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Acid whey causes a major disposal problem for the dairy industry due to its low pH and high salt concentration. Lactobionic acid (LBA) production by whey fermentation is an inexpensive process. The goal of this work was to employ acid whey for LBA production. Acid whey was fermented in a bioreactor, adding Pseudomonas taetrolens LMG 2336 at 30°C and 6.5 pH, with 1.5‐Lpm oxygen aeration and 350‐rpm agitation. Three fermentation tests were carried out with a different amount of inoculum (10%, 30% and 10% three times within 24 h). Results indicated that repeatedly adding P. taetrolens inoculum to the acid whey substrate allows a complete lactose conversion into LBA, while the lactose oxidation process was insufficient in the sample where the inoculum was only added at the beginning of the fermentation process (only 29.7% LBA production with 10% inoculum). The physiological heterogeneity of P. taetrolens was determined by multiparametric flow cytometry, and results showed that there was a phenotypic adaptation of the microorganism due to the changes observed in its heterogeneity and physiological state. The results achieved will help to recycle acid whey for value‐added product production such as LBA production. [ABSTRACT FROM AUTHOR]

Synbiotic products are a type of functional food with great potential due to consumer interest in foods that improve health and/or reduce the risk of certain diseases. In this study, synbiotic macrocapsules were developed using Lactobacillus paracasei CBA L74 as probiotic and lactobionic acid (LBA) as prebiotic. Firstly, the probiotic was proven to be able to use LBA as the only substrate source checking their growth and lactic acid production. Then, four different types of capsules were produced using sodium alginate as matrix and different hardener solutions (CaCl2 and chitosan). The macrocapsules were characterised regarding their strength, and the best performing ones were used for further analysis. In order to obtain a synbiotic capsule characterized by a longer stability time due to low water activity, the capsules were dried using freeze and thermal drying. Successively, to revitalize the microorganisms, the capsules were rehydrated in two different media (saline solution and yogurt), subjected to simulated in vitro digestion tests and visually characterised. In addition, their viability over time was assessed. As a result, L. paracasei was able to grow using LBA as the only source of carbon with better production of lactic acid for prolonged periods. The more resistant freeze- and thermal-dried capsules showed differences in rehydration kinetics, and visual changes were also observed. In simulated in vitro digestion tests, capsules rehydrated in yogurt showed the best results in terms of survival. Regarding their viability over time, the importance of the use of chitosan was noted. [ABSTRACT FROM AUTHOR]

As well as its beneficial health properties, the incorporation of the prebiotic lactobionic acid (LBA) in fermented dairy products can provide a technological advantage due to its gelling capacities. This study aimed to develop a new functional dairy product containing LBA synthesised within the process itself by the bacterium Pseudomonas taetrolens. A probiotic Lactobacillus casei strain was introduced through a sequential fermentation system. After incubation, in the case of the most effective experimental procedure, a synbiotic fermented milk with 30 g/L of prebiotic LBA was obtained, together with an active L. casei population of 109 cfu/mL and <1% lactose content. [ABSTRACT FROM AUTHOR]

Besides its properties as an antioxidant, stabilizer, or acidifier, lactobionic acid has emerged as a potential prebiotic compound, raising the possibility of being included together with the probiotic microorganism Lactobacillus casei in novel functional fermented foods with synbiotic characteristics. Their manufacturing strategy could benefit from the recently implemented microbial synthesis of lactobionic acid by the strong producer Pseudomonas taetrolens, employing residual dairy whey as raw material. The phenomenon of amensalism established between Pseudomonas and Lactobacillus makes simultaneous fermentation unfeasible. A novel sequential process has been developed in which L. casei is inoculated in a second step. Its ability to utilize lactobionic acid as a carbon and energy source was previously tested. Experimental results showed the capacity of L. casei to work efficiently on the residual substrate fermented by P. taetrolens, producing lactic acid by degrading the remaining lactose, with a lactic acid yield on substrate and productivity of 0.95 g g−1 and 0.20 g L−1 h−1, respectively. Lactobionic acid was barely consumed in this complex growth medium, thus ensuring its presence in the resulting fermented product. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1250-1256, 2017 [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]

The successful development of a lactobionic acid (LBA) bioconversion process on an industrial scale demands the selection of appropriate downstream methodological approaches to achieve product purification once the bioconversion of LBA is completed. These approaches depend on the nature of the substrate available for LBA production, and their necessary implementation could constitute a drawback when compared to the lesser effort required in downstream approaches in the production of LBA obtained by chemical synthesis from refined lactose. Thus, the aim of this research is to separate LBA from an acid whey substrate after bioconversion with Pseudomonas taetrolens. Freeze drying, crystallization, adsorption with activated carbon, microfiltration, centrifugation, and precipitation with 96% (v/v) ethanol were carried out to separate and purify LBA. The closest product to commercial LBA was obtained using precipitation with ethanol, obtaining a white powder with 95 ± 2% LBA concentration. The procedure described in this paper could help to produce LBA on an industrial scale via microbial bioconversion from acid whey, developing a promising biotechnological approach for lactose conversion. [ABSTRACT FROM AUTHOR]

