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1.
Objectives
To improve the production and activity of an alkaline zinc metalloprotease from Salinivibrio proteolyticus in response to ZnSO4 (ionic and nanoparticle forms) and low intensity direct electric current (LIDC).Results
A DC of 50 µA for 10 min increased enzyme production from 35 to 53 U ml?1 when applied to the stationary phase bacterial cells. Zn2+ improved enzyme production better than zinc nanoparticles (52 vs. 43.5 U ml?1). Zinc nanoparticles (0.5 mM) added to an enzyme reaction mixture containing casein (0.65 %) and 20 mM Tris/HCl buffer (pH 8) improved enzyme activity more than Zn2+ (42 vs. 36 U ml?1).Conclusion
LIDC exposure (50 µA, 10 min) to the stationary phase bacterial cells increases metalloprotease production in Salinivibrio. A low concentration of zinc nanoparticles (0.5 mM) increases maximum enzyme activity.2.
Background and aims
A study was performed to investigate the role of fungal metabolites released into the rhizosphere of replanted orchards as a potential biotic component of tree growth decline.Methods
The phytotoxicity of the gamma ray-sterilized crude culture filtrates of sixteen fungal species originating from replanted apple orchards was tested in a bioassay. Low molecular weight compounds released by Fusarium spp. were analyzed.Results
The fungal culture filtrates affected seedling growth and health with an activity that varied from growth inhibition to promotion. Three out of the six species of Fusarium tested produced species-specific mycotoxins such as equisetin and enniatin B and D (<1 μg ml?1 and <6 μg ml?1, respectively) associated with root-tip necrosis, whereas fusaric acid (80–230 μg ml?1) was associated with asymptomatic plant growth inhibition. These findings were consistent with those obtained using pure compounds. Moreover, methoxyconidiol, paecilaminol, integrastatin B and other biologically active compounds, whose fungal origin and phytotoxicity have not yet been reported, were found. in all fungal filtrates.Conclusions
Findings suggest that i) phytopathogenicity of soil borne fungi can be expressed regardless of root infection; ii) a synergistic interaction between co-occurring mycotoxins and other biologically active compounds may explain plant growth inhibition. Iii) fungal metabolites released into soil may represent an underestimated component of nonspecific replant disease.3.
Baolong Wang Xin Wang Chris Wayne Xiangxiang Wang Lei Han Li Ye Qun Zhao Guixiang Jiang Meiqing Feng 《Biotechnology letters》2016,38(5):801-807
Objective
To produce a therapeutic protein (endostatin) by fusion with two fragments of the carboxyl-terminal peptide (CTP) of the human chorionic gonadotropin β-subunit in Pichia pastoris.Results
Two CTP sequences were fused to the C-terminal of human endostatin, and the fusion protein (endo-CTP) was expressed by P. pastoris. Endo-CTP inhibited proliferation of endothelial cells with an IC50 of 7 μg ml?1, and 30 % of cells were annexin V-positive after treatment with 20 μg endo-CTP ml?1 for 48 h. Migration of endothelial cells was inhibited by endo-CTP in a concentration-dependent manner. The half-life of endo-CTP in Sprague–Dawley rats was much longer than that of its commercial counterpart (Endostar).Conclusion
A long-acting endostatin can be produced using CTP technology.4.
Jaya Kumar Arjun Balakrishna Pillai Aneesh Thulasi Kavitha Kumarapillai Harikrishnan 《Biotechnology letters》2018,40(2):343-348
Objectives
To screen soil metagenomic libraries for novel enzymes with enhanced activities.Results
To screen soil metagenomic libraries for novel enzymes with enhanced activities. A novel l-asparaginase was identified from forest soil metagenome and its characteristics were studied. The purified protein had a specific activity of 696 IU mg?1 and optimum activity at pH 7 and 35 °C. Enhanced enzyme activities were observed in the presence of Mg2+, Ca2+ and K+. The Km value, 2 mM, and enzyme specificity constant 7.7 mM?1s?1 indicated that the recombinant enzyme has good substrate affinity to l-asparagine compared with commercially-available Escherichia coli asparaginase. The IC50 value of 0.78 µg ml?1 (0.47 IU ml?1) was observed with HL60 cell line and 0.39 µg ml?1(0.23 IU ml?1) with MOLT-3 and MOLT-4 cell lines, which is better than that of commercially-available drugs.Conclusion
The soil metagenome derived l-asparaginase with enhanced activities could be a potential candidate to develop as a drug in Acute Lymphoblastic Leukemia (ALL) therapy.5.
