FEATURE
Figure 2: Pond interactions without the addition of beneficial bacteria describes the reduction of nitrate to nitrous oxide and finally to nitrogen gas, which returns into the atmosphere (Chรกvez-Crooker and Obreque-Contreras, 2010). Although a range of bacterial species are capable of nitrification and / or denitrification, not all species are applicable for bioremediation products. Recently strains such as Paracoccus sp. and Thiobacillus sp. have gained interest due to its degrading capabilities. Also Bacillus sp. is also well suited to perform several functions in the water cleanup application (Nakano et al., 1998). A single strain, rarely harbours all desired qualities necessary for an efficient degradation of toxic compounds, therefore a combination of strains that perform best for one or several
compounds is more likely to ensure a stable performance.
Beneficial bacteria and enzymes to improve water and soil quality in aquaculture ponds A key factor for successful aquaculture is to understand the interactions between the microbial environment, gut flora and immune system of the shrimp, as well as the factors that determine the persistence of microbial species in the internal and external microbial ecosystems. While natural environments are balanced, the farming environment favours the growth of micro-organisms as it is rich in nutrients and feed waste. Farmed species
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March-April 2013 | International AquaFeed | 29
Figure 3: Pond interactions with the addition of beneficial bacteria are constantly exposed to and challenged by micro-organisms from the surrounding environment. These environmental challenges are obviously influenced by different factors, including farm management and rearing methods. Aquaculture operations generally involve the stocking and feeding of shrimp in open or semi-closed water systems. Semi-closed pond systems have a low water turnover and can accumulate gases, nutrients, metabolites, waste, etc., which can deteriorate the water quality and create anoxic conditions in the soil. This can strongly affect the performance of the farmed species. Thus, good pond manage-