Pure-culture and mixed community biofilm responses to carbon-starvation and UV-C exposure /

10.32920/ryerson.14655747 ◽

2021 ◽

Author(s):

C Alexia Lane

Keyword(s):

Pure Culture ◽

Carbon Dioxide Production ◽

Carbon Starvation ◽

Planktonic Cell ◽

Cellular Systems ◽

Cell Yield ◽

Protective Mechanisms ◽

Yield Responses ◽

Uv C ◽

Mixed Community

Biofilms are known to contribute to disease through inherent protective mechanisms and propagation strategies. These multi-cellular systems also play essential roles in numerous environmental processes. The current study investigated the responses of a mixed community biofilm to carbon-starvation, and measured the effects of UV-C on pure-culture biofilms at different stages of maturity by monitoring metabolic and cell yield responses. Carbon dioxide production and biofilm-derived planktonic cell yield were used at the measurement parameters. The mixed community rapidly responded to induced carbon-starvation under continuous flow conditions by remaining metabolically inactive throughout the 96 and 120 h starvation periods, only to promptly return to a metabolically active state upon the reintroduction of carbon. The effects of UV-C on pure-culture biofilms was negligible, with no log activation being achieved, and metabolic activity remaining static.

Download Full-text

Biofilm form and function: carbon availability affects biofilm architecture, metabolic activity and planktonic cell yield

Journal of Applied Microbiology ◽

10.1111/j.1365-2672.2010.04894.x ◽

2010 ◽

Vol 110 (2) ◽

pp. 387-398 ◽

Cited By ~ 22

Author(s):

E. Bester ◽

O. Kroukamp ◽

M. Hausner ◽

E.A. Edwards ◽

G.M. Wolfaardt

Keyword(s):

Metabolic Activity ◽

Planktonic Cell ◽

Cell Yield ◽

Carbon Availability ◽

Form And Function ◽

Biofilm Architecture ◽

And Function

Download Full-text

Efficiency of Plant UV Irradiation in the Protected Ground

Elektrotekhnologii i elektrooborudovanie v APK ◽

10.22314/2658-4859-2020-67-2-37-43 ◽

2020 ◽

Vol 67 (2) ◽

pp. 37-43

Author(s):

Aleksandr V. Sokolov

Keyword(s):

Plant Growth ◽

Ultraviolet Radiation ◽

Harmful Effect ◽

Research Purpose ◽

Protective Mechanisms ◽

Photosynthetic Organisms ◽

Nutritional Qualities ◽

Recovery Mechanisms ◽

High Doses ◽

Uv C

Plants are photosynthetic organisms that depend on sunlight for energy. Besides photosynthetically active radiation (PAR; 400-700 nm), plants are exposed to ultraviolet radiation, which consists of UV-C (below 280 nm), UV-B (280-320 nm) and UV-A (320-400 nm). Plants respond differently to exposure to low or high doses of ultraviolet light, either by stimulating protective mechanisms, or by activating recovery mechanisms to cope with various types of stress. (Research purpose) The research purpose is in providing an overview of the reactions of plants to ultraviolet radiation, make a relationship between the different ranges of ultraviolet radiation, radiation doses and the effect on plants. (Materials and methods) The article presents an analysis of domestic and foreign articles on the effectiveness of plant irradiation with ultraviolet radiation. (Results and discussion) Authors examined the effects of various ranges of ultraviolet radiation on plants. It was found that some properties of plants can be enhanced with small doses of UV-C, but UV-C strongly inhibits plant growth. Exposure to UV-B causes morphological and anatomical changes in plants: an increase in branching, a decrease in internodes, twisting of leaves, a decrease in leaf area, an accumulation of screening pigments, thickening of leaves, redistribution of chlorophyll. The effects of UV-B and UV-C also affect the volatiles emitted by aromatic plants. Ultraviolet-A can improve the nutritional qualities of green crops without adversely affecting plant growth. (Conclusions) It was found that ultraviolet radiation, depending on the range, has both a harmful effect on plants and a beneficial one. It was found that with certain doses of ultraviolet radiation, the necessary qualities and properties of plants could be obtained.

Download Full-text

Planktonic-Cell Yield of a Pseudomonad Biofilm

Applied and Environmental Microbiology ◽

10.1128/aem.71.12.7792-7798.2005 ◽

2005 ◽

Vol 71 (12) ◽

pp. 7792-7798 ◽

Cited By ~ 58

Author(s):

Elanna Bester ◽

Gideon Wolfaardt ◽

Lydia Joubert ◽

Kerstin Garny ◽

Sanja Saftic

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Growth Rates ◽

Specific Growth ◽

Planktonic Cell ◽

Cell Yield ◽

Differential Growth ◽

Flow Cells ◽

Cultivated Populations ◽

Limited Diffusion

ABSTRACT Biofilm cells differ phenotypically from their free-floating counterparts. Differential growth rates in biofilms are often referred to, particularly in response to limited diffusion of oxygen and nutrients. We observed growth rates of attached Pseudomonas sp. strain CT07 cells that were notably higher than the maximum specific growth rate measured in batch culture. Despite dilution rates in continuous flow cells that exceeded the maximum planktonic specific growth rate by 58 times, sampling of the effluent revealed >109 cells ml−1, suggesting that biofilms function as a source of planktonic cells through high cell yield and detachment. Further investigation demonstrated considerable planktonic cell yield from biofilms as young as 6 h, indicating that detachment is not limited to established biofilms. These biofilm-detached cells were more sensitive to a commercial biocide than associated biofilm- and chemostat-cultivated populations, implying that detached biofilm cells exhibit a character that is distinct from that of attached and planktonic cell populations.

Download Full-text

Label-free, mass-sensitive single-molecule imaging using interferometric scattering microscopy

Essays in Biochemistry ◽

10.1042/ebc20200023 ◽

2020 ◽

Author(s):

Nikolas Hundt

Keyword(s):

Single Molecule ◽

Cellular Systems ◽

Single Molecule Imaging ◽

Label Free ◽

Measurement Sensitivity ◽

Mass Distributions ◽

Quantitative Measurements ◽

Contrast Mechanism ◽

Cellular Components ◽

Scattering Signal

Abstract Single-molecule imaging has mostly been restricted to the use of fluorescence labelling as a contrast mechanism due to its superior ability to visualise molecules of interest on top of an overwhelming background of other molecules. Recently, interferometric scattering (iSCAT) microscopy has demonstrated the detection and imaging of single biomolecules based on light scattering without the need for fluorescent labels. Significant improvements in measurement sensitivity combined with a dependence of scattering signal on object size have led to the development of mass photometry, a technique that measures the mass of individual molecules and thereby determines mass distributions of biomolecule samples in solution. The experimental simplicity of mass photometry makes it a powerful tool to analyse biomolecular equilibria quantitatively with low sample consumption within minutes. When used for label-free imaging of reconstituted or cellular systems, the strict size-dependence of the iSCAT signal enables quantitative measurements of processes at size scales reaching from single-molecule observations during complex assembly up to mesoscopic dynamics of cellular components and extracellular protrusions. In this review, I would like to introduce the principles of this emerging imaging technology and discuss examples that show how mass-sensitive iSCAT can be used as a strong complement to other routine techniques in biochemistry.

Download Full-text