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1.
Objective
To produce tagatose from fructose with a high conversion rate and to establish a high-yield purification method of tagatose from the reaction mixture.Results
Fructose at 1 M (180 g l?1) was converted to 0.8 M (144 g l?1) tagatose by a three-step enzymatic cascade reaction, involving hexokinase, plus ATP, fructose-1,6-biphosphate aldolase, phytase, over 16 h with a productivity of 9 g l?1 h?1. No byproducts were detected. Tagatose was recrystallized from ethanol to a purity of 99.9% and a yield of 96.3%. Overall, tagatose at 99.9% purity was obtained from fructose with a yield of 77%.Conclusion
This is the first biotechnological production of tagatose from fructose and the first application of solvent recrystallization for the purification of rare sugars.2.
Woo-Ri Kang Min-Ju Seo Jung-Ung An Kyung-Chul Shin Deok-Kun Oh 《Biotechnology letters》2016,38(5):817-823
Objective
To produce δ-decalactone from linoleic acid by one-pot reaction using linoleate 13-hydratase with supplementation with whole Yarrowia lipolytica cells.Results
Whole Y. lipolytica cells at 25 g l?1 produced1.9 g l?1 δ-decalactone from 7.5 g 13-hydroxy-9(Z)-octadecenoic acid l?1 at pH 7.5 and 30 °C for 21 h. Linoleate 13-hydratase from Lactobacillus acidophilus at 3.5 g l?1 with supplementation with 25 g Y. lipolytica cells l?1 in one pot at 3 h produced 1.9 g l?1 δ-decalactone from 10 g linoleic acid l?1 via 13-hydroxy-9(Z)-octadecenoic acid intermediate at pH 7.5 and 30°C after 18 h, with a molar conversion yield of 31 % and productivity of 106 mg l?1 h?1.Conclusion
To the best of our knowledge, this is the first production of δ-decalactone using unsaturated fatty acid.3.
Palanisamy Divyalakshmi Devaraj Murugan Chockalingam Lajapathi Rai 《Biotechnology letters》2017,39(12):1883-1888
Objectives
To enhance the performance of microbial fuel cells (MFC) by increasing the surface area of cathode and diligent mechanical disintegration of anaerobic biomass.Results
Tannery effluent and anaerobic biomass were used. The increase in surface area of the cathode resulted in 78% COD removal, with the potential, current density, power density and coulombic efficiency of 675 mV, 147 mA m?2, 33 mW m?2 and 3.5%, respectively. The work coupled with increased surface area of the cathode with diligent mechanical disintegration of the biomass, led to a further increase in COD removal of 82% with the potential, current density, power density and coulombic efficiency of 748 mV, 229 mA m?2, 78 mW m?2 and 6% respectively.Conclusions
Mechanical disintegration of the biomass along with increased surface area of cathode enhances power generation in vertical MFC reactors using tannery effluent as fuel.4.
Gábor Márk Tardy Bálint Lóránt Máté Lóka Balázs Nagy Krisztina László 《Biotechnology letters》2017,39(7):993-999
Objectives
Catalytic efficiency of a nitrogen-doped, mesoporous carbon aerogel cathode catalyst was investigated in a two-chambered microbial fuel cell (MFC) applying graphite felt as base material for cathode and anode, utilizing peptone as carbon source.Results
This mesoporous carbon aerogel containing catalyst layer on the cathode increased the maximum power density normalized to the anode volume to 2.7 times higher compared to the maximum power density obtained applying graphite felt cathode without the catalyst layer. At high (2 and 3) cathode/anode volume ratios, maximum power density exceeded 40 W m?3. At the same time, current density and specific substrate utilization rate increased by 58% resulting in 31.9 A m?3 and 18.8 g COD m?3 h?1, respectively (normalized to anode volume). Besides the increase of the power and the rate of biodegradation, the investigated catalyst decreased the internal resistance from the range of 450–600 to 350–370 Ω.Conclusions
Although Pt/C catalyst proved to be more efficient, a considerable decrease in the material costs might be achieved by substituting it with nitrogen-doped carbon aerogel in MFCs. Such cathode still displays enhanced catalytic effect.5.
