scholarly journals The Ethanologenic Bacterium Zymomonas mobilis Divides Asymmetrically and Exhibits Heterogeneity in DNA Content

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
Katsuya Fuchino ◽  
Helena Chan ◽  
Ling Chin Hwang ◽  
Per Bruheim
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Cell Size ◽  
Dna Content ◽  
Bacterial Cell ◽  
Zymomonas Mobilis ◽  
Biofuel Production ◽  
Public Attention ◽  
Content Type ◽  
Cell Organization

ABSTRACT The alphaproteobacterium Zymomonas mobilis exhibits extreme ethanologenic physiology, making this species a promising biofuel producer. Numerous studies have investigated its biology relevant to industrial applications and mostly at the population level. However, the organization of single cells in this industrially important polyploid species has been largely uncharacterized. In the present study, we characterized basic cellular behavior of Z. mobilis strain Zm6 under anaerobic conditions at the single-cell level. We observed that growing Z. mobilis cells often divided at a nonmidcell position, which contributed to variant cell size at birth. However, the cell size variance was regulated by a modulation of cell cycle span, mediated by a correlation of bacterial tubulin homologue FtsZ ring accumulation with cell growth. The Z. mobilis culture also exhibited heterogeneous cellular DNA content among individual cells, which might have been caused by asynchronous replication of chromosome that was not coordinated with cell growth. Furthermore, slightly angled divisions might have resulted in temporary curvatures of attached Z. mobilis cells. Overall, the present study uncovers a novel bacterial cell organization in Z. mobilis. IMPORTANCE With increasing environmental concerns about the use of fossil fuels, development of a sustainable biofuel production platform has been attracting significant public attention. Ethanologenic Z. mobilis species are endowed with an efficient ethanol fermentation capacity that surpasses, in several respects, that of baker’s yeast (Saccharomyces cerevisiae), the most-used microorganism for ethanol production. For development of a Z. mobilis culture-based biorefinery, an investigation of its uncharacterized cell biology is important, because bacterial cellular organization and metabolism are closely associated with each other in a single cell compartment. In addition, the current work demonstrates that the polyploid bacterium Z. mobilis exhibits a distinctive mode of bacterial cell organization, likely reflecting its unique metabolism that does not prioritize incorporation of nutrients for cell growth. Thus, another significant result of this work is to advance our general understanding in the diversity of bacterial cell architecture.

scholarly journals Cell biological studies of ethanologenic bacterium Zymomonas mobilis

2020 ◽  
Author(s):  
Katsuya Fuchino ◽  
Helena Chan ◽  
Ling Chin Hwang ◽  
Per Bruheim
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Cell Size ◽  
Bacterial Cell ◽  
Zymomonas Mobilis ◽  
Single Cells ◽  
Biofuel Production ◽  
Public Attention ◽  
Biological Studies ◽  
Cell Organization

AbstractAlphaproteobacterium Zymomonas mobilis exhibits extreme ethanologenic physiology, making this species a promising biofuel producer. Numerous studies have investigated its biology relevant to industrial applications and mostly at the population level. However, the organization of single cells in this industrially important, polyploid species has been largely uncharacterized.In the present study, we characterized basic cellular behaviour of Z. mobilis strain Zm6 at a single cell level. We observed that growing Z. mobilis cells often divided at non mid-cell position, which contributed to variant cell size at birth. Yet, the cell size variance was regulated by a modulation of cell cycle span, mediated by a correlation of bacterial tubulin homologue FtsZ-ring accumulation with cell growth. The Z. mobilis culture also exhibited heterogeneous cellular DNA contents among individual cells, which might have been caused by asynchronous replication of chromosome that was not coordinated to cell growth. Furthermore, slightly angled divisions might have rendered temporary curvatures of attached Z. mobilis cells. Overall, the presented study uncovered a novel bacterial cell organization in Z. mobilis, the metabolism of which is not favoured for biosynthesis to build biomass.ImportanceWith increasing environmental concerns about the exhausting use of fossil fuels, a development of sustainable biofuel production platform has been attracting significant public attention. Ethanologenic Z. mobilis species are endowed with an efficient ethanol-fermentation capacity that surpass, in several aspects, that of the baker’s yeast Saccharomyces cerevisiae, the most used microorganism for ethanol productions. For a development of Z. mobilis culture-based biorefinery, an investigation of its uncharacterized cell biology is important, because bacterial cellular organization and metabolism are closely associated with each other in a single cell compartment.In addition, the current work highlights that polyploid bacterium Z. mobilis exhibits a distinctive mode of bacterial cell organization, reflecting its unique metabolism that do not prioritize incorporation of nutrients to cell growth. Thus, another significance of presented work is to advance our general understanding in the diversity of bacterial cell architecture.

