Study of capability of nanostructured zero-valent iron and graphene oxide for bioremoval of trinitrophenol from wastewater in a bubble column bioreactor

BackgroundBioremoval of phenolic compounds using fungi and bacteria has been studied extensively; nevertheless, trinitrophenol bioremediation using modified Oscillatoria cyanobacteria has been barely studied in the literature.ResultsAmong the effective parameters of bioremediation, algal concentration (3.18 g·L⁻¹), trinitrophenol concentration (1301 mg·L⁻¹), and reaction time (3.75 d) were screened by statistical analysis. Oscillatoria cyanobacteria were modified by starch/nZVI and starch/graphene oxide in a bubble column bioreactor, and their bioremoval efficiency was investigated. Modifiers, namely, starch/zero-valent iron and starch/GO, increased trinitrophenol bioremoval efficiency by more than 10% and 12%, respectively, as compared to the use of Oscillatoria cyanobacteria alone.ConclusionsIt was found that starch/nano zero-valent iron and starch/GO could be applied to improve the removal rate of phenolic compounds from the aqueous solution.How to cite: Bavandi R, Emtyazjoo M, Saravi HN, et al. Study of nano-structure zero-valent iron and graphene-oxid capability onbioremoval of trinitrophenol from wastewater in a bubble column bioreactor. Electron J Biotechnol 2019;39. https://doi.org/10.1016/j.ejbt.2019.02.003.     

The 2011 Benjamin Franklin Medal in Chemistry Presented to Kyriacos C. Nicolaou

The Franklin Institute, Philadelphia, Pennsylvania, awards the 2011 Benjamin Franklin Medal in Chemistry to Professor Kyriacos C. Nicolaou for his extraordinary contributions to chemistry, biology, and medicine through the advancement of the art of synthesis as exemplified by the elegant total syntheses of some of nature's most complex biologically active molecules. Nicolaou is recognized as a world leader in the field of total synthesis for his work in chemical synthesis and chemical biology. His total syntheses are legendary, distinguished for their elegance and practicality. Among his most celebrated achievements are the total syntheses of calicheamicin γ₁^I, Taxol^®, brevetoxin B, vancomycin, and thiostrepton. The impact of his work transcends total synthesis, for it often leads to the discovery and invention of new synthetic strategies and technologies as well as biological tools and drug candidates, thereby facilitating discoveries in biology and medicine. Nicolaou's influence on science and society extends beyond his research discoveries. Through his didactic lectures and writings, he motivates and inspires students into the sciences and informs the public about the importance of science and education to society.     

Biosynthetic L-tert-leucine using Escherichia coli co-expressing a novel NADH-dependent leucine dehydrogenase and a formate dehydrogenase

BackgroundL-tert-Leucine has been widely used in pharmaceutical, chemical, and other industries as a vital chiral intermediate. Compared with chemical methods, enzymatic methods to produce L-tert-leucine have unparalleled advantages. Previously, we found a novel leucine dehydrogenase from the halophilic thermophile Laceyella sacchari (LsLeuDH) that showed good thermostability and great potential for the synthesis of L-tert-leucine in the preliminary study. Hence, we manage to use the LsLeuDH coupling with a formate dehydrogenase from Candida boidinii (CbFDH) in the biosynthesis of L-tert-leucine through reductive amination in the present study.ResultThe double-plasmid recombinant strain exhibited higher conversion than the single-plasmid recombinant strain when resting cells cultivated in shake flask for 22 h were used. Under the optimized conditions, the double-plasmid recombinant E. coli BL21 (pETDute-FDH-LDH, pACYCDute-FDH) transformed 1 mol·L^-1 trimethylpyruvate (TMP) completely into L-tert-leucine with greater than 99.9% ee within 8 h.ConclusionsThe LsLeuDH showed great ability to biosynthesize L-tert-leucine. In addition, it provided a new option for the biosynthesis of L-tert-leucine.How to citeWang L, Zhu W, Gao Z, et al. Biosynthetic L-tert-leucine using Escherichia coli co-expressing a novel NADH-dependent leucine dehydrogenase and a formate dehydrogenase. Electron J Biotechnol 2020;47. https://doi.org/10.1016/j.ejbt.2020.07.001     

Enhanced production of prodigiosin by Serratia marcescens FZSF02 in the form of pigment pellets

BackgroundProdigiosin has been demonstrated to be an important candidate in investigating anticancer drugs and in many other applications in recent years. However, industrial production of prodigiosin has not been achieved. In this study, we found a prodigiosin-producing strain, Serratia marcescens FZSF02, and its fermentation strategies were studied to achieve the maximum yield of prodigiosin.ResultsWhen the culture medium consisted of 16.97 g/L of peanut powder, 16.02 g/L of beef extract, and 11.29 mL/L of olive oil, prodigiosin reached a yield of 13.622 ± 236 mg/L after culturing at 26 °C for 72 h. Furthermore, when 10 mL/L olive oil was added to the fermentation broth at the 24th hour of fermentation, the maximum prodigiosin production of 15,420.9 mg/L was obtained, which was 9.3-fold higher than the initial level before medium optimization. More than 60% of the prodigiosin produced with this optimized fermentation strategy was in the form of pigment pellets. To the best of our knowledge, this is the first report on this phenomenon of pigment pellet formation, which made it much easier to extract prodigiosin at low cost. Prodigiosin was then purified and identified by absorption spectroscopy, HPLC, and LCMS. Purified prodigiosin obtained in this study showed anticancer activity in separate experiments on several human cell cultures: A549, K562, HL60, HepG2, and HCT116.ConclusionsThis is a promising strain for producing prodigiosin. The prodigiosin has potential in anticancer medicine studies.How to cite: Lin C, Jia X, Fang Y, et al. Enhanced production of prodigiosin by Serratia marcescens FZSF02 in the form of pigment pellets. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.007     

