title: Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain.
abstract: The cyanobacterium Microcystis aeruginosa is a mesophilic freshwater organism, which cannot tolerate sulphide. However, it was possible to isolate a sulphide-resistant (S(r)) mutant strain that was able to survive in a normally lethal medium sulphide. In order to evaluate the cost of the mutation conferring sulphide resistance in the S(r) strain of M. aeruginosa, the morphology and the photosynthetic performance were compared to that found in the wild-type, sulphide-sensitive (S(s)) strain. An increase in size and a disrupted morphology was observed in S(r) cells in comparison to the S(s) counterpart. Phycoerythrin and phycocyanin levels were higher in the S(r) than in the S(s) cells, whereas a higher carotenoid content, per unit volume, was found in the S(s) strain. The irradiance-saturated photosynthetic oxygen-production rate (GPR max) and the photosynthetic efficiency (measured both by oxygen production and fluorescence, α(GPR) and α(ETR)) were lower in the S(r) strain than in the wild-type. These results appear to be the result of package effect. On the other hand, the S(r) strain showed higher quantum yield of non-photochemical quenching, especially those regulated mechanisms (estimated throughout qN and Y(NPQ)) and a significantly lower slope in the maximum quantum yield of light-adapted samples (Fv'/Fm') compared to the S(s) strain. These findings point to a change in the regulation of the quenching of the transition states (qT) in the S(r) strain which may be generated by a change in the distribution of thylakoidal membranes, which somehow could protect metalloenzymes of the electron transport chain from the lethal effect of sulphide.
authors.affiliation: Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain. elbaes@uma.es.
authors.forename: Elena
authors.initials: E
authors.lastname: Bañares-España
authors.affiliation: Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain.
authors.forename: María
authors.initials: M
authors.lastname: del Mar Fernández-Arjona
authors.affiliation: Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: García-Sánchez
authors.affiliation: Departamento de Química Analítica, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernández-López
authors.affiliation: Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain.
authors.forename: Andreas
authors.initials: A
authors.lastname: Reul
authors.affiliation: Departamento de Productos Naturales, Biología Vegetal y Edafología, Facultad de Farmacia, Universidad de Barcelona, Av. Joan XXIII s/n, 08028, Barcelona, Spain.
authors.forename: Mariona Hernández
authors.initials: MH
authors.lastname: Mariné
authors.affiliation: Departamento de Biología Vegetal, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, E-29071, Málaga, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Flores-Moya
mesh_terms: D002338:Carotenoids / Q000032:analysis / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D005618:Fresh Water / Q000382:microbiology; D046931:Microcystis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010798:Phycocyanin / Q000032:analysis; D010799:Phycoerythrin / Q000032:analysis; D013030:Spain; D013440:Sulfides / Q000494:pharmacology*
chemical_list: D045332:Photosystem II Protein Complex; D013440:Sulfides; D010798:Phycocyanin; D010799:Phycoerythrin; D002734:Chlorophyll; D002338:Carotenoids; D010100:Oxygen
keywords: Cell morphology; Microcystis; Photosynthesis; Sulphide