Wenguang Zhang Dongmei Liu Jianzhuang Ren Pengli Zhou Xinwei Han 《Biotechnology letters》2018,40(2):271-278
Objectives
To investigate the potential role and underlying mechanism of Sirtuin2 (SIRT2) in regulating high glucose (HG)-induced vascular endothelial cell injury by using human umbilical vein endothelial cells (HUVECs).Results
SIRT2 mRNA and protein expression levels were decreased in HG-treated HUVECs. SIRT2 overexpression increased viability, decreased apoptosis and reduced levels of reactive oxygen species in HG-treated HUVECs. SIRT2 overexpression decreased TNF-α expression (146.5 ± 22.8 pg TNF-α ml?1) relative to that in the empty vector group (263.5 ± 18.5 pg TNF-α ml?1) and decreased MCP-1 expression (63.8 ± 9.85 pg MCP-1 ml?1) relative to that in the empty vector group (105.8 ± 8.5 pg MCP-1 ml?1). SIRT2 overexpression decreased the acetylation of p53 by 33% and decreased the acetylation of NF-κB p65 by 58% in HG-treated HUVECs.Conclusion
SIRT2 prevents HG-induced vascular endothelial cell injury through suppressing the p53 and NF-κB signaling pathways.6.
Lei Chen Xiaoming Yi Fajun Deng Wei Fang Xuecheng Zhang Xiaotang Wang Zemin Fang Yazhong Xiao 《Biotechnology letters》2016,38(3):471-476
Objectives
To produce and characterize novel laccases with ethanol tolerance from Trametes versicolor using agriculture by-products as energy source.Results
Trametes versicolor 1017 produces two laccase isoenzymes with a total activity of 10 U ml?1 within 8 days when using wheat bran and peanut powder as energy sources in liquid culture medium. A novel isoenzyme, named Tvlac, was identified, purified and characterized. Its optimum pH and temperature were from 4.5 to 5 and 55 to 60 °C, respectively. Its activity was stimulated by ethanol at 10 % (v/v) which increased the V 0.Conclusions
The biochemical properties of Tvlac substantiate the potential of this enzyme for applications under an aqueous ethanol mixture environment.7.
Xudong Zhu Bessembayev Arman Ju Chu Yonghong Wang Yingping Zhuang 《Biotechnology letters》2017,39(5):739-744
Objectives
To develop an efficient cost-effective screening process to improve production of glucoamylase in Aspergillus niger.Results
The cultivation of A. niger was achieved with well-dispersed morphology in 48-deep-well microtiter plates, which increased the throughput of the samples compared to traditional flask cultivation. There was a close negative correlation between glucoamylase and its pH of the fermentation broth. A novel high-throughput analysis method using Methyl Orange was developed. When compared to the conventional analysis method using 4-nitrophenyl α-D-glucopyranoside as substrate, a correlation coefficient of 0.96 by statistical analysis was obtained.Conclusion
Using this novel screening method, we acquired a strain with an activity of 2.2 × 103 U ml?1, a 70% higher yield of glucoamylase than its parent strain.8.
Chunqiu He Wen Dong Jing Li Yanpeng Li Chao Huang Yanling Ma 《Biotechnology letters》2017,39(9):1381-1388
Objectives
To improve rhamnolipid production and its potential application in removal of crude oil, the recombinant Pseudomonas aeruginosa strain DAB was constructed to enhance yield of rhamnolipids.Results
Strain DAB had a higher yield of 17.3 g rhamnolipids l?1 in the removal process with crude oil as the sole carbon source than 10 g rhamnolipids l?1 of wild-type strain DN1, where 1% crude oil was degraded more than 95% after 14 days cultivation. These rhamnolipids reduced the surface tension of water from 72.92 to 26.15 mN m?1 with CMC of 90 mg l?1. The predominant rhamnolipid congeners were Rha–C10–C10 and Rha–Rha–C10–C10 detected by MALDI-TOF MS analysis with approx. 70% relative abundance, although a total of 21 rhamnolipid congeners were accumulated.Conclusion
Increasing the copy number of rhlAB genes efficiently enhanced the production of rhamnolipids by the recombinant P. aeruginosa DAB and thus presents a promising application for the bioremediation process.9.
