Xiaobei Zhan

Bio: Xiaobei Zhan is an academic researcher from Jiangnan University. The author has contributed to research in topics: Fermentation & Curdlan. The author has an hindex of 20, co-authored 112 publications receiving 1252 citations.

Recent advances in curdlan biosynthesis, biotechnological production, and applications

Abstract: Curdlan is a water-insoluble β-(1,3)-glucan produced by Agrobacterium species under nitrogen-limited condition. Its heat-induced gelling properties render curdlan to be very useful in the food industry initially. Recent advances in the understanding of the role curdlan plays in both innate and adaptive immunity lead to its growing applications in biomedicine. Our review focuses on the recent advances on curdlan biosynthesis and the improvements of curdlan fermentation production both from our laboratory and many others as well as the latest advances on the new applications of curdlan and its derivatives particularly in their immunological functions in biomedicine.

Methanol/sorbitol co-feeding induction enhanced porcine interferon-α production by P. pastoris associated with energy metabolism shift.

Abstract: The production of porcine interferon-α (pIFN-α) by Pichia pastoris was largely enhanced when adopting sorbitol/methanol co-feeding induction strategy at 30 °C in a 10-L fermentor. Analysis of energy regeneration pattern and carbon metabolism revealed that major energy metabolism energizing pIFN-α synthesis shifted from formaldehyde dissimilatory energy metabolism pathway to TCA cycle under the methanol/sorbitol co-feeding induction strategy. The sorbitol/methanol co-feeding induction strategy weakened formaldehyde dissimilatory pathway and repressed the accumulation of toxic metabolite-formaldehyde, reduced theoretical oxygen consumption rate and oxygen supply requirement, and increased energy/methanol utilization efficiency so that more methanol could be effectively used for pIFN-α synthesis. As a result, pIFN-α antiviral activity reached a highest level of 1.8 × 107 IU/mL which was about 10- to 200-folds of those obtained under pure methanol induction at 20 and 30 °C, respectively.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Bacterial exopolysaccharides: biosynthesis pathways and engineering strategies

Abstract: Bacteria produce a wide range of exopolysaccharides which are synthesized via different biosynthesis pathways. The genes responsible for synthesis are often clustered within the genome of the respective production organism. A better understanding of the fundamental processes involved in exopolysaccharide biosynthesis and the regulation of these processes is critical toward genetic, metabolic and protein-engineering approaches to produce tailor-made polymers. These designer polymers will exhibit superior material properties targeting medical and industrial applications. Exploiting the natural design space for production of a variety of biopolymer will open up a range of new applications. Here, we summarize the key aspects of microbial exopolysaccharide biosynthesis and highlight the latest engineering approaches toward the production of tailor-made variants with the potential to be used as valuable renewable and high-performance products for medical and industrial applications.

Sugar alcohols—their role in the modern world of sweeteners: a review

Abstract: Epidemic obesity and diabetes encouraged the changes in population lifestyle and consumers’ food products awareness. Food industry has responded people’s demand by producing a number of energy-reduced products with sugar alcohols as sweeteners. These compounds are usually produced by a catalytic hydrogenation of carbohydrates, but they can be also found in nature in fruits, vegetables or mushrooms as well as in human organism. Due to their properties, sugar alcohols are widely used in food, beverage, confectionery and pharmaceutical industries throughout the world. They have found use as bulk sweeteners that promote dental health and exert prebiotic effect. They are added to foods as alternative sweeteners what might be helpful in the control of calories intake. Consumption of low-calorie foods by the worldwide population has dramatically increased, as well as health concerns associated with the consequent high intake of sweeteners. This review deals with the role of commonly used sugar alcohols such as erythritol, isomalt, lactitol, maltitol, mannitol, sorbitol and xylitol as sugar substitutes in food industry.

Pichia pastoris: A highly successful expression system for optimal synthesis of heterologous proteins

Abstract: One of the most important branches of genetic engineering is the expression of recombinant proteins using biological expression systems. Nowadays, different expression systems are used for the production of recombinant proteins including bacteria, yeasts, molds, mammals, plants, and insects. Yeast expression systems such as Saccharomyces cerevisiae (S. cerevisiae) and Pichia pastoris (P. pastoris) are more popular. P. pastoris expression system is one of the most popular and standard tools for the production of recombinant protein in molecular biology. Overall, the benefits of protein production by P. pastoris system include appropriate folding (in the endoplasmic reticulum) and secretion (by Kex2 as signal peptidase) of recombinant proteins to the external environment of the cell. Moreover, in the P. pastoris expression system due to its limited production of endogenous secretory proteins, the purification of recombinant protein is easy. It is also considered a unique host for the expression of subunit vaccines which could significantly affect the growing market of medical biotechnology. Although P. pastoris expression systems are impressive and easy to use with well-defined process protocols, some degree of process optimization is required to achieve maximum production of the target proteins. Methanol and sorbitol concentration, Mut forms, temperature and incubation time have to be adjusted to obtain optimal conditions, which might vary among different strains and externally expressed protein. Eventually, optimal conditions for the production of a recombinant protein in P. pastoris expression system differ according to the target protein.