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In this study, lactobionic acid (LBA) was incorporated into poly(vinyl alcohol) (PVA) and poly(ε-caprolactone) (PCL) by electrospinning. The antimicrobial effects of the nanofibers were tested using the agar diffusion method. Only the PVA formulations showed antimicrobial activity against Staphylococcus aureus. The PVA and PCL nanofibers containing LBA showed antioxidant activity ranging from 690.33 to 798.67 µM TEAC when tested by the ABTS method. The characterization of nanofibers was performed by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and mechanical analysis. The nanofibers showed a uniform morphology and their average diameters ranged from 295.5 to 2778.2 nm. The LBA addition induced a decrease in the enthalpy of fusion (ΔHm) of PVA and PCL nanofibers, while the Young's modulus was reduced from 20 to 10 MPa in PCL and PCL-LBA nanofibers, respectively. No relevant differences were observed between the FTIR spectra of the control nanofibers and the nanofibers containing LBA. All nanofibers presented hemolysis rate below 2%, thus can be considered as non-hemolytic materials. Further toxicological assessment was performed with the selected formulation PVA10 + LBA. The evaluations by mutagenicity assay, cell survival measurement, cell viability analysis and agar diffusion cytotoxicity test indicated that there are no significant toxic effects. Electrospun nanofibers PVA-LBA and PCL-LBA were successfully produced, showing good thermal and mechanical properties and non-toxic effects. Furthermore, the nanofibers showed antimicrobial activity and antioxidant activity. The findings of this study indicate that PVA and PCL electrospun nanofibers incorporating LBA are promising for use in packaging applications. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a malignant tumor that affects many patients diagnosed with hepatic cell inflammation and liver cirrhosis. Targeted polymeric nanocapsules could facilitate the internalization and accumulation of anticancer drugs. Dual-targeted folic acid/lactobionic acid-poly lactic co-glycolic acid nanocapsules (NCs) were prepared and loaded with pterostilbene (PTN) and characterized for their physicochemical properties, as well as in vitro and in vivo anticancer activity. NCs displayed a size of 222 nm, zeta potential of − 16.5 mV, and sustained release for 48 h. The IC50 of PTN NCs (5.87 ± 0.8 µg/mL) was 20 times lower than unencapsulated PTN (121.26 ± 9.42 µg/mL) on HepG2 liver cancer cells owing to the enhanced cellular uptake of the former, as delineated by flow cytometry. In vivo study on HCC-induced animals delineated the superiority of the dual-targeted NCs over the unencapsulated PTN, which significantly reduced the liver markers ALT, AST, and ALP, as well as the tumor-related markers AFP and Bcl2, and elevated the anti-apoptotic marker caspase 3. Furthermore, the NCs significantly reduced the oxidative stress and exhibited almost comparable histological features to the normal group. Therefore, it can be concluded that the dual-ligated folic acid/lactobionic acid nanocapsules can be considered a promising potential treatment option for hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Recently, deep eutectic solvents (DESs) have attracted considerable interest in analytical chemistry. This work described the enantioseparations of twenty amino alcohol drugs with several DESs based on lactobionic acid (LA) as the sole chiral selector in capillary electrophoresis (CE) firstly. Compared to the single LA system and the ionic liquid/LA synergistic system, the DES system exhibited considerably improved separations. The influences of some key parameters on separations were investigated in detail. This work also experimentally demonstrated that the carboxyl group was indispensable in the process of chiral recognition. The mechanisms of the improvements of DESs on enantioseparations were studied via ultraviolet spectroscopy. Furthermore, the proposed method was used to determine the enantiomeric purity of propranolol hydrochloride successfully. This is the first time that chiral DESs were utilized as the sole chiral selectors in CE, and this strategy has opened up a new prospect for the use of DESs in enantioseparation. [ABSTRACT FROM AUTHOR]

