arr4 is a thermotolerant microorganism with great biotechnological potential for l-(+)-lactic acid production from granulated sugar and yeast extract. The highest l-(+)-lactic acid production was obtained with Ca(OH). The maximum production of l-(+)-lactic acid (206.81 g/L) was observed in exponential feeding using granulated sugar solution (900 g/L) and yeast extract (1%) at 50 °C, pH 6.5, and initial granulated sugar concentration of 100 g/L at 39 h. 5.3 g/L h productivity and 97% yield were observed, and no sugar remained. Comparing the simple batch with exponential fed-batch fermentation, the l(+) lactic acid production was improved in 133.22% and dry cell weight was improved in 83.29%, using granulated sugar and yeast extract. This study presents the highest productivity of lactic acid ever observed in the literature, on the fermentation of thermotolerant sp. as well as an innovative and high-efficiency purification technology, using low-cost substances as Celite and charcoal. The recovery of lactic acid was 86%, with 100% protein removal, and the fermentation medium (brown color) became a colorless solution.

1,3-Propanediol (1,3-PDO) is a bifunctional molecule, and used in applications similar to those of ethylene glycol, propylene glycol, 1,3-butanediol and 1,4-butanediol. The use of glycerol as a feedstock is an alternative to reduce production costs for both 1,3-PDO and biodiesel, since biodiesel glycerol can be used for the production of 1,3-PDO by bacteria. Also, using metabolic engineering, it is possible to manipulate the metabolic routes and obtain high value products, reduce or eliminate the formation of undesirable byproducts. The aim of the study was to produce 1,3-propanediol in E. coli cloned with dha genes from Klebsiella pneumoniae GLC29. Six genes responsible for 1,3-PDO production in Klebsiella pneumoniae GLC29 were cloned. These genes were assembled in pSB1C3 as an expression vector: Genes dhaB1, dhaB2, dhaB3 and dhaT (pSB1C3dhaB123T), and another vector with genes dhaF and dhaG (pSB1C3dhaB123TFG) were derived using Gibson's Assembly technique. Escherichia coli TCS099 and SZ63 stains were used as hosts for 1,3-PDO production, and kept at -80°C for long-term storage. Glycerol was used as the sole or main carbon source in all experiments. Fermentations were performed in flasks in aerobic and anaerobic conditions using minimal media. Also, two stage fermentation (aerobic-anaerobic) was performed for 1,3-propanediol production. Only pSB1C3dhaB123TFG was able to produce high amounts of 1,3-PDO in shake flasks experiments, producing 2.5 g/L in micro-aerobic conditions, using E. coli TCS099 as host. Besides, E. coli SZ63 hosting pSB1C3dhaB123TFG was able to produce high amounts of 1,3-PDO, corresponding to 11.3 g/L of 1,3-PDO using a two-stage fermentation process using low concentration of vitamin B12 (1 mg/L). Plasmid pSB1C3dhaB123TFG shows potential for producing high amounts of 1,3-PDO, specially because of dhaF and dhaG, reaffirming the importance of this genes on 1,3-PDO production, especially with the addition of low amounts of vitamin B12, which is an expensive compound.

No abstract

Lactic acid and its derivatives are widely used in pharmaceutical, leather, textile and food industries. However, until now there have been few systematic reports on fed-batch fermentation for efficient production and high concentration of l-lactic acid by lactic acid bacteria. This study describes the obtainment of L (+) lactic acid from sucrose using the Lactobacillus casei Ke11 strain through different feeding strategies using an accessible pH neutralizer such as CaCO3. The exponential feeding strategy can increase lactic acid production and productivity (175.84 g/L and 3.74 g/L/h, respectively) with a 95% yield, avoiding inhibition by high initial substrate concentration and, combined with the selected agent controller, avoids the cellular stress that could be caused by the high osmotic pressure of the culture media. The purification of the acid using charcoal and celite, followed by the use of a cation exchange column proved to be highly efficient, allowing a high yield of lactic acid, high removal of sugars and proteins. The described process shows great potential for the production of lactic acid, as well as the simple, efficient and low-cost purification method. This way, this work is useful to the large-scale fermentation of L. casei Ke11 for production of l-lactic acid.

Biodiesel glycerol can be used for the production of 1,3-propanediol by bacteria. In this study on the production of 1,3-propanediol by Klebsiella pneumoniae GLC29 was possible to optimize media culture the production of 1,3-propanediol using statistical experimental design techniques and response surface methodology, where 11 variables were tested and only 5 were found significant (glycerol, yeast extract, ammonium sulfate, vitamin B12 and fumarate). Subsequently, production of 1,3-propanediol was verified in 0,75 liter reactors, both in batch and exponential fedbatch. It was possible to achieve 23.6 g/l of 1,3-propanediol in batch cultures using pure glycerol, 27 g/l of 1,3-propanediol in batch cultures using biodiesel glycerol, and 29.9 g/l of 1,3-propanediol in exponential fed-batch using biodiesel glycerol.

No abstract