caa a22 4500 477132642 CHVBK 20180405111708.0 cr unu---uuuuu 170330e19970601xx s 000 0 eng 10.1023/A:1018375005791 doi (NATIONALLICENCE)springer-10.1023/A:1018375005791 Tolerance to mercury chloride in Scenedesmus strains [Elektronische Daten] [Elena Capolino, Mario Tredici, Milva Pepi, Franco Baldi] Mercury chloride toxicity was investigated in two strains of Chlorella and in a strain of Scenedesmus isolated from polluted areas in Tuscany (Italy). No Hg resistance was found in the autotrophic microorganisms isolated, but Scenedesmus sp. strain AR-2489, isolated from the Arno river, was able to grow at concentrations of up to 5 mg ml1 of Hg. This concentration was twice that which inhibited growth of the two Chlorella strains and Scenedesmus acutus 8M, the reference strain from a culture collection. Photosynthesizing cells of Scenedesmus sp. AR-2489 showed reduced Hg uptake, with the highest percentage of Hg removal from the medium. Loss of Hg was not due to Hg(0) volatilization, as shown by a comparison test with the broad-spectrum Hg-resistant Pseudomonas putida FB1. The metabolic differences between Scenedesmus sp. strain AR-2489 and Siacatus strain 8M were: (1) higher growth rate (doubling time of 6.0h versus 10.6 h); (2) higher O2 production rate (maximum 2 mmol h mg dry weight); and (3) higher intracellular pH during growth. The latter was imaged with a green fluorescence molecular probe (BCEFC-AM) and observed by scanning confocal laser microscopy (SCLM). The distribution of red-autofluorescence chlorophyll-a showed that strain AR-2489 had a rougher and hence more extended specific chloroplast surface than strain 8M. Hg tolerance in strain AR-2489 was related to the rapid increase in dissolved O in the medium and in intracellular pH; this caused a loss of soluble mercury transformed to insoluble mercury hydroxide, which is thermodynamically more stable at alkaline pH in highly oxygenated systems. Chapman and Hall, 1997 inorganic mercury nationallicence microalgae nationallicence pH molecular probe nationallicence photosynthesis rates nationallicence scanning confocal laser microscopy nationallicence Capolino Elena Centro di Studio dei Microrganismi Autotrofi, CNR Firenze, Italy aut Tredici Mario Centro di Studio dei Microrganismi Autotrofi, CNR Firenze, Italy aut Pepi Milva Dipartimento di Biologia Ambientale, Universita di Siena, Siena, Italy aut Baldi Franco Dipartimento di Biologia Ambientale, Universita di Siena, Siena, Italy aut Biometals Kluwer Academic Publishers 10/2(1997-06-01), 85-94 0966-0844 10:2<85 1997 10 10534 https://doi.org/10.1023/A:1018375005791 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1018375005791 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Capolino Elena Centro di Studio dei Microrganismi Autotrofi, CNR Firenze, Italy aut NATIONALLICENCE 700 1- Tredici Mario Centro di Studio dei Microrganismi Autotrofi, CNR Firenze, Italy aut NATIONALLICENCE 700 1- Pepi Milva Dipartimento di Biologia Ambientale, Universita di Siena, Siena, Italy aut NATIONALLICENCE 700 1- Baldi Franco Dipartimento di Biologia Ambientale, Universita di Siena, Siena, Italy aut NATIONALLICENCE 773 0- Biometals Kluwer Academic Publishers 10/2(1997-06-01), 85-94 0966-0844 10:2<85 1997 10 10534 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer