Influence of Culture Media Formulated with Agroindustrial Wastes on the Antimicrobial Activity of Lactic Acid Bacteria.

The discarding of wastes into the environment is a significant problem for many communities. Still, food waste can be used for lactic acid bacteria (LAB) growth. Here, we evaluated three growth media equivalent to de Mann Rogosa Sharpe (MRS), using apple bagasse, yeast waste, fish flour, forage oats, and cheese whey. Cell-free supernatants of eight LAB strains were tested for antimicrobial activity against nine indicator microorganisms. The supernatants were also evaluated for protein content, reducing sugars, pH, and lactic acid concentration. Cell-free supernatants from fish flour broth (FFB) LAB growth were the most effective. The strain Leuconostoc mesenteroides PIM5 presented the best activity in all media. L. mesenteroides CAL14 completely inhibited L. monocytogenes and strongly inhibited Bacillus cereus (91.1%). The strain L. mesenteroides PIM5 consumed more proteins (77.42%) and reducing sugars (56.08%) in FFB than in MRS broth (51.78% and 30.58%, respectively). Culture media formulated with agroindustrial wastes positively improved the antimicrobial activity of selected LAB, probably due to the production of antimicrobial peptides or bacteriocins.

Construction and Functional Analysis of the Recombinant Bacteriocins Weissellicin-MBF from Weissella confusa MBF8-1.

BACKGROUND: Bacteriocins (Bac1, Bac2, and Bac3) from Weissella confusa MBF8-1, weissellicin- MBF, have been reported as potential alternative substances as well as complements to the existing antibiotics against many antimicrobial-resistant pathogens. Previously, the genes encoded in the large plasmid, pWcMBF8-1, and the spermicidal activity of their synthetic peptides, originally discovered Indonesia, have been studied. Three synthetic bacteriocins peptides of this weissellicin-MBF have been reported for their potential activities, i.e. antibacterial and spermicidal. OBJECTIVE: The aim of this study was to construct the recombinant Bacteriocin (r-Bac) genes, as well as to investigate the gene expressions and their functional analysis. METHODS: Here, the recombinant Bacteriocin (r-Bac) genes were constructed and the recombinant peptides (r-Bac1, r-Bac2, and r-Bac3) in B. subtilis DB403 cells were produced on a large scale. After purification, using the His-tag affinity column, their potential bioactivities were measured as well as their antibacterial minimum inhibitory concentrations against Leuconostoc mesenteroides and Micrococcus luteus, were determined. RESULTS: Pure His-tag-recombinant Bac1, Bac2, and Bac3 were obtained and they could inhibit the growth of L. mesenteroides and M. luteus. CONCLUSION: The recombinant bacteriocin could be obtained although with weak activity in inhibiting gram-positive bacterial growth.

Production of electricity and reduction of high-fat diet-induced IL-6 by glucose fermentation of Leuconostoc mesenteroides.

Electrogenic bacteria can mediate electron transfer to conserve energy and promote growth. To examine bacterial electrogenicity, an L. mesenteroides EH-1 strain was cultured in rich media in the presence and absence of 2% glucose. After 12 h incubation, glucose triggered fermentation of L. mesenteroides EH-1 to produce >10 mmol/l acetate and elicit electricity measured by voltage changes. The electricity production was mediated by glucose fermentation since pre-treatment of L. mesenteroides EH-1 with furfural, a fermentation inhibitor, completely diminished the voltage increases. The deficiency of furfural pre-treated L. mesenteroides EH-1 in electricity production can be restored by the external addition of acetate into the bacterial culture, suggesting the function of acetate as an electron donor. Oral administration of HFD-fed mice with L. mesenteroides EH-1 in the presence or absence of glucose significantly attenuated the high level of pro-inflammatory IL-6 cytokine in blood. Bacterial electricity can be elicited by fermentation. Supplementation of fermenting and electrogenic L. mesenteroides EH-1 may provide a novel approach for the reduction of pro-inflammatory IL-6 cytokine that increased in chronic inflammation, autoimmune diseases, cancers, and infections.

Combination of natural antimicrobials for contamination control in ethanol production.

Presence of bacterial contaminants at levels > 107 colony forming units per milliliter (CFU/mL) during ethanol production processes reduces the alcoholic fermentation yield by 30%. Antibiotics are currently used to control contamination, but their residues may be detected in yeast extract, restricting this by-product trade to several countries. Thus, the objective of this study was to assess antimicrobial activity of the natural compounds hops extract, 4-hydroxybenzoic acid, nisin Z, and lysozyme against Lactobacillus fermentum, Leuconostoc mesenteroides, and Saccharomyces cerevisiae, aiming development of a formula. Minimum Inhibitory Concentration of each antimicrobial was determined for bacteria and subsequently, nisin (30 mg/L) and hops extract (5 mg/L) were tested together, showing inhibitory effects combining doses of each antimicrobial that were equivalent to an eightfold reduction of their original Minimum Inhibitory Concentrations (3.75 and 0.625 mg/L, respectively), resulting in a FICIndex of 0.25. Thereon, a formula containing both compounds was developed and tested in fermentation assays, promoting reductions on bacterial population and no severe interferences in yeast viability or population even at extreme doses. Therefore, these compounds have great potential to successfully substitute conventional antibiotics in the ethanol industry.

