This article deals with the optimization of the various parameters for production of phytase using Achromobacter sp. PB-01 in submerged fermentation (SmF). A semisynthetic medium containing ingredients of phytase screening media (PSM) supplemented with 2% (w/v) sucrose, 1% (w/v) peptone, and 10% (w/v) wheat bran was found to be the best production medium among the various combinations tried. Among various surfactants added to SmF, Triton X-100 (0.1%) exhibited a 16% increase in phytase activity. An overall 11.2 fold enhancement in enzyme activity (0.79 U/mL?8.84 U/mL) was attained when SmF was carried out using 0.5% (v/v) inoculum of a 15 h old culture of Achromobacter sp. PB-01 at an initial pH of 5.5, temperature 30 degrees C and allowed to grow for 48 h. Presence of accessory hydrolytic enzymes in the crude extract further added value as feed additive by mediating efficient degradation of non-starch polysaccharides (NSP). In addition, we also investigated the efficacy of phytase on different agro-industrial residues using in vitro experiments that simulated the conditions of the digestive tract. Results indicate that phytase from our source hydrolyze phytate efficiently with the concomitant liberation of inorganic phosphate, protein, reducing sugar, and calcium. (C) 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012