Influence of Lactic Acid on Cell Cycle Progressions in Lactobacillus bulgaricus During Batch Culture
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Influence of Lactic Acid on Cell Cycle Progressions in Lactobacillus bulgaricus During Batch Culture Shiwei Chen 1 & Haiyue Niu 1 & Yifan Wu 1 & Jialei Sun 1 & Xue Han 1 Lanwei Zhang 1,2
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Received: 28 August 2020 / Accepted: 8 November 2020/ # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Lactic acid has been proved to inhibit the proliferation of lactic acid bacteria in the fermentation process. To shed light on the cell cycle alterations in acidic conditions, the cell division of Lactobacillus bulgaricus sp1.1 in batch culture was analyzed directly by implementing of the intracellular fluorescent tracking assay in different pH adjusted by lactic acid. Cell proliferation and cell division were investigated to be negatively controlled by the decrease of pH, and pH 4.1 was the critical condition of downregulating cell division but retains cell culturability. The cell area and cell length in pH 4.1 were examined by using fluorescent labeling, and they reduced to about 29.18–34.89% and 32.67–40% of cells cultured in the unacidified medium, respectively. The DNA replication initiation was undergoing prompted by the low extent of DNA condensation and higher expression of the dnaA gene in this critical pH. The results indicated that the cell cycle progressions of Lactobacillus bulgaricus sp1.1 in acidic conditions were arrested at intracellular biomass accumulation and cell division stage. These findings provide fundamental insight into cell cycle control of the acidic environment in Lactobacillus bulgaricus sp1.1. Keywords Lactobacillus bulgaricus . Cell division . Cell cycle . DNA condensation . Acid stress
Introduction While lactic acid bacteria (LAB), particularly those of probiotics, offer many potential benefits related to health promoting and dairy fermenting, the proliferation of these species has been limited due to the environmental problems brought about by end-product such as lactic acid [1, 2]. LAB proliferate in a binary fission way that cells must double their mass, replicate their DNA, and equally divide to produce two daughter cells that are typically identical in size [3].
* Xue Han [email protected] * Lanwei Zhang [email protected] Extended author information available on the last page of the article
Applied Biochemistry and Biotechnology
All of these different events are coordinated with each other and have become known as the bacterial cell cycle, and it is the fundamental process to enable the proliferation of bacterial cells. The bacterial cell cycle has been studied extensively in several model bacteria Escherichia coli, Bacillus subtilis, Caulobacter crescentus, and Salmonella enterica, as well as yeast in the past decades. It is traditionally divided into three stages: the period between the last division (birth) and initiation of DNA replication (B period), the period of DNA replication (C period), and the period between chromosome segregation and cell divide into two clonal cells (D period) [4]. In the B period, DNA replication is mediated by initiato
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