Browsing by Author "Hu X"

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    Impact of cell wall polysaccharide modifications on the performance of Pichia pastoris: novel mutants with enhanced fitness and functionality for bioproduction applications.
    (BioMed Central Ltd, 2024-02-17) Cheng B; Yu K; Weng X; Liu Z; Huang X; Jiang Y; Zhang S; Wu S; Wang X; Hu X
    BACKGROUND: Pichia pastoris is a widely utilized host for heterologous protein expression and biotransformation. Despite the numerous strategies developed to optimize the chassis host GS115, the potential impact of changes in cell wall polysaccharides on the fitness and performance of P. pastoris remains largely unexplored. This study aims to investigate how alterations in cell wall polysaccharides affect the fitness and function of P. pastoris, contributing to a better understanding of its overall capabilities. RESULTS: Two novel mutants of GS115 chassis, H001 and H002, were established by inactivating the PAS_chr1-3_0225 and PAS_chr1-3_0661 genes involved in β-glucan biosynthesis. In comparison to GS115, both modified hosts exhibited a looser cell surface and larger cell size, accompanied by faster growth rates and higher carbon-to-biomass conversion ratios. When utilizing glucose, glycerol, and methanol as exclusive carbon sources, the carbon-to-biomass conversion rates of H001 surpassed GS115 by 10.00%, 9.23%, and 33.33%, respectively. Similarly, H002 exhibited even higher increases of 32.50%, 12.31%, and 53.33% in carbon-to-biomass conversion compared to GS115 under the same carbon sources. Both chassis displayed elevated expression levels of green fluorescent protein (GFP) and human epidermal growth factor (hegf). Compared to GS115/pGAPZ A-gfp, H002/pGAPZ A-gfp showed a 57.64% higher GFP expression, while H002/pPICZα A-hegf produced 66.76% more hegf. Additionally, both mutant hosts exhibited enhanced biosynthesis efficiencies of S-adenosyl-L-methionine and ergothioneine. H001/pGAPZ A-sam2 synthesized 21.28% more SAM at 1.14 g/L compared to GS115/pGAPZ A-sam2, and H001/pGAPZ A-egt1E obtained 45.41% more ERG at 75.85 mg/L. The improved performance of H001 and H002 was likely attributed to increased supplies of NADPH and ATP. Specifically, H001 and H002 exhibited 5.00-fold and 1.55-fold higher ATP levels under glycerol, and 6.64- and 1.47-times higher ATP levels under methanol, respectively, compared to GS115. Comparative lipidomic analysis also indicated that the mutations generated richer unsaturated lipids on cell wall, leading to resilience to oxidative damage. CONCLUSIONS: Two novel P. pastoris chassis hosts with impaired β-1,3-D-glucan biosynthesis were developed, showcasing enhanced performances in terms of growth rate, protein expression, and catalytic capabilities. These hosts exhibit the potential to serve as attractive alternatives to P. pastoris GS115 for various bioproduction applications.
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    Inactivation of salmonella enterica serovar enteritidis on chicken eggshells using blue light
    (MDPI (Basel, Switzerland), 2021-08-10) Hu X; Sun X; Luo S; Wu S; Chu Z; Zhang X; Liu Z; Wu J; Wang X; Liu C; Wang X; Santini A
    Salmonella enterica serovar Enteritidis (S. Enteritidis) is a pathogen that poses a health risk. Blue light (BL), an emerging sanitization technology, was employed for the first time in the present study to inactivate S. Enteritidis on eggshell surfaces and its influence on maintaining eggshell freshness was investigated systematically. The results showed that 415 nm-BL irradiation at a dose of 360 J/cm2 reduced 5.19 log CFU/mL of S. Enteritidis in vitro. The test on eggshells inoculated with S. Enteritidis showed that a BL dose at 54.6 J/cm2 caused a 3.73 log CFU reduction per eggshell surface and the impact of BL inactivation could be sustained in post-5-week storage. The quality of the tested eggs (weight loss, yolk index, Haugh unit (HU) and albumen pH) demonstrated that BL treatments had negligible effects on the albumen pH of eggs. However, compared to the control, BL-treated eggs showed lower weight loss and higher HU after 5 weeks of storage at 25◦C and 65% humidity and yolk index in the control group could not be determined after 5 weeks of storage. Besides, the total amino acid content of the BL-treated egg was higher than the control, exhibiting an advantage of BL irradiation in maintaining the nutrient quality of whole eggs. The current study determined the efficacy of BL against S. Enteritidis on eggshell and suggested that BL could be an effective application in maintaining the freshness and quality of eggs.
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    Stakeholder Mapping and Analysis of Off-Site Construction Projects: Utilizing a Power–Interest Matrix and the Fuzzy Logic Theory
    (MDPI (Basel, Switzerland), 2024-09-11) Zhu Q; Xi J; Hu X; Chong H-Y; Zhou Y; Lyu S; Shrestha PP
    Stakeholder management is a crucial component in the implementation of off-site construction (OSC) projects, while stakeholder mapping serves as a practical technique to facilitate an in-depth understanding of different project stakeholders. Various topics have been explored in the OSC stakeholder management field, but research on OSC stakeholder analysis based on stakeholder mapping is still lacking. This study addresses this gap by developing two-dimensional (2D) and three-dimensional (3D) stakeholder mapping models. Data were collected from 167 stakeholders involved in OSC projects. The 2D model utilizes a power–interest matrix to classify 12 identified OSC stakeholder groups, while the 3D model further explores these groups by incorporating an additional dimension of stakeholder salience across different stages of project implementation. The results show that OSC stakeholders predominantly fall into the “key players” or “minimal effort” categories across various project stages. Key players include the client, modular manufacturer, main contractor, government, and designer, while the public and industry organizations generally require minimal effort. Additionally, stakeholders such as the supervision company, supplier, and subcontractor play key roles at specific stages, with varying levels of salience throughout the project lifecycle, reflecting shifts in their influence and involvement. The findings contribute to stakeholder management knowledge by providing an in-depth understanding of OSC stakeholders’ interrelationships during project implementation, especially through uncovered stakeholder mapping in the OSC field.
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    The Koja Web Mapping Application for Context-sensitive Natural Language Spatial Querying
    (CEUR Team, 2023-01-01) Aflaki N; Stock K; Jones CB; Guesgen H; Fukuzawa Y; Morley J; Hu X; Hu Y; Resch B; Kersten J; Stock K
    The locations of objects are often described in natural language relative to some other object using vague and context-sensitive spatial relation terms (e.g. theatre near Trafalgar Square). Koja is a web map application that predicts the distance between a location and reference object based on the spatial relation term specified by the user and language and contextual features. That distance is used to retrieve objects of the specified type within a range of the distance. They are displayed through a map interface to make the process more intuitive and user-friendly.