DIFFERENT Bacillus spp. ISOLATES VARY IN THEIR BIOREMEDIATION CAPACITY.

Poor water quality negatively impacts animal health in aquaculture. After prolonged exposure, challenging water quality is detrimental to animal performance and will cause significant economic losses. Probiotics can be applied to remove toxic compounds and to clean up ponds. Although a range of bacterial species are capable of nitrification and / or denitrification, not all species are applicable for bioremediation products.

Nitrification and Denitrification was investigated for several Bacillus spp. and P. pantotrophus strains under aerobic and anaerobic conditions.

After 24 hours and 48 hours cultivation with active aeration, an increase, steady levels and an efficient reduction of ammonium ions were measured for different strains, reflecting their strain-specific capabilities. In general, the performance of P. pantotrophus PaP#768 and of B. amyloliquefaciens BA#895 was superior in comparison to the other tested strains.

Under anaerobic conditions, all strains reduced nitrite at 24h and 48h, except for B. amyloliquefaciens BA#855. This strain requires 48 hours to decrease the nitrite levels in the culture medium. Under aerobic conditions, most strains reduce nitrite, but often not as efficient as under anaerobic conditions.

Under anaerobic conditions, almost a complete removal of nitrate was detected for P. pantotrophus PaP#768, all B. amyloliquefaciens strains, all P. polymyxa strains, B. licheniformis strains BL#746, BL#857, BL#879 and BL#896, and B. subtilis strains Bio9, BS#588, and BS#652. Compared to these strains, only a low reduction of nitrate was observed for B. licheniformis BL#858 and B. pumilus BP#856. Under aerobic conditions, only four strains, namely P. pantotrophus PaP#768, B. licheniformis BL#857 and BL#858, and less pronounced also P. polymyxa PP#866 reduced nitrate.