Phage Based Green Chemistry for Gold Ion Reduction and Gold Retrieval

The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30–630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h

MOESM1 of Simultaneous determination of rhamnose, xylitol, arabitol, fructose, glucose, inositol, sucrose, maltose in jujube (Zizyphus jujube Mill.) extract: comparison of HPLC–ELSD, LC–ESI–MS/MS and GC–MS

Additional file 1. Table S1 The recoveries of carbohydrates in Jujube extract with different SPE cartridges. Table S2 Recoveries of eight carbohydrates in sample by the HPLC-ELSDmethod (n = 5). Table S3 Recoveries of six carbohydrates in sample by the LC-ESI-MS/MS method (n = 5). Table S4 Recoveries of eight carbohydrates in sample by the GC-MS method (n = 5). Figure S1 The comparison among separation performances of nine analytes under three different elution modes. The mobile phase (flow rate 1.0 mL/min) was a linear gradient prepared from water (A) and acetonitrile (B). a. isocratic elution: 20 % A + 80 % B, (v/v); b. gradient elution: 15 % A (Initial gradient), then increasing to 30 % A until 30 min and held for 5 min; c. The gradient program was (time, % A): 0–14 min, 15 %; 14–25 min, 15–35 %; 25–30 min, 35–45 %; 30-35 min, 45–15 %; 1 rhamnose, 2 xylitol, 3 arabitol, 4 fructose, 5 glucose, 6 inositol, 7 sucrose, 8 maltose. Figure S2 Representative HPLC-ELSD chromatogram of small molecular carbohydrates in jujube extract: 1 rhamnose, 2 xylitol, 3 arabitol, 4 fructose, 5 glucose, 6 inositol, 7 sucrose, 8 maltose. a. Standard substances; b. Jujube extract. Figure S3 (A) The MRM chromatograms of xylose (internal standard), rhamnose, xylitol, glucose, arabitol, fructose and inositol in standard solution. (B) The MRM chromatograms of jujube extract sample. Figure S4 Representative GC-MS chromatogram of small molecular carbohydrates in jujube extract: 1 xylose (internal standard), 2 xylitol, 3 rhamnose, 4 arabitol, 5 fructose, 6 glucose, 7 inositol, 8 surcrose, 9 maltose. (A) Standard substances. (B) Jujube extract

Distribution and function of prophage phiRv1 and phiRv2 among <i>Mycobacterium tuberculosis</i> complex

<div><p><i>Mycobacterium tuberculosis</i> complex (MTBC) is notorious for causing diseases, such as tuberculosis. Tuberculosis caused by <i>M. tuberculosis</i> remains a global public health concern. Two prophages, phiRv1 and phiRv2, can be found among most MTBC genomes. However, no precise functions have been assigned for the two prophages. In this paper, to find out the function of these two prophages, the distribution and function of phiRv1 and phiRv2 in MTBC genomes were analyzed from multiple omics data. We found that complex insertion, deletion, and reorganization appeared on the locus of two prophages in MTBC genomes; some genes of the two prophages can be translated and are functional from proteomic data; the expression of other prophage genes, such as Rv1577c, Rv2650c, Rv2652c, Rv2659c, and Rv2658c, can vary with environmental stresses and might enhance the fitness of MTBC. These data will facilitate our in-depth understanding of their function.</p></div

<i>Mycobacterium tuberculosis</i>-Specific Phagosome Proteome and Underlying Signaling Pathways

The phagosome is very important to host immunity and tissue homeostasis maintenance. The destiny of the phagosome is closely associated with the outcome of the pathogen within. Most pathogens are successfully delivered to the lysosome and destroyed via the fusion of the phagosome with the lysosome. <i>Mycobacterium tuberculosis</i> has evolved multiple tactics to deflect the normal fusion process, such as delaying the phagosome maturation and acidification, thereby evading the immune recognition and subsequent elimination. Identification of the specific constituents of <i>M. tuberculosis</i> phagosome and the underlying signaling pathways are pivotal to define the key molecular features of this process and better targets to control this recalcitrant pathogen. Proteomic profiling is a comprehensive approach to define the protein inventory. In this review, currently available mycobacteria-containing phagosome proteome data were compiled. Ten putative evolutionarily conserved phagosome proteins were summarized. Unique proteins of the <i>M. tuberculosis</i>-containing phagosome proteome were compiled via comparison with other phagosomes, especially the inert latex bead phagosome. Signaling events associated with these unique proteins, such as Rab GTPase and PI3P, were also found and discussed. The data will facilitate better characterization of the <i>M. tuberculosis</i> specific phagosome constituents and involved signaling, and host-derived targets for better tuberculosis control

Lysine succinylation of <i>Mycobacterium tuberculosis</i> isocitrate lyase (ICL) fine-tunes the microbial resistance to antibiotics

