Electronic Journal of Biotechnology最新文献

Background

As a kind of rare sugar alcohol, allitol has important application values in food and medication. In addition, it can be used as a key substrate to produce other d/l-rare sugars. Allitol can be effectively produced by the resting-cell biotransformation method.

Results

Two recombinant Escherichia coli strains, one simultaneously expressing ribitol dehydrogenase (RDH) and formate dehydrogenase (FDH) in fusion (fusion expression strain for short) and the other expressing the above two enzymes individually (individual expression strain for short), were respectively constructed and used for allitol bioproduction. The produced allitol was confirmed by HPLC, mass spectrometry, and polarimetry. The individual expression strain had higher activity, which produced 58.5 g/L allitol from 90 g/L d-allulose (also named d-psicose) in 1 h with an allitol productivity of 58.5 g/L/h under optimized conditions.

Conclusions

The constructed individual expression strain had the highest allitol productivity among the reports. The production process developed in this study was simple, highly efficient, and had the potential for mass production of allitol.

How to cite: Wen X, Lin H, Ren Y, et al. Allitol bioproduction by recombinant Escherichia coli with NADH regeneration system co-expressing Ribitol Dehydrogenase (RDH) and Formate Dehydrogenase (FDH) in individual or in fusion. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.11.007

Background

Marine fungi are considered as a promising source of pharmacologically important extracts and compounds owing to the new chemical structures that they can synthesize due to the environmental conditions of their habitat. The aim of this work is to evaluate the free radical scavenging capacity of methanolic extracts from marine fungi and their relationship to their total phenolic content. For this, the radical tests ABTS, DPPH, and Galvinoxyl were used, comparing these results with the antioxidant Trolox as reference. The total phenol content was quantified using the Folin-Ciocalteu method. All data were analyzed by ANOVA followed by Tukey's post hoc tests (p < 0.001).

Results

The results indicate that Fusarium oxysporum broth extract (Apl) showed a greater capacity for free radical scavenging when compared with the Trolox standard (128% ABTS) as well as the biomass extract of Cladosporium cladosporioides (A.c) with values of (107 % ABTS and 102% Galvinoxyl). In addition, the variation found in the total phenolic content for each bioactive extract suggests that their antioxidant activity is not exclusively related to phenolic compounds and hence might be attributed to other types of metabolites.

Conclusions

This work is the first to report the antioxidant capacity of marine fungi isolated from sponges and corals in Mexico. These results, we consider, support the selection, conservation, and use of marine fungi as an alternative source of phenolic and non-phenolic compounds that could be used in pathologies such as oxidative stress and cancer, among others.

How to cite: Couttolenc A, Medina ME, Trigos Á, et al. Antioxidant capacity of fungi associated with corals and sponges of the reef system of Veracruz, Mexico. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.11.002

Background

The use of single cell protein (SCP) has become a method for alleviating the shortage of protein feed that microorganisms propagate in a suitable culture medium. In this study, SCP was produced by yeast to use the nutrition contained in the biogas slurry of chicken manure.

Results

The results showed that Galactomyces candidum was the most efficient at producing SCP among the seven yeasts studied. The maximum cell dry weight (CDW) 6.79 g/L and protein content 39.39%, were obtained under the fermentation conditions of initial NH₄⁺-N concentration of 2000 mg/L and a C/N ratio of 6:1 with acetate as the pH regulator. The total CDW increased to 9.24 g/L after secondary fermentation. Metal elements had a little effect on the growth of G. candidum. The addition of sulfur not only promoted the synthesis of sulfur-containing amino acid cysteine but also increased protein content by promoting the synthesis of glutamic acid and glutamine.

Conclusions

Future experiments should focus more on achieving high-density cultivation and more efficient utilization of ammonia nitrogen in the biogas slurry.

How to cite: Zhou P, Zhang L, Ding H, et al. Optimization of culture conditions of screened Galactomyces candidum for the production of single cell protein from biogas slurry. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.11.006

Background

Gliomas are common malignant intracranial tumors. Efficacious targeted therapy against gliomas is lacking.

Results

GANT61 combined with the chemotherapy drug doxorubicin for treatment of glioma (LN-229) cells, and the effect of their combination, was tested. The molecular mechanism was explored by target prediction, along with functional analysis using the Gene Ontology (GO) database, enrichment analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, construction of protein–protein interaction (PPI) networks, and protein expression. Combination of GANT61 plus doxorubicin could inhibit the growth of LN-229 cells effectively. Wound-healing data and expression of migration proteins related to epithelial-to-mesenchymal transition showed that this combination could inhibit the migration of LN-229 cells. Sixty-one targets of drug and disease intersected. Functional analysis revealed negative regulation of apoptosis, positive regulation of cell proliferation, and other biological processes related to apoptosis and proliferation. Pathway-enrichment analysis showed drug combination to be related to the cyclic adenosine monophosphate signaling pathway, pathways in cancer, and Hedgehog signaling pathway. Measurement of expression of several proteins related to these pathways revealed expression of BIRC5, GLi1 and GLi2, MMP3 and MMP9 proteins to decrease, and expression of MDM2 and P53 proteins to decrease and increase, respectively.

