Bacterial additives that consistently enhance rotifer growth under synxenic culture conditions 2. Use of single and multiple bacterial probiotics

Axenic rotifers were cultured under synxenic conditions on a bacteria-free artificial diet. The cultures were inoculated either with one of four strains of cultured marine bacteria, or with mixtures of bacteria made up with the same four strains and differing only in the proportions of cells from each strain within the blends. Control cultures were inoculated with bacteria present in Ž . freshly collected samples of seawater SW . The lowest rotifer growth rates were observed in these control cultures. The highest growth rates were determined in cultures inoculated with either Ž . an Alteromonas strain or a mixture of strains M2 composed of a larger proportion of the Alteromonas cells than any of the other microbial constituents. The largest variations in rotifer growth rate between replicate cultures were determined in cultures seeded with SW bacteria, while the lowest were determined in cultures inoculated with either Alteromonas or two blends including mixture M2. Similar results were obtained with both species of rotifers tested, Brachionus plicatilis Muller and B. rotundiformis Tschugunoff. q 2000 Elsevier Science B.V. All ̈ rights reserved.