查找使用阿拉丁产品的科研文献

Single cell oil production by Trichosporon sp.: Effects of fermentation conditions on fatty acid composition and applications in synthesis of structured triacylglycerols

Xi Cao,Yayu Pan,Wei Wei,Tinglan Yuan,Sen Wang,Lingyun Xiang,Yongjun Yuan

Effects of various fermentation conditions on fatty acid composition of single cell oil (SCO) from Trichosporon sp. F1-2 were investigated. Ten carbon sources clustered into two groups using hierarchical clustering algorithm and principal component analysis. Xylose and soluble starch from each group were further studied. SCO using xylose had a high oleic acid content, while the linoleic acid and α-linolenic acid content increased significantly in SCO using soluble starch especially at the sn -2 position. 20 and 31 triacylglycerol (TAG) types were detected, respectively. The increased types were rich in linoleic acid and α-linolenic acid. The effect of C/N ratios was the weakest (distance threshold 3.05), followed by inoculation amounts (3.08), fermentation time (4.30) and nitrogen sources (5.64). The optimum nitrogen source, C/N ratio, inoculation amount and fermentation time for SCO accumulation were ammonium sulfate, 60, 6% and 120 h, respectively. Two different SCOs were produced using xylose and soluble starch under optimum conditions, which were demonstrated to be potential substrates for synthesis of 1,3-distearoyl-2-oleoyl-glycerol (a cocoa butter improver) and MLM-type TAG (the dietary TAG with low caloric value) respectively. Therefore, changing the carbon source can help broaden application fields of SCOs and increase feedstock sources of structured TAG synthesis.

Significantly enhancing the biocatalytic synthesis of chiral alcohols by semi-rationally engineering an anti-Prelog carbonyl reductase from Acetobacter sp. CCTCC M209061

Ping Wei,Ze-Wang Guo,Xiao-Ling Wu,Shan Liang,Xiao-Yang Ou,Pei Xu,Min-Hua Zong,Ji-Guo Yang,Wen-Yong Lou

Chiral alcohols and their derivatives are vital building blocks to synthesize pharmaceutical drugs and high-valued chemicals. Wild-type carbonyl reductase Ac CR from Acetobacter sp. has ideal enantioselectivity toward 11 prochiral substrates ( e.e. >99%) but poor activity. In this work, a semi-rational engineering was performed to enhance the activity of Ac CR. Fortunately, three positive double-mutants (mut-E144A/G152 L, mut-G152 L/Y189 N, and mut-I147 V/G152 L) with specific activity 17–61 folds higher than that of enzyme without modified were achieved. Kinetic studies suggested that the catalytic efficiencies ( k cat / K m ) of these mutants were also well enhanced. Finally, these modified mut- Ac CRs were successfully applied in asymmetric reductions of 11 structurally diverse prochiral substrates (200 mM) with excellent product yields (76.8%–99.1%) and enantiomeric excess ( e.e. >99%), which provides an alternative strategy for efficient synthesis of chiral alcohols for pharmaceuticals industry with ideal yield and enantioselectivity.

High Efficiency Preparation and Characterization of Intact Poly(Vinyl Alcohol) Dehydrogenase from Sphingopyxis sp.113P3 in Escherichia coli by Inclusion Bodies Renaturation

Jia Dongxu,Yang Yu,Peng Zhengcong,Zhang Dongxu,Li Jianghua,Liu Long,Du Guocheng,Chen Jian

Poly(vinyl alcohol) dehydrogenase (PVADH, EC 1.1.99.23) is an enzyme which has potential application in textile industry to degrade the poly(vinyl alcohol) (PVA) in waste water. Previously, a 1,965-bp fragment encoding a PVADH from Sphingopyxis sp. 113P3 was synthesized based on the replacement of the rare codons in Escherichia coli ( E. coli ). In this work, the deduced mature PVADH ( mPVADH ) gene of 1,887 bp was amplified by polymerase chain reaction (PCR) and inserted into the site between Nco I and Hin dIII in pET-32a(+). The constructed recombinant plasmid was transformed into E. coli Rosetta (DE3). In shake flask, the fusion protein of thioredoxin (Trx)-mPVADH was expressed precisely; however, Trx-mPVADH was found to accumulate mainly as inclusion bodies. After isolating, dissolving in buffer containing urea, purification, dialysis renaturation, and digesting with recombinant enterokinase/His (rEK/His), the bioactive mPVADH fragments were obtained with protein concentration of 0.56 g/L and enzymatic activity of 194 U/mL. The K m and V max values for PVA 1799 were 2.33 mg/mL and 15.7 nmol/(min·mg protein), respectively. 1 H-NMR and infrared (IR) spectrum demonstrated that its biological function was oxidizing hydroxyl groups of PVA 1799 to form diketone, and PVA 1799 could be degraded completely by successive treatment with mPVADH and oxidized PVA hydrolase (OPH).

