Application of Acetate as a Substrate for the Production of Value-Added Chemicals in Escherichia coli.

At present, the production of the majority of valuable chemicals is dependent on the microbial fermentation of carbohydrate substrates. However, direct competition is a potential problem for microbial feedstocks that are also used within the food/feed industries. The use of alternative carbon sources, such as acetate, has therefore become a research focus. As a common organic acid, acetate can be generated from lignocellulosic biomass and C1 gases, as well as being a major byproduct in microbial fermentation, especially in the presence of an excess carbon source. As a model microorganism, Escherichia coli has been widely applied in the production of valuable chemicals using different carbon sources. Recently, several valuable chemicals (e.g., succinic acid, itaconic acid, isobutanol, and mevalonic acid) have been investigated for synthesis in E. coli using acetate as the sole carbon source. In this review, we summarize the acetate metabolic pathway in E. coli and recent research into the microbial production of chemical compounds in E. coli using acetate as the carbon source. Although microbial synthetic pathways for different compounds have been developed in E. coli, the production titer and yield are insufficient for commercial applications. Finally, we discuss the development prospects and challenges of using acetate for microbial fermentation.

Genome analysis of Rossellomorea sp. y25, a deep sea bacterium isolated from the sediments of South China Sea.

Rossellomorea sp. y25, a putative new species of yellow pigment-producing, aerobic and chemoheterotrophic bacterium belonging to the family Bacillaceae, was isolated from the sediments at the depth of 1829 m in the South China Sea. In this study, we present the complete genome sequences of strain y25, which consisted of only one circular chromosome with 4,633,006 bp and the content of G + C was 41.76%. A total of 4466 CDSs, 106 tRNA, 33 rRNA, and 101 sRNA genes were obtained. Genomic analysis of strain y25 showed that it has the ability to produce antioxidant carotenoids and a large number of heavy metal resistance genes, such as arsenic, cadmium and zinc. In addition, strain y25 contains a prophage that may contribute to host protection against lysis by related Bacillus-like phages. This is the first report of genome-wide information on a bacterium of the genus Rossellomorea isolated from the deep sea, providing insights into how microorganisms of this genus adapt to deep-sea environments.

Activating autophagy promotes skin regeneration induced by mechanical stretch during tissue expansion.

Background: Tissue expansion, a technique in which skin regeneration is induced by mechanical stretch stimuli, is commonly used for tissue repair and reconstruction. In this study, we aimed to monitor the autophagy levels of expanded skin after the application of expansion stimuli and explore the effect of autophagy modulation on skin regeneration. Methods: A rat scalp expansion model was established to provide a stable expanded skin response to mechanical stretch. Autophagy levels at different time points (6, 12, 24, 48 and 72 h after the last expansion) were detected via western blotting. The effect of autophagy regulation on skin regeneration during tissue expansion was evaluated via skin expansion efficiency assessment, western blotting, immunofluorescence staining, TUNEL staining and laser Doppler blood flow imaging. Results: The autophagic flux reached its highest level 48 h after tissue expansion. Activating autophagy by rapamycin increased the area of expanded skin as well as the thicknesses of epidermis and dermis. Furthermore, activating autophagy accelerated skin regeneration during tissue expansion by enhancing the proliferation of cells and the number of epidermal basal and hair follicle stem cells, reducing apoptosis, improving angiogenesis, and promoting collagen synthesis and growth factor secretion. Conversely, the regenerative effects were reversed when autophagy was blocked. Conclusions: Autophagy modulation may be a promising therapeutic strategy for improving the efficiency of tissue expansion and preventing the incidence of the complication of skin necrosis.