Partitioning studies of L-glutaminase production by Bacillus cereus MTCC 1305 was carried out in different PEG-salt/PEG-dextran system. The partitioning value of L-glutaminase increased with increasing molecular weight of PEG from 2000-4000 kDa and decreased with higher molecular weight of 6000 kDa. Phase system of PEG 4000 (8.5%)/dextran T500 (9.5%) was selected for the extractive fermentative production of L-glutaminase on the basis maximum partition coefficient (1.31). The production of L-glutaminase was found higher in top phase of ATPS (2.09 U/ml) than control media (1.42 U/ml). Overall production of L-glutaminase (1.83 U/ml) was found lower than top phase (2.09 U/ml) in ATPS system. The growth profile with short lag phase and higher cell concentration was obtained for ATPS. The partition coefficient of L-glutaminase increased with increase of system pH and temperature and optimum production was obtained at pH 7.5 and temperature 30 degrees C in top phase of PEG 4000/dextran T500 system. (C) 2012 Elsevier Ltd. All rights reserved.