Physiological and genetic analyses reveal a mechanistic insight into the multifaceted lifestyles of Pseudoalteromonas sp. SM9913 adapted to the deep-sea sediment

Zi-Hao Mi,Zi-Chao Yu,Hai-Nan Su,Lei Wang,Xiu-Lan Chen,Xiuhua Pang,Qi-Long Qin,Bin-Bin Xie,Xi-Ying Zhang,Bai-Cheng Zhou,Yu-Zhong Zhang

Summary Although bacteriobenthos play a major role in the degradation of particulate organic matter in marine sediment, knowledge of the sediment-adapted lifestyles of bacteriobenthos is still scarce. Here, the particle-associated, swimming and swarming lifestyles of the benthonic bacterium P seudoalteromonas sp. SM9913 (SM9913) were illustrated. SM9913 had a clay particle-associated lifestyle, and its exopolysaccharide played an important role in this lifestyle. SM9913 also had swimming and swarming motilities, indicating that it may have swimming and swarming lifestyles in the sediment. The lateral flagella were responsible for the swarming motility, and the polar flagella were responsible for the swimming motility. Iron limitation was an indispensable inductive signal of the swarming motility. An analysis of the motilities of SM9913 and its mutants in clay demonstrated that SM9913 moved in clay by both swimming and swarming motilities. Genomic analysis suggests that having two flagella systems is most likely a common adaptation of some bacteriobenthos to the sediment environment. Our results reveal the lifestyles of benthonic SM9913, providing a better understanding of the environmental adaptation of benthonic bacteria.

Biodegradation of di-n-butylphthalate and phthalic acid by a novel Providencia sp. 2D and its stimulation in a compost-amended soil

Zhao Hai-Ming,Du Huan,Feng Nai-Xian,Xiang Lei,Li Yan-Wen,Li Hui,Cai Quan-Ying,Mo Ce-Hui

A novel 2D strain that could effectively degrade di- n -butylphthalate (DBP) and its major metabolite, phthalic acid (PA), was isolated from compost and identified as Providencia sp . 2D. A complete degradation of DBP (200 mg L −1 ) was observed within 3 days under optimal conditions obtained by response surface methodology. This strain 2D could utilize various phthalic acid esters (PAEs) as substrates for growth, and could co-metabolize DBP in the presence of extra C sources. A novel combination of two common pathways in PA degradation was proposed for DBP degradation pathway, representing the first report of two ring cleavage pathways of the intermediate PA in a microbial species. Strain 2D efficiently enhanced the removal rate of DBP in contaminated soil with a sharp decrease of the DBP half-life compared to non-bioaugmentation treatments. Moreover, the addition of compost improved the degradation rate of DBP in soil by stimulating microbial activity. The results support the feasibility of remediating DBP-contaminated soils inoculated with strain 2D and treated with compost.

Co-metabolism degradation of tetrabromobisphenol A by the newly isolated Sphingobium sp. strain QY1-1: Multiple metabolic pathways, toxicity evaluation, and mechanisms

Junxin Zhang,Minghan Zhu,Xiaofang Ouyang,Yibo Yuan,Shaoyu Tang,Hua Yin

Tetrabromobisphenol A (TBBPA), a hydrophobic and persistent brominated flame retardant, has attracted considerable attention due to its potential ecotoxicity. Herein, a newly isolated Sphingobium sp. strain QY1-1 was employed to degrade TBBPA under optimized conditions determined by response surface methodology and kinetic analysis. Complete degradation of TBBPA was achieved by the fourth day under optimal conditions. Five main transformation pathways, i.e., debromination, hydroxylation, O-methylation, sulfation, and glycosylation, were proposed for TBBPA biodegradation based on 19 intermediates including two novel transformation products. The toxicity prediction of TBBPA and its degradation products suggested that the biodegradation of TBBPA by strain QY1-1 could effectively reduce its biotoxicity in aquatic environments. Moreover, transcriptomic analysis revealed significant up-regulation of multiple genes encoding oxidoreductases, lyases, free radical proteins, transporter proteins, and efflux transporters, particularly in the presence of glucose. This indicated that these functional enzymes could be involved in the transmembrane transport and catabolism of TBBPA and its by-products. Additionally, the overexpression of genes encoding chemotactic proteins and antioxidant-defense-related enzymes implied that the addition of glucose could heighten the adaptability of strain QY1-1 to TBBPA stress. This study provides new insights into the biodegradation of TBBPA by Sphingobium sp. and potential strategies for its enhancement.