Oxidative foliar photo-necrosis produced by the bacteria Pseudomonas cedrina

BackgroundAlthough bioactive metabolites capable of causing oxidative photo-necrosis in plant tissues have been identified in fungi, little is known about this type of mechanism in bacteria. These metabolites act as photosensitizers that generate reactive oxygen species (ROS) capable of causing damage to cells. In addition, these metabolites can pass into an energetically excited state when they receive some luminous stimulus, a condition in which they interact with other molecules present in the environment, such as molecular oxygen (O₂), also known as triplet oxygen (³O₂), generating ROS.ResultsThe suspension of the bacterial culture of Pseudomonas cedrina was shown to produce foliar necrosis in papaya leaves (Carica papaya L.) only in the presence of sunlight, which is evidence of photosensitizing mechanisms that generate singlet oxygen (¹O₂). From the chemical study of extracts obtained from this bacteria, 3-(4-(2-carboxipropyl) phenyl) but-2-enoic acid (1) was isolated. This compound, in the presence of light and triplet oxygen (³O₂), was able to oxidize ergosterol to its peroxide, since it acted as a photosensitizer producing ¹O₂, with which it was corroborated that a photosensitization reaction occurs, mechanism by which this bacterium could prove to cause oxidative foliar photo-necrosis.ConclusionsP. cedrina was able to induce oxidative foliar photo-necrosis because of its potential ability to produce photosensitizing metabolites that generate singlet oxygen in the plants it colonizes. Based on the above, it can be proposed that some bacteria can cause oxidative foliar photo-necrosis as an important mechanism in the pathogenesis of host species.How to cite: Mendoza G, Sánchez-Tafolla L, Trigos A. Oxidative foliar photo-necrosis produced by the bacteria Pseudomonas cedrina. Electron J Biotechnol 2020;44. https://doi.org/10.1016/j.ejbt.2020.01.007     

Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

BackgroundMethanol can be effectively removed from air by biofiltration. However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms, and it can be released out of the cell constituting a secondary emission.ResultsThe total removal of methanol was achieved up to input loads of 263 g m⁻³ h⁻¹ and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m⁻³ h⁻¹ at an input methanol load of 414 g m⁻³ h⁻¹ and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m⁻³ h⁻¹. Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m⁻³ when the methanol load was 672 g m⁻³ h⁻¹ in an empty bed residence times of 60 s.ConclusionsFormaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.How to cite: Guerrero K, Arancibia A, Cáceres M, et al. Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.003.     

Improving micropropagation of some grape cultivars via boron,calcium and phosphate

BackgroundAn efficient regeneration protocol is a priority for the successful application of plant biotechnology. Grape nodal explants were used to develop a micropropagation protocol for Thompson Seedless and Taify cvs. Explants were cultured on MS medium supplemented with Kinetin or benzylaminopurine (BA) and indolebutyric acid (IBA).ResultsFor both cultivars, axillary buds were grown, only, on a medium enriched with kinetin, moreover, shoot tip necrosis and callus formation were observed on Thompson Seedless cv. cultures grown on a medium with BA. Supplementing the growth medium with 100 mM (boron) B and 2.5 mM (calcium) Ca successfully help overcome these phenomena. The highest regenerated shoot numbers (14 and 6.2 explant⁻¹) for Taify and Thompson Seedless cvs., respectively, were on media supplemented with 13.2 µM BA + 4.9 µM IBA and BA 13.2 µM + 5.8 µM IBA, respectively. Moreover, these media supported the developing shoots to have the heaviest dry weights (1.46 and 0.72 mg explant⁻¹) for Taify and Thompson Seedless cvs., respectively. Thompson Seedless cv. regenerated shoot numbers and their dry weights were significantly increased by increasing the MS medium PO₄⁻ concentration. However, these two parameters were significantly decreased for Taify cv. Developing shoots were elongated and rooted on MS medium enriched with 4.9 µM, IBA 100 mM B and 2.5 mM Ca. Plantlets were acclimatized and successfully transferred to the greenhouse conditions.ConclusionsA novel promising protocol for Thomson Seedless and Taify cvs. micropropagation using single nodes has been developed.How to cite: Al-Aizari AA, Al-Obeed RS, Mohamed MA-H. Improving micropropagation of some grape cultivars via boron, calcium and phosphate. Electron J Biotechnol 2020;49. https://doi.org/10.1016/j.ejbt.2020.10.001     

Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

BackgroundMethanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruţa et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission.ResultsThe total removal of methanol was achieved up to input loads of 263 g m⁻³ h⁻¹ and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m⁻³ h⁻¹ at an input methanol load of 414 g m⁻³ h⁻¹ and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m⁻³ h⁻¹. Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m⁻³ when the methanol load was 672 g m⁻³ h⁻¹ in an empty bed residence times of 60 s.ConclusionsFormaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.How to cite: Guerrero K, Arancibia A, Caceres M, et al. Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.04.003.