Bright Singh, I S; Cini, Achuthan; Rosamma, Philip; Manju, N J(Elsevier, May 11, 2009)
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Abstract:
Shrimp grow out systems under zero water exchange mode demand constant remediation of total ammonia
nitrogen (TAN) andNO2
−–Nto protect the crop. To address this issue, aninexpensive and user-friendly technology
using immobilized nitrifying bacterial consortia (NBC) as bioaugmentors has been developed and proposed for
adoption in shrimp culture systems. Indigenous NBC stored at 4 °C were activated at room temperature (28 °C)
and cultured in a 2 L bench top fermentor. The consortia, after enumeration by epifluorescence microscopy,were
immobilized on delignifiedwood particles of a soft wood tree Ailantus altissima (300–1500 μm) having a surface
area of 1.87m2 g−1. Selection of wood particle as substratumwas based on adsorption of NBC on to the particles,
biofilm formation, and their subsequent nitrification potential. The immobilization could be achievedwithin 72 h
with an initial cell density of 1×105 cells mL−1. On experimenting with the lowest dosage of 0.2 g (wet weight)
immobilized NBC in 20 L seawater, a TAN removal rate of 2.4 mg L−1 within three days was observed. An NBC
immobilization device could be developed for on site generation of the bioaugmentor preparation as per
requirement. The product of immobilization never exhibited lag phase when transferred to fresh medium. The
extent of nitrification in a simulated systemwas two times the rate observed in the control systems suggesting the
efficacy in real life situations. The products of nitrification in all experiments were undetectable due to
denitrifying potency, whichmade the NBC an ideal option for biological nitrogen removal. The immobilized NBC
thus generated has been named TANOX (Total Ammonia Nitrogen Oxidizer)