Use of fruit residues for pectinase production by Aspergillus flavipes FP-500 and Aspergillus terreus FP-370

Production and immobilization of pectinases from Penicillium crustosum in magnetic core-shell nanostructures for juice clarification

Global market of food enzymes is held by pectinases, mostly sourced from filamentous fungi via submerged fermentation. Given the one-time use nature of enzymes to clarify juices and wines, there is a crucial need to explore alternatives for enzyme immobilization, enabling their reuse in food applications. In this research, an isolated fungal strain (Penicillium crustosum OR889307) was evaluated as a new potential pectinase producer in submerged fermentation. Additionally, the enzyme was immobilized in magnetic core-shell nanostructures for juice clarification. Findings revealed that Penicillium crustosum exhibited enzymatic activities higher than other Penicillium species, and pectinase production was enhanced with lemon peel as a cosubstrate in submerged fermentation. The enzyme production (548.93 U/mL) was optimized by response surface methodology, determining the optimal conditions at 35 °C and pH 6.0. Subsequently, the enzyme was covalently immobilized on synthesized magnetic core-shell nanoparticles. The immobilized enzyme exhibited superior stability at higher temperatures (50 °C) and acidic conditions (pH 4.5). Finally, the immobilized pectinases decreased 30 % the orange juice turbidity and maintained 84 % of the enzymatic activity after five consecutive cycles. In conclusion, Penicillium crustosum is a proven pectinase producer and these enzymes immobilized on functionalized nanoparticles improve the stability and reusability of pectinase for juice clarification.

Application of Principal Component Analysis (PCA) to the Evaluation and Screening of Multiactivity Fungi

Continued innovation in screening methodologies remains important for the discovery of high-quality multiactive fungi, which have been of great significance to the development of new drugs. Mangrove-derived fungi, which are well recognized as prolific sources of natural products, are worth sustained attention and further study. In this study, 118 fungi, which mainly included Aspergillus spp. (34.62%) and Penicillium spp. (15.38%), were isolated from the mangrove ecosystem of the Maowei Sea, and 83.1% of the cultured fungi showed at least one bioactivity in four antibacterial and three antioxidant assays. To accurately evaluate the fungal bioactivities, the fungi with multiple bioactivities were successfully evaluated and screened by principal component analysis (PCA), and this analysis provided a dataset for comparing and selecting multibioactive fungi. Among the 118 mangrove-derived fungi tested in this study, Aspergillus spp. showed the best comprehensive activity. Fungi such as A. clavatonanicus, A. flavipes and A. citrinoterreus, which exhibited high comprehensive bioactivity as determined by the PCA, have great potential in the exploitation of natural products and the development of new drugs. This study demonstrated the first use of PCA as a time-saving, scientific method with a strong ability to evaluate and screen multiactive fungi, which indicated that this method can affect the discovery and development of new drugs.

Distribution of a novel enzyme of sialidase family among native filamentous fungi

Sialidases (neuraminidases, EC 3.2.1.18) are widely distributed in biological systems but there are only scarce data on its production by filamentous fungi. The aim of this study was to obtain information about sialidase distribution in filamentous fungi from non-clinical isolates, to determine availability of sialidase gene, and to select a perspective producer. A total of 113 fungal strains belonging to Ascomycota and Zygomycota compassing 21 genera and 51 species were screened. Among them, 77 strains (11 orders, 14 families and 16 genera) were able to synthesize sialidase. Present data showed a habitat-dependent variation of sialidase activity between species and within species, depending on location. Sialidase gene was identified in sialidase-positive and sialidase-negative strains. . Among three perspective strains, the best producer was chosen based on their sialidase production depending on type of cultivation, medium composition, and growth temperature. The selected P. griseofulvum Р29 was cultivated in 3L bioreactor at 20 °C on medium supplemented with 0.5% milk whey. The results demonstrated better growth and 2.3-fold higher maximum enzyme activity compared to the shaken flask cultures. Moreover, the early occurring maximum (48 h) is an important prerequisite for future up scaling of the process.

Penicillium oxalicum secretomic analysis identify plant cell wall degrading enzymes important for fruit juice extraction

Pectinases and other carbohydrate-active enzymes are important for the food industry, mainly for juice processing. In addition, the use of peels to produce enzymes can aggregate value to these agro-industrial residues and at the end of the process enhance qualitatively and quantitatively the juice production. In this work, three different extracts produced by Penicillium oxalicum LS09 using agro-industrial residues were optimized and analyzed by mass spectrometry. It was observed an increased production of pectinases in the medium containing orange peel and optimized for production of pectin lyase and pectinesterase (PE). Interestingly, not only pectinases, but also different plant cell wall degrading enzymes (i.e. glucanases, xylanases, arabinases), with a higher ratio (42/73) was identified in the medium optimized for PE. The crude extracts produced by P. oxalicum also reveal the potential for application in the fruit juice industry, showing an increased yield and qualitative characteristics of extracted juices. The presence of other cell wall-degrading enzymes identified by proteomics, reinforce the combination for obtaining clarified and depectinized juice in a single step.