We report a novel production process for lactobionic acid (LBA) production using an engineered Neurospora crassa strain F5. The wild-type N. crassa strain produces cellobiose dehydrogenase (CDH) and uses lactose as a carbon source. N. crassa strain F5, which was constructed by deleting six out of the seven β-glucosidases in the wild type, showed a much slower lactose utilization rate and produced a much higher level of cellobiose dehydrogenase (CDH) than the wild type. Strain N. crassa F5 produced CDH and laccase simultaneously on the pretreated wheat straw with 3 µM of cycloheximide added as the laccase inducer. The deproteinized cheese whey was added directly to the shake flasks with the fungus present to achieve LBA production. Strain F5 produced about 37 g/L of LBA from 45 g/L of lactose in 27 h since deproteinized cheese whey addition. The yield of LBA from consumed lactose was about 85%, and the LBA productivity achieved was about 1.37 g/L/h. [ABSTRACT FROM AUTHOR]

Purpose: Since there is a lack of clear information regarding the benefit to combine supportive therapies (such as artificial tears) to mitomycin C (MMC) in the treatment of ocular surface neoplasia, the primary purpose of the study was to evaluate hyaluronic acid eye drops and hyaluronic acid-conjugated lactobionic acid (LACTOyal FREE) eye drops as supportive therapy. Methods: Retrospective evaluation of patients with ocular surface squamous neoplasia or conjunctival melanocytic tumor treated with MMC, who had used also artificial tears as supportive treatment. A 6-month follow-up with evaluation of subjective and objective tests for ocular surface integrity was conducted. Results: A total of 35 patients were analyzed, most of them with squamous disease (71.4%). The break-up time (BUT), Ocular Surface Disease Index (OSDI) and Schirmer test values showed a significant difference at any time point with overall population. No statistical difference was found among subgroups (Lactoyal vs No Lactoyal). Conclusion: The use of an ancillary therapy based on hyaluronic acid allows to improve both subjective and objective ocular parameters, reducing MMC induced adverse effects. Meantime, hyaluronic acid-conjugated lactobionic acid eye drops highlighted the same advantages with a more positive trend in OSDI results. [ABSTRACT FROM AUTHOR]

Lactobionic acid (LBA) has recently emerged as an important substance in various industries, such as cosmetics, foods, and pharmaceuticals. In this study, we developed a simple, efficient, and high-throughput method for screening LBA-producing microorganisms. First, an agar plate was prepared to isolate LBA-producing microorganisms by utilizing the property of LBA to solubilize colloidal calcium carbonate (CaCO3), resulting in the formation of a clear halo around colonies on a nutrient broth agar plate containing CaCO3. Subsequently, LBA production from the isolated microorganisms was confirmed using high-performance liquid chromatography (HPLC). Approximately 560 colonies from soil samples in Ulsan, Korea were screened and a clear halo was observed around three colonies on the prepared LBA-screening agar plate. The culture supernatants of these three colonies were analyzed by HPLC and it was found that these strains could produce LBA from lactose. Phylogenetic analysis by comparing their 16S rRNA nucleotide sequences revealed that these strains were Pseudomonas spp. and Alcaligenes faecalis. This is the first report highlighting that A. faecalis can produce LBA. As per the aforementioned results, the LBA-screening method that we devised here is highly effective for isolating and identifying new LBA-producing microorganisms. [ABSTRACT FROM AUTHOR]

