Abstract
In this study, three adherent Staphylococcus strains able to use nitrate as electron acceptor were isolated from textile wastewater activated sludge. Based on the biochemical profiles, bacterial strains were identified as Staphylococcus lentus, Staphylococcus warneri and Staphylococcus epidermidis the PCR amplification of the nir genes reveal that S. lentus and S. epidermidis were nirK positive and that S. epidermidis was nirS positive. The three strains were also icaA/icaD positive. To obtain the optimal formulation of pure cultures of the staphylococci, the influence of the different mixtures of organisms was studied using mixture design. The regression model of microorganism composition and main metabolites was established. The most predictable reduction of nitrate was 87.2 and 12% of COD consumption. The results suggested that the predictable production of nitrite would reach a minimum of 6.1 mg/l. Based on this, the response values that satisfied all expectations were optimized using MINITAB(A (R)) 14 analysis software. The most optimal proportion combination was 49.75% of S. lentus (curve value), 36.85% of S. warneri (curve value) and 13.39% S. epidermidis (curve value).