ENZYME-MEDIATED PRODUCTION OF SUGARS FROM SAGO STARCH: STATISTICAL PROCESS OPTIMIZATION

A New Strain of Bacillus tequilensis CGMCC 17603 Isolated from Biological Soil Crusts: A Promising Sand-Fixation Agent for Desertification Control

In arid and semi-arid desert ecosystems, physical, chemical, and vegetative measures were used to prevent wind erosion. However, studies on the utilization of microbial resources for sand fixation are still limited. To fill this gap, a new strain of Bacillus tequilensis CGMCC 17603 with high productivity of exopolysaccharide (EPS) was isolated from biological soil crusts, and its high-density culture technology and sand-fixing ability were studied. The one-factor-at-a-time approach (OFAT) and Box–Behnken design of CGMCC 17603 showed that the optimum culture conditions were pH 8.5, temperature 31 °C, agitation speed 230 rpm, and inoculation quantity 3%, and the optimum medium was 27.25 g/L glucose, 15.90 g/L yeast extract, and 5.61 g/L MgSO4•7H2O. High-density culture showed that the biomass and EPS yield of CGMCC 17603 increased from 9.62 × 107 to 2.33 × 109 CFU/mL, and from 8.01 to 15.61 g/L, respectively. The field experiments showed that CGMCC 17603 could effectively improve the ability of sand fixation and wind prevention. These results indicated that B. tequilensis, first isolated from cyanobacterial crusts, can be considered as an ideal soil-fixing agent to combat desertification in arid and semi-arid areas.

Production and scale-up of a monoclonal antibody against 17-hydroxyprogesterone

The hybridoma 192 was used to produce a monoclonal antibody (MAb) against 17-hydroxyprogesterone (17-OHP), for possible use in screening for congenital adrenal hyperplasia (CAH). The factors influencing the MAb production were screened and optimized in a 2 L stirred bioreactor. The production was then scaled up to a 20 L bioreactor. All of the screened factors (aeration rate, stirring speed, dissolved oxygen concentration, pH, and temperature) were found to significantly affect production. Optimization using the response surface methodology identified the following optimal production conditions: 36.8°C, pH 7.4, stirring speed of 100 rpm, 30% dissolved oxygen concentration, and an aeration rate of 0.09 vvm. Under these conditions, the maximum viable cell density achieved was 1.34 ± 0.21 × 10(6) cells mL(-1) and the specific growth rate was 0.036 ± 0.004 h(-1) . The maximum MAb titer was 11.94 ± 4.81 μg mL(-1) with an average specific MAb production rate of 0.273 ± 0.135 pg cell(-1) h(-1) . A constant impeller tip speed criterion was used for the scale-up. The specific growth rate (0.040 h(-1) ) and the maximum viable cell density (1.89 × 10(6) cells mL(-1) ) at the larger scale were better than the values achieved at the small scale, but the MAb titer in the 20 L bioreactor was 18% lower than in the smaller bioreactor. A change in the culture environment from the static conditions of a T-flask to the stirred bioreactor culture did not affect the specificity of the MAb toward its antigen (17-OHP) and did not compromise the structural integrity of the MAb.