In previous and present studies, four enzymes (GCD1, GCD3, GCD4, and MQO1) have been found to act as lactose-oxidizing enzymes of Pseudomonas taetrolens. To investigate whether the four enzymes were the only lactose-oxidizing enzymes of P. taetrolens, we performed the inactivation of gcd1, gcd3, gcd4, and mqo1 genes in P. taetrolens. Compared to the wild-type strain, the lactobionic acid (LBA)-producing ability of P. taetrolens ∆gcd1 ∆gcd3 ∆gcd4 ∆mqo1 was only slightly decreased, implying that P. taetrolens possesses more lactose-oxidizing enzymes. Interestingly, the four lactose-oxidizing enzymes were all pyrroloquinoline quinone (PQQ)-dependent. To identify other unidentified lactose-oxidizing enzymes of P. taetrolens, we prevented the synthesis of PQQ in P. taetrolens by inactivating the genes related to PQQ synthesis such as pqqC, pqqD, and pqqE. Surprisingly, all three knocked-out strains were unable to convert lactose to LBA, indicating that all lactose-oxidizing enzymes in P. taetrolens were inactivated by eliminating PQQ synthesis. In addition, external PQQ supplementation restored the LBA production ability of P. taetrolens ∆pqqC, comparable to the wild-type strain. These results indicate that all lactose-oxidizing enzymes in P. taetrolens are PQQ-dependent., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The aim of this paper was to assess the prebiotic properties of lactobionic acid in the human gastrointestinal model. Five different strains of probiotic, or potentially probiotic, bacteria were used in the microencapsulation process; these were Lactobacillus casei Shirota, Lactococcus lactis ATCC1, Lactobacillus fermentum, Bifidobacterium bifidum DSM 20456, and Bifidobacterium bifidum DSM 20082. Starch with a concentration of 4% (w/v) and a degree of substitution of 0.03 was used to produce the microcapsules. The alginian microcapsules we produced functioned as a protective barrier for the probiotic microorganisms closed in them, protecting them from adverse conditions in the human digestive tract. The microorganisms could thus survive the encapsulation process and the in vitro model digestion process while retaining the ability to produce biomass. Factors such as pH and time affect the solution of alginate microcapsules. The capsule solution began when a pH of 7.4 was reached; this corresponded to pH in the target probiotic site, an in vitro model of the colon. The capsules had completely dissolved after 24 h of digestion at a pH of 8. The addition of lactobionic acid stimulated the growth of probiotic and potentially probiotic bacteria, thus confirming its prebiotic properties. [ABSTRACT FROM AUTHOR]

The aim of this research was to develop a method of its production from whey using bacteria of the species Pseudomonas taetrolens. Analyses of the lactobionic acid production method from whey showed that the following factors have a significant effect on its efficiency: the frequency of whey batch feeding, pH and the type of bacteria application, i.e. microencapsulated vs. free. Lactose and lactobionic acid were assayed using high performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC–ESI–MS). The highest concentration of lactobionic acid of 22.03 mg/cm3 was obtained when whey was batch fed at 72-h intervals, pH was maintained at 6.25 and bacteria were enclosed in alginate microcapsules. [ABSTRACT FROM AUTHOR]

An in situ zeolite imidazole metal organic framework-90 (ZIF-90) modified capillary was prepared via the method of solvothermal synthesis. The coating of ZIF-90 was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and EOF. Capillary electrochromatography–based enantioseparation of the basic drugs propranolol (PRO), metoprolol (MET), atenolol (ATE), bisoprolol (BIS), and sotalol (SOT) was performed using lactobionic acid (LA) as the chiral selector. Compared with an uncoated silica capillary, the resolutions are greatly improved (PRO 1.40 → 3.23; MET 1.07 → 3.19; ATE 1.07 → 3.15; BIS 1.16 → 3.41; SOT 1.00 → 2.79). Effects of buffer pH values, proportion of organic additives, concentration of lactobionic acid, and applied voltage were investigated. [ABSTRACT FROM AUTHOR]

Lactobionic acid and sorbitol are produced from lactose and fructose in reactions catalyzed by glucose–fructose oxidoreductase and glucono-δ-lactonase, periplasmic enzymes present in Zymomonas mobilis cells. Considering the previously established laboratory-scale process parameters, the bioproduction of lactobionic acid was explored to enable the transfer of this technology to the productive sector. Aspects such as pH, temperature, reuse and storage conditions of Ca-alginate immobilized Z. mobilis cells, and large-scale bioconversion were assessed. Greatest catalyst performance was observed between pH range of 6.4 and 6.8 and from 39 to 43 °C. The immobilized biocatalyst was reused for twenty three 24-h batches preserving the enzymatic activity. The activity was maintained during biocatalyst storage for up to 120 days. Statistically similar results, approximately 510 mmol/L of lactobionic acid, were attained in bioconversion of 0.2 and 3.0 L, indicating the potential of this technique of lactobionic acid production to be scaled up to the industrial level. [ABSTRACT FROM AUTHOR]

