J. BIOSCI. BIOENG., Abstracts of the Articles Printed in Seibutsu-kogaku Kaishi Vol. 80, Nos. 5 & 6 (2002) Ultra-High-Density Culture of the Rotifer Brachionous rotundiformis Using a Membrane Filtration Unit and Its Effect on Bac- terial Abundance in the Rotifer Body. KENJI TANAKA,‘* NORIHIRO TAKEDA,’ YUJI MINAMI,’ MASAKI KURAMOTO,’ KENJI YOSHIMURA,~ and TAKAO YOSHIMATSU~ (Depart- ment of Biological and Environmental Chemistq Kyushu School of Engineering, Kinki Universiv, Iizuka, Fukuoka 82045.55, ’Fukuoka Mariculture Corp., Genkai, Munakata, Fukuoka 811-3~712,~ and Labo- ratoory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu Uni- versity, Hakozaki, Fukuoka 812~85813) Seibutsu-kogaku 80: 181-187. 2002. We have developed a novel culture system designed for ultra- high-density production of the so-called S-type marine rotifer (Bra- chionus rotundiformis), which has become an indispensable initial food item for larval cultures of marine fishes and crustaceans. In our culture system, a membrane-type micro-filtration unit (pore size was 0.4 pm) was incorporated in a culture tank (40 r) to prevent accumula- tion of NH,‘, which is a strong inhibitor of rotifer growth. In rotifer batch culture tests with and without the culture system, freshwater Chlorella paste (Chlorella regularis; packed vol., 600 ml/l) was fed continuously into the culture water using a peristaltic tube pump at feed rates from 3.8-8.0 l/tank/d. Oxygen gas (purity, 90%) was fed at a rate of 0.2 vvm. In the batch culture system with the filtration unit, the culture broth was filtered out through the unit and fresh seawater was supplied to maintain the culture volume in the tank. In batch culture without filtration, the rotifer density reached 40,000 rotifers/ml after 2 d. However, the rotifer density subsequently seriously decreased due to an increase in the NH,’ concentration up to 900 ppm. In contrast, in the culture with filtration the NH,+ concentration remained below 240 ppm after 4d, and as a result the rotifer density reached 160,000 ind./ml. The population of Vibrio sp. in the rotifer body diminished from 1O9 to 1O3 CFU/g-rotifer as a consequence of using the filtration unit. A Bacteriocin Produced by Pediococcws sp. NPIB-38 Isolated from Rice Koji. -Note- MITSUOIU KANEOKE,* KEN-ICHI WATANABE, TOSHIO AOKI, YOSHIHITO NABEKURA, KEIGO SATO, and MOTOTSUGU TSWIOKA (Niigata Prefectural Institute of Brewing, Suido-cho 2, Niigata 951- 8121) Seibutsu-kogaku 80: 223-226. 2002. Pediococcus sp. NPIB-38, isolated from a rice koji, produced an antibacterial substance active against selected strains of LactobaciNus spp. The substance was partially purified and then tested for its sta- bility to heating, organic solvents, various pH values, and proteolytic enzymes. The substance was bactericidal against sensitive indicators, and sensitive to proteolytic enzymes; it was indentified as a bacterio- tin. The bacteriocin was stable from pH 2.0-10.0 and the antimicro- bial activity remained even after autoclaving at 12 1‘C for 10 min. * Corresponding author. * Corresponding author. 622

Ultra-high-density culture of the rotifer Brachionous rotundiformis using a membrane filtration unit and its effect on bacterial abundance in the rotifer body

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Page 1: Ultra-high-density culture of the rotifer Brachionous rotundiformis using a membrane filtration unit and its effect on bacterial abundance in the rotifer body

J. BIOSCI. BIOENG.,

Abstracts of the Articles Printed in Seibutsu-kogaku Kaishi

Vol. 80, Nos. 5 & 6 (2002)

Ultra-High-Density Culture of the Rotifer Brachionous rotundiformis Using a Membrane Filtration Unit and Its Effect on Bac- terial Abundance in the Rotifer Body. KENJI TANAKA,‘* NORIHIRO TAKEDA,’ YUJI MINAMI,’ MASAKI KURAMOTO,’ KENJI YOSHIMURA,~ and TAKAO YOSHIMATSU~ (Depart- ment of Biological and Environmental Chemistq Kyushu School of Engineering, Kinki Universiv, Iizuka, Fukuoka 82045.55, ’ Fukuoka Mariculture Corp., Genkai, Munakata, Fukuoka 811-3~712,~ and Labo- ratoory of Advanced Animal and Marine Bioresources, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu Uni- versity, Hakozaki, Fukuoka 812~85813) Seibutsu-kogaku 80: 181-187. 2002.

We have developed a novel culture system designed for ultra- high-density production of the so-called S-type marine rotifer (Bra- chionus rotundiformis), which has become an indispensable initial food item for larval cultures of marine fishes and crustaceans. In our culture system, a membrane-type micro-filtration unit (pore size was 0.4 pm) was incorporated in a culture tank (40 r) to prevent accumula- tion of NH,‘, which is a strong inhibitor of rotifer growth. In rotifer batch culture tests with and without the culture system, freshwater Chlorella paste (Chlorella regularis; packed vol., 600 ml/l) was fed continuously into the culture water using a peristaltic tube pump at feed rates from 3.8-8.0 l/tank/d. Oxygen gas (purity, 90%) was fed at a rate of 0.2 vvm. In the batch culture system with the filtration unit, the culture broth was filtered out through the unit and fresh seawater was supplied to maintain the culture volume in the tank. In batch culture without filtration, the rotifer density reached 40,000 rotifers/ml after 2 d. However, the rotifer density subsequently seriously decreased due to an increase in the NH,’ concentration up to 900 ppm. In contrast, in the culture with filtration the NH,+ concentration remained below 240 ppm after 4d, and as a result the rotifer density reached 160,000 ind./ml. The population of Vibrio sp. in the rotifer body diminished from 1 O9 to 1 O3 CFU/g-rotifer as a consequence of using the filtration unit.

A Bacteriocin Produced by Pediococcws sp. NPIB-38 Isolated from Rice Koji. -Note- MITSUOIU KANEOKE,* KEN-ICHI WATANABE, TOSHIO AOKI, YOSHIHITO NABEKURA, KEIGO SATO, and MOTOTSUGU TSWIOKA (Niigata Prefectural Institute of Brewing, Suido-cho 2, Niigata 951- 8121) Seibutsu-kogaku 80: 223-226. 2002.

Pediococcus sp. NPIB-38, isolated from a rice koji, produced an antibacterial substance active against selected strains of LactobaciNus spp. The substance was partially purified and then tested for its sta- bility to heating, organic solvents, various pH values, and proteolytic enzymes. The substance was bactericidal against sensitive indicators, and sensitive to proteolytic enzymes; it was indentified as a bacterio- tin. The bacteriocin was stable from pH 2.0-10.0 and the antimicro- bial activity remained even after autoclaving at 12 1 ‘C for 10 min.

* Corresponding author.

622