Degradation of chlorinated and non-chlorinated aromatic solvents in soil suspensions by pure bacterial cultures

Summary Experiments were performed to test whether or not high concentrations of CaCl₂ (100 mM) are able to arrest and stabilize internal structures and associated functions in Euglena gracilis Z cells stored in darkness at 4° C. Storage of photoheterotrophically grown green cells in high Ca²⁺ media (2–100 mM) retards pheophytinization of the chlorophylls, preserves photosynthetic activities and stabilizes the structural organization of the associated light-harvesting complexes of the photosystem II units. Alterations of photosynthesis and respiration by chlorpromazine or by temperature are strongly reduced in cells stored under such conditions. More precisely, a chlorpromazine inhibition site is evidenced in the mitochondrial electron pathway and its location in the chloroplastic electron pathway is clarified. Adaptation of Euglena cells from 2 mM to 100 mM Ca²⁺ medium is accompanied by an increase both in the externally bound and total internal calcium concentration. A mechanism involving a Ca²⁺ deposit on internal membranes is proposed. Such interpretation is extended to the storage of cells immobilized in Ca²⁺-alginate gel.Nomenclature (Ca²⁺)ex external calcium concentration - Chl chlorophylls - (Cl^–)ex external chloride concentration - CPZ chlorpromazine or 2-chloro-10-(3-dimethylaminopropyl)-phenothiazine - DCMU diuron or (3,4-dichorophenyl)-1,1-dimethylurea - EGTA ethylene glycol-bis(-aminoethylether) N,N,N ,N-tetraacetic acid - Fc initial level of chlorophyll fluorescence with DCMU - Fmax maximal level of chlorophyll fluorescence with DCMU - Fo level of chlorophyll fluorescence after transients - Ft level of chlorophyll fluorescence with DCMU - Pheo pheophytins - PS I and PS II photosystems I and II - SMi storage mediumOffprint requests to: C. Tamponnet