Gaoxiang Qi Lian Xiong Xiaoqing Lin Chao Huang Hailong Li Xuefang Chen Xinde Chen 《Biotechnology letters》2017,39(1):97-104
Objective
To investigate the inhibiting effect of formic acid on acetone/butanol/ethanol (ABE) fermentation and explain the mechanism of the alleviation in the inhibiting effect under CaCO3 supplementation condition.Results
From the medium containing 50 g sugars l?1 and 0.5 g formic acid l?1, only 0.75 g ABE l?1 was produced when pH was adjusted by KOH and fermentation ended prematurely before the transformation from acidogenesis to solventogenesis. In contrast, 11.4 g ABE l?1 was produced when pH was adjusted by 4 g CaCO3 l?1. The beneficial effect can be ascribed to the buffering capacity of CaCO3. Comparative analysis results showed that the undissociated formic acid concentration and acid production coupled with ATP and NADH was affected by the pH buffering capacity of CaCO3. Four millimole undissociated formic acid was the threshold at which the transformation to solventogenesis occurred.Conclusion
The inhibiting effect of formic acid on ABE fermentation can be alleviated by CaCO3 supplementation due to its buffering capacity.10.
Objectives
With the view of designing a single biocatalyst for biorefining, carbazole dioxygenase was cloned from Pseudomonas sp. and expressed in Rhodococcus sp.Results
The recombinant, IGTS8, degraded both carbazole and dibenzothiophene at 400 mg/l in 24 h. Maximum carbazole degradation was in 1:1 (v/v) hexadecane/aqueous phase. Anthracene, phenanthrene, pyrene, fluoranthene and fluorine were also degraded without affecting the aliphatic component.Conclusions
Recombinant Rhodococcus sp. IGTS8 can function as a single biocatalyst for removing major contaminants of fossil fuels viz. dibenzothiophene, carbazole and polyaromatic compounds.11.
Objectives
To improve the thermostability and catalytic property of a mesophilic 1,3-1,4-β-glucanase by combinational mutagenesis and to test its effect in congress mashing.Results
A mutant β-glucanase (rE-BglTO) constructed by combinational mutagenesis showed a 25 °C increase in optimal temperature (to 70 °C) a 19.5 °C rise in T 50 value and a 15.6 °C increase in melting temperature compared to wild-type enzyme. Its half-life values at 60 and 70 °C were 152 and 99 min, which were 370 and 800 % higher than those of wild-type enzyme. Besides, its specific activity and k cat value were 42,734 U mg?1 and 189 s?1 while its stability under acidic conditions was also improved. In flask fermentation, the catalytic activity of rE-BglTO reached 2381 U ml?1, which was 63 % higher than that of wild-type enzyme. The addition of rE-BglTO in congress mashing decreased the filtration time and viscosity by 21.3 and 9.6 %, respectively.Conclusions
The mutant β-glucanase showed high catalytic activity and thermostability which indicated that rE-BglTO is a good candidate for application in the brewing industry.12.
Objectives
To search for a novel glutamate decarboxylase (GAD) with an optimum pH towards near-neutrality in order to improve production of gamma-aminobutyric acid (GABA) in recombinant hosts.Results
A novel glutamate decarboxylase, BmGAD, from Bacillus megaterium was overexpressed and purified. BmGAD was approximately 53 kDa by SDS-PAGE analysis. Its optimum activity was at pH 5 and 50 °C. BmGAD had a specific activity of 59 ± 5.2 U mg?1 at pH 6, which is the highest value reported so far. The apparent Km and Vmax values of BmGAD were 8 ± 0.5 mM and 150 ± 4.7 U mg?1, respectively. Through site-directed mutagenesis, two BmGAD mutants (E294R and H467A) showed higher Vmax values than that of wild-type, with the values of 210 ± 6.9 and 180 ± 4.1 U mg?1 at pH 5 and 50 °C, respectively.Conclusions
The unusual high activity of BmGAD at pH 6 makes it an attractive GABA-producing candidate in industrial application.13.
Objectives
To evaluate the influence of hydraulic retention time (HRT) and cheese whey (CW) substrate concentration (15 and 25 g lactose l?1) on the performance of EGSB reactors (R15 and R25, respectively) for H2 production.Results
A decrease in the HRT from 8 to 4 h favored the H2 yield and H2 production rate (HPR) in R15, with maximum values of 0.86 ± 0.11 mmol H2 g COD?1 and 0.23 ± 0.024 l H2 h?1 l?1, respectively. H2 production in R25 was also favored at a HRT of 4 h, with maximum yield and HPR values of 0.64 ± 0.023 mmol H2 g COD?1 and 0.31 ± 0.032 l H2 h?1 l?1, respectively. The main metabolites produced were butyric, acetic and lactic acids.Conclusions
The EGSB reactor was evaluated as a viable acidogenic step in the two-stage anaerobic treatment of CW for the increase of COD removal efficiency and biomethane production.14.
