Growth characteristics of Rhodopseudomonas palustris cultured outdoors, in an underwater tubular photobioreactor, and investigation on photosynthetic efficiency

Abstract

The underwater tubular photobioreactor is a fully controlled outdoor system to study photosynthetic bacteria. Before growing bacteria cells outdoors, two modified van Niel medium (vN-A, vN-B) were tested under artificial light. During exponential growth, the specific growth rates were 0.0416 and 0.0434 h(-1), respectively; vN-B was chosen for outdoor experiments. The growth behavior of Rhodopseudomonas palustris was investigated under a natural light-dark cycle (sunrise-sunset, 15L/9D) and a forced light-dark cycle (9:00-19:00, 10L/14D). Relationships between solar radiations, daily growth rates, and biomass output rates were also investigated. After determining the elemental biomass molar composition and its combustion heat, some trends of photosynthetic efficiency (PE) were obtained over daylight. The PE trends were always of the oscillatory type, with the exception of that achieved at low biomass concentration. Under a natural light/dark cycle, the maximum PE (11.2%) was attained at sunset, while under a forced light/dark cycle, the highest PE (8.5%) was achieved in the morning. Three initial biomass concentrations were investigated (0.65, 1.01, and 1.54 g l(-1)). The stoichiometric equation for bacteria cells indicated that 87.7% of the carbon of acetic acid was converted to biomass and only 12.3% was lost as CO(2).

Influence of Precursors and Inhibitor on the Production of Extracellular 5-Aminolevulinic Acid and Biomass byRhodopseudomonas palustrisKG31

“…21) Moreover, the bacteria are able to fix molecular nitrogen. 22) Accordingly, the influence of added succinate, glycine, and LA on the biomass yield was evaluated.…”

Green energy from Rhodopseudomonas palustris grown at low to high irradiance values, under fed-batch operational conditions

“…Growth was determined from the bacteriochlorophyll (Bchl) concentration (Carlozzi et al 2006). Cultures were irradiated with a 250 W OSRAM Power-star HQI-TS lamp, and the irradiance was measured using a Quantum/Radiometer/Photometer (model LI-185B, LI-COR, Lincoln, Nebraska, USA).…”

The technology of microalgal culturing

“…In tubular photobioreactors, the cultures are pumped through long, transparent tubes. The tubes are organised horizontally Carlozzi et al 2006), vertically (Carlozzi 2000;Converti et al 2006;, inclined (VunjakNovakovic et al 2005), or as a helix (Hai et al 2000;Travieso et al 2001;Scragg et al 2002;Fernandéz et al 2003;Hall et al 2003). Mechanical pumps or airlifts create the pumping force.…”