Enhanced nitrogen removal via Yarrowia lipolytica-mediated nitrogen and related metabolism of Chlorella pyrenoidosa from wastewater

We investigated the optimum co-culture ratio with the highest biological nitrogen removal rate, revealing that chemical oxygen demand, total nitrogen (TN), and ammoniacal nitrogen (NH3-N) removal was increased in the Chlorella pyrenoidosa and Yarrowia lipolytica co-culture system at a 3:1 ratio. Compared with the control, TN and NH3-N content in the co-incubated system was decreased within 2–6 days. We investigated mRNA/microRNA (miRNA) expression in the C. pyrenoidosa and Y. lipolytica co-culture after 3 and 5 days, identifying 9885 and 3976 differentially expressed genes (DEGs), respectively. Sixty-five DEGs were associated with Y. lipolytica nitrogen, amino acid, photosynthetic, and carbon metabolism after 3 days. Eleven differentially expressed miRNAs were discovered after 3 days, of which two were differentially expressed and their target mRNA expressions negatively correlated with each other. One of these miRNAs regulates gene expression of cysteine dioxygenase, hypothetical protein, and histone-lysine N-methyltransferase SETD1, thereby reducing amino acid metabolic capacity; the other miRNA may promote upregulation of genes encoding the ATP-binding cassette, subfamily C (CFTR/MRP), member 10 (ABCC10), thereby promoting nitrogen and carbon transport in C. pyrenoidosa. These miRNAs may further contribute to the activation of target mRNAs. miRNA/mRNA expression profiles confirmed the synergistic effects of a co-culture system on pollutant disposal

Protective effects of the flavonoid fraction obtained from pomelo fruitlets through ultrasonic-associated microwave extraction against AAPH-induced erythrocyte hemolysis

Pomelo fruitlet is a side-product of pomelo, and this study aimed to extract the antioxidative flavonoid compounds from pomelo fruitlets with high efficiency through ultrasonic-associated microwave methods. Scanning electron microscopy analysis indicated that the spatial structure of the pomelo fruitlet powder was changed; microwaves and ultrasonic waves facilitated the formation of globular and curved surfaces, respectively. Ultrasonic-microwave synergistic pretreatment resulted in significantly higher yield. Each type of flavonoid compound was characterized using PR-LCMS analysis, and naringin with high nutritive value was detected in all groups. After purifying the flavone fractions with AB-8 macroporous resin, naringin, 2"-O-acetyl-3′-O-methylrutin, and 5,7,8,3′-tetrahydroxy-3,4′-dimethoxy were identified, which could act as free radical scavengers to protect erythrocytes from AAPH-induced hemolysis. This study strongly improved the effects of ultrasonic-microwave synergetic methods on the high utilization of pomelo fruitlets, especially in terms of flavonoid extraction and bioavailability

The effect of heating on the formation of 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal in unsaturated vegetable oils: Evaluation of oxidation indicators

The formation of 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE) in vegetable oils and model oil systems were quantitatively assessed by RP-HPLC. Regardless of heating temperature, HHE was only detected in rapeseed and linseed oil, while HNE was detected in all tested oils. Intrinsic tocopherols suppressed HHE/HNE formation, but with similar inhibition rates (10.49–16.04%). Linear correlations were observed between HHE/ HNE contents and corresponding n-3/6 fatty acid content in oils (R² = 0.989/0.971). Model oil system revealed that HHE/HNE formation was closely related to methyl linolenate (MLN) and methyl linoleate (ML) contents. Low levels of ML (< 0.5%) and MLN (< 1.0%) did not lead to HHE/HNE formation. Therefore, HHE/HNE was classified as the characteristic aldehydes of n-3 and n-6 type oils, respectively. Heat map evaluation and regression analysis indicated HHE could predict the n-3 type oils oxidation, while HNE was a good indicator to estimate the oxidative deterioration of n-6 and n-9 type oils

Study on Quality Change of Waxberry in Storage Period by Slow Freezing and Fast Freezing

