Statistical Optimization of Medium for Pullulan Production by Aureobasidium pullulans NCPS2016 Using Fructose and Soybean Meal Hydrolysates

Potential of Pullulan-Based Polymeric Nanoparticles for Improving Drug Physicochemical Properties and Effectiveness

Pullulan, a natural polysaccharide with unique biocompatibility and biodegradability, has gained prominence in nanomedicine. Its application in nanoparticle drug delivery systems showcases its potential for precision medicine.

AIM OF STUDY

This scientific review aims to comprehensively discuss and summarize recent advancements in pullulan-based polymeric nanoparticles, focusing on their formulation, characterization, evaluation, and efficacy.

METHODOLOGY

A search on Scopus, PubMed, and Google Scholar, using "Pullulan and Nanoparticle" as keywords, identified relevant articles in recent years.

RESULTS

The literature search highlighted a diverse range of studies on the pullulan-based polymeric nanoparticles, including the success of high-selectivity hybrid pullulan-based nanoparticles for efficient boron delivery in colon cancer as the active targeting nanoparticle, the specific and high-efficiency release profile of the development of hyalgan-coated pullulan-based nanoparticles, and the design of multifunctional microneedle patches that incorporated pullulan-collagen-based nanoparticle-loaded antimicrobials to accelerate wound healing. These studies collectively underscore the versatility and transformative potential of pullulan-based polymeric nanoparticles in addressing biomedical challenges.

CONCLUSION

Pullulan-based polymeric nanoparticles are promising candidates for innovative drug delivery systems, with the potential to overcome the limitations associated with traditional delivery methods.

Characteristic analysis and fermentation optimization of a novel Aureobasidium pullulans RM1603 with high pullulan yield

A high-yielding microbial polysaccharide-producing strain, named RM1603, was isolated from rhizosphere soil and identified by morphological and phylogenetic analysis. The extracellular polysaccharides (EPS) were identified by thin-layer chromatography and infrared spectroscopy. The fermentation conditions were optimized by single factor experiments in shake flasks and a 5-L fermentor. The results of morphological and phylogenetic tree analysis showed that RM1603 was a strain of Aureobasidium pullulans. Its microbial polysaccharide was identified as pullulan, and the EPS production capacity reached 33.07 ± 1.03 g L-1 in shake flasks. The fermentation conditions were optimized in a 5-L fermentor, and were found to encompass an initial pH of 6.5, aeration rate of 2 vvm, rotor speed of 600 rpm, and inoculum size of 2 %. Under these conditions, the pullulan yield of RM1603 reached 62.52 ± 0.24 g L-1. Thus, this study contributes RM1603 as a new isolation with high-yielding pullulan and potential application value in biotechnology.

Advanced culture strategy shows varying bioactivities of sulfated polysaccharides of Poria cocos

This study compares the bioactivity of six sulfated polysaccharides derived from glucose- and sucrose-feeding extracted from P. cocos. Anti-inflammatory potentials of these polysaccharides were evaluated by pretreating lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells. Of the tested polysaccharides, the sulfated polysaccharide derived from sucrose-feeding at the concentration of 40 g/l (referred to as "suc 40") exhibited the highest anti-inflammatory activity, of 83 %, and 33 % inhibition of IL-6 and TNF-α secretion, respetively. It achieved this by inhibiting the p-38 and c-Jun N-terminal kinase (JNK) MAPK signaling pathways. On the other hand, the sulfated polysaccharide derived from glucose-feeding at a concentration of 20 g/l (referred to as "glc 20") demonstrated the greatest anti-lung cancer activity. This was achieved by inducing apoptotic-related molecules, such as poly (ADP-ribose) polymerase (PARP) and CHOP. Furthermore, glc 20 had the highest contents of sulfate, fucose, and mannose compared to the other tested polysaccharides. This suggests that the composition of monosaccharide residues are critical factors influencing the anti-inflammatory and anti-cancer activities of these sulfated polysaccharides. Overall, this study highlights the potential of sulfated polysaccharides derived from P. cocos to function as bioactive compounds with anti-inflammatory and anti-cancer properties.