Van Dung Pham Sivachandiran Somasundaram Seung Hwan Lee Si Jae Park Soon Ho Hong 《Biotechnology letters》2016,38(2):321-327
Objectives
To direct the carbon flux from Krebs cycle into the gamma-aminobutyric acid (GABA) shunt pathway for the production of GABA by protein scaffold introduction in Escherichia coli.Results
Escherichia coli was engineered to produce GABA from glucose by the co-localization of enzymes succinate semialdehyde dehydrogenase (GadD), GABA aminotransferase (PuuE) and GABA transporter (GadC) by protein scaffold. 0.7 g GABA l?1 was produced from 10 g glucose l?1 while no GABA was produced in wild type E. coli. pH 6 and 30 °C were optimum for GABA production, and GABA concentration increased to 1.12 g GABA l?1 when 20 g glucose l?1 was used. When competing metabolic networks were inactivated, GABA increased by 24 % (0.87 g GABA l?1).Conclusions
The novel GABA production system was constructed by co-localization of GABA shunt enzymes.6.
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.7.
Sisi Patricia Lolita Ameria Hye Sook Jung Hee Sook Kim Sang Soo Han Hak Sung Kim Jin Ho Lee 《Biotechnology letters》2015,37(8):1637-1644
Objective
To examine the role of a gene encoding flavin-containing monooxygenase (cFMO) from Corynebacterium glutamicum ATCC13032 when cloned and expressed in Escherichia coli for the production of indigo pigments.Results
The blue pigments produced by recombinant E. coli were identified as indigo and indirubin. The cFMO was purified as a fused form with maltose-binding protein (MBP). The enzyme was optimal at 25 °C and pH 8. From absorption spectrum analysis, the cFMO was classified as a flavoprotein. FMO activity was strongly inhibited by 1 mM Cu2+ and recovered by adding 1–10 mM EDTA. The enzyme catalyzed the oxidation of TMA, thiourea, and cysteamine, but not glutathione or cysteine. MBP-cFMO had an indole oxygenase activity through oxygenation of indole to indoxyl. The recombinant E. coli produced 685 mg indigo l?1 and 103 mg indirubin l?1 from 2.5 g l-tryptophan l?1.Conclusion
The results suggest the cFMO can be used for the microbial production of both indigo and indirubin.8.
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.9.
Maranda Esterhuizen-Londt Stefanie Hertel Stephan Pflugmacher 《Biotechnology letters》2017,39(10):1537-1545
Objectives
To evaluate the remediation efficiency of Mucor hiemalis by comparing media elimination, uptake, and biotransformation of microcystin-LR with exposure to pure toxin versus a crude bloom extract.Results
With exposure to the extract, the elimination rate of microcystin-LR from the media, which was 0.28 ng MC-LR l?1 h?1, was significantly higher compared to that achieved with exposure to the pure toxin (0.16 ng MC-LR l?1 h?1) after 24 h. However, intracellular breakdown of microcystin-LR was significantly lower in the extract exposed pellets compared to the pure toxin treated fungal pellets over time. This coincided with reduced intracellular glutathione S-transferase activity with crude extract exposure which could be responsible for the detection of only the glutathione conjugate of microcystin-LR.Conclusion
This paper signifies the importance of using laboratory exposure scenarios which resemble conditions in nature to fully understand and evaluate remediation efficiency. There is merit in using M. hiemalis for mycoremediation of cyanotoxins in surface waters.10.
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.11.
Jiandong Zhang Zhimei Cui Honghong Chang Xiaojun Fan Qiuyong Zhao Wenlong Wei 《Biotechnology letters》2016,38(9):1559-1564
Objectives
To investigate the efficiency of a cofactor regeneration enzyme co-expressed with a glycerol dehydrogenase for the production of 1,3-dihydroxyacetone (DHA).Results
In vitro biotransformation of glycerol was achieved with the cell-free extracts containing recombinant GlyDH (glycerol dehydrogenase from Escherichia coli), LDH (lactate dehydrogenase form Bacillus subtilis) or LpNox1 (NADH oxidase from Lactobacillus pentosus), giving DHA at 1.3 g l?1 (GlyDH/LDH) and 2.2 g l?1 (GlyDH/LpNox1) with total turnover number (TTN) of NAD+ recycling of 6039 and 11100, respectively. Whole cells of E. coli (GlyDH–LpNox1) co-expressing both GlyDH and LpNox1 were constructed and converted 10 g glycerol l?1 to DHA at 0.2–0.5 g l?1 in the presence of zero to 2 mM exogenous NAD+. The cell free extract of E. coli (GlyDH–LpNox) converted glycerol (2–50 g l?1) to DHA from 0.5 to 4.0 g l?1 (8–25 % conversion) without exogenous NAD+.Conclusions
The disadvantage of the expensive consumption of NAD+ for the production of DHA has been overcome.12.
