Decrease in Transcriptomic Liberality during Batch Cultivation of Streptococcus salivarius ssp. thermophilus in Milk- A Comparative Observation with CHO Cells

Abstract

Batch cultivation imposes physiological constraints on cells, often resulting in characteristic transcriptomic changes. In Chinese hamster ovary (CHO) cells, transcriptomic liberality, defined as the α-diversity of intracellular transcriptomes, has been shown to decrease during batch culture. To investigate whether this phenomenon also occurs in prokaryotes, we analyzed RNA-seq data from Streptococcus salivarius ssp. thermophilus cultured under standard milk fermentation conditions. Samples were collected at four phases of fermentation corresponding to distinct pH milestones (lag phase at 2 h, pH 6.0; mid-exponential at 5 h, pH 5.1; late-exponential at 7 h, pH 4.5; stabilization phase). Raw counts obtained from a published dataset were used to calculate liberality. We observed a progressive decrease in liberality across fermentation phases, consistent with previous findings in CHO cells. These results suggest that the decline in transcriptomic liberality represents a general feature of batch cultivation across both prokaryotic and eukaryotic systems.