Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes

ABSTRACT Environmental cues can stimulate a variety of single-cell responses, as well as collective behaviors that emerge within a bacterial community. These responses require signal integration and transduction, which can occur on a variety of time scales and often involve feedback between processe...

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Autores principales:	Rosanna Man Wah Chau, Devaki Bhaya, Kerwyn Casey Huang
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/dff6d05c634b447bb696f7457304ac77
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spelling	oai:doaj.org-article:dff6d05c634b447bb696f7457304ac772021-11-15T15:50:59ZEmergent Phototactic Responses of Cyanobacteria under Complex Light Regimes10.1128/mBio.02330-162150-7511https://doaj.org/article/dff6d05c634b447bb696f7457304ac772017-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02330-16https://doaj.org/toc/2150-7511ABSTRACT Environmental cues can stimulate a variety of single-cell responses, as well as collective behaviors that emerge within a bacterial community. These responses require signal integration and transduction, which can occur on a variety of time scales and often involve feedback between processes, for example, between growth and motility. Here, we investigate the dynamics of responses of the phototactic, unicellular cyanobacterium Synechocystis sp. PCC6803 to complex light inputs that simulate the natural environments that cells typically encounter. We quantified single-cell motility characteristics in response to light of different wavelengths and intensities. We found that red and green light primarily affected motility bias rather than speed, while blue light inhibited motility altogether. When light signals were simultaneously presented from different directions, cells exhibited phototaxis along the vector sum of the light directions, indicating that cells can sense and combine multiple signals into an integrated motility response. Under a combination of antagonistic light signal regimes (phototaxis-promoting green light and phototaxis-inhibiting blue light), the ensuing bias was continuously tuned by competition between the wavelengths, and the community response was dependent on both bias and cell growth. The phototactic dynamics upon a rapid light shift revealed a wavelength dependence on the time scales of photoreceptor activation/deactivation. Thus, Synechocystis cells achieve exquisite integration of light inputs at the cellular scale through continuous tuning of motility, and the pattern of collective behavior depends on single-cell motility and population growth. IMPORTANCE The photosynthetic cyanobacterium Synechocystis sp. exhibits phototaxis that is dependent on the incident light wavelength through the action of various photoreceptors. In natural environments, cells experience a set of highly dynamic and complex light inputs, yet how cells transduce multiple or dynamic inputs into motion is unknown. In this study, we measured the phototactic behaviors of single cells and communities as a function of light intensity or when illuminated by combinations of lights of different wavelengths or incidence directions. Responses to a spectrum of light regimes revealed that Synechocystis sp. integrates information about the light environment to tune its phototactic response, which is likely generated by competition among photoreceptors and the degree of wavelength-regulated growth to sensitively control the direction and degree of movement.Rosanna Man Wah ChauDevaki BhayaKerwyn Casey HuangAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 8, Iss 2 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Rosanna Man Wah Chau Devaki Bhaya Kerwyn Casey Huang Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
description	ABSTRACT Environmental cues can stimulate a variety of single-cell responses, as well as collective behaviors that emerge within a bacterial community. These responses require signal integration and transduction, which can occur on a variety of time scales and often involve feedback between processes, for example, between growth and motility. Here, we investigate the dynamics of responses of the phototactic, unicellular cyanobacterium Synechocystis sp. PCC6803 to complex light inputs that simulate the natural environments that cells typically encounter. We quantified single-cell motility characteristics in response to light of different wavelengths and intensities. We found that red and green light primarily affected motility bias rather than speed, while blue light inhibited motility altogether. When light signals were simultaneously presented from different directions, cells exhibited phototaxis along the vector sum of the light directions, indicating that cells can sense and combine multiple signals into an integrated motility response. Under a combination of antagonistic light signal regimes (phototaxis-promoting green light and phototaxis-inhibiting blue light), the ensuing bias was continuously tuned by competition between the wavelengths, and the community response was dependent on both bias and cell growth. The phototactic dynamics upon a rapid light shift revealed a wavelength dependence on the time scales of photoreceptor activation/deactivation. Thus, Synechocystis cells achieve exquisite integration of light inputs at the cellular scale through continuous tuning of motility, and the pattern of collective behavior depends on single-cell motility and population growth. IMPORTANCE The photosynthetic cyanobacterium Synechocystis sp. exhibits phototaxis that is dependent on the incident light wavelength through the action of various photoreceptors. In natural environments, cells experience a set of highly dynamic and complex light inputs, yet how cells transduce multiple or dynamic inputs into motion is unknown. In this study, we measured the phototactic behaviors of single cells and communities as a function of light intensity or when illuminated by combinations of lights of different wavelengths or incidence directions. Responses to a spectrum of light regimes revealed that Synechocystis sp. integrates information about the light environment to tune its phototactic response, which is likely generated by competition among photoreceptors and the degree of wavelength-regulated growth to sensitively control the direction and degree of movement.
format	article
author	Rosanna Man Wah Chau Devaki Bhaya Kerwyn Casey Huang
author_facet	Rosanna Man Wah Chau Devaki Bhaya Kerwyn Casey Huang
author_sort	Rosanna Man Wah Chau
title	Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
title_short	Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
title_full	Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
title_fullStr	Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
title_full_unstemmed	Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes
title_sort	emergent phototactic responses of cyanobacteria under complex light regimes
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/dff6d05c634b447bb696f7457304ac77
work_keys_str_mv	AT rosannamanwahchau emergentphototacticresponsesofcyanobacteriaundercomplexlightregimes AT devakibhaya emergentphototacticresponsesofcyanobacteriaundercomplexlightregimes AT kerwyncaseyhuang emergentphototacticresponsesofcyanobacteriaundercomplexlightregimes
_version_	1718427430678429696

Emergent Phototactic Responses of Cyanobacteria under Complex Light Regimes

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