Preparation of biomembrane by immobilizing enriched ammonia-oxidizing bacteria (AOB) in polyvinyl alcohol (PVA) for biosensor

A biomembrane that was used to make a biosensor for detecting inhibitor of ammonia oxidation was prepared by entrapping enriched ammonia-oxidizing bacteria (AOB) in polyvinyl alcohol (PVA). AOB were enriched by fed batch cultivation with using return activated sludge from A²/O process as seed. Enrichment of AOB was confirmed by denaturing gradient gel electrophoresis (DGGE) analysis. The optimum conditions based on orthogonal test results for biomembrane preparation were found as follows: mixing 30%(w/w) enriched cell with membrane matrix (12% (w/v) PVA and 3% (w/v) sodium alginate(SA), pouring mixture on a petri dish, dried for 1 hr, and solidified by soaking this membrane in a cross-linking agent (25% (w/v) NaNO₃ and 2% (w/v) CaCl₂) for 1 h. A biosensor was fabricated by attaching the prepared biomembrane on an oxygen electrode. The bioactivity of prepared biosensor which was measured as DO drop was 1.4 mgO₂/l, shows that PVA and SA can be used to immobilize AOB to produce a biosensor for detecting inhibitor of ammonia oxidation.