Yak yogurt, which is rich in microorganisms, is a naturally fermented dairy product prepared with ancient and modern techniques by Chinese herdsmen in the Qinghai-Tibet Plateau. The objective of this research was to assess the impact of Lactobacillus bulgaricus and Streptococcus thermophilus starter cultures on the quality and shelf life of yak yogurt, as well as the genetic stability across multiple generations, in comparison to commercially available plain yogurt and peach oat flavor yogurt. Following that, the samples were evenly divided into four treatment groups denoted as T1 (treatment 1), T2, T3, and T4, with each group employing a distinct source of yogurt formulation. T1 included L. bulgaricus, T2 comprised S. thermophilus, T3 consisted of plain yogurt, and T4 represented peach oat yogurt flavor. The findings indicate that T1 yogurt consistently presents a lower pH and higher acidity compared to the other three yogurt types throughout the entire generation process. Moreover, the fat content in all generations of the four yogurt types exceeds the national standard of 3.1 g/100 g, while the total solid content shows a tendency to stabilize across generations. The protein content varies significantly among each generation, with T1 and T4 yogurt indicating higher levels compared to the T2 and T3 yogurt groups. In terms of overall quality, T1 and T4 yogurt are superior to T2 and T3 yogurt, with T1 yogurt being the highest in quality among all groups. The findings revealed that the inclusion of L. bulgaricus led to enhanced flavor, texture, and genetic stability in yak yogurt. This study will serve as a valuable source of data, support, and methodology for the development and screening of compound starters to be utilized in milk fermentation in future research and applications.

Chinese hamster ovary (CHO) cells are a popular choice in biopharmaceuticals because of their beneficial traits, including high-density suspension culture, safety, and exogenously produced proteins that closely resemble natural proteins. Nevertheless, a decline in the expression of exogenous proteins is noted as culture time progresses. This is a consequence of foreign gene recombination into chromosomes by random integration. The current investigation employs CRISPR-Cas9 technology to integrate foreign genes into a particular chromosomal location for sustained expression. Results demonstrate the successful integration of enhanced green fluorescent protein (EGFP) and human serum albumin (HSA) near base 434814407 on chromosome NC_048595.1 of CHO-K1 cells. Over 60 successive passages, monoclonal cell lines were produced that consistently expressed all relevant external proteins without discernible variation in expression levels. In conclusion, the CHO-K1 cell locus, NC_048595.1, proves an advantageous locus for stable exogenous protein expression. This study provides a viable approach to establishing a CHO cell line capable of enduring reliable exogenous protein expression.