Oral Presentation 18th International Congress on Photobiology 2024

Phototaxis and motility in natural and synthetic communities (#70)

Devaki Bhaya 1 , Freddy Bunbury 1 2 , Carlos Rivas 1 , Victoria Calatrava 1 , Arthur Grossman 1 , Andrey Malkovskiy 1 , Lydia-Marie Joubert 3 , Amar Parvate 4 , James Evans 4
  1. Carnegie Institution, Stanford University, Stanford, CALIFORNIA, United States
  2. University of Chicago, Chicago, IL, United States
  3. SLAC, Stanford University, Stanford, California, United States
  4. Environmental Molecular Sciences Laboratory,, Pacific Northwest National Laboratory, Richland, WA, United States

Phototrophic biofilm communities in most environments experience major changes in light levels throughout a diel cycle. We examined photo motility in two related cyanobacterial isolates (Synechococcus sp.) from thermal springs in Yellowstone National Park. Both isolates exhibited phototaxis and photokinesis but with differences in speed and motility bias and responses to specific wavelengths. The repertoire of photoreceptors and signal transduction elements in both isolates were examined.In conjunction with in situ observations, we suggest that phototactic strategies may be versatile and tuned to the light and local environment. In this context, we have attempted to model the collective behavior of cyanobacteria in unicellular cyanobacteria to predict phototaxis under different conditions. We also developed a binary consortium using Synechococcus OS-B’ (Syn OS-B) and the filamentous anoxygenic phototroph Chloroflexus MS-CIW-1 (Chfl MS-1).Chfl MS-1 formed bundles of filaments that moved in all directions with no directional bias to light while Syn OS- B’ exhibited positive phototaxis. This binary consortium displayed cooperative behavior: moving further than either species alone and formed ordered arrays where both species aligned with the light source. The binary consortium produced more adherent biofilm than individual species, consistent with the close interspecies association revealed by electron microscopy. Using new techniques of microscopy, microfluidics, mutants, metabolomics and transcriptomics coupled with our current analyses may give us a more predictive understanding of spatial organization and how phototrophic communities build stratified biofilms

  1. Bunbury F, Rivas C, Calatrava V, Shelton AN, Grossman A, Bhaya D. Differential Phototactic Behavior of Closely Related Cyanobacterial Isolates from Yellowstone Hot Spring Biofilms. Appl Environ Microbiol. 2022 May 24;88(10):e0019622. doi: 10.1128/aem.00196-22. Epub 2022 May 2. PMID: 35499327; PMCID: PMC9128501.
  2. Menon SN, Varuni P, Bunbury F, Bhaya D, Menon GI. Phototaxis in Cyanobacteria: From Mutants to Models of Collective Behavior. mBio. 2021 Dec 21;12(6):e0239821. doi: 10.1128/mBio.02398-21. Epub 2021 Nov 23. PMID: 34809455; PMCID: PMC8609350.
  3. Illuminating microbial mat assembly: Cyanobacteria and Chloroflexota cooperate to structure light-responsive biofilms Freddy Bunbury, Carlos Rivas, Victoria Calatrava, Andrey Malkovskiy, Lydia-Marie Joubert, Amar Parvate, James E Evans, Arthur R Grossman, Devaki Bhaya bioRxiv 2024.07.24.605005; doi: https://doi.org/10.1101/2024.07.24.605005