Statistical optimization of pullulan production from Asian palm kernel and evaluation of its properties

Advances in Aureobasidium research: Paving the path to industrial utilization

We here explore the potential of the fungal genus Aureobasidium as a prototype for a microbial chassis for industrial biotechnology in the context of a developing circular bioeconomy. The study emphasizes the physiological advantages of Aureobasidium, including its polyextremotolerance, broad substrate spectrum, and diverse product range, making it a promising candidate for cost-effective and sustainable industrial processes. In the second part, recent advances in genetic tool development, as well as approaches for up-scaled fermentation, are described. This review adds to the growing body of scientific literature on this remarkable fungus and reveals its potential for future use in the biotechnological industry.

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.

Study on Filtration Performance of PVDF/PUL Composite Air Filtration Membrane Based on Far-Field Electrospinning

At present, the situation of air pollution is still serious, and research on air filtration is still crucial. For the nanofiber air filtration membrane, the diameter, porosity, tensile strength, and hydrophilicity of the nanofiber will affect the filtration performance and stability. In this paper, based on the far-field electrospinning process and the performance effect mechanism of the stacked structure fiber membrane, nanofiber membrane was prepared by selecting the environmental protection, degradable and pollution-free natural polysaccharide biopolymer pullulan, and polyvinylidene fluoride polymer with strong hydrophobicity and high impact strength. By combining two kinds of fiber membranes with different fiber diameter and porosity, a three-layer composite nanofiber membrane with better hydrophobicity, higher tensile strength, smaller fiber diameter, and better filtration performance was prepared. Performance characterization showed that this three-layer composite nanofiber membrane had excellent air permeability and filtration efficiency, and the filtration efficiency of particles above PM 2.5 reached 99.9%. This study also provides important reference values for the preparation of high-efficiency composite nanofiber filtration membrane.

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.

Ipomoea carnea: a novel biosorbent for the removal of methylene blue (MB) from aqueous dye solution: kinetic, equilibrium and statistical approach

The biosorption potential of cost-effective and agricultural residue, Ipomoea carnea wood (ICW) was examined by the removal of cationic dye, methylene blue (MB) from aqueous solution. The surface morphology, structural and thermal properties of untreated ICW were analyzed using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Thermo-gravimetric Analysis (TGA), respectively. The effects of different parameters namely concentration of biosorbent, initial pH, initial MB composition and temperature on biosorption capacity and biosorption (%) were studied. The kinetic and equilibrium models were developed to fit the experimental data on MB biosorption. The maximum biosorption capacity of 39.38 mg g^-1 was obtained at 40 °C using Langmuir model. The removal of MB was found to be significantly varying with temperature. Box-Behnken design was applied to optimize the biosorption parameters. The optimized condition for MB biosorption was evaluated as dosage of 3.1 g L^-1, pH of 7.04, Temperature of 49.1 °C, MB concentration of 30.48 mg L^-1 and maximum biosorption (%) of 83.87. The regeneration of ICW was investigated by five cycles using a suitable eluting agent. Hence, ICW without any pretreatment and chemical modification is a potential candidate for the removal of MB in terms of availability and economy of the process.Novelty statementIpomoea carnea wood (ICW) without any pretreatment explored a potential biosorbent for the removal of methylene blue (MB) in terms of availability and economy of the process.The physico-chemical properties of ICW characterized using Scanning Electron Microscopy, Fourier transform infrared spectroscopy and Thermo-gravimetric Analysis showed ICW as a promising biosorbent for MB removal.Presence of heterogeneous with rugged morphological structure, cavities, irregular shape and size of large pores provide the better biosorption capability for MB molecules using ICW without any pretreatment or chemical modification.Analysis of kinetic and isotherm models was performed to examine the better fitness of experimental data with model. Thermodynamic parameters indicating feasible and endothermic MB biosorption.Statistical design of experiments is used to optimize the condition and corresponding maximum MB removal using Derringer's desired function methodology.Untreated ICW is a potential reusable biosorbents, effectively employed in successive biosorption and desorption process for the removal of MB from aqueous solutions.

Pullulan – Biopolymer with Potential for Use as Food Packaging

The materials used in food packaging based on non-biodegradable synthetic polymers pose a serious threat of pollution to the environment. Hence, research is now focused on developing eco-friendly and biodegradable packaging obtained from natural polymers. Pullulan is a microbial exopolysaccharide, obtained on a commercial scale by the yeast-like fungus Aureobasidium pullulans. It is a water-soluble, non-toxic and non-mutagenic edible biopolymer with excellent film-forming abilities and adhesive properties. Furthermore, pullulan presents great potential to fabricate thin, transparent, odorless and tasteless edible films and coating used as packaging material. This review article presents an overview on the basic mechanical and barrier properties of a pullulan-based film. It also describes the modification methods applied in order to obtain multifunctional materials in terms of satisfactory physico-mechanical performance and antimicrobial activity for food packaging.

Derivatization approaches and applications of pullulan

Pullulan (PUL), a linear exo-polysaccharide, is useful in industries as diverse as food, cosmetics and pharmaceuticals. PUL presents many favorable characteristics, such as renewable origin, biocompatibility, stability, hydrophilic nature, and availability of reactive sites for chemical modification. With an inherent affinity to asialoglycoprotein receptors, PUL can be used for targeted drug delivery to the liver. Besides, these primary properties have been combined with modern synthetic approaches for developing multifunctional biomaterials. This is evident from numerous studies on approaches, such as hydrophobic modification, cross-linking, grafting and transformation as a polyelectrolyte. In this review, we have discussed up-to-date advances on chemical modifications and emerging applications of PUL in targeted theranostics and tissue engineering. Besides, we offer an overview of its applications in food, cosmetics and environment remediation.