Kato Kosuke, Nakamura Madoka, Serata Masaki, Okumura Takekazu
Yakult Central Institute, 5-11 Izumi Kunitachi-shi, Tokyo 186-8650, Japan.
Curr Res Microb Sci. 2025 Jun 26;9:100430. doi: 10.1016/j.crmicr.2025.100430. eCollection 2025.
LCPS-1 is a cell wall polysaccharide (CWPS) of (formerly ) strain Shirota (LcS). LCPS-1 enhances the acid tolerance of LcS; however, the mechanism of action remains unclear. This study aimed to elucidate how LCPS-1 enhances LcS growth and survivability under acidic conditions. When cultured in media acidified with hydrochloric, lactic, or acetic acid, wild-type LcS showed significantly more growth than an LCPS-1-deficient mutant strain ( < 0.01), indicating that LCPS-1 confers enhanced protection against proton ( ) stress. Wild-type LcS also exhibited a significant 73-83 % reduction ( < 0.01) in negative surface potential compared to that of the mutant. Additionally, wild-type LcS showed significantly more growth than the mutant ( < 0.01) in the presence of cupric oxide, which releases bactericidal Cu ions. In contrast, wild-type LcS was slightly more susceptible than the mutant to lethal concentrations of hydroxide ions. These findings suggest that LCPS-1 modulates the surface electric potential of LcS cells, thereby influencing the interaction strength between the cell walls and environmental ions, ultimately altering the tolerance of the cells to ionic stress factors. These findings provide crucial insights into the role of CWPSs in modulating the surface electric potential of microorganisms, which affects microbial interactions with environmental ions. This enhanced understanding of CWPS function enables the development of more resilient probiotic strains, potentially improving their efficacy in various industrial and therapeutic applications.
LCPS-1是（原）志村菌株（LcS）的一种细胞壁多糖（CWPS）。LCPS-1可增强LcS的耐酸性；然而，其作用机制仍不清楚。本研究旨在阐明LCPS-1如何在酸性条件下增强LcS的生长和生存能力。当在用盐酸、乳酸或乙酸酸化的培养基中培养时，野生型LcS的生长明显多于LCPS-1缺陷突变株（P<0.01），表明LCPS-1赋予了对质子（H⁺）应激更强的保护作用。与突变株相比，野生型LcS的表面负电位也显著降低了73 - 83%（P<0.01）。此外，在释放杀菌铜离子的氧化铜存在的情况下，野生型LcS的生长明显多于突变株（P<0.01）。相反，野生型LcS对致死浓度的氢氧根离子比突变株稍敏感。这些发现表明，LCPS-1调节LcS细胞的表面电势，从而影响细胞壁与环境离子之间的相互作用强度，最终改变细胞对离子应激因素的耐受性。这些发现为CWPSs在调节微生物表面电势方面的作用提供了关键见解，而这会影响微生物与环境离子的相互作用。对CWPS功能的这种深入理解有助于开发更具韧性的益生菌菌株，有可能提高它们在各种工业和治疗应用中的功效。
