scholarly journals Bacterial growth in multicellular aggregates leads to the emergence of complex lifecycles

2021 ◽  
Author(s):  
Julia A Schwartzman ◽  
Ali Ebrahimi ◽  
Grayson Chadwick ◽  
Yuya Sato ◽  
Victoria Orphan ◽  
...  
Keyword(s):  
Resource Limitation ◽  
Growth Conditions ◽  
Cell Physiology ◽  
Spatial Gradient ◽  
Phenotypic Differentiation ◽  
Carbon And Nitrogen ◽  
Type Iv ◽  
Metabolic Functions ◽  
Storage Granules

In response to environmental stresses such as starvation, many bacteria facultatively aggregate into multicellular structures that can attain new metabolic functions and behaviors. Despite the ubiquity and relevance of this form of collective behavior, we lack an understanding of how the spatiotemporal dynamics of aggregate development emerge from cellular physiology. Here, we show that the coupling between growth and spatial gradient formation leads to the emergence of a complex lifecycle, akin to those known for multicellular bacteria. Under otherwise carbon-limited growth conditions, the marine bacterium Vibrio splendidus 12B01 forms multicellular groups to collectively harvest carbon from the brown-algal polysaccharide alginate. This is achieved during growth on dissolved alginate polymer through formation of spherical, clonal clusters of cells that grow up to 40 μm in radius. Clusters develop striking spatial patterning as they grow due to phenotypic differentiation of sub-populations into a 'shell' of static cells surrounding a motile 'core'. Combining in situ measurements of cell physiology with transcriptomics, we show that shell cells express adhesive type IV pili, while motile core cells express carbon storage granules. The emergence of shell and core phenotypes is cued by opposing gradients of carbon and nitrogen that form within cell clusters due to local metabolic activity. Eventually, the shell ruptures, releasing the carbon-storing core, and we show that carbon-storing cells more readily propagate on alginate than non-carbon storing cells. We propose that phenotypic differentiation promotes the resilience of 12B01 groups by enabling clonal groups to grow larger and propagate more effectively. Phenotypic differentiation may be a widespread, but overlooked, strategy among bacteria to enhance resilience in the context of resource limitation.

Growth of Epitaxial IrSi3 Layers on Si(111)

1989 ◽  
Vol 160 ◽  
Author(s):  
T. L. Lin ◽  
C. W. Nieh
Keyword(s):  
Surface Morphology ◽  
Molecular Beam ◽  
Solid Phase ◽  
Single Mode ◽  
Growth Conditions ◽  
Tem Analysis ◽  
Mbe Growth ◽  
Good Surface ◽  
Transmission Electron

AbstractEpitaxial IrSi3 films have been grown on Si (111) by molecular beam epitaxy (MBE) at temperatures ranging from 630 to 800 °C and by solid phase epitaxy (SPE) at 500 °C. Good surface morphology was observed for IrSi3 layers grown by MBE at temperatures below 680 °C, and an increasing tendency to form islands is noted in samples grown at higher temperatures. Transmission electron microscopy (TEM) analysis reveals that the IrSi3 layers grow epitaxially on Si(111) with three epitaxial modes depending on the growth conditions. For IrSi3 layers grown by MBE at 630 °C, two epitaxial modes were observed with ~ 50% area coverage for each mode. Single mode epitaxial growth was achieved at a higher MBE growth temperature, but with island formation in the IrSi3 layer. A template technique was used with MBE to improve the IrSi3 surface morphology at higher growth temperatures. Furthermore, single-crystal IrSi3 was grown on Si(111) at 500 °C by SPE, with annealing performed in-situ in a TEM chamber.

Growth Conditions of a Thermophilic Geobacillus sp. as an Enhanced Oil Recovery Material

2012 ◽  
Vol 496 ◽  
pp. 457-460
Author(s):  
Xiang Ping Kong
Keyword(s):  
Enhanced Oil Recovery ◽  
Bacterial Growth ◽  
Oil Recovery ◽  
Nitrogen Sources ◽  
Growth Conditions ◽  
Good Growth ◽  
Strictly Aerobic ◽  
Aerobic Bacterium ◽  
Carbon And Nitrogen Sources ◽  
Carbon And Nitrogen

The growth conditions of a Geobacillus sp. were investigated by single-factor experiments. The strain was strictly aerobic bacterium, and could grow on hydrocarbons as the sole carbon source. The optimum carbon and nitrogen sources were 3.0% sucrose and 0.20% KNO3, respectively. The range of temperature, salinity and pH for the bacterial growth was 35-70 °C, 0-10% NaCl and 5.5-9.5, and good growth was obtained at 35-65 °C, 0.5-8% NaCl and 6.0-9.0, respectively. Particularly, the optimum temperature for the bacterial growth was between 50 °C and 60 °C. The strain had wide adaptability to the extreme conditions, and may be potentially applied to microbial enhanced oil recovery and oil-waste bioremediation technology.