Lactobionic acid (LBA) was produced by fermentation of Pseudomonas taetrolens. First, to increase the production of LBA by P. taetrolens, we controlled the pH of culture medium by CaCO3 addition (30 g/L) and then examined the initial lactose concentration ranging from 50 to 200 g/L and the growth temperature ranging from 20 to 37 °C. Both the LBA production titer (180 g/L) and the productivity (2.5 g/L h) were highest at 200 g/L lactose concentration and 25 °C of cell growth temperature in shake-flask culture. Although the production of LBA (178 g/L) was almost similar during the batch fermentation of P. taetrolens using 5 L bioreactor, the LBA productivity highly increased to 4.9 g/L h. The method using ethanol precipitation and ion-exchange chromatography was developed to recover the pure LBA from the fermentation broth. The optimum volume of ethanol and pH of culture medium for the precipitation of Ca2+ salt form of LBA were six volume of ethanol and pH 6.5, respectively. The cation-exchange resin T42 finally showed the best recovery yield (97.6%) of LBA from the culture supernatant. The production titer (178 g/L) and the productivity (4.9 g/L h) of lactobionic acid in this study were highest among the previous studies ever reported using P. taetrolens as a production strain of LBA. [ABSTRACT FROM AUTHOR]

Pseudomonas taetrolens constitutes an efficient platform for the biosynthesis of lactobionic acid, a potentially prebiotic compound. Unfortunately, an amensalistic interaction has been demonstrated between P. taetrolens and probiotic lactic acid bacteria (LAB), characterized by the competitive exclusion of P. taetrolens, hindering the in situ production of fermented dairy products with synbiotic properties. In the present research, encapsulation was explored as a barrier to the diffusion of the antimicrobial metabolites generated by LAB. Mixed fermentations involving P. taetrolens LMG 2336 and Lactobacillus casei CECT 475 were cultivated, entrapping both microorganisms alternately. Alginate, alginate/starch and carboxymethyl cellulose/k-carrageenan were tested as encapsulating agents. The immobilization of L. casei in 2% alginate/2% starch beads was found to be the best strategy, improving the production of lactobionic acid by 182% with respect to co-cultures with free cells. This study proves the potential of LAB encapsulation for the protection of sensitive strains in mixed food fermentations. [ABSTRACT FROM AUTHOR]

The aim of this research was to analyze the antioxidant and prebiotic properties of lactobionic acid and to develop a method of producing it from whey using the bacterium Pseudomonas taetrolens. Prebiotic properties were tested with selected bacterial strains that exhibit probiotic properties, while the antioxidant efficacy was tested using cold-pressed rapeseed oil. A particularly evident prebiotic effect was observed with the bacterium Lactobacillus fermentum with a lactobionic acid concentration of 16 mg/cm3. The growth curves of microorganisms in a substrate with various levels of lactobionic acid showed similarities between Lactococcus lactis, Lactobacillus acidophilus DSM 20242, Lactobacillus acidophilus L-AH1, Lactobacillus acidophilus NCDO, Lactobacillus delbrueckii A, Lactobacillus casei, Lactobacillus casei Shirota, Bifidobacterium bifidum DSM 20215, and Bifidobacterium bifidum DSM 20456, where a short logarithmic growth phase could be distinguished, in comparison to the growth of Lactobacillus fermentum and Lactobacillus acidophilus CH-5, where the logarithmic growth phase was extended. Bifidobacterium bifidum DSM 20082 and Bifidobacterium bifidum DSM 20239 form a separate group. The greater the amount of lactobionic acid added, the higher its activity. The greatest oxidation inhibition efficacy in rapeseed oil was recorded on day 10 of storage at 60 °C with an acid content of 10 mg/cm3. Expressed as a percentage reduction of peroxide value, this effect was 19.6%. The best result for preparations of lactobionic acid were found at 1 cm3 (22.03 mg/cm3), amounting to 7.3% on day 10 of the rapeseed oil thermostat test. [ABSTRACT FROM AUTHOR]

