## 3 Results and Discussion
### Phylogenetic Analysis of the 2 GPP Selected Strain
The ML tree was inferred with PhyML, and the node support was estimated with the SH-aLRT test. Support values \(\geq\) 100% SH-aLRT are displayed with black circles at nodes. Concerning the experiments performed with agitation at 120 rpm, the best stirring condition was 5 g\(\cdot\)L\({}^{-1}\), which produced 1.94 g\(\cdot\)L\({}^{-1}\) of lactic acid. The yield of lactic acid production (Y\({}_{\text{LA/Gly}}\)) was 0.54, and the yield of 1,3-propanediol (Y\({}_{\text{1,3-PDO/Gly}}\)) was 0.36. It can be observed that, in the experiments in which the cream was more diluted in the medium, the production of lactic acid was lower, since a lower number of cells metabolized glycerol and, consequently, less lactic acid was produced. [PERSON] et al. [46] carried out a fed-batch fermentation with _K. pneumoniae_ and concluded that the inoculation of cells at 4.8 g\(\cdot\)L\({}^{-1}\) resulted in a reduced production of 1,3-propanediol. The fed-batch with 3.2 g\(\cdot\)L\({}^{-1}\) of inoculum concentration produced 81.1 g\(\cdot\)L\({}^{-1}\) of 1,3-propanediol. In this experiment, it was possible to infer the opposite: higher inoculum concentrations produced more 1,3-propanediol. Another analyzed factor was agitation. When fermentation was performed in a flask in an incubator without an agitation, there was less oxygen, which favors the bacteria's anaerobic pathway, corroborating with [PERSON] et al. [20], who suggested that anaerobic conditions favor the production of 1,3-propanediol and pyruvate. The same can be verified by comparing the same inoculum concentration (4.2 g\(\cdot\)L\({}^{-1}\)) with and without agitation. The experiment performed in the incubator and without agitation showed a lactic acid production that was twice as high as the one produced in the rotary shaker experiment at 120 rpm, as shown in Table 4.  
In this experiment, it was inferred that the reductive and oxidative anaerobic metabolisms occurred simultaneously. The biomass and lactic acid are generated by the reductive metabolism of glycerol while 1,3-propanediol is generated by oxidative metabolisms. The production of only two final products is desirable. The next experiments were performed to minimize the synthesis of 1,3-propanediol and increase lactic acid production [20]. In all fermentations, there was a decrease in glycerol concentration. However, glycerol consumption was higher in the experiment without aeration, showing that the lower the amount of oxygen in the medium, the more glycerol will be metabolized for lactic acid production. This result corroborates the idea that the bacteria produce more of the product of interest under anaerobic conditions. About 93% of glycerol was consumed in the fermentation with 4.2 g\(\cdot\)L\({}^{-1}\) of inoculum without agitation. Table 4 shows that the production of 1,3-propanediol was lower than in the mini-reactor experiment. This result is desirable, as the product of interest is lactic acid. The production behavior of 1,3-propanediol is similar to that of lactic acid; the fewer the incubated cells, the lower the production. Additionally, experiments without agitation have a higher production of 1,3-propanediol. [PERSON] et al. [16] showed that, under anaerbiosis, _K. pneumoniae_ produces more 1,3-propanediol (6.88 g\(\cdot\)L\({}^{-1}\)). Considering the experiment with the highest lactic acid biconversion, the yield of lactic acid (Y\({}_{\text{LA/Gly}}\)) was 0.81, and the yield of 1,3-propanediol (Y\({}_{\text{1,3-PDO/Gly}}\)) was 0.55. The yield of 1,3-propanediol was similar to that obtained by [PERSON] et al. [47], which resulted in yields between 0.32 to 0.54 through _Clostridium butylticum_ batch fermentation. [PERSON] et al. [48] achieved a yield (Y\({}_{\text{LA/Gly}}\)) of 0.9 for lactic acid using _E. coli_ AC-521 fed-batch fermentation.