CULTURE CONDITIONS INFLUENCE THE GROWTH DYNAMICS AND THE PRODUCTION OF COCCONEIS SCUTELLUM (BACILLARIOPHYTA)¹

Abstract

The optimal conditions for the growth of two conspecific benthic diatoms were defined through factorial experimentation. We investigated the roles of light spectrum, nutrient availability, and culture conditions on the laboratory production of Cocconeis scutellum scutellum Ehrenb. and C. scutellum parva Grunow. Diatoms were cultivated in petri dishes, and inverted optical microscopy was used to periodically record their abundance. Growth curves were constructed from these data for each culture condition. In addition, at the end of the experiment we performed weight measurements to determine the total production for each of the considered conditions. We found that cultivation in nonsealed (NS) petri dishes (permitting gas exchange) represented the most productive technique. Cell density and biomass varied among light spectra, although this effect was inconsistent. For example, the Sylvania Gro-Lux lamp (GL) produced the lowest cell density but highest biomass, suggesting that it may promote the production of larger cells. Surprisingly, of the culture media tested, f/2 (a media commonly used for the culture of diatoms) was the least productive. Diatom density and biomass were variably dependent on the combination of experimental culture conditions and strain used. These physical and chemical factors act mainly on given features of the diatom growth curve. These results permitted us to devise adequate culture protocols, to produce a biotechnologically important substance: a proapoptotic compound that specifically destroys the androgenic gland of a shrimp and could find novel applications in human medicine.

Light and temperature effects on bioactivity in diatoms

“…This study indicates that more bioactive compounds could potentially be gained from single isolates of diatoms by repeatedly cultivating the isolates with more than just one fixed set of cultivation conditions, and similar approaches has been applied in e.g. the studies by Zupo et al ( 2011 ) and Mouget et al ( 2005 ). Lastly, light and temperature are only two factors and many other factors could be adjusted to trigger cryptic bioactivity in diatoms and hopefully lead to discovery of novel bioactive compounds.…”

“…Variations in cultivation conditions may turn metabolic pathways on and off and thus trigger synthesis of chemicals. In a study by Zupo et al ( 2011 ) on the diatom Cocconeis scutellum , it was shown that optimal growth and production of a specific bioactive compound varied with cultivation conditions. A similar approach called OSMAC (One Strain Many Compounds) that involve systematically testing various fermentation conditions has proven successful when searching for bioactive compounds from bacteria (Bode et al 2002 ).…”

Bioactive Molecules from Marine Diatoms and Their Value for the Nutraceutical Industry

“…They are also among the primary sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) important in the marine food webs [ 21 ], both planktonic and benthic, and, usually, their growth rates are sufficiently high in culture conditions [ 22 , 23 ] according to the species. In addition, diatoms play an essential role in the biogeochemical cycles of carbon, nitrogen, phosphorus and silica [ 24 ] and are present in almost every type of water basin, including extreme environments [ 25 ].…”

Substratum‐Associated Microbiota

“…Activity of the land-based microbial cyanobacterial mat was low at 0° C but increased with higher temperatures, whereas activity of the green algal biofilm from seasonal ice was higher at 0° C than at the other temperatures. Zupo et al (2011) investigated the roles of light spectra, nutrient availability, and culture conditions on the laboratory production of two conspecific benthic diatoms (Cocconeis scutellum) to determine optimal conditions for growth. Orlova et al (2011)…”