Continuous Synthesis of Ag/TiO 2

A facile and environmental friendly synthesis strategy based on pulsed laser ablation has been developed for potential mass production of Ag-loaded TiO2 (Ag/TiO2) nanoparticles. By sequentially irradiating titanium and silver target substrates, respectively, with the same 1064 nm 100 ns fiber laser, Ag/TiO2 particles can be fabricated. A postannealing process leads to the crystallization of TiO2 to anatase phase with high photocatalytic activity. The phase composition, microstructure, and surface state of the elaborated Ag/TiO2 are characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) techniques. The results suggest that the presence of silver clusters deposited on the surface of TiO2 nanoparticles. The nanostructure is formed through laser interaction with materials. Photocatalytic activity evaluation shows that silver clusters could significantly enhance the photocatalytic activity of TiO2 in degradation of methylene blue (MB) under UV light irradiation, which is attributed to the efficient electron traps by Ag clusters. Our developed Ag/TiO2 nanoparticles synthesized via a straightforward, continuous, and green pathway could have great potential applications in photocatalysis

Transcriptional Regulation of Aerobic Metabolism in Pichia pastoris Fermentation.

In this study, we investigated the classical fermentation process in Pichia pastoris based on transcriptomics. We utilized methanol in pichia yeast cell as the focus of our study, based on two key steps: limiting carbon source replacement (from glycerol to methonal) and fermentative production of exogenous proteins. In the former, the core differential genes in co-expression net point to initiation of aerobic metabolism and generation of peroxisome. The transmission electron microscope (TEM) results showed that yeast gradually adapted methanol induction to increased cell volume, and decreased density, via large number of peroxisomes. In the fermentative production of exogenous proteins, the Gene Ontology (GO) mapping results show that PAS_chr2-1_0582 played a vital role in regulating aerobic metabolic drift. In order to confirm the above results, we disrupted PAS_chr2-1_0582 by homologous recombination. Alcohol consumption was equivalent to one fifth of the normal control, and fewer peroxisomes were observed in Δ0582 strain following methanol induction. In this study we determined the important core genes and GO terms regulating aerobic metabolic drift in Pichia, as well as developing new perspectives for the continued development within this field

Distribution of differential genes in the redox function tree during the transition from time point 1 to 3.

<p>The green cycle nodes represent genes, and the red triangle nodes represent GO term.</p

Main GO terms affected by differential genes and patterns during the transition from time point 1 to 3 and 3 to 5.

<p>Each box represents one pattern of a model expression profile. The upper number in the profile box is the model profile number, and the lower one is the p-value used to summarize the different gene expression patterns. (A) The 1–3 time points in the 8 expression patterns were clustered, respectively. Genes expressed during the 1–3 time points were distributed in No. 6,1, 0 and 7 pattern (p<0.05). The core gene during the first three time points was associated with redox function. (B) The 3–5 time points in the 8 constructed expression patterns were clustered, respectively. The main GOTerms were affected by differential genes. Genes expressed during the 3–5 time points were distributed in the No.3 and No.5 pattern (p<0.05). The core gene during the 3–5 time points was associated with protein transport.</p

Cellular changes during carbon source replacement.

<p>A: Cells during carbon source replacement. B: Common cell. C: Methanol treatment increased cell volume and peroxisome production.</p

Transcriptional Regulation of Aerobic Metabolism in <i>Pichia pastoris</i> Fermentation

<div><p>In this study, we investigated the classical fermentation process in <i>Pichia pastoris</i> based on transcriptomics. We utilized methanol in pichia yeast cell as the focus of our study, based on two key steps: limiting carbon source replacement (from glycerol to methonal) and fermentative production of exogenous proteins. In the former, the core differential genes in co-expression net point to initiation of aerobic metabolism and generation of peroxisome. The transmission electron microscope (TEM) results showed that yeast gradually adapted methanol induction to increased cell volume, and decreased density, via large number of peroxisomes. In the fermentative production of exogenous proteins, the Gene Ontology (GO) mapping results show that <i>PAS_chr2-1_0582</i> played a vital role in regulating aerobic metabolic drift. In order to confirm the above results, we disrupted <i>PAS_chr2-1_0582</i> by homologous recombination. Alcohol consumption was equivalent to one fifth of the normal control, and fewer peroxisomes were observed in Δ0582 strain following methanol induction. In this study we determined the important core genes and GO terms regulating aerobic metabolic drift in <i>Pichia</i>, as well as developing new perspectives for the continued development within this field.</p></div

Core genes in differential gene co-expression network during the transition from time point 1 to 3.

<p>Cycle node represents gene, the real line and dotted line between two nodes represent direct and indirect interactions between genes respectively. The red nodes represent genes with the K-core value greater than or equal to 10, the blue nodes represent genes with the K-core value less than 10.</p

Core genes of co-expression network in two time periods.

<p>Core genes of co-expression network in two time periods.</p

Key events in fermentation.

<p>Key events in fermentation.</p

Co-expression network core of differential genes.

<p>Time Point 3 to 5. Cycle nodes represent genes; the real line and dotted line between two nodes represent direct and indirect interactions between genes, respectively. The red nodes represent genes with the K-core value greater than or equal to 4, the blue nodes represent genes with the K-core value less than 4.</p