Hyper-Production of Pullulan by a Novel Fungus of Aureobasidium melanogenum ZH27 through Batch Fermentation

Pullulan, which is a microbial exopolysaccharide, has found widespread applications in foods, biomedicines, and cosmetics. Despite its versatility, most wild-type strains tend to yield low levels of pullulan production, and their mutants present genetic instability, achieving a limited increase in pullulan production. Therefore, mining new wild strains with robust pullulan-producing abilities remains an urgent concern. In this study, we found a novel strain, namely, Aureobasidium melanogenum ZH27, that had a remarkable pullulan-producing capacity and optimized its cultivation conditions using the one-factor-at-a-time method. To elucidate the reasons that drove the hyper-production of pullulan, we scrutinized changes in cell morphology and gene expressions. The results reveal that strain ZH27 achieved 115.4 ± 1.82 g/L pullulan with a productivity of 0.87 g/L/h during batch fermentation within 132 h under the optimized condition (OC). This pullulan titer increased by 105% compared with the initial condition (IC). Intriguingly, under the OC, swollen cells featuring 1-2 large vacuoles predominated during a rapid pullulan accumulation, while these swollen cells with one large vacuole and several smaller ones were prevalent under the IC. Moreover, the expressions of genes associated with pullulan accumulation and by-product synthesis were almost all upregulated. These findings suggest that swollen cells and large vacuoles may play pivotal roles in the high level of pullulan production, and the accumulation of by-products also potentially contributes to pullulan synthesis. This study provides a novel and promising candidate for industrial pullulan production.

Light calcium carbonate improves pullulan biosynthesis by Aureobasidium pullulans under high concentration of sugar

The effects of light calcium carbonate (CaCO₃) on pullulan biosynthesis by Aureobasidium pullulans NCPS2016 were investigated. Light CaCO₃ enhanced pullulan production by 12.4 % when added to the low concentration of fructose broth compared with K₂HPO₄. Pullulan production was further improved when increasing both the concentrations of light CaCO₃ and fructose. Compared to K₂HPO₄, light CaCO₃ improved the activities of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucosyltransferase relevant to pullulan biosynthesis, and the gene transcriptional levels of UDP-glucose pyrophosphorylase, α-phosphoglucose mutase, UDP-glucosyltransferase, and glucose kinase were enhanced. During 30-liter fermentation, 144.3 g/L of purified pullulan was produced from 200 g/L of fructose and 15 g/L of light CaCO₃ within 168 h, with the yield and productivity of 0.72 g/g and 0.86 g/L/h respectively. This is the first report that light CaCO₃ improves pullulan production significantly.

Exclusive Biosynthesis of Pullulan Using Taguchi’s Approach and Decision Tree Learning Algorithm by a Novel Endophytic Aureobasidium pullulans Strain

Pullulan is a biodegradable, renewable, and environmentally friendly hydrogel biopolymer, with potential uses in food, medicine, and cosmetics. New endophytic Aureobasidium pullulans (accession number; OP924554) was used for the biosynthesis of pullulan. Innovatively, the fermentation process was optimized using both Taguchi’s approach and the decision tree learning algorithm for the determination of important variables for pullulan biosynthesis. The relative importance of the seven tested variables that were obtained by Taguchi and the decision tree model was accurate and followed each other’s, confirming the accuracy of the experimental design. The decision tree model was more economical by reducing the quantity of medium sucrose content by 33% without a negative reduction in the biosynthesis of pullulan. The optimum nutritional conditions (g/L) were sucrose (60 or 40), K2HPO4 (6.0), NaCl (1.5), MgSO4 (0.3), and yeast extract (1.0) at pH 5.5, and short incubation time (48 h), yielding 7.23% pullulan. The spectroscopic characterization (FT-IR and 1H-NMR spectroscopy) confirmed the structure of the obtained pullulan. This is the first report on using Taguchi and the decision tree for pullulan production by a new endophyte. Further research is encouraged for additional studies on using artificial intelligence to maximize fermentation conditions.

High-level production of pullulan from high concentration of glucose by mutagenesis and adaptive laboratory evolution of Aureobasidium pullulans

The cost of carbon sources and the low efficiency of the fermentation titer limit the industrial application of pullulan. In this study, a hypertonic-tolerant strain with efficient utilization of glucose was obtained using a double strategy. Initially, a strain for efficient synthesis of pullulan from glucose was generated by mutagenesis. Subsequently, the mutant was directionally evolved on the plate containing a high glucose concentration to enhance high osmotic resistance. The enzyme activities and the transcriptional levels involved in pullulan biosynthesis and high osmotic tolerance in mutants were increased. Nitrogen source and inorganic salts also significantly affected the production of pullulan by M233-20 from high concentration of glucose. The pullulan titer of 162.1 g/L was obtained using the response surface methodology in the flask. The strain M233-20 produced 162.3 g/L pullulan in a 30-L bioreactor with a yield of 0.82 g/g glucose. Hence, this work provides a potential industrial pullulan producer M233-20 and a strategy to develop excellent strain.