Self-assembled quantum dots and nanoholes by molecular beam epitaxial growth and atomically precise in situ etching

2002 ◽  
Vol 722 ◽  
Author(s):  
S. Kiravittaya ◽  
R. Songmuang ◽  
O. G. Schmidt
Keyword(s):  
Quantum Dots ◽  
Molecular Beam ◽  
Flat Surface ◽  
Local Strain ◽  
Growth Conditions ◽  
Etching Depth ◽  
Molecular Beam Epitaxial ◽  
Self Assembled ◽  
Molecular Beam Epitaxial Growth

AbstractEnsembles of homogeneous self-assembled quantum dots (QDs) and nanoholes are fabricated using molecular beam epitaxy in combination with atomically precise in situ etching. Self-assembled InAs QDs with height fluctuations of ±5% were grown using a very low indium growth rate on GaAs (001) substrate. If these dots are capped with GaAs at low temperature, strong room temperature emission at 1.3 νm with a linewidth of 21 meV from the islands is observed. Subsequently, we fabricate homogeneous arrays of nanoholes by in situ etching the GaAs surface of the capped InAs QDs with AsBr3. The depths of the nanoholes can be tuned over a range of 1-6 nm depending on the nominal etching depth and the initial capping layer thickness. We appoint the formation of nanoholes to a pronounced selectivity of the AsBr3 to local strain fields. The holes can be filled with InAs again such that an atomically flat surface is recovered. QDs in the second layer preferentially form at those sites, where the holes were initially created. Growth conditions for the second InAs layer can be chosen in such a way that lateral QD molecules form on a flat surface.

scholarly journals First in situ estimations of small phytoplankton carbon and nitrogen uptake rates in the Kara, Laptev, and East Siberian seas

2018 ◽  
Author(s):  
Bhavya P. Sadanandan ◽  
Jang Han Lee ◽  
Ho Won Lee ◽  
Jae Joong Kaang ◽  
Jae Hyung Lee ◽  
...  
Keyword(s):  
Sea Ice ◽  
Nitrogen Uptake ◽  
N Uptake ◽  
Total Carbon ◽  
The Arctic ◽  
Carbon And Nitrogen ◽  
Uptake Rates ◽  
Wide Range ◽  
Small Phytoplankton

Abstract. Carbon and nitrogen uptake rates by small phytoplankton (0.7–5 μm) in the Kara, Laptev, and East Siberian seas in the Arctic Ocean were quantified using in situ isotope labelling experiments for the first time as part of the NABOS (Nansen and Amundsen Basins Observational System) program during August 21 to September 22, 2013. The depth integrated C, NO3−, and NH4+ uptake rates by small phytoplankton showed a wide range from 0.54 to 15.96 mg C m−2 h−1, 0.05 to 1.02 and 0.11 to 3.73 mg N m−2 h−1, respectively. The contributions of small phytoplankton towards the total C, NO3−, and NH4+ was varied from 24 to 89 %, 32 to 89 %, and 28 to 89 %, respectively. The turnover times for NO3− and NH4+ by small phytoplankton during the present study point towards the longer residence times (years) of the nutrients in the deeper waters, particularly for NO3−. Relatively, higher C and N uptake rates by small phytoplankton obtained during the present study at locations with less sea ice concentrations points towards the possibility of small phytoplankton thrive under sea ice retreat under warming conditions. The high contributions of small phytoplankton towards the total carbon and nitrogen uptake rates suggest capability of small size autotrophs to withstand in the adverse hydrographic conditions introduced by climate change.