scholarly journals Single-cell growth inference of Corynebacterium glutamicum reveals asymptotically linear growth

2020 ◽  
Author(s):  
Joris Messelink ◽  
Fabian Meyer ◽  
Marc Bramkamp ◽  
Chase P. Broedersz
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Corynebacterium Glutamicum ◽  
Cell Size ◽  
Linear Growth ◽  
Growth Dynamics ◽  
Asymptotically Linear ◽  
Inference Method ◽  
Growth Modes ◽  
Regulation Mechanisms

AbstractIn many bacteria, protein mass production is thought to be rate limiting for growth, implying exponential growth at the single cell level. To maintain cell-size homeostasis in proliferating populations of exponentially growing bacteria, tight growth and division mechanisms are required. However, it remains unclear whether these considerations set universal physical limits to bacterial growth. Here, we characterize the growth dynamics of the actinobacterium Corynebacterium glutamicum - a promising candidate for uncovering novel growth modes. This bacterium exhibits apical cell wall synthesis and division site selection systems appear to be absent, as reflected by a broad distribution of division asymmetries. We develop a novel growth inference method that averages out measurement noise and single-cell variability to obtain elongation rate curves as a function of birth length. Using this approach, we find that C. glutamicum exhibits asymptotically linear single-cell growth. To explain this growth mode, we model elongation as being rate-limited by the apical growth mechanism mediated by cell wall transglycosylases. This model accurately reproduces the observed elongation rate curves, and we further validate the model with growth measurements on a transglycosylase deficient ΔrodA mutant. Finally, with simulations we show that asymptotically linear growth yields a narrower distribution of cell lengths, suggesting that this growth mode can act as a substitute for tight division length and division symmetry regulation.SignificanceRegulation of growth and cell size is crucial for the optimization of bacterial cellular function. So far, single bacterial cells have been found to grow exponentially, which implies the need for tight regulation mechanisms to maintain cell size throughout growth and division cycles. Here, we characterize the growth behavior of the apically growing bacterium Corynebacterium glutamicum, by developing a novel and broadly applicable inference method for single-cell growth dynamics. We find that this bacterium grows asymptotically linearly, enabling it to maintain a narrow distribution of cell sizes, despite having a large variability of single-cell growth features. Our results imply a novel interplay between mode of growth and division regulation mechanisms, which may extend to other bacteria with non-exponential growth modes.

scholarly journals Single-cell growth inference of Corynebacterium glutamicum reveals asymptoticallylinear growth

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Joris Jan Boudewijn Messelink ◽  
Fabian Meyer ◽  
Marc Bramkamp ◽  
Chase P Broedersz
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Corynebacterium Glutamicum ◽  
Cell Size ◽  
Linear Growth ◽  
Growth Dynamics ◽  
Growth Mode ◽  
Bacterial Cells ◽  
Asymptotically Linear ◽  
Regulation Of Growth

