Microalgal cell immobilization for the long-term storage of the marine diatom Haslea ostrearia

Abstract

To preserve the characteristics of the marine diatom Haslea ostrearia during long term storage, particularly size and shape, the algal cells were immobilized in alginate beads and stored at 4 • C at reduced irradiance up to 4 months. Two clones of different size (Ho34, 63 μm and Ho40, 78 μm) were studied. With Ho34, a 10.4% decrease of the size was shown after 120 days, by using the conventional storage management, while it did not exceed 2.2% with immobilized cells. Consequently, H. ostrearia would have auxosporulated after 9 months compared to 52 months. At the same time, the rate of distortion (aberrant valve structure) free Ho34 cells reached 86% while no distorted immobilized cells were observed. Chorophyll content in cells showed that all the cells were alive up to 60 days and after this time cells immobilized in the core of the beads most probably suffered from the poor light diffusion. Culturability of the immobilized cells was tested immediately after their immobilization and after 60 and 120 days of storage. The delay (at least 5 days) before immobilized cells released from the beads decreased with the time of storage, because of the embrittlement of the beads during the storage. Once in fresh medium, the cells actively multiplied. We concluded that immobilization strongly slowed down the decrease in frustule size with time and allowed the storage of concentrated and calibrated inocula which could be inoculated directly in liquid culture medium without needing to dissolve the beads.

Cold Storage of Six Marine Benthic Diatoms Native to the Mexico Pacific Coast

“…Various microalgal species have been preserved by several methods, such as drying, freeze-drying (Day and McLellan 1995), storage under oil, lyophilization (Kirsop and Doyle 1991), and storage at low and ultra-low temperatures (Lee and Soldo 1992;Day et al 1997). However, live storage maintains the viability for many microalgal species and is less expensive, easier to maintain, and does not require chemical additives (Romo and Pérez-Martínez 1997;Gaudin et al 2006).…”

“…A continuous supply of live microalgae could be maintained under storage conditions without cryoprotectants. The storage by refrigeration (temperature 4 C in darkness) of different species of live microalgae cells can provide a balance of key nutrients: proteins, carbohydrates, lipids, essential micronutrients, and antioxidants, saving time and reducing the total cost of production (Benemann 1992;Coutteau and Sorgeloos 1992;Gaudin et al 2006). The storage of live microalgae cultures can contribute to phycological research and industrial projects in aquaculture and biotechnology (Cañavate and Lubián 1995).…”

A novel algal biofilm membrane photobioreactor for attached microalgae growth and nutrients removal from secondary effluent

“…Regarding chlorophyll content, as Table 1 (Tamponnet et al, 1985;Gaudin et al, 2006). The present study shows that attached culture of microalgae also gives rise to higher chlorophyll content, relative to suspended culture.…”

Chlorococcum humicola (Nageli) Rabenhorst as a Renewable Source of Bioproducts and Biofuel

“…Long-term storage of algal stock in sodium alginate beads in pure culture form is useful for stock culture management (Gaudin, Lebeau, & Robert , 2006) as well as long term storage of the algal seeds (Faafeng, Donk, & Källqvist, 1994) for biomass production and production of secondary metabolites (Moreno-Garrido, 2008). Immobilized algae can also be used in wastewater treatment (Travieso et al, 1996) …”