In Situ Monitoring of the Smear-Out of the Ge Profile in GAS Source SiGe MBE Using Rheed Intensity Oscillations

1992 ◽  
Vol 263 ◽  
Author(s):  
K. Werner ◽  
S. Butzke ◽  
J.W. Maes ◽  
O.F.Z. Schannen ◽  
J. Trommel ◽  
...  
Keyword(s):  
Growth Rate ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Catalytic Effect ◽  
Growth Conditions ◽  
In Situ Monitoring ◽  
Marked Contrast ◽  
Si Substrates ◽  
Gas Source

ABSTRACTWe have studied the deposition of GexSi1−x layers on (100) Si substrates by gas source molecular beam epitaxy (GSMBE) using disilane and germane.The investigation of RHEED intensity oscillations during growth reveals the well known rate enhancement obtained when adding a small amount of germane to the disilane flux. However, when exposing a previously deposited Ge layer to a pure disilane flux the growth rate during the first few monolayers remains at an enhanced value but returns to its homoepitaxial value after about 10 to 15 monolayers. This behaviour was observed under a variety of growth conditions. It is in marked contrast to the experience obtained in conventional Si/Ge MBE and suggests a catalytic effect of the particular surface present during GSMBE growth. We propose that this effect is caused by the surface segregation of Ge species and leads to a smear-out of the Ge profile in the layer.

Integrin switching regulates normal trophoblast invasion

Development ◽  
1994 ◽  
Vol 120 (12) ◽  
pp. 3657-3666 ◽  
Author(s):  
C.H. Damsky ◽  
C. Librach ◽  
K.H. Lim ◽  
M.L. Fitzgerald ◽  
M.T. McMaster ◽  
...  
Keyword(s):  
First Trimester ◽  
Uterine Wall ◽  
Trophoblast Invasion ◽  
Collagen Type Iv ◽  
Fibronectin Receptor ◽  
Type Iv ◽  
Invasive Capacity ◽  
Functional Consequences

Cells invade extracellular matrices in a regulated manner at specific times and places during normal development. A dramatic example is trophoblast invasion of the uterine wall. Previous studies have shown that differentiation of trophoblasts to an invasive phenotype is accompanied by temporally and spatially regulated switching of their integrin repertoire. In the first trimester human placenta, alpha 6 integrins are restricted to cytotrophoblast (CTB) stem cells and downregulated in invasive CTBs, whereas alpha 5 beta 1 and alpha 1 beta 1 integrins are upregulated in differentiating and invasive CTBs. The goal of the present study was to determine whether these changes have functional consequences for CTB invasiveness. Using an in vitro invasion model, we determined first that aggregates of invading first trimester CTBs in vitro undergo the same pattern of integrin switching as was observed in situ, thereby validating the utility of the model. We then showed that antibody perturbation of interactions involving laminin or collagen type IV and their integrin alpha 1/beta 1 receptor inhibited invasion by CTBs, whereas perturbing interactions between fibronectin and the alpha 5/beta 1 fibronectin receptor accelerated invasion. Finally, we report that later gestation CTBs, which display greatly decreased invasive capacity, are also unable to upregulate alpha 1 beta 1 complexes, providing further evidence that this integrin is critical for CTB invasion. This gestational regulation is transcriptional. These data indicate that integrin switching observed during differentiation in situ has significant functional consequences for CTB invasion. The data suggest further that differentiating CTBs upregulate counterbalancing invasion-accelerating and invasion-restraining adhesion mechanisms. We propose that this contributes to regulating the depth of CTB invasion during normal implantation.

NMR methods for in-situ biofilm metabolism studies: spatial and temporal resolved measurements

2005 ◽  
Vol 52 (7) ◽  
pp. 7-12 ◽  
Author(s):  
P.D. Majors ◽  
J.S. McLean ◽  
J.K. Fredrickson ◽  
R.A. Wind
Keyword(s):  
Magnetic Resonance ◽  
Cell Metabolism ◽  
Shewanella Oneidensis ◽  
Growth Conditions ◽  
Magnetic Resonance Images ◽  
Ex Situ ◽  
Adherent Cell ◽  
Growth Environment ◽  
Environment Control

We are developing novel nuclear magnetic resonance (NMR) microscopy, spectroscopy and combined NMR/optical techniques for the study of biofilms under known, controlled growth conditions. Objectives include: time and depth-resolved metabolite concentrations with isotropic spatial resolution on the order of 10 microns, metabolic pathways and flux rates, mass transport and ultimately their correlation with gene expression by optical microscopy in biofilms. We describe the implementation of ex-situ grown biofilms to improve growth environment control and NMR analysis. In-situ NMR depth resolved metabolite profiling techniques are introduced and demonstrated for a Shewanella oneidensis strain MR-1 biofilm. Finally, initial combined confocal fluorescence and magnetic resonance images are shown for a GFP-labeled Shewanella biofilm. These methods are equally applicable to other biofilm systems of interest; thus they may provide a significant contribution toward the understanding of adherent cell metabolism.

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