Algicidal properties of fermentation products from Bacillus cereus strain JZBC1 dissolving dominant dinoflagellate species Scrippsiella trochoidea, Prorocentrum micans, and Peridinium umbonatum

Intensive and semi-intensive aquaculture systems typically produce high loads of nutrients in their discharge, potentially leading to the development and persistence of harmful algal blooms (HABs). Algicidal bacteria, which inhibit algal growth or kill algal cells, offer a promising biocontrol strategy for reducing HAB. The strain JZBC1, which displays strong algicidal activity against the HAB species Scrippsiella trochoidea, was previously isolated from a dinoflagellate bloom area and identified as Bacillus cereus. In this study, strain JZBC1 was fermented in 2 L and 50 L systems, and then, algicidal properties of JZBC1 fermentation products on the harmful dinoflagellate species S. trochoidea, Prorocentrum micans, and Peridinium umbonatum were examined. Bacterial concentrations of strain JZBC1 reached 6.23 × 109 and 4.47 × 109 CFU/mL in 2 L and 50 L cultures, respectively, and thus effectively expanded during fermentation. Strain JZBC1 showed substantial algicidal activities and a wide algicidal range toward harmful dinoflagellates. Vegetative JZBC1 cells exhibited the best inhibitory and algicidal effects in 1 day. Strain JZBC1 can be formulated into a powder, and the spores can be activated before field application to increase their efficacy. These findings will facilitate large-scale fermentation production and application of Bacillus strain JZBC1 for controlling dinoflagellate blooms in aquaculture ponds.