Equimolar amounts of lactobionic acid and sorbitol may be obtained in a reaction catalyzed by the enzymes glucose-fructose oxidoreductase and glucono-δ-lactonase, which are found in the periplasm of Zymomonas mobilis. These reactions are generally conducted using immobilized bacterial cells, and the cell treatment and immobilization steps are costly and time-consuming. This study evaluated alternatives to simplify the preparation of calcium alginate-immobilized biocatalyst and its application in different operation modes and types of reactors. It was possible to eliminate cell permeabilization with cetyltrimethylammonium bromide, and the reticulation of Z. mobilis cells with glutaraldehyde sufficed to inhibit the fermentative metabolism of carbohydrates by the bacterium, with accumulation of bioconversion products. When the process was carried out in a mechanically stirred reactor in batch mode, 530 mmol L of products were obtained in 24 h. The process was also tested in fed-batch mode so as to use of a larger amount of lactose, since it could not be used in the batch because of its low solubility in water. Under this condition, final products concentration reached 745 mmol L within 42 h. Similar results were obtained for reactions conducted in a pneumatically stirred reactor in batch and fed-batch modes, proving the potential use of this process in several industrial settings. [ABSTRACT FROM AUTHOR]

Pseudomonas taetrolens has recently been revealed as an effective microbial producer of lactobionic acid from carbohydrates contained in dairy byproducts. In terms of food industrial applications, the implementation of lactobionic acid biosynthesis coupled with the classic bacterial production of lactic acid appears an important goal. This research paper studies the simultaneous fermentation of residual cheese whey by P. taetrolens and Lactobacillus casei to co-produce lactic and lactobionic acids. Experimental data showed the importance of the interactions established between the two microorganisms. Changes in physiology, viability, growth, and productive capacity were tested experimentally. Lactobacillus was not seen to suffer any appreciable stress, but considerable variations were observed in the Pseudomonas behavior presumably owing to inhibitory lactic metabolites, interaction that can be classified as microbial amensalism. As to production, lactic acid remained without significant changes in mixed fermentations, whereas the production of lactobionic acid decreased sharply due to the competitive exclusion of Pseudomonas. [ABSTRACT FROM AUTHOR]

Pt and Au catalysts, 2 wt% metal loading, supported on SiO and AlO were used to study the effect of metal and support on the liquid-phase oxidation of lactose. Pt-based catalysts were prepared by incipient wetness impregnation while Au-based catalysts were obtained by the precipitation-deposition method. Catalytic tests were carried out in aqueous phase at 65 °C, using O as oxidizing agent and keeping pH constant at 9 by controlled addition of NaOH aqueous solution. In all of the cases, the only product of reaction detected and quantified was lactobionic acid. It was found that Pt supported on AlO was more active than Pt supported on SiO. This was explained on the basis that metal Pt dispersion on AlO was three times higher than on SiO. At the same time, Au/AlO catalyst was more active than Pt/AlO catalysts. The higher activity of Au/AlO was attributed to Au nanoparticles interacting with the support, as determined by transmission electron microscopy. It was also verified that Au/AlO activity was almost the same after two consecutive runs, indicating a good stability of the Au active phase. Kinetic studies were carried out by varying the initial concentration of lactose in the reaction mixture. A negative order respect to the reactant, determined applying a pseudo-homogeneous model, was estimated, which indicates that lactose molecules are strongly adsorbed on the surface of metal Au nanoparticles. A LHHW model, assuming that oxygen chemisorption was the controlling step, allowed to explain the negative order respect to lactose. [ABSTRACT FROM AUTHOR]