Enzymatic saccharification of banana peel and sequential fermentation of the reducing sugars to produce lactic acid

An integral bioprocess to produce lactic acid (LA) from banana peel (BP) was studied. Oxidases produced by Trametes versicolor and hydrolases produced by Aspergillus flavipes and Aspergillus niger saccharified BP at optimal conditions: 230 rpm, 66 g/L BP, and 73.5% (v/v) of enzymatic crude extract (using equal quantities of the enzymatic extracts). At bioreactor scale (1 L), the joint action of oxidases and hydrolases released 18 g/L of reducing sugars (RS) after 24 h (60% corresponded to glucose), consuming the BP polysaccharides. Lactobacillus delbrueckii fermented the released RS, producing 10 g/L of LA; while in the sequential fermentation (inoculating L. delbrueckii after saccharification), 28 g/L of LA were produced, observing an apparent decrease in feedback inhibition of hydrolases below 1.5 g/L of RS. This process is susceptible for upscaling to produce high LA concentrations and represents a platform to utilize agroindustrial wastes to obtain value-added products.

Optimized production and isolation of antibacterial agent from marine Aspergillus flavipes against Vibrio harveyi

Statistical methodologies, including Plackett-Burman design and Box-Behnken design, were employed to optimize the fermentation conditions for the production of active substances against aquatic pathogen Vibrio harveyi by marine-derived Aspergillus flavipes strain HN4-13. The optimal crucial fermentation values for maximum production of active substances against V. harveyi were obtained as follows: X₁ (peptone) = 0.3%, X₂ (KCl) = 0.25%, and X₃ (inoculum size) = 4.5%. The predicted diameter of inhibitory zone against V. harveyi was 23.39 mm, and the practical value reached 23.71 ± 0.98 mm with a 62.3% increase. Bioassay-guided fractionation resulted in the acquisition of two compounds whose structures were identified as questin (1) and emodin (2). Questin exhibited the same antibacterial activity against V. harveyi as streptomycin (MIC 31.25 µg/mL). This is the first time to report questin as a potential antibacterial agent against aquatic pathogen V. harveyi.

Production of pectinases for quality apple juice through fermentation of orange pomace

Production of pectinases by Aspergillus niger was successfully carried out through solid state fermentation. Orange pomace was used as substrate to produce pectinases using a wild type of A. niger isolated from a rotten orange texture. Some of the important parameters affecting exo- and endo-pectinases activities such as temperature, moisture, C/N ratio were optimized. The results indicated that the produced pectinases exhibited maximum activity in temperature range of 45-55 °C and the maximum enzyme productivity occurred at 70% moisture content and C/N ratio of 10. The enzyme kinetic was studied using Michaelis-Menten and Logistic model and the equation were fitted to experimental data for both exo- and endo-pectinases activities. In evaluation of kinetic model, it was found that Monod model presented perfectly fitted with experimental data. Monod kinetic parameters [Formula: see text] for exo-pectinase activities were [Formula: see text] mM, respectively. The Monod kinetic parameters [Formula: see text] for endo-pectinase activity were [Formula: see text] and [Formula: see text] respectively. Finally, the performances of the produced pectinases were evaluated on natural apple juice. It was confirmed that concentration of soluble sugar, clarity and viscosity of the juice and the yield of extracted juice were significantly improved by the enzymatic hydrolysis activity of pectinases.

Scaling-up and ionic liquid-based extraction of pectinases from Aspergillus flavipes cultures

The viability of the scaling-up of pectinases production by Aspergillus flavipes at 5L-bioreactor scale has been demonstrated by keeping constant the power input, and a drastic increase in the endo- and exopectinolytic enzyme production was recorded (7- and 40-fold, respectively). The main process variables were modelled by means of logistic and Gompertz equations. In order to overcome the limitations of the conventional downstream strategies, a novel extraction strategy was proposed on the basis of the adequate salting-out potential of two biocompatible cholinium-based ionic liquids (N_1112OHCl and N_1112OHH₂PO₄) in aqueous solutions of Tergitol, reaching more than 90% of extraction.