Optimization of hazelnut husk medium for pullulan production by a domestic A. pullulans strain

Hazelnut husk is one of the most abundant agricultural residue in Turkey. Valorization of this lignocellulosic biomass would provide a promoting alternative for economical production of pullulan. In this study, dried hazelnut husk hydrolysate was used directly as fermentation medium for pullulan production by a domestic strain of Aureobasidium pullulans. The aim of this work was the optimization of some fermentation medium parameters by central composite design using response surface methodology (RSM). The effects of (NH₄)₂SO₄ concentration, the volume of concentrated H₂SO₄ and the amount of ground hazelnut husk on pullulan production were optimized by RSM. The optimum levels of the fermentation parameters defined as 7.2 gL^-1, 2.5 mL and 20 g, respectively. The maximum pullulan and exopolysaccharide concentrations were determined as 74.39 and 75.95 gL^-1_, respectively in the optimum conditions. Specific growth rate of the strain was found as 0.097 h^-1. FTIR spectral attributes confirmed the structure of pullulan. Thermal decomposition temperature of synthesized pullulan was found as 247.15 °C. This study showed that hazelnut husk was one of the novel substrate for production of the pullulan by A. pullulans AZ-6. No previous work was found to utilize dried hazelnut husk as fermentation medium for pullulan production by A. pullulans.

Pullulan Oxidation in the Presence of Hydrogen Peroxide and N-Hydroxyphthalimide

The C-6 in the maltotriose unit of pullulan was oxidized in an alkaline medium (pH = 10), utilizing a green method that included hydrogen peroxide (H₂O₂) as an oxidant and N-hydroxyphthalimide (NHPI) as a catalyst for various reaction times. The structure of the resulting oxidized pullulans (PO) was carefully characterized by titration, intrinsic viscosity, FTIR, ¹³C-NMR, and zeta potential. The content of carboxyl groups in PO was dependent on reaction time and varied accordingly. Furthermore, a fast reaction rate was found in the first 2-3 h of the reaction, followed by a decreased rate in the subsequent hours. FTIR and ¹³C-NMR proved that the selective oxidation of the primary alcohol groups of pullulan was achieved. The oxidation also caused the glycoside linkages in the pullulan chain to break, and the viscosity of the pullulan itself went down.

Downstream processing and structural confirmation of pullulan - A comprehensive review

Pullulan is a microbial polymer, commercially produced from Aureobasidium pullulans. Downstream processing of pullulan involves a multi-stage process which should be efficient, safe and reproducible. In liquid-liquid separations, firstly cell free extract is separated. Cell biomass can be separated after fermentation either by centrifugation or filtration. Due to practically insolubility of pullulan in organic solvents, ethanol and isopropanol are the most commonly used organic solvents for its recovery. Pullulan can also be purified by chromatographic techniques, but these are not cost effective for the purification of pullulan. Efficient aqueous two-phase system can be used for the purification of pullulan. The current review describes the methods and perspectives used for solid-liquid separation, liquid-liquid separations and finishing steps for the recovery of pullulan. Techniques used to determine the structural attributes of pullulan have also been highlighted.

Evaluation of Some Agro-Industrial Wastes as Fermentation Medium for Pullulan Production by Aureobasidium pullulans AZ-6

Agro-industrial wastes are rich sources of some nutrients. Thus, utilization of wastes seems to be ecologically sound and economically advantageous. The aim of this work was to investigate the potential usage of various agro-industrial wastes as fermentation medium for pullulan production by a domestic strain; Aureobasidium pullulans AZ-6. In this study, different agro-industrial wastes; various citrus peels, grape pomace, the hydrolysates of hazelnut and chestnut shells, sugarcane molasses residue, dried and fresh hazelnut husks and pumpkin peel, were used as fermentation media without adding any extra nutritional component for pullulan production by A. pullulans AZ-6. As a result, among the tested media, the maximum pullulan concentration was obtained as 33.59 gL^-1 using the sugarcane molasses residue, and followed by the corresponding value of 30.02 gL^-1 obtained in the dried hazelnut husk hydrolysate medium. Therefore, the usage of agro-industrial wastes as fermentation media is considered to make pullulan production cost effective. In addition, waste treatment from this aspect solves a relevant environmental problem. In this study, sugarcane molasses residue and dried hazelnut husk hydrolysate were used directly as fermentation media for pullulan production for the first time. Pullulan production from sugarcane molasses residue and dried hazelnut husk hydrolysate media might be a promising substrate for economical point of view.