Objectives: To use the glucose-fructose oxidoreductase (GFOR) from Zymomonas mobilis and expressed in Escherichia coli for lactobionic acid production by conversion of lactose from whey. Results: The highest concentrations of lactobionic acid (3.2 mg ml) during oxidation of whey-derived lactose by E. coli was at 24 h. Introduction of GFOR gene from Z. mobilis, into E. coli improved enzyme yields compared to what is obtainable by fermentation of the donor strain. The production of lactobionic acid by E. coli was 2.6-times higher than by Z. mobilis. Conclusions: Recombinants of E. coli overexpressing the GFOR gene from Z. mobilis produced higher amount of lactobionoic acid from whey-derived lactose. [ABSTRACT FROM AUTHOR]

Microbial cell immobilization has long been considered as a potential bioprocessing strategy to increase both microorganisms' tolerance and fitness in fermentation systems. To date, little emphasis has been put on how the entrapped cells respond to the bioprocessing stresses encountered during the cultivation. The present work presents for the first time a methodology to decipher the real health status of the entrapped microorganisms by combining multiparameter flow cytometry with confocal fluorescence microscopy as monitoring tools. Comparison between resting free and immobilized cell-based systems enabled to characterize the spatial-temporal physiological response of entrapped Pseudomonas taetrolens cells during lactobionic acid production in submerged cultivation. Whereas cellular leakage from beads led to planktonic cells that faced a progressive loss of membrane integrity, immobilized cells underwent a prompt stress-induced physiological response featured by the predominance of cellular damaging. Moreover, visualization without matrix de-entrapment through confocal fluorescence microscopy revealed the overtime formation of cellular micro-colonies inside the beads. These micro-colonies comprised a shell made of dead cells, whereas the inward cells remained metabolically active. The proposed approach herein raises the possibility of using flow cytometry and confocal fluorescence microscopy as indicators of microbial cell immobilization, providing further key information on the health status and robustness of entrapped microorganisms. [ABSTRACT FROM AUTHOR]

Class I cellobiose dehydrogenases (CDHs) are extracellular hemoflavo enzymes produced at low levels by the Basidiomycetes (white rot fungi). In presence of suitable electron acceptors, e.g., cytochrome c, 2,6-dichlorophenol-indophenol, or metal ions, it oxidizes cellobiose to cellobionolactone. A stringent requirement for disaccharides makes CDH also useful for conversion of lactose to lactobionic acid, an important ingredient in pharma and detergent industry. In this work, class I CDH was produced using a newly identified white rot fungus Termitomyces sp. OE147. Four media were evaluated for CDH production, and maximum enzyme activity of 0.92 international unit (IU)/ml was obtained on Ludwig medium under submerged conditions. Statistical optimization of N source, which had significant effect on CDH production, using Box-Behnken design followed by optimization of inoculum size and age resulted in an increase in activity to 2.9 IU/ml and a productivity of ~25 IU/l/h. The nearly purified CDH exhibited high activity of 26.4 IU/mg protein on lactose indicating this enzyme to be useful for lactobionic acid synthesis. Some of the internal peptide sequences bore 100 % homology to the CDH produced in Myceliophthora thermophila. The fungal isolate was amenable to scale up, and an overall productivity of ~18 IU/l/h was obtained at 14-l level. [ABSTRACT FROM AUTHOR]

Lactobionic acid is a relatively new product derived from lactose oxidation, with high potential applications as a bioactive compound. Conducted experiments confirmed that both the time and temperature influenced the production of lactobionic acid during bioconversion of lactose using the Pseudomonas taetrolens bacteria. The study also investigated the effect of inoculum concentration on the production of lactobionic acid as a result of oxidation of whey-derived lactose. The highest concentration of lactobionic acid during oxidation of whey-derived lactose at a temperature of 30 °C by microorganisms. P. taetrolens was obtained during 50-h oxidation of the medium, which contained 25 % addition of the inoculum, in which the count of live cells was 2.85 × 10 CFU/ml. [ABSTRACT FROM AUTHOR]