Objective
To selectively enrich an electrogenic mixed consortium capable of utilizing dark fermentative effluents as substrates in microbial fuel cells and to further enhance the power outputs by optimization of influential anodic operational parameters.Results
A maximum power density of 1.4 W/m3 was obtained by an enriched mixed electrogenic consortium in microbial fuel cells using acetate as substrate. This was further increased to 5.43 W/m3 by optimization of influential anodic parameters. By utilizing dark fermentative effluents as substrates, the maximum power densities ranged from 5.2 to 6.2 W/m3 with an average COD removal efficiency of 75% and a columbic efficiency of 10.6%.Conclusion
A simple strategy is provided for selective enrichment of electrogenic bacteria that can be used in microbial fuel cells for generating power from various dark fermentative effluents.13.
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.14.
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.15.
Objective
To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica.Results
Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l?1, 100 g wet cells l?1, and 25 g LA l?1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l?1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l?1.Conclusion
Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.16.
Objectives
To assess the effects of light intensity and quality on the growth and phycobiliproteins (PBP) accumulation in Nostoc sphaeroides Kützing (N. sphaeroides).Results
Dry weights, dry matter, protein, chlorophyll and PBP contents were higher under 90 μmol m?2 s?1 than under other intensities (both higher and lower). Phycocyanin and allophycocyanin increased with light intensity while phycoerythrin decreased. Fresh weights, protein and PBP contents increased at the highest rates under blue light. Red light resulted in higher values of dry matter, phycocyanin and chlorophyll a.Conclusion
White light at 90 μmol m?2 s?1 or blue light 30 μmol m?2 s?1 were optimal for the growth and phycobiliprotein accumulation in N. sphaeroides.17.
Qingdai Liu Xiaoqian Ma Haijiao Cheng Ning Xu Jun Liu Yanhe Ma 《Biotechnology letters》2017,39(6):913-919
Objectives
To improve the production of α-ketoglutaric acid (α-KG) from l-glutamate by whole-cell biocatalysis.Results
A novel and highly active l-glutamate oxidase, SmlGOX, from Streptomyces mobaraensis was overexpressed and purified. The recombinant SmlGOX was approx. 64 kDa by SDS-PAGE. SmlGOX had a maximal activity of 125 ± 2.7 U mg?1 at pH 6.0, 35 oC. The apparent Km and Vmax values of SmlGOX were 9.3 ± 0.5 mM and 159 ± 3 U mg?1, respectively. Subsequently, a co-expression plasmid containing the SmlGOX and KatE genes was constructed to remove H2O2, and the protein levels of SmlGOX were improved by codon optimization. Finally, by optimizing the whole-cell transformation conditions, the production of α-KG reached 77.4 g l?1 with a conversion rate from l-glutamate of 98.5% after 12 h.Conclusions
An efficient method for the production of α-KG was established in the recombinant Escherichia coli, and it has a potential prospect in industrial application.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.
Objectives
To find an l-glutamate oxidase (LGox), to be used for the quantitative analysis of l-glutamic acid, an lgox gene encoding LGox from Streptomyces diastatochromogenes was isolated, cloned and characterized.Results
The gene had an ORF of 1974 bp encoding a protein of 657 amino acid residues. In comparison to the LGox precursor, the proteinase K-treated enzyme exhibited improved affinity to substrate and with a K m of 0.15 mM and V max of 62 μmol min?1 mg?1. The 50% thermal inactivation temperature of the proteinase K treated enzyme was increased from 50 to 70 °C. The enzyme exhibited strict specificity for l-glutamate.Conclusions
LGox treated by proteinase K exhibited strict specificity for l-glutamate, good thermostability and high substrate affinity.20.
Xiaobo Dong Haiyun Li Yucheng Jiang Mancheng Hu Shuni Li Quanguo Zhai 《Biotechnology letters》2016,38(9):1483-1491