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Title: Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation

Abstract

In this paper, we study the morphological transition of bacterial colonies exposed to ultraviolet radiation by modifying the bacteria model proposed by Delprato et al. Our model considers four factors: the lubricant fluid generated by bacterial colonies, a chemotaxis initiated by the ultraviolet radiation, the intensity of the ultraviolet radiation, and the bacteria's two-stage destruction rate with given radiation intensities. Using this modified model, we simulate the ringlike pattern formation of the bacterial colony exposed to uniform ultraviolet radiation. The following is shown. (1) Without the UV radiation the colony forms a disklike pattern and reaches a constant front velocity. (2) After the radiation is switched on, the bacterial population migrates to the edge of the colony and forms a ringlike pattern. As the intensity of the UV radiation is increased the ring forms faster and the outer velocity of the colony decreases. (3) For higher radiation intensities the total population decreases, while for lower intensities the total population increases initially at a small rate and then decreases. (4) After the UV radiation is switched off, the bacterial population grows both outward as well as into the inner region, and the colony's outer front velocity recovers to a constant value.more » All these results agree well with the experimental observations [Phys. Rev. Lett. 87, 158102 (2001)]. Along with the chemotaxis, we find that lubricant fluid and the two-stage destruction rate are critical to the dynamics of the growth of the bacterial colony when exposed to UV radiation, and these were not previously considered.« less

Authors:
; ; ; ; ;  [1]
  1. Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049 (China)
Publication Date:
OSTI Identifier:
20709834
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; Journal Volume: 72; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevE.72.051913; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRONMENTAL POLLUTANT EFFECTS ON LIVING ORGANISMS AND BIOLOGICAL MATERIALS; BACTERIA; BIOLOGICAL EFFECTS; FLUIDS; LUBRICANTS; POPULATIONS; ULTRAVIOLET RADIATION; VELOCITY

Citation Formats

Zhang Shengli, Zhang Lei, Liang Run, Zhang Erhu, Liu Yachao, and Zhao Shumin. Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation. United States: N. p., 2005. Web. doi:10.1103/PhysRevE.72.051913.
Zhang Shengli, Zhang Lei, Liang Run, Zhang Erhu, Liu Yachao, & Zhao Shumin. Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation. United States. doi:10.1103/PhysRevE.72.051913.
Zhang Shengli, Zhang Lei, Liang Run, Zhang Erhu, Liu Yachao, and Zhao Shumin. Tue . "Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation". United States. doi:10.1103/PhysRevE.72.051913.
@article{osti_20709834,
title = {Lubricating bacteria model for the growth of bacterial colonies exposed to ultraviolet radiation},
author = {Zhang Shengli and Zhang Lei and Liang Run and Zhang Erhu and Liu Yachao and Zhao Shumin},
abstractNote = {In this paper, we study the morphological transition of bacterial colonies exposed to ultraviolet radiation by modifying the bacteria model proposed by Delprato et al. Our model considers four factors: the lubricant fluid generated by bacterial colonies, a chemotaxis initiated by the ultraviolet radiation, the intensity of the ultraviolet radiation, and the bacteria's two-stage destruction rate with given radiation intensities. Using this modified model, we simulate the ringlike pattern formation of the bacterial colony exposed to uniform ultraviolet radiation. The following is shown. (1) Without the UV radiation the colony forms a disklike pattern and reaches a constant front velocity. (2) After the radiation is switched on, the bacterial population migrates to the edge of the colony and forms a ringlike pattern. As the intensity of the UV radiation is increased the ring forms faster and the outer velocity of the colony decreases. (3) For higher radiation intensities the total population decreases, while for lower intensities the total population increases initially at a small rate and then decreases. (4) After the UV radiation is switched off, the bacterial population grows both outward as well as into the inner region, and the colony's outer front velocity recovers to a constant value. All these results agree well with the experimental observations [Phys. Rev. Lett. 87, 158102 (2001)]. Along with the chemotaxis, we find that lubricant fluid and the two-stage destruction rate are critical to the dynamics of the growth of the bacterial colony when exposed to UV radiation, and these were not previously considered.},
doi = {10.1103/PhysRevE.72.051913},
journal = {Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics},
number = 5,
volume = 72,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}
  • We report a novel morphological transition in a Bacillus subtilis colony initially growing under ambient conditions, after ultraviolet radiation exposure. The bacteria in the central regions of the colonies are observed to migrate towards the colony edge forming a ring during uniform spatial exposure. When the radiation is switched off, the colonies were observed to grow both inward into the evacuated regions as well as outward indicating that the pattern is not formed due to depletion of nutrients at the center of the colony. We also propose a reaction-diffusion model in which waste-limited chemotaxis initiated by the UV radiation leadsmore » to the observed phenomenology.« less
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  • Springtime ozone depletion and the resultant increase in ultraviolet-B (UV-B) radiation [280-320 nanometers (nm)] have deleterious effects on primary productivity. To assess damage to cellular components other than the photosynthetic apparatus, we isolated total community DNA from samples in the field before, during, and after the 1993 springtime depletion in stratospheric ozone. The effort was motivated by the concern that the ozone-dependent increases in UV-B radiation may increase DNA damage within primary producers. This increase in damage could result in changes of species composition as well as hereditary changes within species that can influence the competitiveness of these organisms inmore » their natural community. Previous studies have focused on DNA damage in isolated cultures of antarctic phytoplankton that were irradiated with UV-B under lab conditions. These studies clearly indicate variable species sensitivities to the increase in UV-B flux. These studies, however, did not resolve the question of whether such damage occurred in field samples collected from actively mixing, polyphyletic phytoplankton communities. Potential species composition changes and the resultant changes in the trophic dynamics cannot be interpreted in terms of DNA damage unless this damage can be documented in samples isolated under these dynamic natural conditions. 7 refs., 2 figs.« less