-A Plackett-Burman experimental design was used to evaluate seven medium components added to molasses (corn steep liquor, sodium acetate, magnesium sulfate, manganese sulfate, ammonium citrate, potassium phosphate and Tween 80). Corn steep liquor (CSL), K 2 HPO 4 and Tween 80 increased lactic acid production. The concentrations of these three components as well as the molasses were further optimized using the response surface method. A maximal lactic acid production of 94.8 g L -1 was obtained when the concentrations of molasses, CSL, K 2 HPO 4 and Tween 80 were 193.50 g L -1 , 37.50 mL L -1 , 2.65 g L -1 and 0.83 mL L -1 , respectively. However, in both shaker and bioreactor, approximately one fourth of the sugar added initially was not utilized after 48 hours of fermentation. Future studies that consider high conversion of sugar into final product as well as high volumetric productivity are necessary to improve the fermentation process and to reduce the downstream costs.

a b s t r a c tInterest in the development of the bioproduction of 1,3-propanediol, an important chemical intermediate with various industrial applications, has increased in recent years. Klebsiella pneumoniae is one of the most studied and efficient bacteria for 1,3-propanediol production from glycerol. A new isolate of K. pneumoniae was investigated using response surface methodology by central composite design for the production of 1,3-propanediol using glycerol. The effects of pH, temperature, stirrer speed, and glycerol concentration on the production and productivity of 1,3-propanediol were examined. Considering both production and productivity, the best conditions for glycerol conversion in 1,3-propanediol are: a pH range of 6.9-7.1, a temperature between 33 and 38.5 • C, a stirrer speed of 110-180 rpm, and a glycerol concentration of 39-49 g l −1 . Batch fermentation carried out at a pH of 7.0, a temperature of 35 • C, a stirrer speed of 150 rpm, and a glycerol concentration of 40 g l −1 produced 20.4 g 1,3-propanediol l −1 , with a maximum volumetric productivity of 2.92 g l −1 h −1 and a yield of 0.51 g g −1 . The main byproducts were acetic acid (approximately 7.0 g l −1 ) and formate (approximately 3.7 g l −1 ). The newly isolated K. pneumoniae GLC29 showed potential for the conversion of glycerol into 1,3-propanediol, with high production and productivity.

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A Gram-positive, endospore-forming, alkalitolerant bacterial strain, designated CGII, was isolated from the wastewater of a cassava flour mill in the state of São Paulo, Brazil and submitted to phylogenetic studies and biochemical tests. The 16S rRNA gene sequence indicated the highest degree of genomic similarity with MLB2 strains of Bacillus lehensis (100%). A two-level central composite rotatable design was then employed to optimize the medium composition and culture conditions for the production of the enzyme cyclodextrin glycosyltransferase (CGTase) in shake-flask and bioreactors. CCTase activity was measured under different production conditions, such as culture medium, agitation and aeration. Highest enzyme production by B. lehensis was achieved in 72 h with a maximal activity of 134.05 U mL −1 . The response surface method demonstrated that the proposed model achieved a good level of agreement with experimental data, with a correlation coefficient of 0.910, thereby confirming the adequate reliability of the model.

Pseudomonas aeruginosa PACL strain, isolated from oil-contaminated soil taken from a lagoon, was used to investigate the efficiency and magnitude of biosurfactant production, using different waste frying soybean oils, by submerged fermentation in stirred tank reactors of 6 and 10 l capacities. A complete factorial experimental design was used, with the goal of optimizing the aeration rate (0.5, 1.0, and 1.5 vvm) and agitation speed (300, 550, and 800 rpm). Aeration was identified as the primary variable affecting the process, with a maximum rhamnose concentration occurring at an aeration rate of 0.5 vvm. At optimum levels, a maximum rhamnose concentration of 3.3 g/l, an emulsification index of 100%, and a minimum surface tension of 26.0 dynes/cm were achieved. Under these conditions, the biosurfactant production derived from using a mixture of waste frying soybean oil (WFSO) as a carbon source was compared to production when non-used soybean oil (NUSO), or waste soybean oils used to fry specific foods, were used. NUSO produced the highest level of rhamnolipids, although the waste soybean oils also resulted in biosurfactant production of 75-90% of the maximum value. Under ideal conditions, the kinetic behavior and the modeling of the rhamnose production, nutrient consumption, and cellular growth were established. The resulting model predicted data points that corresponded well to the empirical information.