Respiration Quotient Variability: Bacterial Evidence
Vol. 519: 47–59, 2015 MARINE ECOLOGY PROGRESS SERIES Published January 20 doi: 10.3354/meps11062 Mar Ecol Prog Ser Respiration quotient variability: bacterial evidence V. Romero-Kutzner1,*, T. T. Packard1, E. Berdalet2, S. O. Roy3, J.-P. Gagné4, M. Gómez1 1EOMAR, Grupo de Ecofisiología de Organismos Marinos, Universidad de Las Palmas de Gran Canaria 35017, Spain 2Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta, 37-49, 08003 Barcelona, Spain 310 Ryan Court, Embrun, Ontario K0A 1W0, Canada 4Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada ABSTRACT: Respiratory metabolism was compared between 2 different physiological states of acetate- and pyruvate-grown cultures of Pseudomonas nautica and Vibrio natriegens. Here, we analyze 35 h and 520 h experiments in which time-courses of protein, pyruvate, acetate, respira- tory CO2 production (RCO2), respiratory O2 consumption (RO2), isocitrate dehydrogenase (IDH) activity, and potential respiration (Φ) were measured. Respiratory quotients (RQs) were calculated as the ratio of the respiration rates (RCO2/RO2). Such RQs are widely used in ocean ecosystem mod- els, in calculations of carbon flux, and in evaluations of the ocean’s metabolic balance. In all the cultures, the RQ tended to increase. In the case of P. nautica on acetate, the RQ rose nearly an order of magnitude from values below 1 during carbon-substrate sufficiency to values close to 10 during carbon-substrate deficiency. In all the cultures, the respiration rates during the growth period paralleled the biomass increase, but after the substrates were exhausted, the respiration rates fell. In contrast, through this same transition period, the IDH activity and the Φ remained rel- atively high for the first 10 h of carbon-substrate deprivation, and then, these enzyme activities fell slowly, along with the biomass, as the carbon-substrate deprivation continued.
[Show full text]