Breeding of Saccharomyces cerevisiae with a High-Throughput Screening Strategy for Improvement of S-Adenosyl-L-Methionine Production.

S-adenosyl-l-methionine (SAM), a vital physiologically active substance in living organisms, is produced by fermentation over Saccharomyces cerevisiae. The main limitation in SAM production was the low biosynthesis ability of SAM in S. cerevisiae. The aim of this work is to breed an SAM-overproducing mutant through UV mutagenesis coupled with high-throughput selection. Firstly, a high-throughput screening method by rapid identification of positive colonies was conducted. White colonies on YND medium were selected as positive strains. Then, nystatin/sinefungin was chosen as a resistant agent in directed mutagenesis. After several cycles of mutagenesis, a stable mutant 616-19-5 was successfully obtained and exhibited higher SAM production (0.41 g/L vs 1.39 g/L). Furthermore, the transcript levels of the genes SAM2, ADO1, and CHO2 involved in SAM biosynthesis increased, while ergosterol biosynthesis genes in mutant 616-19-5 significantly decreased. Finally, building on the above work, S. cerevisiae 616-19-5 could produce 10.92 ± 0.2 g/L SAM in a 5-L fermenter after 96 h of fermentation, showing a 2.02-fold increase in the product yield compared with the parent strain. Paving the way of breeding SAM-overproducing strain has improved the good basis for SAM industrial production.

Mapping research trends of chronic ocular graft-versus-host disease from 2009 to 2020: a bibliometric analysis.

PURPOSE: To evaluate the global scientific output of research on ocular chronic Graft versus host disease (cGVHD) and explore the current status and trends in this field over the past decade by bibliometric analysis. METHODS: The bibliometric search was performed in the Web of Science Core Collection (WoSCC) database. VOSviewer v.1.6.16 was used to map the knowledge domain. The annual number of publications and citations, distribution of countries and organizations, productivity of authors and journals, international collaborations, cited references, and keywords in the field of ocular cGVHD were visualized. RESULTS: In total, 398 peer-reviewed publications from 2009 to 2020 on ocular cGVHD were retrieved. The United States among all countries had the highest number of publications and citations, and Keio University was the most effective institution. Dana, R ranks the highest regarding the number of publications and citations on ocular cGVHD. Cornea and Biology of Blood and Marrow Transplantation were the most-cited journals in ocular cGVHD studies from ophthalmology and hematology, respectively. The top-cited references were primarily centered on dry eye. The keywords constituted three clusters: (1) consensus criteria and epidemiology of ocular cGVHD, (2) preclinical medical research of ocular cGVHD, and (3) treatment. CONCLUSION: Based on the data retrieved from WoSCC, a comparative analysis of the quantity and quality of papers on ocular cGVHD was conducted through bibliometric methods. This may contribute to better understanding of the status of ocular cGVHD study. The three major research topics shed new light on the ocular cGVHD study as well as meaningful materials for scholars to identify potential collaborators and promising partner institutions.