Regulation of growth and cell size is crucial for the optimization of bacterial cellular function. So far, single bacterial cells have been found to grow predominantly exponentially, which implies the need for tight regulation to maintain cell size homeostasis. Here, we characterize the growth behavior of the apically growing bacterium Corynebacterium glutamicum using a novel broadly applicable inference method for single-cell growth dynamics. Using this approach, we find that C. glutamicum exhibits asymptotically linear single-cell growth. To explain this growth mode, we model elongation as being rate-limited by the apical growth mechanism. Our model accurately reproduces the inferred cell growth dynamics and is validated with elongation measurements on a transglycosylase deficient ΔrodA mutant. Finally, with simulations we show that the distribution of cell lengths is narrower for linear than exponential growth, suggesting that this asymptotically linear growth mode can act as a substitute for tight division length and division symmetry regulation.

scholarly journals The Length of Lipoteichoic Acid Polymers Controls Staphylococcus aureus Cell Size and Envelope Integrity

2020 ◽  
Vol 202 (16) ◽  
Author(s):  
Anthony R. Hesser ◽  
Leigh M. Matano ◽  
Christopher R. Vickery ◽  
B. McKay Wood ◽  
Ace George Santiago ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Growth ◽  
Cell Size ◽  
Cell Envelope ◽  
Lipoteichoic Acid ◽  
Beta Lactam ◽  
Content Type ◽  
Beta Lactam Antibiotics ◽  
Outer Leaflet ◽  
Glycolipid Anchor

ABSTRACT The opportunistic pathogen Staphylococcus aureus is protected by a cell envelope that is crucial for viability. In addition to peptidoglycan, lipoteichoic acid (LTA) is an especially important component of the S. aureus cell envelope. LTA is an anionic polymer anchored to a glycolipid in the outer leaflet of the cell membrane. It was known that deleting the gene for UgtP, the enzyme that makes this glycolipid anchor, causes cell growth and division defects. In Bacillus subtilis, growth abnormalities from the loss of ugtP have been attributed to both the absence of the encoded protein and the loss of its products. Here, we show that growth defects in S. aureus ugtP deletion mutants are due to the long, abnormal LTA polymer that is produced when the glycolipid anchor is missing from the outer leaflet of the membrane. Dysregulated cell growth leads to defective cell division, and these phenotypes are corrected by mutations in the LTA polymerase gene, ltaS, that reduce polymer length. We also show that S. aureus mutants with long LTA are sensitized to cell wall hydrolases, beta-lactam antibiotics, and compounds that target other cell envelope pathways. We conclude that control of LTA polymer length is important for S. aureus physiology and promotes survival under stressful conditions, including antibiotic stress. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of community- and hospital-acquired infections and is responsible for a large fraction of deaths caused by antibiotic-resistant bacteria. S. aureus is surrounded by a complex cell envelope that protects it from antimicrobial compounds and other stresses. Here, we show that controlling the length of an essential cell envelope polymer, lipoteichoic acid, is critical for controlling S. aureus cell size and cell envelope integrity. We also show that genes involved in LTA length regulation are required for resistance to beta-lactam antibiotics in MRSA. The proteins encoded by these genes may be targets for combination therapy with an appropriate beta-lactam.

scholarly journals Relationship among Several Key Cell Cycle Events in the Developmental Cyanobacterium Anabaena sp. Strain PCC 7120

2006 ◽  
Vol 188 (16) ◽  
pp. 5958-5965 ◽  
Author(s):  
Samer Sakr ◽  
Melilotus Thyssen ◽  
Michel Denis ◽  
Cheng-Cai Zhang
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Cell Division ◽  
Cell Growth ◽  
Cell Size ◽  
Dna Content ◽  
Small Cells ◽  
Filamentous Cyanobacterium ◽  
Pcc 7120 ◽  
Heterocyst Development