Conclusions

This study provides a: (a) new direction for targeted therapy of gliomas; (b) theoretical basis for drug research and molecular-mechanism research on gliomas.

How to cite: Chen J, Zhang Q, Zhang G et al. Molecular mechanism of GANT61 combined with doxorubicin in the treatment of gliomas based on network pharmacology. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.11.001.

Background

Biopolymer based edible films have emerged as potential alternatives for conventional plastics in food packaging industry. The properties such as thickness, water vapour transmission rate (WVTR) and transparency of these films would be significantly influenced by the solution components and concentration and process conditions (pH, temperature and relative humidity of drying).

Results

Control and glycerol blended pectin films were developed as per 2³ (two-level three-factor) factorial design of experiments by varying glycerol fraction (25% and 40% w/w) and solution concentration (3% and 5% w/v). The films made from 5% solution showed good moisture barrier properties. Glycerol addition reduced the moisture barrier capability of the films compared to control pectin films. Statistical analysis suggests that, the solution pH and drying temperature considerably affect film properties while the effect of relative humidity of drying is not evident enough. However, the interaction effect of relative humidity (H) with the pH and temperature appeared significant. Regression models were fitted to the data by considering the main and interaction effects, which were significantly affecting a particular property.

Conclusions

Detailed analysis reveals that for obtaining pectin based films with less thickness, low WVTR and high transparency, the optimal conditions preferred are low pH = 3, high T = 48°C and low to medium humidity of drying (H = 40–50%). The fitted regression models were statistically significant at 90% confidence level, pass Lack-of-fit analysis and are adequate to describe the effects of different factors on the targeted film properties.

How to cite: Mehraj S, Sistla YS. Optimization of process conditions for the development of pectin and glycerol based edible films: statistical design of experiments. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.11.004

Background

Engineering thermal adaptations of enzymes is a popular field of study. Enzymes active at low temperature have been used in many industries; however, reports seldom describe improvements in enzyme activity at low temperatures using protein engineering.

Results

Multiple amino acid sequence alignment of glycoside hydrolase (GH) family 32 showed an unconserved region located in the catalytic pocket. The exo-inulinase InuAGN25 showed the highest frequency of charged amino acid residues (47.4%) in this region among these GH 32 members. Notably, five consecutive charged amino acid residues (¹³⁷EEDRK¹⁴¹) were modeled as a loop fragment in this region of InuAGN25. Deletion of the loop fragment broke two salt bridges, one cation–π interaction, and the α-helix–loop–310-helix structure at the N-terminal tail. The mutant exo-inulinase RfsMutE137Δ5 without the loop fragment was expressed in Escherichia coli, digested using human rhinovirus 3C protease for removal of the fused sequence at the N-terminus, and purified using immobilized metal affinity chromatography. Compared to the wild-type enzyme, the optimum temperature and t_1/2 at 50°C of purified RfsMutE137Δ5 decreased by 10°C and 31.7 min, respectively, and the activities at 20°C and 30°C increased by 11% and 18%, respectively.

Conclusions

In this study, we engineered the loop to obtain the mutant exo-inulinase that showed an improved performance at low temperatures. These findings suggest that the loop may be a useful target in formulating rational designs for engineering thermal adaptations of GH 32 exo-inulinases.

How to cite: He L, Zhang R, Shen J. et al. Improving the low-temperature properties of an exo-inulinase via the deletion of a loop fragment located in its catalytic pocket. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.09.004

Background

Hepatocellular carcinoma (HCC) is a malignant tumor with complex pathogenesis. In HCC, the possible roles of transcriptional factor WD repeat and HMG-box DNA binding protein 1 (WDHD1) remain unclear. Hence, our study is aimed at verifying the prognosis prediction ability and potential biological mechanisms of WDHD1 in HCC.

Results

In this study, a total of 7171 clinical samples were obtained to quantitatively analyze the protein and mRNA expression levels of WDHD1 by using immunohistochemistry, gene microarrays, and high-throughput sequencing technologies. The result of in-house immunohistochemistry assay indicated that WDHD1 protein was remarkably overexpressed in HCC tissues compared with the non-HCC tissues (AUC > 0.99, the single Standardized Mean Difference [SMD] = 4.46). The overexpression trend of WDHD1 was validated by the comprehensive analysis based on a total of 4004 HCC tissues and 3167 controls (SMD = 1.333; AUC = 0.91). Moreover, the higher WDHD1 expression resulted in the poorer prognosis of HCC, as assessed by overall survival and relapse-free survival analyses (pooled hazard ratios > 1). WDHD1-coexpressed genes were screened out for enrichment analyses to enquire the prospective signaling pathways of WDHD1 in HCC and to probe the potential transcriptional targets of WDHD1. The WDHD1-coexpressed genes were mainly involved in the division process of chromosome and cell nucleus in HCC. UBA52 was identified as a crucial target of WDHD1.

Conclusions

WDHD1 may act as an oncogene in HCC and it has the potential to become a novel marker for predicting the prognosis of HCC patients, which may benefit from the early intervention of HCC.

