U (VI) tolerance affects Shewanella sp. RCRI7 biological responses: growth, morphology and bioreduction ability.

Native Shewanella sp. RCRI7 is recently counted as an operative bacterium in the uranium bio-reduction. The aim of this study was to investigate the effects of uranium tolerance on the morphology and population of RCRI7, following its potential removal capacity in different time intervals. In this research, the bacterial growth and uranium removal kinetic were evaluated in aerobic TSB medium, uranium-reducing condition (URC), aerobic uranium-containing (AUC) and anaerobic uranium-free (AUF) solution, following evaluations of omcAB gene expressions. In addition, spectrophotometry analyses were performed in URC confirming the bio-reduction mechanism. It was found that the bacteria can grow efficiently in the presence of 0.5 mM uranium anaerobically, unlike AUC and AUF solutions. Since the bacterium's adsorption capacity is quickly saturated, it can be deduced that uranium reduction should be dominant as incubation times proceed up to 84 h in URC. In 92 h incubation, the adsorbed uranium containing unreduced and reduced (U (IV) monomeric), was released to the solution due to either increased pH or bacterial death. In AUC and AUF, improper conditions lead to the reduced bacterial size (coccus-shape formation) and increased bacterial aggregations; however, membrane vesicles produced by the bacteria avoid the uranium incrustation in AUC. In overall, this study implies that Shewanella sp. RCRI7 are well tolerated by uranium under anaerobic conditions and the amount of regenerated uranium increases over time in the reduced form.

Evaluation of mtr cluster expression in Shewanella RCRI7 during uranium removal.

In recent years, bioremediation is considered as an efficient method to remove the pollutants from the industrial wastewater. In this study, quantitative gene expressions (Real-time RT-PCR) of mtr gene cluster (mtrA, mtrB, mtrC, mtrD, mtrE, mtrF and omcA) in five different uranium concentrations (0.1, 0.25, 0.5, 1 and 2 mM) were performed with ICP and microscopic live cell counting analysis under anaerobic condition, by Shewanella RCRI7 as a native bacterium. The results indicated that the amount of uranium removal and live-cell counting were decreased in the higher uranium concentrations (1 and 2 mM), due to the uranium toxicity, suggesting 0.5 mM as the optimum uranium concentration for Shewanella RCRI7 resistance. The expression of mtrCED and omcA genes presented increasing trend in the lower uranium concentrations (0.1, 0.25 and 0.5 mM) and a decreasing trend in 1 and 2 mM, while mtrABF, presented an inverse pattern, proving the alternative role of mtrF for mtrC and omcA, as the substantial multiheme cytochromes in Extracellular Electron Transfer (EET) pathway. These data are a proof of these gene vital roles in the EET pathway, proposing them for genetic engineering toward EET optimization, as the certain pathway in heavy metal bioremediation process.

Optical biosensing of Streptococcus agalactiae based on core/shell magnetic nanoparticle-quantum dot.

An immunomagnetic optical probe based on a core/shell magnetic nanoparticle-quantum dot was fabricated for detection of Streptococcus agalactiae, the causative agent of pneumonia and meningitis in newborns. The silica-coated magnetic nanoparticles conjugated with anti-S. agalactiae monoclonal antibody provided high specificity for pre-enrichment of bacteria from biological samples with a complex matrix such as milk. Compared with conventional methods such as culture and molecular techniques, the combination of fluorescent quantum dot and magnetic nanoparticle enhanced the sensitivity and speed of bacterial identification. The bio-functionalized fluorescent-magnetic nanoparticles were characterized by TEM, SEM, VSM, XRD, DLS, and FTIR and applied to the detection of S. agalactiae with a limit of 10 and 102 CFU/mL in PBS and milk, respectively. This immunomagnetic optical probe can be used for rapid isolation, sensitive, and specific detection of targeted bacteria without any treatment in clinical and animal samples in the presence of other infectious agents.

Nanosized aptameric cavities imprinted on the surface of magnetic nanoparticles for high-throughput protein recognition.

The authors introduce a new kind of surface artificial biomimetic receptor, referred to as aptameric imprinted polymer (AIP), for separation of biological macromolecules. Highly dispersed magnetic nanoparticles (MNPs) were coated with silica and then functionalized with methacrylate groups via silane chemistry. The aptamer was covalently immobilized on the surface of nanoparticles via a "thiol-ene" click reaction. Once the target analyte (bovine serum albumin; BSA) has bound to the aptamer, a polymer is created by 2-dimensional copolymerization of short-length poly(ethylene glycol) and (3-aminopropyl)triethoxysilane. Following removal of BSA from the polymer, the AIP-MNPs presented here can selectively capture BSA with a specific absorbance (κ) as high as 65. When using this AIP, the recovery of BSA from spiked real biological samples is >97%, and the adsorption capacity is as high as 146 mg g-1. In our perception, this method has a wide scope in that it may be applied to the specific extraction of numerous other biomolecules. Graphical abstract Schematic presentation of the AIP (aptamer-imprinted polymer) introduced here. The surface of silica coated magnetic nanoparticles is modified with a polymer that is covalently modified with an aptamer against bovine serum albumin (BSA).

The effect of not-anaerobicization and discolored bacteria on uranium reduction by Shewanella sp. RCRI7.

