Pathogen Inhibition

The strains in AquaStar® are capable of inhibiting a wide range of aquaculture pathogens, both Gram-negative and Gram-positive (Table 1).

Figure 1: The ability of AquaStar® probiotics to attach to epithelial cells from fish intestine. The value represents the number of probiotic cells that can attach to a single enterocyte.

Figure 2: Mortality of shrimp fed control (grey) or AquaStar® (green) diets after a V. parahaemolyticus immersion challenge

Figure 3: Enzyme production (protease, amylase and cellulase) of multiple Bacillus spp. candidates. The red box indicates the strain chosen for AquaStar® products.

Enzyme Production

Bacillus spp. are well known for their ability to produce enzymes. In the gut these can contribute to better feed digestibility and reduced FCR. If applied in the water they can break down organic matter in the environment, facilitating the release of highly digestible components and preventing the accumulation of toxic sediments. This effect can be further stimulated by the addition of enzyme cocktails, as in AquaStar® PondZyme.

However, the ability of Bacillus spp. to produce enzymes is highly variable, and the strain chosen for AquaStar® products demonstrated the highest combined protease, amylase and cellulase activity (Figure 3).

Figure 4: The concentration of N-waste with AquaStar®, after 0, 24 and 48 hours in aerobic and anaerobic conditions

Figure 5: The concentration of H2S after 216 hours, relative to 0 hours, with AquaStar® (light blue) and without (dark blue)

Hydrogen Sulfide Removal

Hydrogen sulfide (H2S) is generated as organic matter decomposes, and is extremely toxic in very low concentrations. AquaStar® strains can reduce the abundance of H2S in water and sediments (Figure 5).