Effect of carbohydrate-feeding strategy on the production, physiochemical changes, anti-inflammation activities of polysaccharides of Poria cocos

The aim of this research was to physiochemically characterize the structure and study the pharmaceutical benefits of the polysaccharide (PS) produced by Poria cocos using two selected carbohydrates (sucrose, and potato dextrose broth) in the in vitro culture system. A direct dosage effect was shown as sucrose- or PDB-based medium on the PS yield of Paragalago cocos. Very low-molecular-weight PS (<1 kDa) were largely synthesized by sucrose and PDB feeding. Sucrose-feeding mycelia of P. cocos results in a direct dosage effect in the fructose component in the PS. Sucrose and PDB feeding increased the glucose content but decreased the galactose content of PS. This study examined the anti-inflammatory activities of PS in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. At 100 μg/mL and 50 μg/mL, PS from 10 g/L PDB- treatment, denoted as PDB 10, pretreatment showed maximal inhibition of TNF-α and IL-6 release, respectively. Mechanically, PDB10 attenuated IκB from degradation in LPS-induced macrophages, and down-regulated LPS-induced phosphorylation of ERK/AKT/p-38. PDB10 showed dose-dependent inhibition of the LPS induced TGFRII signaling pathways.

High-efficiency production of Tremella aurantialba polysaccharide through basidiospore fermentation

This study aims to develop a spore fermentation method instead of fruiting body extraction for the production of Tremella aurantialba polysaccharide (TAPS). The purified spore strain Tremella aurantialba NX-20 was isolated for TAPS fermentation. The fermented TAPS and the extracted TAPS had the same monosaccharide composition but higher molecular weight. The conditions for TAPS fermentation by NX-20 were optimized, which were 25 °C, pH 7, 10% initial inoculum and 5 days. To further reduce the processing steps and costs of the medium, tofu wastewater (TW) was used to replace defatted soybean meal (DSM). In a 7.5 L fermentation tank, 40 g/L glucose with 10-fold diluted TW was used as the medium. For TAPS fermentation, a maximum yield of 15.02 ± 0.40 g/L was achieved. In conclusion, this study provides a feasible strategy for the efficient preparation of TAPS through spore fermentation.

Improved Pullulan Production and Process Optimization Using Novel GA-ANN and GA-ANFIS Hybrid Statistical Tools

Pullulan production from Aureobasidiumpullulans was explored to increase yield. Non-linear hybrid mathematical tools for optimization of process variables as well as the pullulan yield were analyzed. The one variable at a time (OVAT) approach was used to optimize the maximum pullulan yield of 35.16 ± 0.29 g/L. The tools predicted maximum pullulan yields of 39.4918 g/L (genetic algorithm coupled with artificial neural network (GA-ANN)) and 36.0788 g/L (GA coupled with adaptive network based fuzzy inference system (GA-ANFIS)). The best regression value (0.94799) of the Levenberg-Marquardt (LM) algorithm for ANN and the epoch error (6.1055 × 10-5) for GA-ANFIS point towards prediction precision and potentiality of data training models. The process parameters provided by both the tools corresponding to their predicted yield were revalidated by experiments. Among the two of them GA-ANFIS results were replicated with 98.82% accuracy. Thus GA-ANFIS predicted an optimum pullulan yield of 36.0788 g/L with a substrate concentration of 49.94 g/L, incubation period of 182.39 h, temperature of 27.41 °C, pH of 6.99, and agitation speed of 190.08 rpm.

Utilization of kitchen waste for production of pullulan to develop biodegradable plastic

Pullulan has many useful characteristics but, its high cost limits its potential applications. In the present work, kitchen waste (KW), which otherwise has zero commercial value, was evaluated for the economical production of pullulan. Before fermentation, the KW was hydrolyzed into free sugars using an in-house produced cocktail of enzymes. During hydrolysis, 46 ± 3.5 g/l and 31 ± 2.2 g/l of total reducing sugars and glucose were released, respectively. Hydrolyzed kitchen waste was then used as substrate for fermentation by Aureobasidium pullulans MTCC 2013 yielding 20.46 ± 2.01 g/l pullulan. Further, effect of different nitrogen sources was evaluated and yeast extract (3%) was found to be the best, yielding (24.77 ± 1.06 g/l) exopolysaccharide (EPS). The pullulan produced from KW was characterized in terms of organoleptic properties, physical strength, Fourier-transform infrared spectroscopy (FTIR), and H nuclear magnetic resonance (H NMR) analysis. The results corroborated well with commercial pullulan. The biodegradable nature and water solubility of the film developed from pullulan was also confirmed. To the best of our knowledge, this is the first report on the validation of the biodegradability of in-house produced pullulan. Thus, kitchen waste appears to be a promising option for economical pullulan production. Additionally, the method may also prove to be helpful for managing the increasing load of municipal solid waste in an eco-friendly and scientific way.