ABSTRACT When grown in the absence of a source of combined nitrogen, the filamentous cyanobacterium Anabaena sp. strain PCC 7120 develops, within 24 h, a differentiated cell type called a heterocyst that is specifically involved in the fixation of N2. Cell division is required for heterocyst development, suggesting that the cell cycle could control this developmental process. In this study, we investigated several key events of the cell cycle, such as cell growth, DNA synthesis, and cell division, and explored their relationships to heterocyst development. The results of analyses by flow cytometry indicated that the DNA content increased as the cell size expanded during cell growth. The DNA content of heterocysts corresponded to the subpopulation of vegetative cells that had a big cell size, presumably those at the late stages of cell growth. Consistent with these results, most proheterocysts exhibited two nucleoids, which were resolved into a single nucleoid in most mature heterocysts. The ring structure of FtsZ, a protein required for the initiation of bacterial cell division, was present predominantly in big cells and rarely in small cells. When cell division was inhibited and consequently cells became elongated, little change in DNA content was found by measurement using flow cytometry, suggesting that inhibition of cell division may block further synthesis of DNA. The overexpression of minC, which encodes an inhibitor of FtsZ polymerization, led to the inhibition of cell division, but cells expanded in spherical form to become giant cells; structures with several cells attached together in the form of a cloverleaf could be seen frequently. These results may indicate that the relative amounts of FtsZ and MinC affect not only cell division but also the placement of the cell division planes and the cell morphology. MinC overexpression blocked heterocyst differentiation, consistent with the requirement of cell division in the control of heterocyst development.

scholarly journals Applying single-cell capture technologies to studies of bacterial cell-size regulation

2020 ◽  
Vol 66 (3) ◽  
pp. 384-392
Author(s):  
Zhixin Ma ◽  
Fan Liang ◽  
Chenli Liu ◽  
Yufang Deng ◽  
Shuqiang Huang ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Size ◽  
Bacterial Cell ◽  
Cell Capture ◽  
Size Regulation

scholarly journals Downward regulation of cell size in Paramecium tetraurelia: effects of increased cell size, with or without increased DNA content, on the cell cycle

1982 ◽  
Vol 57 (1) ◽  
pp. 315-329
Author(s):  
C.D. Rasmussen ◽  
J.D. Berger
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Dna Synthesis ◽  
Cell Size ◽  
Dna Content ◽  
Cell Mass ◽  
Cycle Duration ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Rates Of Growth

Two temperature-sensitive cell-cycle mutants were used to generate abnormally large cells (size estimated by protein content) with either normal or increased DNA contents. The first mutant, cc1, blocks DNA synthesis, but allows cell growth at the restrictive temperature. The cells do not progress through the cell cycle while at the restrictive temperature, but do recover and complete the cell cycle when returned to permissive conditions. The progeny have increased cell size and normal DNA content. Downward regulation of cell size occurs during the ensuing cell cycle at permissive temperature. Two processes are involved. First, the G1 period is reduced or eliminated. As initial cell size increases there is a progressive shortening of the cell cycle to 75% of normal. This limit cell-cycle duration is reached when the initial mass of the cell is equal to or greater than that of normal cells at the time of DNA synthesis initiation (0.25 of a cell cycle). Cells with the limit cell cycle begin macronuclear DNA synthesis immediately after fission. The durations of the S period and fission are normal. Second, the rate of cell growth is unaffected by the increase in cell size, and results in the partitioning of excess cell mass between the daughter cells at the next fission. The second mutant, cc2, blocks cell division, but allows DNA synthesis to occur at a reduced rate so that cells with up to about 140% of the normal initial DNA content and twice the normal cell mass can be produced. The pattern of cell-cycle shortening is the same as in ccl. The rates of growth and both the rate and amount of DNA synthesis are proportional to the initial DNA content. This suggests that the rates of growth and DNA synthesis are limited by the transcriptional activity of the macronucleus in both cc1 and cc2 cells when they begin the cell cycle with experimentally increased cell mass. Increases in both cell size and initial DNA content are required to bring about increases in the rates of growth and DNA accumulation.

scholarly journals Candida glabrata Med3 Plays a Role in Altering Cell Size and Budding Index To Coordinate Cell Growth