Purification and properties of a novel quizalofop-p-ethyl-hydrolyzing esterase involved in quizalofop-p-ethyl degradation by Pseudomonas sp. J-2

Zhang Hui,Li Mengya,Li Jie,Wang Guangli,Liu Yuan

Quizalofop- p -ethyl (QPE) is a post-emergence herbicide that effectively controls grass weeds and is often detected in the environment. However, the biochemical and molecular mechanisms of QPE degradation in the environment remains unclear. In this study, a highly effective QPE-degrading bacterial strain J-2 was isolated from acclimated activated sludge and identified as a Pseudomonas sp., containing the QPE breakdown metabolite quizalofop acid (QA) identified by Liquid Chromatography-Ion Trap-Mass Spectrometry (LC-IT-MS n ) analysis. A novel QPE hydrolase esterase-encoding gene qpeH was cloned from strain J-2 and functionally expressed in Escherichia coli BL21 (DE3). The specific activity of recombinant QpeH was 198.9 ± 2.7 U mg −1 for QPE with K m and K cat values of 41.3 ± 3.6 μM and 127.3 ± 4.5 s −1 . The optimal pH and temperature for the recombinant QpeH were 8.0 and 30 °C, respectively and the enzyme was activated by Ca 2+ , Cd 2+ , Li + , Fe 3+ and Co 2+ and inhibited by Ni 2+ , Fe 2+ , Ag + , DEPC, SDS, Tween 80, Triton X, β-mercaptoethanol, PMSF, and pCMB. In addition, the catalytic efficiency of QpeH toward different AOPP herbicides in descending order was as follows: fenoxaprop-P-ethyl > quizalofop-P-tefuryl > QPE > haloxyfop-P-methyl > cyhalofopbutyl > clodinafop-propargyl. On the basis of the phylogenetic analysis and multiple sequence alignment, the identified enzyme QpeH, was clustered with esterase family V, suggesting a new member of this family because of its low similarity of amino acid sequence with esterases reported previously.

Characterization and Optimization of Fermentation Conditions of Roseateles sp. L2-2, a Novel Chitin-Degrading Bacterium from the Intestine of Odorrana margaretae

Yanmei Cai,Xinyu Li,Shuang Chen,Qichao Liu,Hongxiang Lu,Jiahui Xie,Wei Li,Guiying Chen

Microorganisms with chitin-degrading capabilities play a crucial role in the biological control of crop pests and diseases as well as in the treatment of organic waste. In this study, a chitin-degrading bacterium, designated L2-2, was isolated from the intestine ofOdorrana margaretaecollected in Mount Emei, Sichuan, China. Based on physiological and biochemical characteristics, 16S rRNA gene sequencing, and phylogenetic analysis of 31 conserved housekeeping genes in the whole genome, strain L2-2 was identified as a member of the genusRoseateles, namedRoseatelessp. L2-2. This strain is able to grow on agar medium with colloidal chitin as the sole carbon source and form clear hydrolysis zones. After optimizing fermentation conditions (including concentrations of nitrogen and carbon sources, culture time, and pH), the enzyme activity was increased to 3.46 U/mL, which was 24 times higher than the initial enzyme activity. Functional genome annotation showed that the strain contains genes encoding endochitinases of the GH18, GH23, and GH46 families, as well as genes encoding β-glucosidases of the GH1, GH2, GH3, and GH109 families, indicating its genetic basis for chitin-degrading potential. This study expands the diversity of known chitin-degrading bacteria and provides a promising microbial resource for the bioremediation of chitinous waste and sustainable pest control in agriculture.

