Light spectrum modifies the utilization pattern of energy sources in Pseudomonas sp. DR 5-09

• Published in: PloS one Vol. 12; no. 12; p. e0189862
• Main Authors: Gharaie, Samareh, Vaas, Lea A I, Rosberg, Anna Karin, Windstam, Sofia T, Karlsson, Maria E, Bergstrand, Karl-Johan, Khalil, Sammar, Wohanka, Walter, Alsanius, Beatrix W
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.12.2017; Public Library of Science (PLoS)
• Subjects: Bacteria; Bioinformatics and Systems Biology; Bioinformatik och systembiologi; Biology and Life Sciences; Biomass; DNA damage; Energy consumption; Energy sources; Evolution; Flowers & plants; Growth; Habits; Horticulture; Humidity; In vitro methods and tests; Laser surgery; Leaves; Light; Light emitting diodes; Lighting; Medicine and Health Sciences; Microbiology; Microbiota; Microorganisms; Mikrobiologi; Monochromatic light; Optimization; Oxidative stress; Photosynthesis; Phototrophic bacteria; Phyllosphere; Physical Sciences; Physiological aspects; Plant Leaves - microbiology; Proteins; Pseudomonas; Pseudomonas - metabolism; Pseudomonas - radiation effects; Reproducibility; Signal transduction; Spectra; Substrates; Trädgårdsvetenskap/hortikultur; Utilization; Wavelengths; United States; Sweden; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0189862

Despite the overruling impact of light in the phyllosphere, little is known regarding the influence of light spectra on non-phototrophic bacteria colonizing the leaf surface. We developed an in vitro method to study phenotypic profile responses of bacterial pure cultures to different bands of the visible light spectrum using monochromatic (blue: 460 nm; red: 660 nm) and polychromatic (white: 350-990 nm) LEDs, by modification and optimization of a protocol for the Phenotype MicroArray™ technique (Biolog Inc., CA, USA). The new protocol revealed high reproducibility of substrate utilization under all conditions tested. Challenging the non-phototrophic bacterium Pseudomonas sp. DR 5-09 with white, blue, and red light demonstrated that all light treatments affected the respiratory profile differently, with blue LED having the most decisive impact on substrate utilization by impairing respiration of 140 substrates. The respiratory activity was decreased on 23 and 42 substrates under red and white LEDs, respectively, while utilization of one, 16, and 20 substrates increased in the presence of red, blue, and white LEDs, respectively. Interestingly, on four substrates contrasting utilization patterns were found when the bacterium was exposed to different light spectra. Although non-phototrophic bacteria do not rely directly on light as an energy source, Pseudomonas sp. DR 5-09 changed its respiratory activity on various substrates differently when exposed to different lights. Thus, ability to sense and distinguish between different wavelengths even within the visible light spectrum must exist, and leads to differential regulation of substrate usage. With these results, we hypothesize that different light spectra might be a hitherto neglected key stimulus for changes in microbial lifestyle and habits of substrate usage by non-phototrophic phyllospheric microbiota, and thus might essentially stratify leaf microbiota composition and diversity.