ecological and economical problems. Thus, the production of MELs from used waste cooking oil using the biotransformation route is one of the better alternatives to utilize it efficiently and economically. This work aims at the production of MELs using waste cooking oil instead of soybean oil and evaluating the major characteristics and compositions of MELs. The titers reached 61.50 g/L by the optimization of culture medium, higher than the counterpart (10.25 ± 0.32 g/L) of the nonoptimized medium. MELs exhibited good surface activity and better performance in contrast to MELs grown on soybean oil. The water phase behavior of MEL‐A was also evaluated. The process showed higher productivity of MELs with better surface activity and application stability than the conventional process using soybean oil. The findings of this study imply that the use of inexpensive fermentation substrates associated with straightforward downstream processing is expected to have a great impact on the economy of MEL production.

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In this study, we introduce a simple and green method for synthesis of gold nanoparticles (AuNPs) using microbial glycolipid mannosylerythritol lipid (MEL) produced from Ustilago maydis CGMCC 5.203 and to evaluate their biomedical activities. MEL was found 10.3 g/L using sunflower oil. The formation of MEL-AuNPs was verified using UV–visible spectrum, XRD, TEM, FTIR, SEM, and EDX. In the biomedical examinations, MEL-AuNPs demonstrated potential cytotoxicity against HepG2 cells, and IC 50 values were found to be 100 and 75 µg/mL for 24 h and 48 h of exposure, respectively, which indicates its good performance against cancer cells. The IC 50 value of MEL-AuNPs was found to be 115 and 124 µg/mL for DPPH and ABTS scavenging activities, respectively. The biosynthesized MEL-AuNPs significantly inhibited cell growth of pathogenic Gram-positive and Gram-negative bacteria. These findings indicated that MEL plays a crucial role in the rapid biofabrication method of metallic NPs possessed the potential of biomedical activities.

Mannosylerythritol lipids (MELs) are natural glycolipid biosurfactants which have potential applications in the fields of food, cosmetic and medicine. In this study, MELs were produced from vegetable oil by Pseudozyma aphidis. Their structural data through LC/MS, GC/MS and NMR analysis revealed that MEL-A with two acetyls was the major compound and the identified homologs of MEL-A contained a length of C8 to C14 fatty acid chains. This glycolipid exhibited a surface tension of 27.69 mN/m at a critical micelle concentration (CMC), self-assembling into particles in the water solution. It was observed to induce cell growth-inhibition and apoptosis of B16 melanoma cells in a dose-dependent manner, as well as cause cell cycle arrest at the S phase. Further quantitative RT-PCR analysis and western blotting revealed an increasing tendency of both mRNA and protein expressions of Caspase-12, CHOP, GRP78 and Caspase-3, and a down-regulation of protein Bcl-2. Combined with the up regulation of signaling IRE1 and ATF6, it can be speculated that MEL-A-induced B16 melanoma cell apoptosis was associated with the endoplasmic reticulum stress (ERS).

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Betulinic acid is a product of plant secondary metabolism which has shown various bioactivities. Several CYP716A subfamily genes were recently characterized encoding multifunctional oxidases capable of C-28 oxidation. CYP716A12 was identified as betulin C-28 oxidase, capable of modifying betulin. This study aimed to induce the transformation of betulin to betulinic acid by co-expressing enzymes CYP716A12 from Medicago truncatula and ATR1 from Arabidopsis thaliana in Saccharomyces cerevisiae. The microsome protein extracted from the transgenic yeast successfully catalyzed the transformation of betulin to betulinic acid. We also characterized the optimization of cell fragmentation, protein extraction method, and the conversion conditions. Response surface methodology was implemented, and the optimal yield of betulinic acid reached 18.70%. After optimization, the yield and the conversion rate of betulin were increased by 83.97% and 136.39%, respectively. These results may present insights and strategies for the sustainable production of betulinic acid in multifarious transgenic microbes.

Several chitosan sodium tripolyphosphate (TPP) nanoparticles embedded with Torreya grandis aril essential oils (TEOs) were synthesized using an emulsion-ionic gelation technique. Mannosylerythritol lipid A (MEL-A), a type of biosurfactant, was selected as the emulsifier. In order to replace acetic acid, an ionic liquid (IL) was employed to dissolve chitosan. The physical properties, diameters, morphology, embedding rate, and antibacterial effects of those essential oil loaded chitosan (CS) nanoparticles were characterized. The results demonstrated that chitosan nanoparticles can be successfully prepared in an ionic liquid containing system and the diameters for nanoparticles in acetic acid and ionic liquid solutions are 144.1 ± 1.457 and 219.0 ± 4.045 nm. After loading with essential oils, the size increased to 349.6 ± 10.55 and 542.9 ± 16.74 nm, respectively. Antibacterial properties were investigated by the observation of the inhibition zone against S. aureus. The results revealed that TEO loaded nanoparticles synthesized in acid and IL aqueous systems have stronger antibacterial activities than CS nanoparticles.