Online recovery of nisin during fermentation and its effect on nisin production in biofilm reactor

An online removal of nisin by silicic acid coupled with a micro-filter module was proposed as an alternative to reduce detrimental effects caused by adsorption of nisin onto producer, enzymatic degradation by protease, and product inhibition during fermentation. In this study, silicic acid was successfully used to recover nisin from the fermentation broth of Lactococcus lactis subsp. lactis NIZO 22186. The effect of pH (at 6.8 and 3.0) during adsorption process and several eluents (deionized water, 20% ethanol, 1 M NaCl, and 1 M NaCl + 20% ethanol) for desorption were evaluated in a small batch scale. Higher nisin adsorption onto silicic acid was achieved when the adsorption was carried out at pH 6.8 (67% adsorption) than at pH 3.0 (54% adsorption). The maximum recovery was achieved (47% of nisin was harvested) when the adsorption was carried out at pH 6.8 and 1 M NaCl + 20% ethanol was used as an eluent for desorption. Most importantly, nisin production was significantly enhanced (7,445 IU/ml) when compared with the batch fermentation without the online recovery (1,897 IU/ml). This may possibly be attributed to preventing the loss of nisin due the detrimental effects and a higher biomass density achieved during online recovery process, which stimulated production of nisin during fermentation.     

Antimicrobial activities of Ferulago essential oils

Essential oils from Ferulago asparagifolia Boiss., F. galbanifera (Miller) W. Koch, F. humilis Boiss. (Endemic), F. trachycarpa Boiss. growing in Turkey were evaluated against 15 microorganisms for their antifungal and antibacterial activity using an agar tube dilution and microdilution broth susceptibility assay, respectively. The essential oil compositions were investigated by GC/MS. Inhibitory effects against Escherichia coli, Enterobacter aerogenes, Candida albicans, Gaeumannomyces graminis var. tritici, Sclerotium rolfsii and Fusarium moniliforme were remarkable. Results are discussed in comparison with the chemical composition of the essential oils.     

Enhanced production ofd(−)-lactic acid by mutants ofLactobacillus delbrueckii ATCC 9649

Summary Chemical mutagenesis with ethyl methanesulfonate (EMS) was used to develop strains ofLactobacillus delbrueckii (ATCC 9649) that tolerated increased lactic acid concentrations while continuously producing the acid. Three mutants (DP2, DP3 and DP4) were compared with wild-typeL. delbrueckii by standing fermentations with different glucose concentrations. All three mutants produced higher levels of lactic acid than the wild-type. In pH-controlled (pH 6.0) stirred-tank-batch fermentations, mutant DP3 in 12% glucose, 1% yeast extract/mineral salt/oleic acid medium produced lactic acid at a rate that was more than 2-times faster than the wild-type. Mutant DP3 also produced 77 g/l lactic acid compared with 58 g/l for the wild-type. Overall, compated with wild-type, the mutants DP2 and DP3 exhibited faster specific growth rates, shorter lag phases, greater lactic acid yields, tolerated higher lactic acid concentrations, and produced as much as 12% lactic acid in 12% glucose, 3% yeast extract/mineral salt/oleic acid medium which required an additional 9% glucose when the residual glucose concentration decreased to 3%. Mutant DP3 was stable for over 1.5 years (stored freeze dried). The strain development procedure was very successful; mutants with enhanced lactic acid-producing capacity were obtained each time the procedure was employed.Journal Paper No. J-14087 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Projects No. 2889 and 0178.     

Enhanced pullulan production in a biofilm reactor by using response surface methodology

Pullulan is a linear homopolysaccharide that is composed of glucose units and often described as α-1, 6-linked maltotriose. In this study, response surface methodology using Box–Behnken design was employed to study the effects of sucrose and nitrogen concentrations on pullulan production. A total of 15 experimental runs were carried out in a plastic composite support biofilm reactor. Three-dimensional response surface was generated to evaluate the effects of the factors and to obtain the optimum condition of each factor for maximum pullulan production. After 7-day fermentation with optimum condition, the pullulan production reached 60.7 g/l, which was 1.8 times higher than the result from initial medium, and was the highest yield reported to date. The quality analysis demonstrated that the purity of produced pullulan was 95.2%, and its viscosity was 2.5 centipoise (cP), which is higher than the commercial pullulan and related to its molecular weight. Fourier transform infrared spectroscopy (FTIR) also suggested that the produced exopolysaccharide was pullulan.     

