Mechanisms underlying the antimicrobial effects of cold plasma on Kazachstania bulderi in bayberry juice through transcriptomic analysis

Bayberry lacks a fruit skin covering and is prone to microbial contamination after harvest. Related products, such as Bayberry juice, can also be affected. Cold plasma (CP) shows promising antimicrobial applications in fruit juice, but its antimicrobial efficacy and underlying mechanisms against yeast remain inadequately explored. Therefore, this study aimed to elucidate the antimicrobial activity of CP against Kazachstania bulderi in bayberry juice, investigate its mechanisms through transcriptomic analysis. Results revealed that CP exhibited excellent antibacterial efficacy. Flow cytometry and transmission electron microscopy showed that CP caused wrinkling of yeast cell membranes and walls, mechanical damage to organelles and leakage of cellular contents. Transcriptomic sequencing identified a total of 1200 differentially expressed genes, primarily involved in amino acid synthesis, ribosome function, DNA repair, cell membrane and cell wall biosynthesis, and central carbon metabolism pathways. These changes indicated that CP induced cell membrane rupture and content efflux, leading to disruption of intracellular metabolic homeostasis, and that these damages induced the yeast itself to respond to CP stress through a series of stress responses such as the synthesis of amino acids and proteins and DNA repair. Regarding potential effects on juice nutrition and flavor, experimental results indicated that treatment had no significant impact on total phenols, total soluble solids, ascorbic acid, polyphenol oxidase, reducing sugars, total acidity, color, and key aroma components of bayberry juice. Additionally, CP alleviated the decline in total antioxidant capacity and total phenol content during juice storage, as well as the degradation of anthocyanins. This study suggests that cold plasma may be a promising method for juice sterilization and provides new insights into the inactivate mechanisms of cold plasma on yeast.