Determination of elemental distribution and evaluation of elemental concentration in single Saccharomyces cerevisiae cells using single cell-inductively coupled plasma mass spectrometry

Abstract

Single-cell analysis using inductively coupled plasma mass spectrometry (SC-ICP-MS) is a method to obtain qualitative and quantitative information of the elemental content and distribution of single cells. Six intrinsic target elements were analyzed in yeast cells at different cell growth phases cultured in medium with different phosphorus concentrations (0, 7, 14 mM) to study its effect on cell growth and composition. SC-ICP-MS results were compared to those obtained by the acid digestion and the average ratio was 0.81. The limits of detection of this method were 0.08, 2.54, 12.5, 0.02, 0.02 and 0.08 fg/cell for Mg, P, K, Mn, Cu and Zn, respectively. During the exponential growth phase, the cells exhibited higher elemental contents, wider distribution for most elements and larger cell size in comparison to the stationary growth phase. Phosphorus-free conditions reduced the average P content in single cells of stationary growth phase from 650 to 80 fg. Phosphorus deficiency led to decreasing intracellular concentrations not only of P, but also of K, Cu, and to increasing Zn concentration after 48 h. Mg maintained its concentration at approximate 0.11 fg μm–3 and did not change significantly under the three investigated conditions after 48 h. Accordingly, Mg content was successfully used to estimate the intracellular concentration of other intrinsic elements in single yeast cells. SC-ICP-MS is suited to determine target elements in single yeast cells, allows the study of heterogeneity of cell composition and effects of stressors on the elemental content, distribution and concentrations of intrinsic elements.

Exploring the Extent of Phosphorus and Heavy Metal Uptake by Single Cells of Saccharomyces cerevisiae and Their Effects on Intrinsic Elements by SC-ICP-TOF-MS

“…For S. cerevisiae cells in this study, the transport efficiency (ϕ cell ) was 0.21% ( Table 1 ). This value agrees with literature values, all less than 1% ( Meyer et al, 2018 ; Qin et al, 2021a ). The data in Table 1 suggest that the transport efficiency of particles decreases with increasing particle mass and size.…”

“…If then placed in a medium containing P, the higher PHO level leads to enhanced P uptake; this phenomenon is known as polyP hyperaccumulation ( Liss and Langen, 1962 ; Lawry and Jensen, 1979 ). Previously, this yeast strain was shown to exhibit a wider distribution of P content during its exponential growth phase compared to its stationary phase; this was interpreted as reflecting the larger diversity in the development of the individual cells in this period of rapid development ( Qin et al, 2021a ). The wider distribution of P content in the 1.55 g L –1 P-excess medium may indicate that this cell culture developed more rapidly and had already entered its exponentially growing phase when analyzed; in agreement with this, the microscopic pictures revealed more budding cell structures on the cell surface ( Supplementary Figure 2 ).…”

“…The other constituents of the medium remained unchanged. The medium composition is described in Supplementary Table 1 and a previous paper ( Qin et al, 2021a ).…”

“…Between each cell measurement using the SC-ICP-TOF-MS method, 1% HNO 3 and ultrapure water were separately introduced to wash and clean the sample transportation system for at least 3 min. The integration time was set to 3 ms per sample ( Qin et al, 2021a ), and the measurement mode was selected as time-resolved. In this study, the cell suspension with a cell number concentration of 5 × 10 5 cells ml –1 was delivered at an injection speed of 0.33 ml min –1 for measurement ( Qin et al, 2021b ).…”

“…There are more discoveries at the single-cell level reported employing this method. For instance, S. cerevisiae was found to exhibit a broader distribution of elements (e.g., Mg, P, and K) in the exponential growth phase compared with the stationary phase ( Qin et al, 2021a ). Furthermore, the elemental distributions of iron (Fe), zinc (Zn), Cu, and manganese (Mn) were shown not to be identical in three different human cells, namely, HeLa, A549, and 16HBE cells through cell suspension analysis ( Wang et al, 2015 ).…”