Triggering the switch from growth to lactobionic acid formation in Pseudomonas taetrolens is crucial to attain a high-yield bio-production system. This study elucidates how the growth-coupled and uncoupled lactobionic acid formation ratio can be modulated through the application of temperature-control strategies. Whereas the combination of high initial cell densities with a temperature value of 30 °C stimulated the onset of the lactobionic acid production phase from early cultivation times, temperature-stat conditions below 28 °C and above 30 °C led to a growth-coupled lactobionic acid formation with reduced cell growth. Further implementation of a temperature-control bioprocessing strategy at 28 °C with a pH-shift cultivation at 6.5 resulted in higher lactobionic acid yields (98%), volumetric productivity (2.04 g/L h), and specific productivity rates (1.73 g/g h) within only 24 h. Controlling the culture temperature at 28 °C via either temperature-stat or -shift bioprocessing strategies led to an overproduction of lactobionic acid, overcoming the low-yield mixed-growth-associated production patterns found at temperatures different than 28 °C. This novel temperature-driven approach provides a step forward in the bio-based production of lactobionic acid at high specific production rates and yields by uncoupling completely the production phase from the cell growth. [ABSTRACT FROM AUTHOR]

Substrate versatility of Pseudomonas taetrolens was evaluated for the first time in a co-fermentation system combining cheese whey and glucose, glycerol or lactose as co-substrates. Results showed that P. taetrolens displayed different production patterns depending on the co-substrate supplied. Whereas the presence of glucose led to a simultaneous co-production of lactobionic (78 g/L) and gluconic acid (8.8 g/L), lactose feeding stimulated the overproduction of lactobionic acid from whey with a high specific productivity (1.4 g/g h) and yield (100%). Co-substrate supply of glycerol conversely led to reduced lactobionic acid yield (82%) but higher cell densities (1.8 g/L), channelling the carbon source towards cell growth and maintenance. Higher carbon availability impaired the metabolic activity as well as membrane integrity, whereas lactose feeding improved the cellular functionality of P. taetrolens . Insights into these mixed carbon source strategies open up the possibility of co-producing lactobionic and gluconic acid into an integrated single-cell biorefinery. [ABSTRACT FROM AUTHOR]

Abstract: Lactobionic acid has appeared on the commercial scene as a versatile polyhydroxy acid with numerous promising applications in the food, medicine, pharmaceutical, cosmetics and chemical industries. This high value-added bio-product has recently received growing attention as a bioactive compound, providing an excellent chemical platform for the synthesis of novel potentially biocompatible and biodegradable drug delivery vehicles. Recent advances in tissue engineering and nanomedicine have also underlined the increased importance of this organic acid as a key biofunctionalization agent. The growing commercial relevance of lactobionic acid has therefore prompted the development of novel systems for its biotechnological production that are both sustainable and efficient. The present review explores recent advances and studies related to lactobionic acid bio-production, whether through microbial or enzymatic approaches, highlighting the key bioprocessing conditions for enhanced bio-production. Detailed overviews of the current microbial cell factories as well as downstream processing methodologies for lactobionic acid production are also presented. Furthermore, the potential prospects and current applications of this polyhydroxy acid are also discussed, with an emphasis on the role of lactobionic acid as a key platform in the development of novel drugs, biomaterials, nanoparticles and biopolymer systems. [Copyright &y& Elsevier]

Abstract: High-level production of lactobionic acid from whey by Pseudomonas taetrolens under fed-batch fermentation was achieved in this study. Different feeding strategies were evaluated according to the physiological status and fermentation performance of P. taetrolens. A lactobionic acid titer of 164g/L was obtained under co-feeding conditions affording specific and volumetric productivities of 1.4g/gh and 2.05g/Lh, respectively. Flow cytometry assessment revealed that P. taetrolens cells exhibited a robust physiological status, which makes them particularly well-suited for employing concentrated nutrient solutions to further prolong the growth and production phases. Such detailed knowledge of the physiological status has been revealed to be a key issue to further support the development of high-yield lactobionic acid production processes under feeding strategies. The present study has demonstrated the feasibility of P. taetrolens to achieve high-level bio-production of lactobionic acid from whey through fed-batch cultivation, suggesting its major potential for industrial-scale implementation. [Copyright &y& Elsevier]

Abstract: The influence of dissolved oxygen availability on cell growth and lactobionic acid production from whey by Pseudomonas taetrolens has been investigated for the first time. Results from pH-shift bioreactor cultivations have shown that high agitation rate schemes stimulated cell growth, increased pH-shift values and the oxygen uptake rate by cells, whereas lactobionic acid production was negatively affected. Conversely, higher aeration rates than 1.5Lpm neither stimulated cell growth nor lactobionic acid production (22% lower for an aeration rate of 2Lpm). Overall insights into bioprocess performance enabled the implementation of 350rpm as the optimal agitation strategy during cultivation, which increased lactobionic productivity 1.2-fold (0.58–0.7g/Lh) compared to that achieved at 1000rpm. Oxygen supply has been shown to be a key bioprocess parameter for enhanced overall efficiency of the system, representing essential information for the implementation of lactobionic acid production at a large scale. [Copyright &y& Elsevier]

Abstract: Lactobionic acid finds applications in the fields of pharmaceuticals, cosmetics and medicine. The production of lactobionic acid from whey by Pseudomonas taetrolens was studied in shake-flasks and in a bioreactor. Shake-flask experiments showed that lactobionic acid was a non-growth associated product. A two-stage pH-shift bioconversion strategy with a pH-uncontrolled above 6.5 during the growth phase and maintained at 6.5 during cumulative production was adopted in bioreactor batch cultures. An inoculation level of 30% promoted high cell culture densities that triggered lactobionic acid production at a rate of 1.12g/Lh. This methodology displayed efficient bioconversion with cheese whey as an inexpensive substrate for lactobionic acid production. [Copyright &y& Elsevier]