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The effect of light on growth and agar content of Gelidium pulchellum (Gelidiaceae, Rhodophyta) in culture
Sousa-Pinto, I.; Murano, E.; Coelho, S.; Felga, A.; Pereira, R. (1999). The effect of light on growth and agar content of Gelidium pulchellum (Gelidiaceae, Rhodophyta) in culture. Hydrobiologia 399: 329-338
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117, more
Peer reviewed article  

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  • Sousa-Pinto, I., more
  • Murano, E.
  • Coelho, S.
  • Felga, A.
  • Pereira, R., more

    Investigation of light conditions suitable for cultivation of Gelidium pulchellum (Turner) Kurtz was performed under controlled laboratory conditions at 20 °C and in the range of irradiance of 10-430 µmol photons m-2 s-1. Growth, measured as fresh weight increment, increased with irradiance up to 130 µmol m-2 s-1 and no significant photoinhibition was observed up to 430 µmol m-2 s-1. Maximum growth rate (10.0% day-1) was obtained at 130-240 µmol m-2 s-1 under continuous light and aeration. The effect of irradiance on agar yield and quality was assessed. Agar yield varied from 31 to 38.6% of the algal dry weight, and variation was not related to irradiance. However, the yield of agar molecules soluble at 95 °C increased with increasing irradiance. A similar trend was found for sulphate content in both series of extracts, at 95 and 121 °C. On the contrary, the molecular weight and the degree of methylation of agar molecules in the 95 °C extracts decreased with increasing light intensity. As a consequence of the variations in sulphate content, molecular weight and molecular weight distribution, the gel strength was considerably lower at high light intensity. Starch content varied from 0.9 to 7.7% of the algal dry weight, and apparently was not related with irradiance.

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