2018 ◽  
Vol 84 (15) ◽  
Author(s):  
Hui Liu ◽  
Lulin Kong ◽  
Yanli Qi ◽  
Xiulai Chen ◽  
Liming Liu
Keyword(s):  
Cell Growth ◽  
Cell Size ◽  
Candida Glabrata ◽  
Mrna Level ◽  
Growth Defect ◽  
Mrna Levels ◽  
Acetyl Coa ◽  
Content Type ◽  
Quantitative Expression ◽  
Transcriptomics Data

ABSTRACT Candida glabrata is a promising microorganism for the production of organic acids. Here, we report deletion and quantitative-expression approaches to elucidate the role of C. glabrata Med3AB (CgMed3AB), a subunit of the mediator transcriptional coactivator, in regulating cell growth. Deletion of CgMed3AB caused an 8.6% decrease in final biomass based on growth curve plots and 10.5% lower cell viability. Based on transcriptomics data, the reason for this growth defect was attributable to changes in expression of genes involved in pyruvate and acetyl-coenzyme A (CoA)-related metabolism in a Cgmed3abΔ strain. Furthermore, the mRNA level of acetyl-CoA synthetase was downregulated after deleting Cgmed3ab, resulting in 22.8% and 21% lower activity of acetyl-CoA synthetase and cellular acetyl-CoA, respectively. Additionally, the mRNA level of CgCln3, whose expression depends on acetyl-CoA, was 34% lower in this strain. As a consequence, the cell size and budding index in the Cgmed3abΔ strain were both reduced. Conversely, overexpression of Cgmed3ab led to 16.8% more acetyl-CoA and 120% higher CgCln3 mRNA levels, as well as 19.1% larger cell size and a 13.3% higher budding index than in wild-type cells. Taken together, these results suggest that CgMed3AB regulates cell growth in C. glabrata by coordinating homeostasis between cellular acetyl-CoA and CgCln3. IMPORTANCE This study demonstrates that CgMed3AB can regulate cell growth in C. glabrata by coordinating the homeostasis of cellular acetyl-CoA metabolism and the cell cycle cyclin CgCln3. Specifically, we report that CgMed3AB regulates the cellular acetyl-CoA level, which induces the transcription of Cgcln3, finally resulting in alterations to the cell size and budding index. In conclusion, we report that CgMed3AB functions as a wheel responsible for driving cellular acetyl-CoA metabolism, indirectly inducing the transcription of Cgcln3 and coordinating cell growth. We propose that Mediator subunits may represent a vital regulatory target modulating cell growth in C. glabrata.

scholarly journals Osmolyte homeostasis controls single-cell growth rate and maximum cell size of Saccharomyces cerevisiae

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Tom Altenburg ◽  
Björn Goldenbogen ◽  
Jannis Uhlendorf ◽  
Edda Klipp
Keyword(s):  
Growth Rate ◽  
Cell Wall ◽  
Cell Growth ◽  
Single Cell ◽  
Cell Size ◽  
Single Cells ◽  
Turgor Pressure ◽  
Thermodynamic Quantities ◽  
Cell Growth Rate ◽  
Final Size

Abstract Cell growth is well described at the population level, but precisely how nutrient and water uptake and cell wall expansion drive the growth of single cells is poorly understood. Supported by measurements of single-cell growth trajectories and cell wall elasticity, we present a single-cell growth model for yeast. The model links the thermodynamic quantities, such as turgor pressure, osmolarity, cell wall elasto-plasticity, and cell size, applying concepts from rheology and thin shell theory. It reproduces cell size dynamics during single-cell growth, budding, and hyper-osmotic or hypo-osmotic stress. We find that single-cell growth rate and final size are primarily governed by osmolyte uptake and consumption, while bud expansion requires additionally different cell wall extensibilities between mother and bud. Based on first principles the model provides a more accurate description of size dynamics than previous attempts and its analytical simplification allows for easy combination with models for other cell processes.

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