In this study, the effects of slow freezing (−20 ℃) and quick freezing (−80 ℃) on the cell wall structure of waxberry fruits were investigated, and the changes of main nutrient quality components during storage were also studied. The moisture content and migration of waxberry fruits during storage were observed by low field NMR. The results showed that the cell wall morphology of quick-frozen waxberry fruits maintained well, and there were obvious gaps in the cross section of the cell wall of slow-frozen waxberry fruits. During the storage period of 25 days, the water content of fruit gradually decreased, but the range of water transfer of quick-frozen waxberry was small, and the total lateral relaxation time was larger than the relaxation time of slow-frozen waxberry, indicating that quick-frozen waxberry could effectively maintain fruit water activity. The free water signal value of quick-frozen waxberry decreased only by 18%, while the free water signal value of slow-frozen waxberry decreased by 47.75%, indicating that quick-frozen waxberry was beneficial to maintaining fruit water content. In addition, fruit nutrients decreased gradually, but the total sugar content, titratable acid content, total phenols and anthocyanins contents were 13.64 mg/g, 13.43 g/L, 15.43 mg/mL and 0.53 μmol/g, respectively, at the end of storage stage of quick-frozen waxberry. The retention rates of main nutritional indexes were higher than those of slow frozen waxberry. Therefore, quick-freezing can effectively delay the loss of nutrients in waxberry fruits

Formation of malondialdehyde, 4-hydroxy-hexenal and 4-hydroxy-nonenal during deep-frying of potato sticks and chicken breast meat in vegetable oils

The present work investigated the formation of three toxic aldehydes, malondialdehyde (MDA), 4‐hydroxy‐hexenal (HHE) and 4‐hydroxy‐nonenal (HNE), during deep‐frying of different foods in corn oil (CO), rapeseed oil (RO) and linseed oil (LO). Besides, their contents in French fries (FF) and fried chicken breast meat (FCBM) were also explored. Results showed that the MDA/HHE/HNE levels in frying groups were all lower than those in control, indicating the incorporation into the fried foods. Apart from the different levels, MDA/HHE/HNE in FF and FCBM possessed similar variation tendencies, revealing the matrix‐mediated distribution. The combined exposure assessment based on the threshold of toxicological concern (TTC) levels was conducted, and risks of exceeding the limitation values (1.5 μg kg bw⁻¹ day⁻¹) for HNE in CO and HHE in LO were exhibited. The consumption of both FF and FCBM should be regulated, considering the levels of MDA, HHE and HNE these fried foods may contain

Phenolic amides (avenanthramides) in oats – an update review

ABSTRACTOats (Avena sativa L.) are one of the worldwide cereal crops. Avenanthramides (AVNs), the unique plant alkaloids of secondary metabolites found in oats, are nutritionally important for humans and animals. Numerous bioactivities of AVNs have been investigated and demonstrated in vivo and in vitro. Despite all these, researchers from all over the world are taking efforts to learn more knowledge about AVNs. In this work, we highlighted the recent updated findings that have increased our understanding of AVNs bioactivity, distribution, and especially the AVNs biosynthesis. Since the limits content of AVNs in oats strictly hinders the demand, understanding the mechanisms underlying AVN biosynthesis is important not only for developing a renewable, sustainable, and environmentally friendly source in both plants and microorganisms but also for designing effective strategies for enhancing their production via induction and metabolic engineering. Future directions for improving AVN production in native producers and heterologous systems for food and feed use are also discussed. This summary will provide a broad view of these specific natural products from oats

Heterogeneous Catalysis of Ozone Using Iron–Manganese Silicate for Degradation of Acrylic Acid

Iron–manganese silicate (IMS) was synthesized by chemical coprecipitation and used as a catalyst for ozonating acrylic acid (AA) in semicontinuous flow mode. The Fe-O-Mn bond, Fe-Si, and Mn-Si binary oxide were formed in IMS on the basis of the results of XRD, FTIR, and XPS analysis. The removal efficiency of AA was highest in the IMS catalytic ozonation processes (98.9% in 15 min) compared with ozonation alone (62.7%), iron silicate (IS) catalytic ozonation (95.6%), and manganese silicate catalytic ozonation (94.8%). Meanwhile, the removal efficiencies of total organic carbon (TOC) were also improved in the IMS catalytic ozonation processes. The IMS showed high stability and ozone utilization. Additionally, H2O2 was formed in the process of IMS catalytic ozonation. Electron paramagnetic resonance (EPR) analysis and radical scavenger experiments confirmed that hydroxyl radicals (•OH) were the dominant oxidants. Cl−, HCO3−, PO43−, Ca2+, and Mg2+ in aqueous solution could adversely affect AA degradation. In the IMS catalytic ozonation of AA, the surface hydroxyl groups and Lewis acid sites played an important role