How to cite: He R-Q, Li J-D, He W-Y, et al. Prognosis prediction ability and prospective biological mechanisms of WDHD1 in hepatocellular carcinoma tissues. Electron J Biotechnol 2022;55. https://doi.org/10.1016/j.ejbt.2021.12.001

Background

Hydroxycinnamic acids and some of their derivatives are molecules with interesting biological activities; for instance, hydroxylated hydroxycinnamic esters have proved to have antifungal properties, and thus the generation of these molecules is of industrial importance. In this study, the direct esterification capacity of the pure recombinant type B feruloyl esterase from Aspergillus terreus (AtFAE B) was evaluated by its ability to catalyze the synthesis of isobutyl o-coumarate, an interesting antifungal molecule. A ternary solvent system (isooctane/isobutanol/water) was employed to improve the synthesis of isobutyl o-coumarate, assessing different substrate concentrations, enzyme load, water percentages and pH and temperature values.

Results

AtFAE B showed the highest initial rate at 18% (v/v) isobutanol and 50 mM o-coumaric acid, 0.04 mg/ml of enzyme, 4% (v/v) water without buffer and 40°C. AtFAE B half-lives at 30°C, 40°C and 50°C were 16.5 h, 1.75 h and 3.5 min, respectively. Thus, we decided to evaluate the bioconversion yield at 30°C, where the enzyme showed the highest operational stability. At this temperature, we obtained a yield of ~80% after only 8 h of reaction, using a 78:18:4 isooctane:isobutanol:water ternary solvent system, with 50 mM of o-coumaric acid.

Conclusions

Under these improved conditions, the productivity was 1.06 g isobutyl o-coumarate/L*h with a biocatalyst yield of 209.6 kg isobutyl o-coumarate/kg free AtFAE B, demonstrating the promising potential of AtFAE B to accept the non-canonical o-coumaric acid as the substrate and to achieve the synthesis of isobutyl o-coumarate.

How to cite: Vega-Rodríguez AD, Armendáriz-Ruiz MA, Grajales-Hernández DA, et al. Improved synthesis of the antifungal isobutyl o-coumarate catalyzed by the Aspergillus terreus type B feruloyl esterase. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.08.001

Background

Synthesis of selenium nanoparticles from selenite by Shewanella sp. HN-41 demonstrated that particle size depended on the reaction time and biomass of cells. The slow reaction and low biomass tended to form small particles. In this study, Shewanella sp. HN-41 was introduced into the anode of a nonexternal circuit bioelectrochemical system (nec_BES) to convert chemical energy from lactate to low electron current to the cathode, where selenite was reduced.

Results

Our experiment with two systems, one bioelectrochemical system with a cathode flushed with nitrogen and the other with a no-nitrogen-flushing cathode, showed that the former could not produce Se nanoparticles after 21 d, but the latter formed them with an average size of 37.7 nm. The SEM and TEM images demonstrated that the particle size of 10 nm occupied over 10% and most of the particles were in the range of 30–60 nm. The XRD result and SAED image demonstrated no clear peaks of crystal and proved that the Se nanoparticles are amorphous.

Conclusions

The clean Se nanoparticles were synthesized and completely separated from bacterial cells in the bioelectrochemical system. This study opened a new approach for the biological synthesis of metal nanoparticles. Finally, the Se products in the range of 30–60 nm can be tested for antimicrobial activities in medical applications.

How to cite: Ho CT, Nguyen T-H, Lam T-T, et al. Biogenic synthesis of selenium nanoparticles by Shewanella sp. HN-41 using a modified bioelectrochemical system. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.07.004

Background

Qaidam cattle are local breeds that habitats in northwest China. It has many excellent characteristics, such as high cold and roughage tolerance, low oxygen adaptability, and tender meat quality. Copy number variation (CNV) can induce phenotypic changes in animals by a variety of effects, and thus affects the biological functions of the animals. To explore the molecular mechanism of its adaptation to extreme cold weather and muscle fat development, the CNV variations in the genome of three Qaidam cattle were detected by whole-genome sequencing, in this study.

Results

A total of 16,743 CNVs and 9498 copy number variable regions (CNVRs) were obtained after the screening, which accounts for 2.18% of the bovine genome. The CNVR length detected ranged from 0.3 KB to 10.77 KB, with a total length of 58.17 MB and an average length of 6.12 KB/ CNVR. Through functional enrichment of CNVR related genes, LDHB, and ME1 genes were screened as the key genes for Qaidam cattle to adapt to the cold and low oxygen environments, whereas KIT and FGF18 genes might be related to the coat color and growth. In the CNVR overlapped with QTLs, variation in CAPN1 and CAST genes might be closely related to the tender meat quality of Qaidam cattle.

Conclusions

Therefore, this study provides new genetic insights on the environmental adaptability and important economic traits of Qaidam cattle.

How to cite: Guo S, Wu X, Pei J, et al. Genome-wide CNV analysis reveals variants associated with high-altitude adaptation and meat traits in Qaidam cattle. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.07.006