In vitro growth characteristics of five candidate aquaculture probiotics and two fish pathogens grown in fish intestinal mucus

Abstract

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 (V) 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 (W) (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.

In vitro selection of bacteria with potential for use as probiotics in marine shrimp culture

“…The faster growth rate found for strain L. plantarum 2 indicates it has superior performance compared to the others (Table 2). Faster growth rate and lower doubling time of bacteria make commercial production processes more efficient and may result in greater competitiveness in vivo of the strain (Vine et al, 2004a). The growth kinetics results obtained from the strains isolated from shrimp were greater for maximum growth rate and final viable cell count, and lower for doubling time, in comparison with the strains of probiotics with aquaculture potential isolated by Vine et al (2004a).…”

“…This stage normally involves the isolation of dozens or even hundreds of strains. Following isolation, several in vitro selection tests are usually performed, such as pathogen inhibition (Guo et al, 2009), production of digestive enzymes (Ochoa-Solano, 2006), production of antimicrobial substances (Vázquez et al, 2005;Sugita et al, 2007), growth rate (Vine et al, 2004a), and ability to adhere to the intestinal epithelium (Vine et al, 2004b), in order to select certain strains for in vivo assays.…”

Effect of a phytogenic feed additive on the susceptibility of Onchorhynchus mykiss to Aeromonas salmonicida

“…The most studied among these have been probiotics: supplemental live bacteria that beneficially affect their host (Gatesoupe 1999, Gomez-Gil et al 2000, Verschuere et al 2000, Irianto & Austin 2002, Vine et al 2004, Burr et al 2005, Balcázar et al 2006, KesarcodiWatson et al 2008, Wang et al 2008. For example, addition of the probiotic Lactobacillus plantarum pro tected larvae of blue swimming crab Portunus pelagicus from infections by Vibrio harveyi (Talpur et al 2012).…”

Probiotics in Aquaculture - Benefits to the Health, Technological Applications and Safety

“…Intake of probiotics has been demonstrated to modify the composition of the microbiota, and therefore assist in returning a disturbed microbiota (by antibiotics or other risk factors) to its normal beneficial composition (Gómez and Balcázar, 2008). As for the mechanisms during this physiological process, the production of antimicrobial substances, competition for nutrients or adhesion receptors, inhibition of virulence gene expression and enhancement of the immune response are all included (Irianto and Austin, 2002;Nikoskelainen, et al, 2003;Vine et al, 2004;Kim and Austin, 2006;Balcázar, et al, 2007). However, the exact mechanism by which these probiotics do this is not known.…”