Moreover the EPS-induced increased expression of the human defensin HBD-2 in vaginal cells was also verified, identifying a possible connection with C. albicans growth inhibition [24]. Results Strain identification and H2O2 production A Lactobacillus strain isolated from human vaginal secretion was Acalabrutinib in vitro allotted to crispatus subspecies by 16S ribosomal DNA sequencing [25] and it was named L. crispatus L1. In

particular, PCR products were pooled, purified and sequenced. In addition, the ability of 72 Lactobacillus strains to produce H2O2 was evaluated. The percentage of strains classified as strong, medium, weak and negative H2O2 producers was 23, 34, 38 and 5%, respectively. L. crispatus L1 was found to be the best of the isolates in the

laboratory collection. In vitro digestion Results from shake flask experiments simulating the passage through the gastrointestinal tract showed a good resistance of L. crispatus L1 to the in vitro digestion process. The bacterial dose significantly influenced results, as shown in Figure 1a clearly indicating that 1.8⋅109 cells∙ml−1 corresponds to the minimal required initial concentration of cells necessary to survive gastric juices. Incubation in simulated pancreatic juices (Figure 1b) with different Oxgall concentrations (10 mg and 25 mg) did not affect viability, whereas a slight increase of the cell number within 4 h was observed. Moreover, 5-Fluoracil treated cells reached a final biomass yield comparable with that of the control cells (data not shown). Figure 1 Simulation of human digestion in shake flasks. (a) Survival of L. crispatus L1 to gastric juices (pH 2.0, pepsine 3 g∙l−1). Response of different doses of bacteria, high (1.8 · 109 cells∙ml−1)

and low (6.0 · 108 cells∙ml−1), to the treatment. (b) Survival of L. crispatus L1 to pancreatic juices (pH 4.0, Phenylethanolamine N-methyltransferase pancreatine 2 g∙l−1, Oxgall in different concentrations). Effect of two different concentrations of bile salts on the viability of 1.0 · 109 cells∙ml−1.The asterisks indicate a statistically significant difference between samples with P < 0.01. Shakeflask experiments A semidefined medium containing soy peptone (10 g∙l−1) and yeast extract (2.5 g∙l−1) was used to investigate the amount of biomass and lactic acid produced using different carbon sources (Table 1). The final titer of biomass produced in shake flasks was very similar in all the media analysed. The production of lactic acid was quite high ranging between 7.5 and 13.1 g∙l−1 (Table 1) and resulting in relevant Yp/s ranging between 0.68 and 0.89 g∙g−1. The Yp/s on dextrins could not be calculated due to the presence of high molecular weight carbohydrates (glucose residues >7) that were not degraded and metabolized as evidenced by High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD) analyses. Table 1 Growth of L.