Shewanella sp. RCRI7 is a native strain capable of reducing uranium in anaerobic conditions. In order to employ this bacterium for the bioremediation, the mutual effects of uranium and the bacteria are studied in two different approaches. The optimal settings for the bacterial proliferation capacity and uranium reduction without anaerobicization of the environment, as well as the related effects of bioremediation and bacterial color under uranium-reducing conditions, have been investigated in this study. Uranium reduction procedure was analyzed using XRD, spectrophotometry and ICP-AES. In addition, the uranium's effect on the population of the first-generation of the bacteria as well as the color and growth of the second-generation were investigated using neobar lam and CFU (Colony Forming Unit), respectively. Uranium toxicity reduced the population of non-anaerobicized bacteria more than the anaerobicized bacteria after one day of incubation, while the amount of uranium extracted by the bacteria was almost the same. In both situations, the bacteria were able to reduce uranium after two weeks of incubation. In addition to the cell counts, uranium toxicity disrupts the growth and development of healthy second-generation anaerobicized bacteria, as created creamy-colored colonies grow slower than red-colored colonies. Furthermore, due to malfunctioning cytochromes, unlike red bacteria, creamy-colored bacteria were unable to extract the optimum amount of uranium. This study reveals that reduced uranium can be produced in a deprived environment without anaerobicization. Creamy-colored Shewanella can remove soluble uranium, however the most effective bacteria have red cytochromes. These findings represent a big step forward in the industrialization of uranium bioremediation.

Resolving the challenge of insoluble production of mature human growth differentiation factor 9 protein (GDF9) in E. coli using bicistronic expression with thioredoxin.

Growth differentiation factor 9 (GDF9) is an oocyte-derived protein with fundamental functions in folliculogenesis. While the crucial contributions of GDF9 in follicular survival have been revealed, crystallographic studies of GDF9 structure have not yet been carried out, essentially due to the insoluble expression of GDF9 in E. coli and lack of appropriate source for structural studies. Therefore, in this study, we investigated the impact of different expression rate of bacterial thioredoxin (TrxA) using bicistronic expression constructs to induce the soluble expression of mature human GDF9 (hGDF9) driven by T7 promoter in E. coli. Our findings revealed that in BL21(DE3), the high rate of TrxA co-expression at 30 °C was sufficiently potent for the soluble expression of hGDF9 and reduction of inclusion body formation by 4 fold. We also successfully confirmed the bioactivity of the purified soluble hGDF9 protein by evaluation of follicle-stimulating hormone receptor gene expression in bovine cumulus cells derived from small follicles. This study is the first to present an effective approach for expression of bioactive form of hGDF9 using TrxA co-expression in E. coli, which may unravel the current issues regarding structural analysis of hGDF9 protein and consequently provide a better insight into hGDF9 functions and interactions.

Novel probe based on rhodamine B and quinoline as a naked-eye colorimetric probe for dual detection of nickel and hypochlorite ions.

This work demonstrates the design and straightforward syntheses of several novel probe-based on rhodamine B and 2-mercaptoquinoline-3-carbaldehydes as a naked-eye colorimetric probe, indicating a sensitive and selective recognition towards nickel (II) with a limit of detection 0.30 µmol L-1 (0.02 mg L-1). Further, by employing the oxidation property of hypochlorite (OCl-), this novel probe parallelly has been deployed to detect hypochlorite in laboratory conditions with a limit of detection of 0.19 µmol mL-1 and in living cells. Regarded to negligible cell toxicity toward mammalian cells, this probe has the potential to determine these analytes in in-vivo investigation and foodstuff samples.

Fabrication and optimization of electrospun polymeric nanofibers loaded with 5-fluorouracil and rosemary extract.

BACKGROUND: Topical 5-fluorouracil [5FU] is one of the mostly prescribed medications for different types of skin cancer; however, it is associated with drug resistance and adverse effects. Rosemary extract has promising dose-dependent antitumor effects, as well as a synergistic effect in combination with 5-fluorouracil besides sensitizing the 5-FU-resistant cells. OBJECTIVE: Polymeric nanofibers loaded with 5FU and rosemary extract were optimized to combine both ingredients in one controlled release drug delivery system, aiming to enhance the efficacy while retaining the adverse effects. METHOD: Polymeric nanofibers loaded with 5-FU and rosemary were fabricated via electrospinning technique. Design expert software was utilized to study the effect of independent variables including polymer concentration, voltage, and feeding rate on the characteristics of the resulting nanofibers. Afterwards, the FTIR spectrum and release kinetic of the drug and extract from the optimized nanofibers and their cytotoxic effect against A375 cell line were investigated. RESULTS: The formulation composed of 6.65% PVA electrospun at 1 mL.h-1 and 17.5kV was chosen as the optimum fabrication condition. The mean diameter of the optimized nanofibers was 755 nm. The drug and rosemary extract contents were 75.38 and 93.42%, respectively. The fabrication yield was 100%, bioadhesion force was 1.28 N, and bead abundance was 10 per field. The cytotoxicity of the optimized formulation was significantly higher than the control groups. CONCLUSION: According to the appropriate loading percent, release efficiency and release kinetics, bioadhesion force, and cytotoxicity, these nanofibers could be further investigated as a topical treatment option to increase the efficacy of 5-FU.