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1.
Lifei Chen Chunling Ma Ruiming Wang Jianlou Yang Haijie Zheng 《Biotechnology letters》2016,38(10):1769-1774
Objectives
To improve 1,3-propanediol (1,3-PD) production and reduce byproduct concentration during the fermentation of Klebsiella pneumonia.Results
Klebsiella. pneumonia 2-1ΔldhA, K. pneumonia 2-1ΔaldH and K. pneumonia 2-1ΔldhAΔaldH mutant strains were obtained through deletion of the ldhA gene encoding lactate dehydrogenase required for lactate synthesis and the aldH gene encoding acetaldehyde dehydrogenase involved in the synthesis of ethanol. After fed-batch fermentation, the production of 1,3-PD from glycerol was enhanced and the concentrations of byproducts were reduced compared with the original strain K. pneumonia 2-1. The maximum yields of 1,3-PD were 85.7, 82.5 and 87.5 g/l in the respective mutant strains.Conclusion
Deletion of either aldH or ldhA promoted 1,3-PD production in K. pneumonia.2.
Objectives
To characterize the genes responsible for ethanol utilization in Pichia pastoris.Results
ADH3 (XM_002491337) and ADH (FN392323) genes were disrupted in P. pastoris. The ADH3 mutant strain, MK115 (Δadh3), lost its ability to grow on minimal ethanol media but produced ethanol in minimal glucose medium. ADH3p was responsible for 92 % of total Adh enzyme activity in glucose media. The double knockout strain MK117 (Δadh3Δadh) also produced ethanol. The Adh activities of X33 and MK116 (Δadh) strains were not different. Thus, the ADH gene does not play a role in ethanol metabolism.Conclusion
The PpADH3 is the only gene responsible for consumption of ethanol in P. pastoris.3.
Xuechang Wu Lijie Zhang Xinna Jin Yahong Fang Ke Zhang Lei Qi Daoqiong Zheng 《Biotechnology letters》2016,38(7):1097-1106
4.
Objectives
To enhance acid tolerance of Candida glabrata for pyruvate production by engineering AMP metabolism.Results
The physiological function of AMP deaminase in AMP metabolism from C. glabrata was investigated by deleting or overexpresseing the corresponding gene, CgAMD1. At pH 4, CgAMD1 overexpression resulted in 59 and 51% increases in biomass and cell viability compared to those of wild type strain, respectively. In addition, the intracellular ATP level of strain Cgamd1Δ/CgAMD1 was down-regulated by 22%, which led to a 94% increase in pyruvate production. Further, various strengths of CgAMD1 expression cassettes were designed, thus resulting in a 59% increase in pyruvate production at pH 4. Strain Cgamd1Δ/CgAMD1 (H) was grown in a 30 l batch bioreactor at pH 4, and pyruvate reached 46.1 g/l.Conclusion
CgAMD1 overexpression plays an active role in improving acid tolerance and pyruvate fermentation performance of C. glabrata at pH 4.5.
Chelladurai Rathnasingh Jong Myoung Park Duk-ki Kim Hyohak Song Yong Keun Chang 《Biotechnology letters》2016,38(6):975-982
Objectives
To improve the production of 2,3-butanediol (2,3-BD) in Klebsiella pneumoniae, the genes related to the formation of lactic acid, ethanol, and acetic acid were eliminated.Results
Although the cell growth and 2,3-BD production rates of the K. pneumoniae ΔldhA ΔadhE Δpta-ackA strain were lower than those of the wild-type strain, the mutant produced a higher titer of 2,3-BD and a higher yield in batch fermentation: 91 g 2,3-BD/l with a yield of 0.45 g per g glucose and a productivity of 1.62 g/l.h in fed-batch fermentation. The metabolic characteristics of the mutants were consistent with the results of in silico simulation.Conclusions
K. pneumoniae knockout mutants developed with an aid of in silico investigation could produce higher amounts of 2,3-BD with increased titer, yield, and productivity.6.
Objectives
To reduce the unpleasant odor during 1-deoxynojirimycin (DNJ) production, the genes of leucine dehydrogenase (bcd) and phosphate butryltransferase (ptb) were deleted from Bacillus amyloliquefaciens HZ-12, and the concentrations of branched-chain short fatty acids (BCFAs) and DNJ were compared.Results
By knockout of the ptb gene, 1.01 g BCFAs kg?1 was produced from fermented soybean by HZ-12Δptb. This was a 56% decrease compared with that of HZ-12 (2.27 g BCFAs kg?1). Moreover, no significant difference was found in the DNJ concentration (0.7 g kg?1). After further deletion of the bcd gene from HZ-12Δptb, no BCFAs was detected in fermented soybeans with HZ-12ΔptbΔbcd, while the DNJ yield decreased by 26% compared with HZ-12.Conclusions
HZ-12Δptb had decreased BCFAs formation but also maintained the stable DNJ yield, which contributed to producing DNJ-rich products with decreased unpleasant smell.7.