Utilization of High-Fructose Corn Syrup for Biomass Production Containing High Levels of Docosahexaenoic Acid by a Newly Isolated Aurantiochytrium sp. YLH70

Yu Xin-Jun,Yu Zhi-Qiang,Liu Ying-Liang,Sun Jie,Zheng Jian-Yong,Wang Zhao

High-fructose corn syrup (HFCS) is an agro-source product and has been the most commonly used substitute for sugar as sweetener in food industry due to its low price and high solution property. In this study, the F55 HFCS, rich in fructose and glucose, was first tested for biomass and docosahexaenoic acid productions as a mixed carbon source by a newly isolated Aurantiochytrium sp.YLH70. After the compositions of the HFCS media were optimized, the results showed that the HFCS with additions of metal ion and vitamin at low concentrations was suitable for biomass and docosahexaenoic acid productions and the metal ion and sea salt had the most significant effects on biomass production. During the 5-l fed-batch fermentation, total HFCS containing 180 g l −1 reducing sugar was consumed and yields of biomass, lipid, and DHA could reach 78.5, 51, and 20.1 g l −1 , respectively, at 114 h. Meanwhile, the daily productivity and the reducing sugar conversion yield for docosahexaenoic acid were up to 4.23 g l −1 day −1 and 0.11 g g −1 . The fatty acid profile of Aurantiochytrium sp.YLH70 showed that 46.4 % of total fatty acid was docosahexaenoic acid, suggesting that Aurantiochytrium sp.YLH70 was a promising DHA producer.

Improvement of Alcaligenes sp.TB performance by Fe-Pd/multi-walled carbon nanotubes: Enriched denitrification pathways and accelerated electron transport

Zeyu Wang,Luyao Dai,Jiachao Yao,Tianjiao Guo,Dzmitry Hrynsphan,Savitskaya Tatsiana,Jun Chen

Aiming at the accumulation of NO 2 − -N and N 2 O during denitrification process, this work focused to improve the denitrification performance by Pd-Fe embedded multi-walled carbon nanotubes (MWCNTs). The main conclusions were as follows: 30 mg/L Pd-Fe/MWCNTs have shown an excellent promotion on denitrification (completely TN removal at 36 h). Meanwhile, enzyme activity results indicated that the generation of NO 2 − -N, NH 4 + -N by Pd-Fe/MWCNTs led the occur of short-cut denitrification by increasing 203.9% the nitrite reductase activity. Furthermore, electrochemical results and index correlation analysis confirmed that the electron exchange capacity (1.401 mmol eg −1 ) of Pd-Fe/MWCNTs was positively related to nitrite reductase activity, indicating its crucial role in electron transport activity (0.46 μg O 2 /(protein·min) at 24 h) during denitrification process by Pd-Fe/MWCNTs played a role of chemical reductant and redox mediator.

Biogenic synthesis of ferrous(III) oxide and Fe3O4/SiO2 using Chlorella sp. and its adsorption properties of water contaminated with copper(II) ions

Shireen Ibrahim Hamadamin,Sewgil Saaduldeen Anwer,Parween Mohsin Abdulkareem,Kwestan Hassan Sdiq

Transcriptome Mechanism of Utilizing Corn Steep Liquor as the Sole Nitrogen Resource for Lipid and DHA Biosynthesis in Marine Oleaginous Protist Aurantiochytrium sp.

Dong-Sheng Wang,Xin-Jun Yu,Xiao-Yu Zhu,Zhao Wang,Hui-Juan Li,Zhi-Peng Wang

In the current study, corn steep liquor (CSL) is evaluated as an ideal raw agro-material for efficient lipid and docosahexaenoic acid DHA production byAurantiochytriumsp. Low CSL level in medium (nitrogen deficiency) stimulated the biosynthesis of lipids and DHA while inhibiting cellular growth. The transcriptomic profiles of theAurantiochytriumsp. cells are analyzed and compared when cultured under high (H group), normal (N group), and low (L group) levels of CSL in the medium. The discriminated transcriptomic profiles from the three groups indicates that changes in CSL level in medium result in a global change in transcriptome ofAurantiochytriumsp. The overall de novo assembly of cDNA sequence data generated 61,163 unigenes, and 18,129 of them were annotated in at least one database. A total of 5105 differently expressed (DE) genes were found in the N group versus the H group, with 2218 downregulated and 2887 upregulated. A total of 3625 DE genes were found in the N group versus the L group, with 1904 downregulated and 1721 upregulated. The analysis and categorization of the DE genes indicates that the regulation mechanism of CSL involved in the perception and transduction of the limited nitrogen signal, the interactions between the transcription factors (TFs) and multiple downstream genes, and the variations in downstream genes and metabolites, in sequence, are illuminated for the first time in the current study.Keywords:Aurantiochytriumsp.;nitrogen-deficiency;RNA-seq;corn steep liquor (CSL);signal transduction;DHA