Linpei Zhang Hao Huang Hao Wang Jian Chen Guocheng Du Zhen Kang 《Biotechnology letters》2016,38(12):2103-2108
Objectives
To improve the production and molecular mass of the glycosaminoglycan hyaluronan (HA) in Bacillus subtilis by engineering hyaluronan synthase (HAS) from Streptococcus zooepidemicus.Results
By mutating regions within HAS intracellular domains, five positive variants exhibiting higher HA production (from 1.22 to 2.24 g l?1) and molecular mass values (from 1.20 to 1.36 × 106 Da) were constructed and characterized. Overexpression of the V5 variant and the genes tuaD and glmU increased HA production and molecular mass to 2.8 g l?1 and 2.4 × 106 Da, respectively.Conclusions
This study provides a novel strategy for improving HA production and its molecular mass.15.
Objective
To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics.Results
AuNPs had a characteristic absorption maximum at 535 nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12 nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1 mM) by NaBH4 had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39 min?1 with addition of 1.45 × 10?2 mM AuNPs.Conclusions
An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.16.
Tatyana Laurinavichene Kestutis Laurinavichius Evgeny Shastik Anatoly Tsygankov 《Biotechnology letters》2018,40(2):309-314
Objectives
To prove the possibility of efficient starch photofermentation in co-culture of heterotrophic and phototrophic bacteria over prolonged period.Results
Repeated batch photofermentation of starch was demonstrated in co-culture Clostridium butyricum and Rhodobacter sphaeroides under microaerobic conditions. It continued 15 months without addition of new inoculum or pH regulation when using 4–5 g starch l?1 and 0.04 g yeast extract l?1. The complete degradation of starch without volatile fatty acids accumulation was shown in this co-culture. The average H2 yield of 5.2 mol/mol glucose was much higher than that in Clostridium monoculture. The species composition of co-culture was studied by q-PCR assay. The concentration of Clostridium cells in prolonged co-culture was lower than in monoculture and even in a single batch co-culture. This means that Clostridia growth was significantly limited whereas starch hydrolysis still took place.Conclusion
The prolonged repeated batch photofermentation of starch by co-culture C. butyricum and R. sphaeroides provided efficient H2 production without accumulation of organic acids under conditions of Clostridia limitation.17.
Wenwen Zhang Zhaohui Chen Mengmeng Wu Zhong Shi Feng Zhu Guoqiang li Ting Ma 《Biotechnology letters》2016,38(6):991-997
Objective
To improve the production of welan gum and obtain a carotenoid-free strain while reducing the fermentation and post-treatment costs.Results
The vitreoscilla globin (vgb) gene combined with the β-galactosidase (lacZ) promoter was inserted into the phytoene synthase (crtB) gene region of the chromosome in Alcaligenes sp. ATCC31555. When the recombinant strain was grown in a 5 l fermentor, welan gum was produced at 24 ± 0.4 g l?1 compared to 21 g ± 0.4 g l?1 in the wild type. Furthermore, the carotenoid-free welan gum produced using Alcaligenes sp. ATCC31555 VHb strain was less expensive with improved properties.Conclusions
Alcaligenes sp. ATCC31555 VHb strain was a better neutral welan-producing strain with a higher production than the wild-type strain.18.
Objectives
To evaluate the effects of 12 biotic and abiotic elicitors for increasing the production of plumbagin in Plumbago indica root cultures.Results
Most elicitors showed minimal effects on the root dry weight, except for 250 mg chitosan l?1 and 10 mM l-alanine that markedly decreased root biomass by about 40 % compared to the untreated root cultures (5 g l?1). Treatments with 100 µM AgNO3 significantly increased intracellular plumbagin production by up to 7.6 mg g?1 DW that was 4-fold more than the untreated root cultures (1.9 mg g?1 DW). In contrast, treatments with 150 mg chitosan l?1, 5 mM l-alanine, and 50 µM 1-naphthol significantly enhanced the extracellular secretion of plumbagin by up to 10.6, 6.9, and 5.7 mg g?1 DW, respectively, and increased the overall production of plumbagin by up to 12.5, 12.5, and 9.4 mg g?1 DW, respectively.Conclusions
Chitosan (150 mg l?1), l-alanine (5 mM), and 1-naphthol (50 µM) were the best elicitors to enhance plumbagin production in P. indica root cultures.19.
Maranda Esterhuizen-Londt Stefanie Hertel Stephan Pflugmacher 《Biotechnology letters》2017,39(10):1537-1545