>Fermentative preparation of single cell detritus from seaweed, Undaria pinnatifida, suitable as a replacement hatchery diet for unicellular algae

Fermentative preparation of single cell detritus from seaweed, Undaria pinnatifida, suitable as a replacement hatchery diet for unicellular algae

M. Uchida, M. Murata-2002

Aquaculture, 207(3-4): 345-357
Abstract:

Single cell detritus (SCD) is a product ca. 5.8-11.5 ľm in diameter prepared by decomposing seaweed to a cellular level, and is expected to be utilized as a fisheries-diet in place of unicellular algae. The present paper details the culture conditions for the effective preparation of SCD from Undaria pinnatifida based on a fermentative method. The suitable NaCl concentration of the culture water for SCD-preparation was in the range of 2.5-3.5% (w/v) judged from the convenience for culture-treatment and the stability of the SCD-products. The temperature during culture did not make a marked difference on the productivity of the SCD in the range of 5-50 °C. As for the cellulase concentration, the addition of more than 1% was necessary to avoid rotting and to obtain a fermented culture. However, the addition of a microbial mixture composed of a lactic acid bacterium and two species of yeast at the start was effective to obtain a successfully fermented culture at a lower cellulase concentration of 0.25%. Under optimum conditions of culture containing 5% Undaria (on dry basis), 3.5% NaCl, 0.5% cellulase with an addition of the microbial mixture, SCD was produced at 5.8×10⁷ cells/ml after 6 days of incubation at 20 °C. The presently developed method needs no facilities for temperature conditioning, lightening, and air supplying, but needs only a plastic tank for obtaining the SCD. Here, we suggest a novel fisheries-diet of "marine silage", which is produced from the combination of two principles, conversion of seaweed to SCD and induction of lactic acid fermentation utilizing activities of a microbial mixture composed of a lactic acid bacterium and yeast.

(National Research Institute of Fisheries Science, 2-12-4, Fukuura, Kanazawa, Yokohama 236, Japan, Tel.: +81-45-788-7661; fax: +81-45-788-5001, e-mail: uchida@affrc.go.jp)

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