Isolation, identification, and tolerance analysis of yeast during the natural fermentation process of Sidamo coffee beans.

Yeast, which plays a pivotal role in the brewing, food, and medical industries, exhibits a close relationship with human beings. In this study, we isolated and purified 60 yeast strains from the natural fermentation broth of Sidamo coffee beans to screen for indigenous beneficial yeasts. Among them, 25 strains were obtained through morphological characterization on nutritional agar medium from Wallerstein Laboratory (WL), with molecular biology identifying Saccharomyces cerevisiae strain YBB-47 and the remaining 24 yeast strains identified as Pichia kudriavzevii. We investigated the fermentation performance, alcohol tolerance, SO2 tolerance, pH tolerance, sugar tolerance, temperature tolerance, ester production capacity, ethanol production capacity, H2S production capacity, and other brewing characteristics of YBB-33 and YBB-47. The results demonstrated that both strains could tolerate up to 3% alcohol by volume at a high sucrose mass concentration (400 g/L) under elevated temperature conditions (40 ℃), while also exhibiting a remarkable ability to withstand an SO2 mass concentration of 300 g/L at pH 3.2. Moreover, S. cerevisiae YBB-47 displayed a rapid gas production rate and strong ethanol productivity. whereas P. kudriavzevii YBB-33 exhibited excellent alcohol tolerance. Furthermore, this systematic classification and characterization of coffee bean yeast strains from the Sidamo region can potentially uncover additional yeasts that offer high-quality resources for industrial-scale coffee bean production.

[Effect of tumor necrosis factor alpha and beta on ionizing radiation-induced apotosis].

Present paper described the effect of human tumor necrosis factor alpha (hTNFalpha) and beta (hTNFbeta) on apoptosis induced by ionizing radiation in human embryonic lung cell line 2BS diploid cells and human lung cancer cell line A549 and SPC cells. The results showed that both hTNFalpha and hTNFbeta significantly inhibited 7Gy gamma-ray-induced apoptosis in 2BS cells. In contrast, hTNFalpha or hTNFbeta can increase the sensitivity of tumor cell lines (A549 and SPC cells) to radiation. Therefore, the results suggested that TNFalpha and TNFbeta had potential as a therapeutic agent to protect normal cell from the radiation-induced apoptosis and to sensitize the tumour cells for the damage effect of ionizing radiation.