Gas chromatography

Measuring of nitrogenase activity through hydrogen production by gas chromatography.

The method is used for nitrogenase activity investigation and hydrogen production by cells of different microorganisms (cyanobacteria, purple bacteria).

For nitrogenase activity measuring a cell suspension is used. The studied cell suspension is placed in a leakproof vessel with the gas phase. The volume of the gas phase is usually 80–95% of the vessel volume. The vessel could be thermostated at a optimum temperature, lightened, if necessary. The suspension is stirred to increase the contact of the gas and liquid phases. During the reaction, hydrogen stored in a liquid, than passes into the gas phase in accordance with the laws of equilibrium. Measuring makes at regular time intervals by sampling from the gas phase (usually 1–3% of the total), and the composition of the gas phase sample is analyzed by gas chromatography. Curve of kinetics changes of the hydrogen content in the gas phase is plots. Straight-line portion of the curve is the rate of hydrogen production. Depending on the aim, hydrogen production rate calculated per unit volume (for example, per ml of suspension), one active ingredient (of dry weight biomass, mg chlorophyll / bacteriochlorophyll, mg protein etc.) or on the illuminated surface unit per unit time.

At School for Young Scientists Nitrogenase activity of Rhodobacter sphaeroides strains cultures (wild type strain and mutant with reduced pigment content) will be measured through hydrogen production.

Contacts for any questions: Zinaida Eltsova. e-mail:
Scientist in Biotechnology and Physiology of Phototrophic organisms Lab