PRODUCTION OF MICROBIAL RENNIN FROM MUCOR-MIEHEI IN A CONTINUOUSLY FED FERMENTER

In this study, microbial production of rennin, a milk-clotting enzyme, from a commercial strain of Mucor miehei NRRL 3420 has been investiga ted in a continuously fed femtenter for prolonged times. The spherical film-type growth of the culture has been accomplished in the fermente r and the effects of medium pH, mixing and dilution rates, and feed D- glucose concentration on milk-clotting activity have been elaborated. In the fermenter, optimum operational parameters have been determined as 400 rpm 0.125 day(-1), and 7.5 g l(-1) for mixing rare, dilution ra te, and feed D-glucose concentration respectively. Under these conditi ons, the fermenter operated 575 h continuously producing 1.24 IU ml(-1 ) maximum milk-cloning activity without concentration. ra the fermente r sample at maximum milk cloning activity, the R factor and specific m ilk-clotting activity were determined as 1.55 X 10(-3) IU PU-1 and 5.2 8 IU mg(-1) medium protein, 'respectively, denoting competitive charac teristics of a commercial rennet after concentration. (C) 1998 Elsevie r Science Inc.