Genomic Analysis of Surfactant-Producing Bacillus vallismortis TIM68: First Glimpse at Species Pangenome and Prediction of New Plipastatin-Like Lipopeptide.

Surfactants are applied in several industrial processes when the modification of interface activity and the stability of colloidal systems are required. Lipopeptides are a class of microbial biosurfactants produced by species of the Bacillus genus. The present study aimed at assembling and analyzing the genome of a new Bacillus vallismortis strain, TIM68, that was shown to produce surfactant lipopeptides. The draft genome was also screened for common virulence factors and antibiotics resistance genes to investigate the strain biosafety. Comparative genomics analyses, i.e., synteny, average nucleotide identity (ANI), and pangenome, were also carried out using strain TIM68 and publicly available B. vallismortis complete and partial genomes. Three peptide synthetase operons were found in TIM68 genome, and they were surfactin A, mojavensin, and a novel plipastatin-like lipopeptide named vallisin. No virulence factors that render pathogenicity to the strain have been identified, but a region of prophage, that may contain unknown pathogenic factors, has been predicted. The pangenome of the species was characterized as closed, with 57% of genes integrating the core genome. The results obtained here on the genetic potential of TIM68 strain should contribute to its exploration in biotechnological applications.

Evaluation of thermal and non-thermal processing effect on non-prebiotic and prebiotic acerola juices using 1H qNMR and GC-MS coupled to chemometrics.

The effects of thermal (pasteurization and sterilization) and non-thermal (ultrasound and plasma) processing on the composition of prebiotic and non-prebiotic acerola juices were evaluated using NMR and GC-MS coupled to chemometrics. The increase in the amount of Vitamin C was the main feature observed after thermal processing, followed by malic acid, choline, trigonelline, and acetaldehyde. On the other hand, thermal processing increased the amount of 2-furoic acid, a degradation product from ascorbic acid, as well as influenced the decrease in the amount of esters and alcohols. In general, the non-thermal processing did not present relevant effect on juices composition. The addition of prebiotics (inulin and gluco-oligosaccharides) decreased the effect of processing on juices composition, which suggested a protective effect by microencapsulation. Therefore, chemometric evaluation of the 1H qNMR and GC-MS dataset was suitable to follow changes in acerola juice under different processing.

Cashew juice containing prebiotic oligosaccharides.

The enzyme dextransucrase in a medium containing sucrose and an acceptor as substrate synthesizes prebiotics oligosaccharides. The cashew apple juice works as a source of acceptors because it is rich in glucose and fructose (enzyme acceptors). The use of cashew apple juice becomes interesting because it aims at harnessing the peduncle of the cashew that is wasted during the nut processing, which is the product of greater economic expression. The production of dextransucrase enzyme was done by fermentative process by inoculating the bacterium Leuconostoc mesenteroides NRRL B512F into a culture medium containing sucrose as the only carbon source. Thus, the aim of this work was the production of prebiotic oligosaccharides by enzymatic process with addition of the dextransucrase enzyme to the clarified cashew apple juice. Dextran yield was favored by the combination of low concentrations of sucrose and reducing sugars. The formation of oligosaccharides was favored by increasing the concentration of reducing sugars and by the combination of high concentrations of sucrose and reducing sugars, the highest concentration of oligosaccharides obtained was 104.73 g/L and the qualitative analysis showed that at concentrations of 25 g/L and 75 g/L of sucrose and reducing sugar, respectively, it is possible to obtain oligosaccharides of degree of polymerization up to 12. The juice containing prebiotic oligosaccharide is a potential new functional beverage.

Stability Study of Crude Dextransucrase from Leuconostoc citreum NRRL B-742.

In the present work, the stability of crude dextransucrase from Leuconostoc citreum B-742 was evaluated in synthetic and in cashew apple juice culture broth. Optimum stability conditions for dextransucrase from L. citreum B-742 were different from the reported for its parental industrial strain enzyme (L. mesenteroides B-512F). Crude dextransucrase, from L. citreum B-742, produced using cashew apple juice as substrate, presented higher stability than the crude enzyme produced using synthetic culture medium, showing the same behavior previously reported for dextransucrase from L. mesenteroides B-512F. The crude enzyme presented good stability in cashew apple juice for 48 h at 25°C and pH 6.5.

Enzyme synthesis of oligosaccharides using cashew apple juice as substrate.

The use of agriculture substrates in industrial biotechnological processes has been increasing because of their low cost. In this work, the use of clarified cashew apple juice was investigated as substrate for enzyme synthesis of prebiotic oligosaccharide. The results showed that cashew apple juice is a good source of reducing sugars and can be used as substrate for the production of dextransucrase by Leuconostoc citreum B-742 for the synthesis of oligosaccharides using the crude enzyme. Optimal oligosaccharide yield (approximately 80%) was obtained for sucrose concentrations lower than 60 g/L and reducing sugar concentrations higher than 100 g/L.

Kinetic study of mannitol production using cashew apple juice as substrate.

The use of agriculture excess as substrate in industrial fermentations became an interesting alternative to reduce production costs and to reduce negative environmental impact caused by the disposal of these products. In this work, a kinetic study of mannitol production using cashew apple juice as substrate was studied. The carbohydrates of cashew apple juice are glucose and fructose. Sucrose addition favored the yield of mannitol (85%) at the expense of lower productivity. The best results were obtained applying only cashew apple juice as substrate, containing 50 g L(-1) of total reducing sugar (28 g L(-1) of fructose), yielding 18 g L(-1) of mannitol with 67% of fructose conversion into mannitol and productivity of 1.8 g L(-1) h(-1).