Kinetic and thermodynamic investigations of cell-wall degrading enzymes produced by Aureobasidium pullulans via induction with orange peels: application in lycopene extraction

Characterization of a purified novel Aureobasidium pullulans NAC8 lipase and covalent-immobilization for use in the biodegradation of oil-contaminated wastewater

The aim of this study was to purify, characterize, and evaluate the potential of the immobilized extracellular lipase from Aureobasidium pullulans NAC8 (ApL) for the biodegradation of oil-contaminated wastewater. ApL was purified using aqueous two-phase partitioning (ATPS) and its biochemical properties determined. The enzyme was then covalently immobilized and characterized through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The performance of immobilized ApL in oil-contaminated wastewater was tested for its ability to remove chemical oxygen demand (COD), hydrolyze lipids, and produce free fatty acids. The purification fold and yield of ApL were 3.5 and 66 %, respectively. The purified enzyme had a subunit molecular weight of 30 kDa, with an optimum pH of 6.5 and an optimum temperature of 50 °C. The enzyme's catalytic efficiency for pNPP and pNPB was 1.53 × 105 and 2.3 × 105 in aqueous media, and 1.74 × 105 and 2.7 × 105 in organic solvent. Thermodynamic analysis revealed values for ∆H* (16.4 kJ/mol), ∆S* (-214 J/mol/K), and ∆G* (70.1-88.4 kJ/mol), indicating stability against thermal denaturation between 40 and 70 °C. The immobilized enzyme retained 70 % of its activity after ten catalytic cycles. In oil-contaminated wastewater, it achieved 83 % COD removal, 7.4 % lipid hydrolysis, and 15 % free fatty acid production after five cycles. The biochemical characteristics of the purified and immobilized ApL suggest that it has significant potential for industrial applications, particularly in the biodegradation of oil-contaminated wastewater. Its stability and high catalytic efficiency make it a promising candidate for long-term environmental and industrial use.

Waste and by-products as sources of lycopene, phytoene, and phytofluene - Integrative review with bibliometric analysis

Food loss and waste are severe social, economic, and environmental issues. An example is the incorrect handling of waste or by-products used to obtain bioactive compounds, such as carotenoids. This review aimed to present a comprehensive overview of research on lycopene, phytoene, and phytofluene obtained from waste and by-products. In this study, an integrative literature approach was coupled with bibliometric analysis to provide a broad perspective of the topic. PRISMA guidelines were used to search studies in the Web of Science database systematically. Articles were included if (1) employed waste or by-products to obtain lycopene, phytoene, and phytofluene or (2) performed applications of the carotenoids previously extracted from waste sources. Two hundred and four articles were included in the study, and the prevalent theme was research on the recovery of lycopene from tomato processing. However, the scarcity of studies on colorless carotenoids (phytoene and phytofluene) was evidenced, although these are generally associated with lycopene. Different technologies were used to extract lycopene from plant matrices, with a clear current trend toward choosing environmentally friendly alternatives. Microbial production of carotenoids from various wastes is a highly competitive alternative to conventional processes. The results described here can guide future forays into the subject, especially regarding research on phytoene and phytofluene, potential and untapped sources of carotenoids from waste and by-products, and in choosing more efficient, safe, and environmentally sustainable extraction protocols.

Purification of Aspergillus tamarii mycelial fructosyltransferase (m-FTase), optimized FOS production, and evaluation of its anticancer potential

In the present study, generation of prebiotic fructooligosaccharides (FOS) using Aspergillus tamarii FTase was optimized by applying response surface methodology. Optimal FOS (251 g L^-1 ) was generated at 28.4°C, pH 7.0 and 50% (w/v) sucrose leading to 1.97-fold yield enhancement. The m-FTase was purified using ultrafiltration followed by HiTrap Q HP anion exchange chromatography resulting in 2.15-fold purified FTase with 12.76 U mg^-1 specific activity. Purified FTase (75 kDa) had K_m and V_max values of 1049.717 mM and 2.094 µmol min^-1  mg^-1 , respectively. FOS incorporation led to upregulation of caspase 3, caspase 9, and Bax genes suggesting mitochondrial apoptosis activation in cancer cells. The study describes characteristics of purified FTase from A. tamarii, production optimization of FOS and unravels the role of FOS in anticancer activity against HT-29 cells. PRACTICAL APPLICATION: This study provides detailed insights of kinetic and thermodynamic characteristics of purified FTase, a prebiotic FOS-generating enzyme. Moreover, the role of the apoptotic genes involved in anticancer activity, and the prebiotic potential of FOS is also investigated. These findings are important in the context of FOS applications, and the optimized production strategies make it useful for industrial application.