Microbial physiological responses resulting from inappropriate bioprocessing conditions may have a marked impact on process performance within any fermentation system. The influence of different pH-control strategies on physiological status, microbial growth and lactobionic acid production from whey by Pseudomonas taetrolens during bioreactor cultivations has been investigated for the first time in this work. Both cellular behaviour and bioconversion efficiency from P. taetrolens were found to be negatively influenced by pH-control modes carried out at values lower than 6.0 and higher than 7.0. Production schemes were also influenced by the operational pH employed, with asynchronous production from damaged and metabolically active subpopulations at pH values lower than 6.0. Moreover, P. taetrolens showed reduced cellular proliferation and a subsequent delay in the onset of the production phase under acidic conditions (pH < 6.0). Unlike cultivations performed at 6.5, both pH-shift and pH-stat cultivation strategies performed at pH values lower than 6.0 resulted in decreased lactobionic acid production. Whereas the cellular response showed a stress-induced physiological response under acidic conditions, healthy functional cells were predominant at medium operational pH values (6.5-7.0). P. taetrolens thus displayed a robust physiological status at initial pH value of 6.5, resulting in an enhanced bioconversion yield and lactobionic acid productivity (7- and 4-fold higher compared to those attained at initial pH values of 4.5 and 5.0, respectively). These results have shown that pH-control modes strongly affected both the physiological response of cells and the biological performance of P. taetrolens, providing key information for bio-production of lactobionic acid on an industrial scale. [ABSTRACT FROM AUTHOR]

Aiming to develop polymeric self-assembly nanocarriers with potential applications in active drug targeting to the liver, linear and branched poly(ethylene oxide)-poly(propylene oxide) amphiphiles were conjugated to lactobionic acid (LA), a disaccharide of galactose and gluconic acid, by the conventional Steglich esterification reaction. The conjugation was confirmed by ATR/FT-IR, H-NMR, and C-NMR spectroscopy. Elemental analysis and MALDI-TOF mass spectrometry were employed to elucidate the conjugation extent and the final molecular weight, respectively. The critical micellar concentration (CMC), the size and size distribution and zeta potential of the pristine and modified polymeric micelles under different conditions of pH and temperature were characterized by dynamic light scattering (DLS). Conjugation with LA favored the micellization process, leading to a decrease of the CMC with respect to the pristine counterpart, this phenomenon being independent of the pH and the temperature. At 37 °C, micelles made of pristine copolymers showed a monomodal size distribution between 12.8 and 24.4 nm. Conversely, LA-conjugated micelles showed a bimodal size pattern that comprised a main fraction of relatively small size (11.6-22.2 nm) and a second one with remarkably larger sizes of up to 941.4 nm. The former corresponded to single micelles, while the latter would indicate a secondary aggregation phenomenon. The spherical morphology of LA-micelles was visualized by transmission electron microscopy (TEM). Finally, to assess the ability of the LA-conjugated micelles to interact with lectin-like receptors, samples were incubated with concanavalin A at 37 °C and the size and size distribution were monitored by DLS. Findings indicated that regardless of the relatively weak affinity of this vegetal lectin for galactose, micelles underwent agglutination probably through the interaction of a secondary site in the lectin with the gluconic acid unit of LA. [ABSTRACT FROM AUTHOR]