Physicochemical properties and prebiotic activities of polysaccharides from longan pulp based on different extraction techniques.

Longan pulp polysaccharides were extracted with hot water (LP-H), superfine grinding (LP-S) and superfine grinding-assisted enzymatic treatments (LP-SE). The yields, physicochemical properties and prebiotic activities of polysaccharides were investigated. Compared with LP-H and LP-S, the yield, sugar content, solubility, arabinose and mannose percentage of LP-SE increased while its apparent viscosity, particle size, Mw and glucose percentage declined. Three LPs contained similar glycosidic linkage of →3)-α-l-Araf-(1→, →3,6)-ß-d-Galp-(1→ and α-l-Rhap(l→, while they each contained specific glycosidic linkage of →4)-ß-d-Glcp(l→, →4)-ß-d-Galp-(1→ and →5)-α-l-Araf-(1→ in LP-H, LP-S and LP-SE, respectively. Moreover, LP-SE exhibited stronger stimulation than LP-H and LP-S on the proliferation of Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus fermentum and Leuconostoc mesenteroides. The results indicated three extraction methods had some effect on chemical composition and structure of polysaccharide. LP-SE extracted by superfine grinding-assisted enzymatic treatment exhibited the highest prebiotic activities, which have a great potential in applying in functional food and medical industry.

Bacteremia by Leuconostoc mesenteroides in an immunocompetent patient with chronic Chagas disease: a case report.

BACKGROUND: The Leuconostoc mesenteroides are members of the Streptococcae family and currently has been recognized as potential pathogens. This case describes a bacteremia caused by L. mesenteroides in an immunocompetent patient affected by Chagas disease. CASE PRESENTATION: A 67-year-old female patient with chagasic megaesophagus and megacolon was submitted to a Heller myotomy for achalasia in 2000 and endoscopic dilatation in 2015. Patient was admitted to the Nutrology Ward in May 2016 with protein-calorie malnutrition associated with achalasia and receiving enteral nutrition. In July 2016, the patient underwent a Serra-Doria surgery. In the third postoperative day she presented an important abdominal distension. She was submitted to a new surgical intervention, and then a terminal ileum perforation was detected, leading the surgeon to perform an enterectomy with side-to-side anastomosis. The next day after the surgery (4th postoperative day) the patient presented a decreased level of consciousness (Glasgow coma scale = 8), hypotension and hypoxemia. In two samples of blood cultures there was growth of Leuconostoc mesenteroides. Susceptibility pattern was evaluated by the diffusion disk method. The microorganism was susceptible to penicillin, ampicillin, chloramphenicol, erythromycin, and fluoroquinolones, but resistant to rifampin, tetracycline, vancomycin and teicoplanin. CONCLUSION: We concluded that infections caused by L. mesenteroides is serious and should be considered not only in settings of immunosuppression and prolonged antimicrobial use, but also in immunocompetent patients undergoing surgeries involving the gastrointestinal tract.

Microbial inactivation and MLF performances of Tempranillo Rioja wines treated with PEF after alcoholic fermentation.

This study was performed with the aim of reducing the microbial communities of wines after alcoholic fermentation to improve the establishment of commercial Oenococcus oeni inoculum for developing the malolactic fermentation. Microbial community reduction was accomplished by applying Pulsed Electric Field (PEF) technology to four different wines. Overall, significant reductions in yeast population were observed. To a lesser extent, lactic acid bacteria were reduced while acetic acid bacteria were completely eliminated after the PEF treatment. In three out of the four tested wines, a decrease in the competitive pressure between microorganisms due to the detected reduction led to a general but slight shortening of the malolactic fermentation duration. In the wine with the most adverse conditions to commercial starter establishment, the shortest malolactic fermentation was reached after PEF treatment. Finally, the sensorial quality of three out of the four treated wines was considered better after the PEF treatment. Therefore, PEF technology meant an important tool for improving the malolactic fermentation performance.

Sugar Beet Pulp as Leuconostoc mesenteroides T3 Support for Enhanced Dextransucrase Production on Molasses.

Sugar beet pulp (SBP) and molasses, as an agro industrial waste material, are produced in large amounts annually. Thus, a major challenge nowadays is to develop procedures that could increase the value of the generated waste. In this study, SBP as a support for cell immobilization and molasses as a source of nutrients were used for a dextransucrase (DS) production by Leuconostoc mesenteroides T3. The influence of SBP in native form (SBP-N) and after treatment with NaOH (SBP-NaOH) on DS production was investigated. The optimal medium composition for the maximum DS production was determined by varying the concentration of molasses, SBP, and sucrose. The maximum DS yield of 2.02 U/ml was obtained in the medium with 2.5 % of molasses, 2.5 % SBP-NaOH, and 4 % of sucrose concentration. Scanning electron microscopy (SEM) showed immobilization of Lc. mesenteroides T3 cells onto SBP-NaOH. According to the obtained results, the production of DS on molasses could be improved by using NaOH-treated SBP as a carrier for whole-cell immobilization. Our study reveals the basis for the development of process for DS production with additional reduction of expenses by using waste materials for obtaining the valuable biotechnological product.