Tailoring the Antibody Response to Aggregated A? Using Novel Alzheimer-Vaccines

Recent evidence suggests Alzheimer-Disease (AD) to be driven by aggregated Aß. Capitalizing on the mechanism of molecular mimicry and applying several selection layers, we screened peptide libraries for moieties inducing antibodies selectively reacting with Aß-aggregates. The technology identified a pool of peptide candidates; two, AFFITOPES AD01 and AD02, were assessed as vaccination antigens and compared to Aβ1-6, the targeted epitope. When conjugated to Keyhole Limpet Hemocyanin (KLH) and adjuvanted with aluminum, all three peptides induced Aß-targeting antibodies (Abs). In contrast to Aß1-6, AD01- or AD02-induced Abs were characterized by selectivity for aggregated forms of Aß and absence of reactivity with related molecules such as Amyloid Precursor Protein (APP)/ secreted APP-alpha (sAPPa). Administration of AFFITOPE-vaccines to APP-transgenic mice was found to reduce their cerebral amyloid burden, the associated neuropathological alterations and to improve their cognitive functions. Thus, the AFFITOME-technology delivers vaccines capable of inducing a distinct Ab response. Their features may be beneficial to AD-patients, a hypothesis currently tested within a phase-II-study.     

Synthesis,structural, cytotoxic and pharmacokinetic evaluation of some thiosemicarbazone derivatives

Iron(III) and nickel(II) complexes bearing a thiosemicarbazone framework were synthesized by a one‐pot synthesis method. The structures were characterized by elemental analysis, IR, ¹H NMR, APCI Mass, conductivity, magnetic moment measurements. Molecular and crystal structures of the iron(III) complex were obtained from single‐crystal X‐ray diffraction. The findings showed that the metal atom adopts a slightly distorted square‐pyramidal coordination, with the four donor atoms of the thiosemicarbazone ligand defining the basal plane and a chloride atom occupying the apical position. In the crystal lattice, the structure is stabilized by intermolecular O─H···O and C─H···O interactions. The cytotoxic activity was studied by MTT assay, the expression levels of cytochrome P450 (CYP) enzymes by Western blot, and the lipophilicity (LogP) by using the shake‐flask method, another pharmacokinetic parameter. The findings showed that the IC ₅₀ values decreased with the decrease of the LogP values of the substances. Cytochrome P450 expression levels were found specific for each compound and each cell line. As a result, the pharmacokinetic properties of the newly synthesized thiosemicarbazone compounds are crucial for oral administration and provide us with clues for prospective in vivo studies.     

The importance of oxidative stress in patients with chronic renal failure whose hypertension is treated with peritoneal dialysis

Increased oxidative stress is a well-known phenomenon in dialysis patients. However, the contribution of hypertension to the oxidative stress in peritoneal dialysis patients has not yet been assessed. The present study aimed to investigate if hypertension had an additional effect on oxidative stress in peritoneal dialysis patients. A total of 50 patients treated with peritoneal dialysis were divided into two groups: The patients with mean of last three blood pressure results as 135/90 mmHg and above were considered hypertensive, the patients with lower blood pressure were considered normotensive. The control group included 25 healthy individuals. Serum malondialdehyde (MDA), advanced oxidation protein product (AOPP), myeloperoxidase (MPO), catalase (CAT) and glutathione peroxidase (GSH-Px) levels were measured in all groups. MDA level, an indicator of lipid peroxidation, was significantly higher in the hypertensive group compared to the control group, while the increase in the normotensive group was not significant. However, the difference between the hypertensive and normotensive groups was significant. The levels of AOPP, an indicator of protein oxidation level, and MPO, an indicator of neutrophil activation, were not different between the groups, while the activities of antioxidant CAT and GSH-Px decreased in both normotensive and hypertensive groups compared to the control group, and there was no significant difference between the patient groups. This study shows that both normotensive and hypertensive peritoneal dialysis patients have increased-oxidative stress and decreased antioxidant levels and hypertension might have an additional effect on oxidative stress by increasing MDA level in peritoneal dialysis patients.     

A rapid detection of multidrug-resistant Mycobacterium tuberculosis by a nitrate reductase assay on blood agar

The susceptibility of 49 Mycobacterium tuberculosis clinical isolates to isoniazid (INH) and rifampisin (RIF) (28 multi-drug resistant-tuberculosis samples) was determined by a nitrate reductase assay (NRA) on blood agar. Agreement between the NRA and other testing methods was found to be 93.8% for both INH and RIF. The sensitivity, specificity, positive predictive value and negative predictive value for INH were 92.8%, 94.2%, 86.6% and 97%, respectively. The sensitivity, specificity, positive predictive value and negative predictive value for RIF were 90.4%, 96.4%, 95% and 93.1%. In conclusion, we show here that blood agar can be used effectively for the NRA test.