Bacillus is the main genus in commercial probiotics and bioremediation products for tropical aquaculture. Germinated Bacillus produce enzymes that improve digestion and feed utilization, leading to better growth rates and feed conversion ratios. They also compete with bacterial pathogens, reducing disease risks, and maintain water quality by breaking down organic waste. This work aimed to document Sanolife Bacillus germination and evaluate methods to enhance it.
Material & Methods: A phase-contrast microscopy method was adapted to document the germination process. The germinant receptor genes were identified from the whole genome sequence of 3 Sanolife Bacillus strains. The spore receptor-associated nutrients were used to select the suitable nutrients for each strain. Nutrients mixes were designed based on the information and included in germination trials. With the information generated, a shrimp trial was carried out to evaluate effects of the selected nutrient mix and protocol of germination on shrimp performance and survival. Samples of hepatopancreas were collected to determine the molecular levels of stress and immunity gene markers.
Results: Microscopic observations revealed that 50-60% of spores had germinated into vegetative cells after 1 hour in pond water, with this figure rising to nearly 90% after 4 hours. Gene receptors were identified during the genome annotation. Based on this, 3 specific nutrient mixes of amino acids, sugars and ions were formulated and tested. 2 of these mixes improved the germination of probiotics by 16%. One mix was selected for the shrimp trial. The combination probiotic-mix led to a significant improvement in final weight and FCR (Fig. 1) and an upregulation of immune and stress related genes.
Conclusions: Bacillus spores are germinated and active when added to the shrimp tanks. The germination process can be optimized and boosted, leading to an improvement in performance and health status of the shrimp. These findings contribute to a constant improvement of probiotic development, always focusing on practical solutions to add value to the shrimp aquaculture industry.