Effects of Bacteria on Artemia franciscana Cultured in Different Gnotobiotic Environments

Abstract

The use of probiotics is receiving considerable attention as an alternative approach to control microbiota in aquaculture farms, especially in hatching facilities. However, application with consistent results is hampered by insufficient information on their modes of action. To investigate whether dead bacteria (allowing investigation of their nutritional effect) or live bacteria (allowing evaluation of their probiotic effect) have any beneficial effect towards Artemia franciscana and, subsequently, if live bacteria have probiotic effects beyond the effects observed with dead bacteria, a model system was employed using gnotobiotic Artemia as a test organism. Nauplii were cultured in the presence of 10 bacterial strains combined with four different major axenic live feeds (two strains of Saccharomyces cerevisiae and two strains of Dunaliella tertiolecta) differing in their nutritional values. In combination with poor-and medium-quality live feeds, dead bacteria exerted a strong effect on Artemia survival but a rather weak or no effect on individual length and constituted a maximum of only 5.9% of the total ash-free dry weight supplied. These effects were reduced or even disappeared when mediumto good-quality major feed sources were used, possibly due to improvements in the health status of Artemia. Some probiotic bacteria, such as GR 8 (Cytophaga spp.), improved (not always significantly) the performance of nauplii beyond the effect observed with dead bacteria, independently of the feed supplied. The present approach can be an excellent system to study the exact mode of action of bacteria, especially if combined with challenge tests or other types of analysis (e.g., transcriptome and proteonomic analysis).

Endobiotic bacteria and their pathogenic potential in cnidarian tentacles

“…Unclear allocation of sequence data at species level led to the formation of groups # 1 to # 4. Some authors reported similar findings of different bacterial species (Ivanova et al 2003 for Shewanella species; Marques et al 2005;Venkateswaran et al 1998 for Vibrio species; Mc Aucliffe et al 2003 for Mycoplasma species). The application of larger 16S rDNA or 23S rDNA fragments might be more appropriate in future experiments.…”

Identification of Vibrio campbellii isolated from diseased farm-shrimps from south India and establishment of its pathogenic potential in an Artemia model

“…After identification of disease-associated strains, the next major task was to evaluate the virulence potential of each strain. Artemia is an excellent model to study the mode of action of probiotics and pathogenic bacteria under gnotobiotic conditions (Marques et al, 2005). Austin et al (2005) evaluated the pathogenic potential of several vibrios using rainbow trout and Artemia as test organisms.…”

“…After 48 h, the numbers of live Artemia nauplii in each tube were counted and the mean percentage mortality (M obs ) with standard deviation (SD) was calculated. Nauplii were not fed throughout the experimental period to keep the experimental set-up contamination free as described by Marques et al (2005). Generally Artemia can survive in a healthy condition for up to 72 h without feeding (OrozcoMedina et al, 2002).…”

Efficacy of heterologous and homologous heat shock protein 70s as protective agents to Artemia franciscana challenged with Vibrio campbellii

“…As the susceptibility of Artemia to pathogenic V. campbellii depends on the quality of feed fed [27], a test was performed by feeding induced and non-induced bacterial strains to Artemia in order to examine their nutritional value. Artemia nauplii fed with E. coli had significantly (P < 0.05) higher survival and length compared with the non-fed Artemia (Table 4).…”