Probiotic effect of Vibrio midae SY9, Cryptococcus sp. SS1 and Debaryomyces hansenii AY1 on the growth and disease resistance of farmed Haliotis midae
Master Thesis
2005
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University of Cape Town
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Abstract
Although the South African abalone, Haliotis midae, has been commercially harvested since 1949, successful cultivation of this species only began in the 1980s. Since then, the abalone mariculture industry has expanded dramatically and currently produces between 500 and 800 tons of abalone per year with a net farm gate value of approximately R125 million. However, disease has had a severe impact on the international aquaculture industry and is anticipated to become an increasingly important factor, together with the slow growth rate of H. midae, that will negatively impact on the further development and success of the local abalone mariculture industry. Thus, the future of H. midae mariculture in South Africa depends in part on the development of methods to enhance the growth rate and disease resistance of farmed H. midae. Erasmus et al. (1997) showed that abalone enteric bacteria enhanced digestive efficiency by secreting polysaccharolytic enzymes and it was suggested from these results that these bacterial enzymes could affect the growth rate of abalone. Furthermore, an overwhelming body of evidence has shown that probiotic microorganisms can significantly improve the growth rate and disease resistance of aquacultured animals. The aim of this study was to isolate enteric microorganisms from H. midae that are capable of hydrolyzing the various protein and starch substrates included in formulated abalone feeds. Upon identification, the selected microbes would be tested for their ability to colonize the digestive tract, improve digestion, growth and immunity of farmed H. midae.
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Macey, B. 2005. Probiotic effect of Vibrio midae SY9, Cryptococcus sp. SS1 and Debaryomyces hansenii AY1 on the growth and disease resistance of farmed Haliotis midae. University of Cape Town.