Patent ID: 7229785

Claim:
An in situ fluorescence method for external on-line monitoring of the physiological state a sulfur-deprived algal culture inside a closed photobioreactor system to ascertain the culture's production of H 2 under sulfur depletion, comprising: a) providing a sample of sulfur-deprived algal culture containing photosynthetic components; b) illuminating said sample with artificial or natural illumination; c) determining the onset of H 2 photoproduction by measuring the percentage of H 2 in a produced gas phase at multiple times to ascertain the point immediately after the anerobiosis subsequent to the physiological phases of O 2 production and O 2 consumption sequence to obtain data regarding H 2 production as a function of time; and d) determining any abrupt change in the following three in situ fluorescence parameters: i) an abrupt increase in F t (the steady-state level of chlorophyll fluorescence in light adapted cells); ii) an abrupt decrease in F m ′ (the maximal saturating light induced fluorescence level in light adapted cells); and' iii) a precipitous and abrupt decrease in ΔF/F m ′=(F m ′−F t )/F m ′ (the calculated photochemical activity of photosystem II (PSII)) that signals the full reduction of the plastoquinone pool between PSII and PSI, which indicates the start of anaerobic conditions that in turn induces the synthesis of the hydrogenase enzyme required for subsequent H 2 production, and thereafter slowing down of the abrupt decrease and partial recovery of ΔF/F m ′ signals at least partial oxidation of the plastoquinone pool as the main factor to regulate H 2 production under sulfur depletion.