8.
Tian Tang Qun Gao Hua Lin Francis Biville Jingyuan Xiong Xiaofang Pei Bo Zheng Xiaoli Zou Chuan Wang 《Metabolomics : Official journal of the Metabolomic Society》2017,13(12):157
Introduction
ClpXP protease is an important proteolytic system in Salmonella enterica serovar typhimurium (S. typhimurium). Inactivation of ClpXP by deletion of clpP resulted in overproduction of RpoS and a growth defect phenotype. Only one report has indicated that deleting rpoS can restore the growth of a S. typhimurium clpP mutant to the wild-type level. Whether overproduction of RpoS is responsible for the growth deficiency resulting from clpP disruption and how ClpXP affects the cell metabolism of S. typhimurium remain to be elucidated.Objectives
The aim of this study is to investigate the effect of ClpXP on cell metabolism of S. typhimurium and explore the possible co-effect of RpoS associated with ClpXP in cell metabolism.Method
We constructed a clpP rpoS double deletion mutant TT-19 (ΔclpP ΔrpoS TT-1) using a two-step phage transduction technique. We then compared the metabolite fingerprints of Salmonella rpoS deletion mutant TT-14 (ΔrpoS TT-1), clpP deletion mutant TT-16 (ΔclpP TT-1), and clpP rpoS double deletion mutant TT-19 (ΔclpP ΔrpoS TT-1) with those of the wild-type strain TT-1 by using gas chromatography coupled with mass spectrometry (GC–MS).Results
Deletion of rpoS recovered only a part of the growth of Salmonella clpP mutant. Further metabolome analysis indicated that clpP disruption changed the levels of 16 extra- and 19 intracellular substances, while the extracellular concentrations of 4 compounds (serine, l-5-oxoproline, l-glutamic acid, and l-tryptophan) and intracellular concentrations of 10 compounds (l-isoleucine, glycine, serine, l-methionine, l-phenylalanine, malic acid, citric acid, urea, putrescine, and 6-hydroxypurine) returned to their wild-type levels when rpoS was also deleted.Conclusion
ClpXP affects the cell metabolism of S. typhimurium partially in an RpoS-dependent manner.9.
Dagmara Głód 《Biotechnology letters》2017,39(5):767-773
Objective
To generate Candida antarctica lipase A (CAL-A) mutants with modified fatty acid selectivities and improved lipolytic activities using error-prone PCR (epPCR).Results
A Candida antarctica lipase A mutant was obtained in three rounds of epPCR. This mutant showed a 14 times higher ability to hydrolyze triacylglycerols containing conjugated linoleic acids, and was 12 and 14 times more selective towards cis-9, trans-11 and trans-10, cis-12 isomers respectively, compared to native lipase. Lipolytic activities towards fatty acid esters were markedly improved, in particular towards butyric, lauric, stearic and palmitic esters.Conclusion
Directed molecular evolution is an efficient method to generate lipases with desirable selectivity towards CLA isomers and improved lipolytic activities towards esters of fatty acids.10.
Objective
To determine the effects of the extra N-terminal seven-amino-acid sequence on the function of chitosanase CsnA.Results
Sequence and structure analysis indicated that the mature CsnA contains a seven-amino-acid extension in a disordered form at the N-terminus. To determine the function of this sequence, both mature CsnA and its N-terminus-truncated mutant, CsnAΔN, were expressed in Escherichia coli and characterized. Compared with CsnAΔN, CsnA exhibited a 15 °C higher temperature optimum, enhanced pH stability, thermostability and catalytic efficiency. The underlying mechanisms responsible for these changes were analyzed by circular dichroism (CD) spectroscopy. CD analysis revealed that the deletion of the N-terminal sequence resulted in a decrease in the Tm of 4.3 °C and this sequence altered the secondary structure of the enzyme.Conclusions
The N-terminal sequence is essential for the stability and activity of chitosanase CsnA.11.
12.