<p>Lysine succinylation (Ksucc) is a newly identified protein posttranslational modification (PTM), which may play an important role in cellular physiology. However, the role of lysine succinylation in antibiotic resistance remains elusive. Isocitrate lyase (ICL) is crucial for broad-spectrum antibiotics tolerance in <i>Mycobacterium tuberculosis</i> (Mtb). We previously found that MtbICL (Rv0467) has at least three succinylated lysine residues, namely K189, K322, and K334.To explore the effect of succinylation on the activity of MtbICL, mutants’ mimicry of the lysine succinylation were generated by site-directed mutagenesis. ICL-K189E mutant strain is more sensitive than the wild-type to rifampicin and streptomycin, but not isoniazid. For the <i>in vitro</i> activity of the purified isocitrate lyase, only K189E mutant showed significantly decreased activity. Crystal structure analysis showed that Lys189 Glu dramatically increased the pKa of Glu188 and decreased the pKa of Lys190, whereas had negligible effect on other residues within 5 Å as well as disruption of the electrostatic interaction between Lys189 and Glu182, which might prevent the closure of the active site loop and cause severe reduction of the enzyme activity. Considering the genetic, biochemical, and crystallographical evidences together, the succinylation of specific ICL residue can fine-tune the bacterial resistance to selected antibiotics. The decreased enzymatic activity resulting from the succinylation-changed electrostatic interaction might underlie this phenotype. This study provided the first insight into the link between lysine succinylation and antibiotic resistance.</p

Surface Ligand Chemistry of Gold Nanoclusters Determines Their Antimicrobial Ability

Surface properties of nanoparticles (NPs) could greatly influence their biomedical efficacy. This paradigm drives many NPs-based antimicrobial agents as the common belief that a more positively charged surface would favor intimate interactions with the negatively charged bacterial cell wall, leading to a higher overall antimicrobial efficacy. Surprisingly, this study shows the opposite effect when using ultrasmall gold nanoclusters (Au NCs) as a model to investigate the effect of surface properties on their antimicrobial performance. Leveraging on the molecular properties of ultrasmall Au NCs, the surface properties of thiolate-protected Au NCs could be precisely controlled at the atomic level, generating a family of Au NCs with the same number of gold atoms but different surface properties. By tuning the type and ratio of surface ligands on Au NCs, more negatively charged Au NCs would produce more reactive oxygen species (ROS), leading to a better bacterial killing efficiency. This finding is in stark contrast to the previous paradigm and suggests the complexities of the nanomaterial-cell interactions, shedding some light on the design of high-performance NP-based antimicrobial agents

Antimicrobial Gold Nanoclusters

Bulk gold (Au) is known to be chemically inactive. However, when the size of Au nanoparticles (Au NPs) decreases to close to 1 nm or sub-nanometer dimensions, these ultrasmall Au nanoclusters (Au NCs) begin to possess interesting physical and chemical properties and likewise spawn different applications when working with bulk Au or even Au NPs. In this study, we found that it is possible to confer antimicrobial activity to Au NPs through precise control of their size down to NC dimension (typically less than 2 nm). Au NCs could kill both Gram-positive and Gram-negative bacteria. This wide-spectrum antimicrobial activity is attributed to the ultrasmall size of Au NCs, which would allow them to better interact with bacteria. The interaction between ultrasmall Au NCs and bacteria could induce a metabolic imbalance in bacterial cells after the internalization of Au NCs, leading to an increase of intracellular reactive oxygen species production that kills bacteria consequently

Characterization of a putative ArsR transcriptional regulator encoded by <i>Rv2642</i> from <i>Mycobacterium tuberculosis</i>

Characterization of a putative ArsR transcriptional regulator encoded by <i>Rv2642</i> from <i>Mycobacterium tuberculosis</i

Template-Assisted Fabrication of Thin-Film Composite Forward-Osmosis Membrane with Controllable Internal Concentration Polarization

The internal concentration polarization (ICP) of solutes in the porous substrate layer may reduce the water flux of a forward-osmosis (FO) membrane. Here we present an efficient design by using a novel silica template strategy to address this ICP issue. In particular, a thin-film composite (TFC) FO membrane was prepared by incorporating silica nanoparticles (SiNPs) into the poly­(ether sulfone) (PES) support layer, followed by the removal of the as-encapsulated SiNPs by hydrofluoric acid (HF) etching, leading to the formation of a highly porous and interconnected-pore structure of the support layer. Such porous structure favors the salt back diffusion in the substrate layer, leading to an improved net osmotic pressure across the selective layer. In addition, the HF treatment also contributes to a more hydrophilic top polyamide layer, further improving the performance of the membrane. The effects of the silica template on the morphology and properties of the as-designed TFC FO membrane are systematically investigated, and two major contributors for the enhanced water flux of the membrane have also been identified. The materials and strategy developed in this study will be of potential for the fabrication of high-quality FO membranes

Fast Synthesis of Thiolated Au₂₅ Nanoclusters via Protection–Deprotection Method

This letter reports a new synthesis strategy for atomically precise Au nanoclusters (NCs) by using a protection–deprotection method. The key in our synthesis strategy is to introduce a surfactant molecule to protect thiolate-Au^I complexes during their reduction. The protecting layer provides a good steric hindrance and controls the formation rate of thiolated Au NCs, which leads to the direct formation of atomically precise Au NCs inside the protecting layer. The protecting layer was then removed from the surface of thiolated Au NCs to bring back the original functional groups on the NCs. The protection–deprotection method is simple and facile and can synthesize high-purity thiolated Au₂₅ NCs <i>within</i> 10 min. Our synthesis protocol is fairly generic and can be easily extended to prepare Au₂₅ NCs protected by other thiolate ligands