Vine Niall G, Leukes Winston D, Kaiser Horst
Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa.
FEMS Microbiol Lett. 2004 Feb 9;231(1):145-52. doi: 10.1016/S0378-1097(03)00954-6.
The selection of probiotics for aquaculture is usually based on their antagonism towards pathogens. However, other criteria such as growth, attachment to intestinal mucus and production of beneficial compounds should also be considered. We suggest a protocol for the isolation and selection of potential probiotic bacteria based on their in vitro growth characteristics and propose a ranking index (RI) to screen potential aquaculture probionts. We suggest that the lag period and doubling time are the most important criteria for the comparison of growth curves, hence the RI is based on the doubling time (t(d)) and lag period (lambda) obtained from the growth profile of each bacterium. Bacteria were isolated from the gut of the common clownfish, Amphiprion percula, and screened for antagonistic activity towards seven aquatic pathogens. All five candidate probiotics showed antagonism to various aquatic pathogens. When grown in intestinal fish mucus no probiotic had a RI higher than the two tested pathogens (Aeromonas hydrophila and Vibrio alginolyticus). However, candidate probiont AP1 had a faster specific growth rate (micro) (0.05) than the pathogens (0.049 and 0.047 respectively), while AP5 grown in marine broth had a shorter lag period than the pathogens. Strategies to increase probiotic concentration include the inoculation of high concentrations and the preconditioning of these bacteria to reduce the lag period. It should be tested whether or not such strategies will allow the probiotic bacteria to dominate initially and thereby gain a competitive advantage. This could become an important aspect under in vivo conditions where both attachment and nutrient supply differ from that found in in vitro studies.
水产养殖中益生菌的选择通常基于它们对病原体的拮抗作用。然而，其他标准，如生长、对肠道黏液的附着以及有益化合物的产生，也应予以考虑。我们基于潜在益生菌的体外生长特性，提出了一种分离和选择它们的方案，并提出了一个排名指数（RI）来筛选潜在的水产养殖益生菌。我们认为延迟期和倍增时间是比较生长曲线的最重要标准，因此RI基于从每种细菌的生长曲线中获得的倍增时间（t(d)）和延迟期（λ）。从普通小丑鱼（眼斑双锯鱼）的肠道中分离出细菌，并筛选它们对七种水产病原体的拮抗活性。所有五种候选益生菌均对多种水产病原体表现出拮抗作用。在鱼肠道黏液中生长时，没有一种益生菌的RI高于两种受试病原体（嗜水气单胞菌和解淀粉芽孢杆菌）。然而，候选益生菌AP1的比生长速率（μ）（0.05）比病原体（分别为0.049和0.047）更快，而在海洋肉汤中生长的AP5的延迟期比病原体短。提高益生菌浓度的策略包括接种高浓度菌以及对这些细菌进行预处理以缩短延迟期。应该测试这些策略是否能使益生菌最初占据主导地位，从而获得竞争优势。在体内条件下，附着和营养供应与体外研究不同，这可能会成为一个重要方面。