Korey J. Brownstein Mahmoud Gargouri William R. Folk David R. Gang 《Metabolomics : Official journal of the Metabolomic Society》2017,13(11):133
Introduction
Botanicals containing iridoid and phenylethanoid/phenylpropanoid glycosides are used worldwide for the treatment of inflammatory musculoskeletal conditions that are primary causes of human years lived with disability, such as arthritis and lower back pain.Objectives
We report the analysis of candidate anti-inflammatory metabolites of several endemic Scrophularia species and Verbascum thapsus used medicinally by peoples of North America.Methods
Leaves, stems, and roots were analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and partial least squares-discriminant analysis (PLS-DA) was performed in MetaboAnalyst 3.0 after processing the datasets in Progenesis QI.Results
Comparison of the datasets revealed significant and differential accumulation of iridoid and phenylethanoid/phenylpropanoid glycosides in the tissues of the endemic Scrophularia species and Verbascum thapsus.Conclusions
Our investigation identified several species of pharmacological interest as good sources for harpagoside and other important anti-inflammatory metabolites.13.
14.
15.
Marie GB Hansen Mette Christoffersen Line R Thuesen Morten R Petersen Anders M Bojesen 《Acta veterinaria Scandinavica》2010,52(1):3
Background
Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.Methods
A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP®4DX ® ELISA test.Results
Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.Conclusions
Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.16.
17.
Rongguang Zhang Chen Wang Wenbin Cheng Guangcai Duan Qingfeng Shi Shuaiyin Chen Qingtang Fan 《Biotechnology letters》2018,40(3):585-590
Objective
To develop a safe and effective oral vaccine against Helicobacter pylori using its HpaA protein expressed in Lactococcus lactis.Results
The gene encoding HpaA was obtained by PCR and ligated to pNZ8110-lysM following digestion with NaeI + SphI. The recombinant plasmid was transferred into E. coli for multiplication, and then into L. lactis. The recombinant L. lactis was induced to express HpaA, resulting in two products of 29 and 25 kDa, both of which yielded positive immunoreaction with mouse antisera against H. pylori, as confirmed by immunoblot assays. The 29 kDa product constituted 12% of the cell lysates. Oral inoculation with the engineered L. lactis evoked significantly elevated serum IgG level in mice (P < 0.05).Conclusions
A novel engineered L. lactis strain was developed that efficiently produces whole HpaA protein with desired antigenicity and potent immunogenicity. It provides a basis for approaches to L. lactis-delivered anti-H. pylori vaccination.18.
Chengqian Zhu Xiao Jiang Yongqiang Zhang Jie Lin Shuilin Fu Heng Gong 《Biotechnology letters》2015,37(9):1783-1790
Objective
To improve 1,3-propanediol production in Klebsiella pneumoniae, the effects of puuC expression in lactate- and lactate/2,3-butanediol-deficient strains were assessed.Results
Overexpression of puuC (encoding an aldehyde dehydrogenase) inhibited 1,3-propanediol production and increased 3-hydroxypropionic acid formation in both lactate- and lactate/2,3-butanediol-deficient strains. An improvement in 1,3-propanediol production was only achieved in a lactate-deficient strain via moderate expression of puuC; at the end of the fermentation, 1,3-propanediol productivity increased by 14 % compared with the control. Further comparative analysis of the metabolic flux distributions in different strains indicated that 3-hydroxypropionic acid formation could play a considerable role in cell metabolism in K. pneumoniae.Conclusion
An improvement in 3-hydroxypropionic acid formation would be beneficial for cell metabolism, which can be accomplished by enhancing 1,3-propanediol productivity in a lactate-deficient strain via moderate expression of puuC.19.
Background
Recent studies showed that long non-coding RNA (lncRNA) plays an important role in many life activities. RPPH1 is one of the lncRNA genes that are expressed differently between breast cancer and normal tissues by the lncRNA gene chip. Our study was conducted to examine the regulation of lncRNA RPPH1 in breast cancer.Methods
Two cell lines, MCF-7 and MDA-MB-231, were selected to be the research objects in this study; RPPH1 overexpression and knockdown models were established by transforming vectors. Real-time polymerase chain reaction, MTT assay, clone formation and cell flow cytometer assay were used to test the function of RPPH1. Dual-luciferase assay was used to detect a target relationship between RPPH1 and miR-122.Results
RPPH1 overexpression promoted cell cycle and proliferation and increased colony formation. In the RPPH1 overexpression model, there was a target relationship between RPPH1 and miR-122, and some of the downstream genes of miR-122, including ADAM10, PKM2, NOD2 and IGF1R, were increased. Moreover, we found that lentivirus-mediated interference of lncRNA RPPH1 inhibited tumour growth in nude mice.Conclusion
Breast cancer progression can be promoted by directly targeting miR-122 through lncRNA RPPH1. This study provided evidence that can serve as the molecular basis for improving treatment options for patients.20.
Sen Miao Hao Wu Yue Zhao Qinggele Caiyin Yanni Li Jianjun Qiao 《Biotechnology letters》2018,40(6):941-948