LAUSR

The application of transparent plastic bags with a gas barrier layer as inexpensive photobioreactors for H 2 production by the cyanobacterium Anabaena sp. PCC 7120 ∆Hup mutant cells was explored outdoors in Moscow region for the first time. Two experiments were performed in July and August, the average daily temperature being 21.7 and 20.6 °C, the average daily light intensity being 290 and 340 µmol photon m −2  s −1 in experiment #1 and #2, respectively. The maximal H 2 production rate was 20.6 mL day −1  L −1 of culture, with accumulation of 33.2 mL L −1 during 5 days and a final H 2 content of 1.1% (v/v). Molecular nitrogen added to the Ar gas at 3.3% significantly affected neither the rate nor the duration of H 2 production. Low morning temperatures as well as high daytime light intensities (especially at low cell concentrations) seemed to reduce the H 2 production rate. The activities obtained were lower as compared to the previously reported data. It could be attributable to suboptimal weather conditions and simple device arrangement. However, results prove that H 2 production by cyanobacteria is still feasible outdoors in plastic bags, the cheapest photobioreactors.