Physiological heterogeneity constitutes a critical parameter in biotechnological systems since both metabolite yield and productivity are often hampered by the presence of undesired physiological cell subpopulations. In the present study, the physiological status and functionality of Pseudomonas taetrolens cells were monitored by multiparameter flow cytometry during fermentative lactobionic acid production at the shake-flask and bioreactor scale. In shake-flask fermentation, the onset of the lactobionic acid production phase was accompanied by a progressive loss of cellular metabolic activity, membrane polarization, and membrane integrity concomitantly to acidification. In fact, population dynamics has shown the prevalence of damaged and dead subpopulations when submitted to a pH < 4 from 16 h onwards. Furthermore, fluorescence-activated cell sorting revealed that these sublethally injured cells were nonculturable. In contrast, P. taetrolens cells exhibited a robust physiological status during bioreactor cultivations performed with a pH-shifted strategy at 6.5, remaining predominantly healthy and metabolically active (>96 %) as well as maintaining bioconversion efficiency throughout the course of the fermentation. Additionally, an assessment of the seed culture's physiological robustness was carried out in order to determine the best seed culture age. Results showed that bioreactor culture performance, growth, and lactobionic acid production efficiency were strongly dependent on the physiological heterogeneity displayed by the seed culture. This study provides the most suitable criteria for optimizing lactobionic acid production efficiency through a novel flow cytometric-based approach based on the physiological status of P. taetrolens. It also constitutes a valuable, broad-ranging methodology for the enhancement of microbial bioprocesses involved in the production of secondary metabolites. [ABSTRACT FROM AUTHOR]

This work presents an analysis on the suitability of the Simulated Moving Bed (and pseudo-SMB) technology on separating the mixture obtained from the lactose oxidation catalyzed by glucose-fructose oxidoreductase and glucono- α-lactonase enzymes. These enzymes from the Zymomonas mobilis bacteria are able to oxidize lactose in presence of fructose to its respective organic acid-lactobionic acid-and sorbitol. Some alternative arrays of chromatographic systems, as fixed bed column, SMB unit, 4 section pseudo-SMB, have been explored to separate the multi-component mixture, in such way to make possible the product recovery and the recycle of substrates to the enzymatic reactor. This study involved the definition of appropriate operating conditions and the prediction of the performance of the separation units, or arrangement of units, through modeling and simulations tools. To define the proper operating conditions, inequalities from equilibrium theory and the concept of the separation volume analysis have been considered. In this analysis, equilibrium and kinetic parameters for the compounds adsorbing on DOWEX 50W-X4 resin, in K and Ca ion-loadings, have been obtained from chromatographic methods (pulse and adsorption-desorption techniques). The enzymatic kinetic of production of lactobionic acid and sorbitol using permeabilized cells of Z. mobilis is shown. The strategy of keeping the highest value of reaction rate by the integration of a chromatographic system proved to be viable when it was found the feasibility to apply the SMB system in cascade. [ABSTRACT FROM AUTHOR]

The electrocatalytic oxidation of lactose has been studied on nanolength scale Au-colloids (5 nm) embedded in carbon felt as electrode (Au-NMC). A preliminary investigation by cyclic voltammetry, used to determine the optimized conditions of electrolysis, showed that the current densities were higher than those obtained on a gauze electrode of gold (Au-GE) with a surface area three times greater. Long-time electrolyses were carried out using a two potential plateau program with different values for the oxidation potentials. Chromatographic and NMR analyses showed that the oxidation of lactose led mainly to lactobionate (91%). [ABSTRACT FROM AUTHOR]

Pseudomonas sp. LS13-1 was isolated as a producer of lactobionic acid from whey and when grown with 207 g whey l-1 (150 g lactose l-1 equivalent) and three intermittent additions of 69 g whey l-1 (50 g lactose l-1 equivalent) in a fed-batch culture at pH 5.5 in a 2-l jar fermenter, it produced 175 g lactobionic acid l-1 after 180 h. In a lactose medium it produced 240 lactobionic acid l-1 from a total of 300 g lactose l-1 after 155 h. With the addition of 20 CaCO3 l-1 instead of pH control, 290 g lactobionic acid l-1 was produced in the lactose medium after 155 h with a yield of higher than 90% (mon mol-1). [ABSTRACT FROM AUTHOR]