PRODUCTION OF CURDLAN USING SUCROSE OR SUGAR-CANE MOLASSES BY 2-STEP FED-BATCH CULTIVATION OF AGROBACTERIUM SPECIES

Maltose and sucrose were efficient carbon sources for the production o f curdlan by a strain of Agrobacterium sp. A two-step, fed-batch opera tion was designed in which biomass was first produced, followed by cur dlan production which was stimulated by nitrogen limitation. There exi sts an optimal timing for nitrogen limitation for curdlan production i n the two-step, fed-batch operation. Maximum curdlan production (60 g L-1) was obtained from sucrose with a productivity of 0.2 g L-1 h(-1) when nitrogen was limited at a cell concentration of 16.0 g L-1. It wa s also noted that the curdlan yield from sucrose was as high as 0.45 g curdlan g(-1) sucrose, and the highest specific production rate was 1 .0 g curdlan g(-1) cells h(-1) right after nitrogen limitation. Of par ticular importance was the use of molasses as a cheap carbon source to produce curdlan in the two-step, fed-batch cultivation. As high as 42 g L-1 of curdlan with a yield of 0.35 g curdlan g(-1) total sugar was obtained after 120 h of fed-batch cultivation.