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ARTICLE IN PRESS
FOOD MICROBIOLOGY
Food Microbiology 23 (2006) 519–525 www.elsevier.com/locate/fm

The functional property of Bacillus for shrimp feeds
J. Leonel Ochoa-Solano, Jorge Olmos-SotoÃ
´n ´ ´n Molecular Microbiology Laboratory, Department of Marine Biotechnology, Centro de Investigacio Cientıfica y de Educacio Superior de Ensenada ´xico (CICESE), Ensenada, Baja California, MeReceived 13 May 2005; received in revised form 30 September 2005; accepted 10 October 2005 Available online 19 December 2005

Abstract In shrimp cultures, feed represents the most expensive production cost. The quantity and quality of diets are primary factors influencing shrimp growth, nitrogen loading of the culture system and disease proliferation. For these reasons there is an interest indeveloping ‘environmentally friendly’ feeds for optimal growth. In this study, Bacillus strains were isolated from marine environments. The isolates were qualitatively assayed for proteases, carbohydrolases and lipases using selective media. The selected strains (9b, 31 and 33) were molecularly identified as Bacillus subtilis, B. megaterium and B. megaterium, respectively. Subsequently the strains weregrown in an inexpensive culture medium (soybean mineral medium (MMS)). The information generated from the present investigation may contribute towards better feed formulations for shrimp at low cost, including bacterial strains as probiotics. r 2005 Elsevier Ltd. All rights reserved.
Keywords: Functional foods; Probiotics; Prebiotics; Enzymes; Digestibility

1. Introduction With the expansionof the commercial farming of Penaeid shrimp and the increased intensification of culture systems, there is a growing demand for well-balanced, nutritionally complete and cost-effective formulated feeds (Linan-Cabello et al., 2002; Bautista-Teruel et al., 2003). ˜ ´ For several years, there has been continuing interest in identifying alternatives to fishmeal for use within aqua feeds (Tacon et al.,1998; FAO, 2002; New and Wijkstrom, ¨ 2002). Originally, the impetus for this was the oftenvariable nature of price and supply of fishmeal. In addition, the concern also rose about the negative impact of fishmeal production on global fish stocks and on the environment (Naylor et al., 2000). Among the ingredients being investigated as alternatives to fishmeal, soybean products (Glycine max) have beensome of the most promising (Storebakken et al., 2000; Swick, 2002), because of the security of supply, price and composition (Cain and Garling, 1995). However, increasing the use of vegetable
ÃCorresponding author. Biotecnologı´ a Marina, P.O. Box 434844 San Diego, CA 92143-4844, USA. Fax: +1 11 52 646 175 05 69. E-mail address: jolmos@cicese.mx (J. Olmos-Soto).

ingredients may reduce thedigestibility of the diet and therefore decrease the food efficiency. For these reasons, it is going to be necessary to use additives to improve the digestibility of the new ingredients and to convert these diets to an effective alternative in shrimp cultures. Functional foods represent one of the most intensively investigated and widely promoted areas in the food and nutrition sciences today (Hasler,2002). A functional food must contain a component producing immune or physiological benefits beyond the traditional nutrients (Clydesdale, 1997). Probiotics are biologically active components that recently have received increasing attention (Hasler, 2002). Probiotic-supplemented functional food could contain single or mixed cultures of micro-organisms capable of improving the health of the host(Fuller, 1992). A probiotic is defined as a living microbial supplements that: (a) positively affects hosts by modifying the host-associated microbial community, (b) improves food degradation enhancing its nutritional value, and (c) improves the quality of the environmental parameters (Verschuere et al., 2000). The genus Bacillus constitutes a diverse group of rod-shaped, Gram-positive bacteria,...
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