Characterisation of antibacterial peptide fractions extracted from pomelo nucleus co‐incubated with Lactobacillus

Pomelo have been widely reported for its unique flavour and high nutritive value, whereas the antibacterial activity of pomelo nucleus peptides was still poorly understood. We characterised a co‐incubation system of pomelo nucleus and Lactobacillus amylolyticus L6 to identify peptides of high application value. We first analysed the structure of pomelo nucleus peptides (GP) and co‐incubated peptides (C‐GP) by scanning electron microscopy, high‐performance gel permeation chromatography, liquid chromatography–tandem mass spectrometry and amino acid analysis. The results showed that the molecular weights, 89% of peptide sequences, and amino acid composition were different in the C‐GP compared with the GP fraction, and the spatial structures were quite diverse; the C‐GP peptide fraction presented irregular, amorphous and interwoven flocs. Notably, only C‐GP had antimicrobial activity against Escherichia coli (minimum inhibitory concentration of 12.50 μg/mL). Further assessment of the mechanism suggested that the hydrophobic groups in the C‐GP peptide fraction were inserted into the hydrophilic sites on the surface of the E. coli cell membrane, leading to the formation of holes and bending. These findings suggest the potential value of pomelo nucleus as a nutrient sourc

Anti-inflammatory effect of alkaloids extracted from Dendrobium aphyllum on macrophage RAW 264.7 cells through NO production and reduced IL-1, IL-6, TNF-alpha and PGE2 expression

Dendrobium aphyllum is an edible plant that is used as a functional food to improve health. We previously examined peptides and polysaccharides extracted from Dendrobium aphyllum; however, we did not investigate D. aphyllum’s alkaloid compounds and their functions. In this study, we detail the composition of alkaloids from Dendrobium aphyllum (DAA), including 2a, 3b-dihydroxy nortropane, 1-methyl-2-[(4Z,7Z)- 4,7-tridecadienyl]-4(1H) quinolone and maokonine, which were first identified by UPLC-MS analysis. Furthermore, the anti-inflammatory activity of DAA on LPS-induced RAW 264.7 macrophages was examined. DAA treatment inhibited LPS-induced NO production and decreased (P < 0.05) IL-1, IL-6, TNF-a and PGE2 secretion in the RAW 264.7 macrophages. DAA treatment also inhibited COX-2 and iNOS mRNA expression in a dose-dependent manner, indicating that these compounds can attenuate the synthesis of the above-mentioned molecules at the transcriptional level, tentatively confirming their anti-inflammatory effect

Additional file 1 of Functional analysis of the dehydratase domains of the PUFA synthase from Emiliania huxleyi in Escherichia coli and Arabidopsis thaliana

Additional file 1: Table S1. Production of SFAs and UFAs in wild type Escherichia coli Rosetta overexpressing EhDH domains. Table S2. Production of SFAs and UFAs in wild-type Escherichia coli Rosetta overexpressing the mutated EhDH domains. Table S3. Primers used for DH domain amplifications. Table S4. Primers used for site-directed mutagenesis of DH domains. Table S5. Primers used for plant experiment. Figure S1. Expression of recombinant proteins when induced with 0.2 mM IPTG in Escherichia coli (E. coli). a SDS-PAGE and WB analysis of the extracellular secretion from E. coli Rosetta strains overexpressing EhDH domains. b WB analysis of the extracellular secretion from E. coli Rosetta strains expressing site-directed mutagenized EhDH domains. SDS-PAGE, the sodium dodecyl sulphate-polyacrylamide gel electrophoresis; WB, western blotting. The marker used in this experiment is 180 kDa Prestained Protein Marker (180, 130, 100, 70, 55, 40, 35, 25, 15 kDa); 1, pET32a-EhDH1; 2, pET32a-EhDH1-M; 3, pET32a-EhDH2; 4, pET32a-EhDH2-M; 5, pET32a-EhDH1-DH2; 6, pET32a-EhDH1-M-DH2; 7, pET32a-EhDH1-DH2-M; 8 pET32a-TcDH1-DH2; 9 pET32a (negative control). Figure S2. Schematic representation of the T-DNA region of the binary plasmid vector expressing tandem EhDH domains