Membrane Inlet Mass Spectrometry: A Powerful Tool for Algal Research

Abstract

Since the first great oxygenation event, photosynthetic microorganisms have continuously shaped the Earth's atmosphere. Studying biological mechanisms involved in the interaction between microalgae and cyanobacteria with the Earth's atmosphere requires the monitoring of gas exchange. Membrane inlet mass spectrometry (MIMS) has been developed in the early 1960s to study gas exchange mechanisms of photosynthetic cells. It has since played an important role in investigating various cellular processes that involve gaseous compounds (O 2 , CO 2 , NO, or H 2) and in characterizing enzymatic activities in vitro or in vivo. With the development of affordable mass spectrometers, MIMS is gaining wide popularity and is now used by an increasing number of laboratories. However, it still requires an important theory and practical considerations to be used. Here, we provide a practical guide describing the current technical basis of a MIMS setup and the general principles of data processing. We further review how MIMS can be used to study various aspects of algal research and discuss how MIMS will be useful in addressing future scientific challenges.

Alternative electron pathways of photosynthesis drive the algal CO2 concentrating mechanism

“…Gas exchange rates were measured using a membrane inlet mass spectrometer 48 and combined NPQ measurements were done as previously described 49 and hyperbolic fit with variability (plain lines, dotted lines). For each replicate, net O2 production was measured following stepwise Ci addition, and normalized to the maximum…”

“…All strains were grown phototrophically under moderate light (80 µmol photons m -2 s -1 ) in minimal medium either under low CO 2 or high CO 2 . Gas exchange rates were measured using a membrane inlet mass spectrometer 48 and combined NPQ measurements were done as previously described 49 . All replicates shown are biological replicates from independent cultures.…”

Mechanism and dynamics of fatty acid photodecarboxylase

“…The column oven temperature was kept at 45°C. (m/z = 45) released by FAP were monitored as described in (41).…”

An analysis of the variability in <i>δ</i><sup>13</sup>C in macroalgae from the Gulf of California: indicative of carbon concentration mechanisms and isotope discrimination during carbon assimilation

“…The preferential DIC uptake of macroalgae is assessed by pH drift experiments (Fernández et al, 2014(Fernández et al, , 2015Hepburn et al, 2011;Narvarte et al, 2020;. Also, it can be determined by simultaneously measuring the CO 2 uptake and O 2 production rates using membrane-inlet mass spectroscopy (MIMS) (Burlacot et al, 2020;Douchi et al, 2019). Macroalgae that are unable to raise the seawater pH to > 9.0 are primarily CO 2 users, while those that can raise the seawater pH > 9.0 (absence of CO 2 ) are HCO − 3 users .…”

“…Also, the change in δ 13 C signature within the range specific to a carbon use strategy (e.g., mixed HCO 3 and CO − 2 user) can be com-plemented by simultaneous measurements of O 2 and CO 2 produced and consumed, respectively, using MIMS. For example, photosynthetic O 2 production in a certain macroalgal species with an active CCM preference (e.g., CO 2 ) is about 10 times higher than a non-active CCM (Burlacot et al, 2020).…”