Physical Activity among Rural Residents in Eastern, Central, and Western Provinces of China: A Cross-Sectional Survey.

Physical activity (PA) in which physical exercise (PE) is an important component is probably the most important intervention for preventing noncommunicable diseases (NCDs). However, few studies on PA and PE of rural residents in China were reported. This study conducted the first population-based cross-sectional survey in three provinces of China in 2021 that examined both PA and PE as well as the associated factors of rural residents. The International Physical Activity Questionnaire Short Form (IPAQ-S) was used, and a total of 3780 rural residents were surveyed. The result showed that 22.2% of the rural residents were physical inactivity and rural residents reporting practice of PE was 54.4%. Binary logistic regression analyses showed that being female, people aged between 15 to 34 years or 60 years old and above, employees of governmental departments/retirees, school students, the unemployed, and people with NCDs were risk factors of PA while ethnic minority groups, smoking, and alcohol consumption were risk factors of PE. Health promotion programme aiming at increasing people's PA in rural China is urgently needed, and it should focus on the population groups of the female, people aged 60 years and above, school students, the unemployed, and people with NCDs.

Polysialic acid biosynthesis and production in Escherichia coli: current state and perspectives.

Polysialic acid (PSA) is a unique polysaccharide that plays critical roles in many bioprocesses, which makes it useful in a wide range of biomedical applications. The increased demand for PSA has led to considerable efforts to improve its production using bacteria, such as Escherichia coli. Bioprocess optimization and metabolic engineering have allowed the efficient production of PSA. This review aims to summarize the metabolism of PSA with an emphasis on the importance of the key pathway components. In addition, this review provides an update on state of the art PSA production using E. coli with a special emphasis on strategies of strain engineering and process development for the enhanced production of PSA.

Enhanced production of polysialic acid by metabolic engineering of Escherichia coli.

A number of reports have described the production of polysialic acid (PSA), focusing on the fermentation and purification of PSA. However, little work has been done to strengthen the synthetic pathway of PSA to improve PSA production. In this study, an efficient process for enhanced production of PSA using a recombinant Escherichia coli strain was developed. To improve the PSA production efficiency, the key enzymes of PSA synthetic pathway were overexpressed separately or in combination, including N-acetylneuraminate (Neu5Ac) 7-O(or 9-O)-acetyltransferase (NeuD), CMP-Neu5Ac synthetase (NeuA), and alpha-Neu5Ac alpha-2,8-sialyltransferase (NeuS). The PSA production was significantly improved by coexpression of NeuD and NeuA. In terms of the efficiency, NeuD was considered as the most important factor. Secondly, the competing pathway of intermediate Neu5Ac was blocked by nanA deletion. The efficient PSA-producing strain E. coli SA9ΔnanA/pDB1S-DA was constructed, and 16.15 ± 1.45 g/L PSA was obtained in the fed-batch culture. The production of PSA by engineered strain was increased by 85 % compared to the original strain. These results provide evidence for improvement of PSA production by regulation of the PSA biosynthetic pathway. The high productivity of our process should make it a promising cost-effective resource for PSA.

Enhanced production of N-acetyl-D-neuraminic acid by multi-approach whole-cell biocatalyst.

N-Acetyl-D-neuraminic acid (Neu5Ac) has attracted considerable interest due to its promising potential applications in medicine. Significant efforts have been made in whole-cell biocatalyst for Neu5Ac production, but the processes often result in suboptimal performance due to poor expression of enzymes, imbalances of pathway components, disturbance of competing pathways, and barriers of mass transport. In this study, we engineered Escherichia coli strains capable of producing Neu5Ac by assembling a two-step heterologous pathway consisting of N-acetyl-D-glucosamine 2-epimerase (AGE) and Neu5Ac aldolase (NanA). Multiple approaches were used to improve the efficiency of the engineered pathway and process for enhanced Neu5Ac production. Firstly, we identified that NanA was the rate-controlling enzyme in this pathway. With increased expression of NanA, a ninefold increase in Neu5Ac production (65 mM) was observed. Secondly, knocking out nanTEK genes blocked Neu5Ac uptake and the competing pathway, which kept the reactions to the synthetic direction as the final product went outside of the cells and enhanced the Neu5Ac production by threefold, resulting in 173.8 mM of Neu5Ac. Thirdly, we improved the performance of the system by promoting substrate transport and optimizing concentrations of substrates. An overall whole-cell biocatalytic process was developed and a maximum titer of 240 mM Neu5Ac (74.2 g/L) was achieved, with productivity of 6.2 g Neu5Ac/L/h and conversion yield of 40 % from GlcNAc. The engineered strain could be reused for at least five cycles with a productivity of >6 g/L/h. It is a cost-effective process for Neu5Ac production with potential applications in large-scale industrial production.

[Advance in researches of drugs derived from marine bacteria].

Marine bacteria are capable of producing a lot of unique bioactive substances, and therefore provide a luxuriant resource for screening new drugs. Bioactive substances derived from marine bacteria have bright prospect in marine drugs development and research.