A heat-resistant intracellular laccase immobilized via cross-linked enzyme aggregate preparation: Characterization, application in bisphenol A removal and phytotoxicity evaluation

Aureobasidium pullulans laccase was immobilized via cross-linked enzyme aggregate (CLEA) and deployed in bisphenol-A (BPA) removal. The immobilization and BPA removal processes were mathematically modeled. The CLEA-treated BPA was evaluated for phytotoxicity. The optimum conditions for CLEA resulting in the highest immobilization yield were ammonium sulfate (60% w/v), glutaraldehyde (30 mM), pH (4.5), time (6 h) and temperature (45 °C). The CLEA retained about 56% of its activity after twelve catalytic cycles. The optimum pH and temperature of the laccase CLEA were 5.5 and 60 °C respectively. The SEM indicated that the laccase CLEA was type II (unstructured). The data obtained from the heat inactivation kinetics and thermodynamic characterization indicated that the CLEA was stable to heat denaturation than the free enzyme. The kinetic parameters obtained for the CLEA with ABTS as substrate were 101.3 µM, 2.94 µmols^-1 mg^-1 and 0.03 dm³ s^-1 mg^-1 for the Km, Kcat and Kcat/Km respectively. The optimum conditions for BPA removal using the CLEA were temperature (30 °C), time (2 h), CLEA (1.0 mg) and BPA concentration (40 mg/L). After the 7th cycle, BPA removal by the laccase CLEA was 63 ± 2.3%. From the germination index values obtained, the CLEA-treated BPA solution showed no phytotoxicity to germinated S. bicolor seeds compared to the untreated (BPA-only) solutions.

Biodegradation of cyanide in cassava wastewater using a novel thermodynamically-stable immobilized rhodanese

Extracellular rhodanese obtained from Aureobasidium pullulans was employed in both free and immobilized forms for the biodegradation of cyanide present in cassava processing mill effluent (CPME). Crosslinking with glutaraldehyde (at an optimum concentration of 5% v/v) before entrapment in alginate beads resulted in the highest immobilization yield of 94.5% and reduced enzyme leakage of 1.8%. Rhodanese immobilized by cross-linking before entrapment (cbe) retained about 46% of its initial activity after eight cycles of catalysis compared to the entrapment in alginate alone (eaa) which lost more than 79% after the fifth catalytic cycle. A cross-examination of thermodynamic (ΔGd*, ΔSd*, ΔHd*) kinetic (kd, t1/2, D and z-values) parameters at 30-70 °C showed that cbe displayed a higher resistance to thermal inactivation when compared to the free enzyme (fe) and (eaa). The efficiency of cyanide biodegradation from the CPME by the fe, eaa and cbe were 55, 62, and 74% respectively after 6 h. Rhodanese immobilized via cbe had a higher resistance to thermal denaturation over other enzyme forms. Hence, this makes cbe adaptable for large-scale detoxification of cyanide from CPME.

Optimization of aqueous two-phase partitioning of Aureobasidium pullulans α-amylase via response surface methodology and investigation of its thermodynamic and kinetic properties

Industrial enzymes such as α-amylase must be thermostable and also easily purified/concentrated. Hence, aqueous two-phase partitioning systems (ATPS) was exploited for the partitioning of α-amylase from Aureobasidium pullulans due to its numerous advantages over conventional purification strategy. A. pullulans α-amylase was partially purified using ATPS via response surface methodology (RSM). The potentials of the ATPS-purified enzyme for possible industrial application such as resistance to thermal inactivation was investigated in comparison with the crude enzyme. PEG-6000 was the polymer of choice for ATPS as it resulted in higher purification factor (PF), %yield (Y), and partition coefficient (PC). At optimum levels (% w/v) of 20, 12 and 7.5 for PEG-6000, sodium citrate and sodium chloride respectively, maximum PF, Y and PC of 4.2, 88%, and 9.9 respectively were obtained. The response model validation and reliability were established based on the closeness between the experimented and predicted values. The kinetic and thermodynamic parameters such as Q₁₀, t_1/2, k_d, D - value, E_d, [Formula: see text] [Formula: see text] of the ATPS-purified α-amylase indicated that it was thermostable at 50 to 60 °C compared to the crude α-amylase. A thermodynamically stable and ATPS-purified α-amylase from A. pullulans has properties easily applicable for most industrial processes.