Axenic culture of Brachionus plicatilis using antibiotics

The rotifer Brachionus plicatilis culture is composed of complex microcosms including bacteria, protozoans, algae, and fungi. Previous studies reported methods to establish axenic rotifer cultures, but further refinement of these techniques is needed, for molecular biological research which requires pure culture to isolate nucleic acids from rotifers only. In order to render rotifer culture axenic, we tested five antibiotics: ampicillin (Amp), chloramphenicol (Cp), kanamycin (Km), nalidixic acid (Na), and streptomycin (Sm) at 30-100 μg/ml. Except for Cp, which reduces rotifer reproduction, all other antibiotics at the tested concentrations did not affect rotifer reproduction or show any toxic effects. A rotifer disinfection method was finally established by treating the resting eggs with 0.25% (w/v) sodium hypochlorite (NaOCl) for 3 min, washing with sterilized sea water, and then exposing the neonates to an Amp, Km, Na, and Sm mixture. Using four nutrient media, we confirmed that this protocol renders the rotifer culture bacterial and fungus free. The axenic rotifer culture generated here is useful not only for genetic analysis of Brachionus plicatilis, but for studying the rotifer life cycle without bacterial influence

Live feeds in aquaculture

Over the past two decades intensive larviculture of several fish and shellfish species has expanded into a multimillion dollar industry. Although much progress has been made in identifying the dietary requirements of the larvae of various aquaculture species, the mass culture of their early larval stages still requires the use of live feeds. Selected either through trial and error approaches or because of their convenience in mass production and use, hatcheries are relying today on three groups of live feed, i.e. various species of microscopic algae, the rotifer Brachionus and the anostracan brine shrimp Artemia .Various species of microalgae are used in feeding mollusc and shrimp larvae and/or in greenwater fish larviculture. As their mass production remains a complex and costly task, and because their dietary value is not always predictable, various types of supplementation and/or substitution products are used in combination with live algae.Selected strains of the rotifer Brachionus are mass-cultured in shrimp and fish hatcheries. The need for microalgae in rotifer culture can be greatly reduced as yeast-based products can be used as more cost-effective diets. The lipid and vitamin composition of Brachionus can be adjusted with selected enrichment products in order to better meet the dietary requirements of the fish larvae.Of all live foods used in fish and crustacean larviculture, the brine shrimp Artemia is the most widely used, not least because of the practical convenience of hatching this zooplankton substitute from commercially available dry cysts. With the fast expansion of shrimp and marine fish hatcheries all over the world, the consumption of Artemia cysts has recently climbed to over 2,000 mt annually. Selected strains are used as starter feeds, whereas nutritionally less-suitable varieties, such as the Great Salt Lake (Utah, USA) strain can be enriched with emulsified or microparticulate products so as to better meet the dietary requirements of the older larval stages of fish and shellfish. Artemia metanauplii can also be used as convenient carriers for oral delivery of chemotherapeutics, vaccines and hormones. Adult Artemia biomass harvested from solar saltworks is used as an excellent source of food in shrimp and fish nurseries

Use of ongrown <i>Artemia</i> in nursery culturing of the tiger shrimp

Juvenile and adult Artemia produced in a semi flow-through culture system were used as food for postlarval shrimp. The growth performance of shrimp reared on such ongrown Artemia live prey is identical to the growth obtained when feeding newly hatched Artemia . However, a significantly better stress resistance is obtained when the postlarvae are exposed to a low salinity in a stress test. Besides nutritional and energetic advantages, the use of Artemia biomass for feeding postlarval shrimp also results in improved economics as expenses for cysts and weaning diets can be reduced