I went to the beach and brought back sand: a story of anoxygenic phototrophic bacteria. Lorena Rangel Microbial Diversity Course 2013 MBL

Introduction Anoxygenic phototrophic bacteria chlorophyll-based photosynthetic energy Overmann The Prokaryotes

Indole-3-acetic acid (IAA) – Plant hormone Signaling compound – Controls root growth, tropism, and plant senescence – Microorganism capable of interfering with IAA signals – Synthesis and Degradation of IAA by bacteria – At least five IAA biosynthetic pathways identified in bacteria – Example: Pseudomonas savastanoi produces IAA to induce tumor formation – Examples of bacterial response to IAA exposure Increased bacterial tolerance – IAA exposure to nonpathogenic E.coli upregulated genes involved in adaptation to unfavorable environments (Bianco et al Arch Microbiol 185, 373) Optimizing conditions for bacterial entry – IAA opens stomata, even in dark (Huang et al Plant Sci 156, 65) Introduction

Sippewissett Salt Marsh Diatoms Cyanobacteria Purple Sulfur Bacteria Green Sulfur Bacteria Purple NonSulfur Bacteria Overmann The Prokaryotes

PNSB GSB PSB All in 10ml Marine Phototrophic Base! Add 1mM Na succinate Illuminate at 850nm Add 5mM Na thiosulfate Add 1mM Na 2 S Illuminate at 850nm Add 3mM Na 2 S Illuminate at 750nm

SHAKE TUBESSHAKE TUBES

GSB PSBPNSB

Purple Sulfur Bacteria Green Sulfur Bacteria Class Gammaproteobacteria Order Chromatiales BChl a or b Internal sulfur granules Phylum Chlorobi BChl c, d, or e and BChl a External sulfur granules

Purple Non-Sulfur Bacteria Highest metabolic flexibility of all phototrophs BChl a or b Class Alphaproteobacteria or Betaproteobacteria

GSB PNSB PSB Chlorin Absorption maxima (nm) Whole Cells BChl a375, 590, 805, BChl b 400, 605, , BChl c , BChl d450, BChl e , BChl g375, 419, 575,

? Rhodovulum sp. JA545 Prosthecochloris aestuarii DSM 271

AcetatePropionate Citrate Hypothesis1: Under limited light conditions PNS bacteria will not grow at rates comparable to “natural” or full light exposure. Treatments 24L 16L:8D 0L Hypothesis2: PNS bacteria will grow at a greater rate when provided a less complex carbon source Treatments 10mM Citrate 10mM Acetate 10mM Propionate

Propionate + Tryp Propionate Acetate + Tryp Acetate Citrate + Tryp Citrate

Do PNSB make IAA? Hypothesis3: PNS bacteria have the ability to make indole-acetic acid. Rhodovulum sp. JA545 Rhodovulum sp. PH10: Indole-3-glycerol phosphate synthase Tryptophan synthase Ouyang et al The Plant Journal 24:

Salkowski Assay Measures specifically for IAA, indolepyruvic acid, and indoleacetamide TryptophanIAA

TryptophanIAA 5-Hydroxyindoleacetic acid Indole-3-acetaldehyde

Main Findings Conclusions Enriched for GSB (Prosthecochloris), PSB and PNSB (Rhodovulum) Propionate encourages faster growth rates of PNSB PNSB may produce low concentrations of indole-like compounds Conclusions Enriched for GSB (Prosthecochloris), PSB and PNSB (Rhodovulum) Propionate encourages faster growth rates of PNSB PNSB may produce low concentrations of indole-like compounds Main Findings Conclusions Enriched for GSB (Prosthecochloris), PSB and PNSB (Rhodovulum) Propionate encourages faster growth rates of PNSB PNSB may produce low concentrations of indole-like compounds Main Findings Conclusions Optimization of carbon sources for future PNSB enrichments First evidence of anoxygenic phototrophic bacteria producing indole Further work on the actual compound produced