Carvalho, A. P.

Malcata, F. Xavier

Monteiro, C.

English

Malcata, F. X.

Repositório Institucional da Universidade Católica Portuguesa

Combined influence of intensity of incident light and temperature in the biochemical profiles of Pavlova lutheri

Combined Influence of Incident Light and Temperature in the Biochemical Profiles of Pavlova lutherii  l   i  i    i   i i l il   l  l t iCarvalho, A. P., Monteiro, C. & Malcata, F.X.Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Rua Dr. António Bernardino de Almeida, 4200-072 Porto, PORTUGALEmail: ana@esb.ucp.ptarval o, . ., o teiro, .  alcata, . .scola erior e iotec ologia, iversi a e atólica ort g esa, a r. tó io er ar i o e l ei a, 4200-072 orto, ail: a a es . c . tIn terms of physical parameters, light and temperature are major factors that affect overall biomass productivities in algal systems. Consequently, it is of great interest to experimentally establish their independent and combined effects, aiming at the optimization of processes involving them. Although the study of each effect isolated has already been described in the literature, extrapolations from studies that hold irradiance constant while varying temperature, or hold temperature constant while varying irradiance may be misleading; there is indeed indication that some species may shift their acclimation strategies in response to the combination of said factors. The factsThe experimentAcknowledgmentsAuthor A. P. Carvalho acknowledges financial support by PRAXIS (ref. BD/2838/93-IF -Portugal).The simultaneous effects of light intensity and temperature were assessed on growth of themicroalga Pavlova lutheri, from Instituto Portuguêsde Investig. Marítima,Lisboa, Portugal.Culture flasks were incubated in aGallenkamp orbital incubator (Sanyo, UK), stirred at 100 rpm and submitted to the desired temperature and light regimes.The problemIn what way does incident light intensity and temperature simultaneously affect the biochemical profiles of the microalga?The experiments were planned according to a factorial design The culture media was ASW (Borowitzka, 1988).THE MEASUREMENTSSBiomassDeterminations of cell number were performed with a Neubauer Improved bright-line haemocytometer (Superior, Germany). Biochemical compoundsTotal proteins were assayed by the Lowry method (Lowry et al., 1951), after previous hydrolysis in 2 N NaOH for 15 min in an ultrasonicator, and a further 5 min at 100°C. Bovine serumalbumine was used as standard. Total carbohydrates were quantified as glucose, according to the phenol/sulphuric acid method (Dubois et al., 1956). Total lipids were determinedgravimetrically by the Bligh-Dyer method (Bligh & Dyer, 1959). The pigment contents were estimated after extraction with plain acetone saturated with magnesium hydroxide carbonate (Merck) at 4°C for 24 h, followed by spectrophotometrical measurements. The concentrations of pigments were calculated using the appropriate equations (Jeffrey and Humphrey, 1975). Intracellular content of carbon, nitrogen and sulphur was determined by elemental analysis (Fisons EA 1108). The resultsThe conclusionsResults obtained at the mid-exponential growth phase show consistent trends along all temperature-light intensity conditions tested for some biochemical parameters, e.g. concentration of carotenoids, whereas for others it is not possible to depict consistent results; this is the case of the amount of carbohydrates, which increases with light intensity for the experiments at a constant temperature of 18°C, although the reverse is observed for the experiments at a constant temperature of 22°C.1014182226 2035506580012345678Carbohydrate content (pg/cell)Temperature Light 1014182226 20355065800123456789Protein content (pg/cell)TemperatureLight 1014182226 20355065800123456789Lipid content (pg/cell)TemperatureLight 1014182226 203550658000.10.20.30.40.50.6Chlorophyll a (pg/cell)TemperatureLight1014182226 203550658000.020.040.060.080.10.120.140.160.180.2Carotenoid content (pg/cell)TemperatureLight 1014182226 20355065800123456789Carbon content (pg/cell)TemperatureLight 1014182226 203550658000.20.40.60.811.21.41.6Nitrogen content (pg/cell)TemperatureLight 1014182226 2035506580012345678Sulphur content (pg/cell)TemperatureLight

Combined influence of incident light and temperature in the biochemical profiles of Pavlova lutheri

https://repositorio.ucp.pt/bitstream/10400.14/5645/1/com-inter_2002_ESB_361002002_Monteiro_Cristina_01.pdf

Combined influence of incident light and temperature in the biochemical profiles of Pavlova lutheri

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Repositório Institucional da Universidade Católica Portuguesa

Repositório Institucional da Universidade Católica Portuguesa