https://www.selleckchem.com/products/17-AAG(Geldanamycin).html Genome and proteome data predict the presence of both the reductive citric acid cycle (rCAC; also called the reductive tricarboxylic acid cycle) and the Calvin-Benson-Bassham cycle (CBB) in "Candidatus Endoriftia persephonae," the autotrophic sulfur-oxidizing bacterial endosymbiont from the giant hydrothermal vent tubeworm Riftia pachyptila. We tested whether these cycles were differentially induced by sulfide supply, since the synthesis of biosynthetic intermediates by the rCAC is less energetically expensive than that by the CBB. R. pachyptila was incubated under in situ conditions in high-pressure aquaria under low (28 to 40 μmol · h-1) or high (180 to 276 μmol · h-1) rates of sulfide supply. Symbiont-bearing trophosome samples excised from R. pachyptila maintained under the two conditions were capable of similar rates of CO2 fixation. Activities of the rCAC enzyme ATP-dependent citrate lyase (ACL) and the CBB enzyme 1,3-bisphosphate carboxylase/oxygenase (RubisCO) did not differ between the two conditionsAC and the CBB. This observation highlights the importance of further study of this symbiosis and other organisms with multiple CO2-fixing pathways, which recent genomics and biochemical studies suggest are likely to be more prevalent than anticipated.A diverse genetic toolkit is critical for understanding bacterial physiology and genotype-phenotype relationships. Inducible promoter systems are an integral part of this toolkit. In Burkholderia and related species, the L-rhamnose-inducible promoter is among the first choices due to its tight control and the lack of viable alternatives. To improve upon its maximum activity and dynamic range, we explored the effect of promoter system modifications in B. cenocepacia with a LacZ-based reporter. By combining the bacteriophage T7 gene 10 stem loop and engineered rhaI transcription factor-binding sites, we obtained a rhamnose-inducible system with a 6.5-fold