Pectinase production by Aspergillus giganteus in solid-state fermentation: optimization, scale-up, biochemical characterization and its application in olive-oil extraction

The application of pectinases in industrial olive-oil processes is restricted by its production cost. Consequently, new fungal strains able to produce higher pectinase titers are required. The aim of this work was to study the capability of Aspergillus giganteus NRRL10 to produce pectinolytic enzymes by SSF and evaluate the application of these in olive-oil extraction. A. giganteus was selected among 12 strains on the basis of high pectinolytic activity and stability. A mixture composed by wheat bran, orange, and lemon peels was selected as the best substrate for enzyme production. Statistical analyses of the experimental design indicated that pH, temperature, and CaCl2 are the main factors that affect the production. Subsequently, different aeration flows were tested in a tray reactor; the highest activity was achieved at 20 L min−1 per kilogram of dry substrate (kgds). Finally, the pectinolytic enzymes from A. giganteus improved the oil yield and rheological characteristics without affecting oil chemical properties.

Effect of passive transport of water through plasma membrane in production of extracellular enzyme

In this article, availability and control of water in solid-state fermentation (SSF) were investigated. Based on passive transport of water through plasma membranes, a new model was proposed for calculation and control of water activities in the mixture of solids. The validity of theoretical model and accuracy of the proposed model were proved by experimental data. This model was used for production of pectinases via mixed-SSF with the aid of a rotary drum bioreactor. It was found that in case of extracellular enzyme production, the new model is in good agreement with experimental data for the control of water activities in the mixed-SSF. Exact control of water activity in SFF, the production of endo- and exo-pectinases was relatively enhanced. Based on theoretical view point, the prominence of this new model in control of water activity was also proved.

Revision of Aspergillus section Flavipedes: seven new species and proposal of section Jani sect. nov

Aspergillus section Flavipedes contains species found worldwide in soils and rhizospheres, indoor and cave environments, as endophytes, food contaminants and occasionally as human pathogens. They produce many extensively studied bioactive secondary metabolites and biotechnologically relevant enzymes. The taxa were revised based on phylogenetic analysis of sequences from four loci (β-tubulin, calmodulin, RPB2, ITS rDNA), two PCR fingerprinting methods, micro- and macromorphology and physiology. Section Flavipedes includes three known and seven new species: A. ardalensis, A. frequens, A. luppii, A. mangaliensis, A. movilensis, A. polyporicola and A. spelaeus. The name A. neoflavipes was proposed for Fennellia flavipes a distinct species from its supposed asexual state A. flavipes. Aspergillus iizukae, A. frequens and A. mangaliensis are the most common and widely distributed species, whereas A. flavipes s. str. is rare. A dichotomous key based on the combination of morphology and physiology is provided for all recognized species. Aspergillus section Jani is established to contain A. janus and A. brevijanus, species previously classified as members of sect. Versicolores, Terrei or Flavipedes. This new section is strongly supported by phylogenetic data and morphology. Section Jani species produce three types of conidiophores and conidia, and colonies have green and white sectors making them distinctive. Accessory conidia found in pathogenic A. terreus were found in all members of sects. Flavipedes and Jani. Our data indicated that A. frequens is a clinically relevant and produces accessory conidia during infection.

Pectinase activity determination: an early deceleration in the release of reducing sugars throws a spanner in the works!

Recently, it has been suggested that pectinases could be used to hydrolyze pectin in biorefineries based on pectin-rich agro-industrial wastes. However, for this to be viable, the cost of their production would need to be lowered significantly. In fact, over the last few decades, there have been many attempts to improve pectinase production by existing strains or to screen for new strains from environmental isolates. In these studies, it is necessary to measure pectinase activities. Many researchers use single-time-point assays that involve incubation of pectinolytic extracts with pectic substrates for a fixed time, followed by determination of the liberated reducing sugars. However, different researchers use quite different conditions for this assay. Furthermore, no attention has been given to the reaction profile during the assay. In the current work, we show, for the first time, that a significant deceleration of the rate of liberation of reducing sugars occurs over the first ten minutes of the reaction. As a consequence, the incubation time used in a single-time-point assay has a large effect on the value obtained for the activity. In fact, we demonstrate that, depending on the particular combination of incubation time, pectin concentration and reaction temperature, the same extract could be reported to have activities that differ by an order of magnitude. In addition, we show that the relative activities obtained with polygalacturonic acid do not correlate with those obtained with pectin. We conclude that it is currently impossible to make meaningful comparisons between pectinase activities reported in the literature by workers who have used different assay conditions. Therefore there is an urgent need for the development of a standardized assay for evaluating the saccharification potential of pectinase complexes.

Evaluation of free and immobilized Aspergillus niger NRC1ami pectinase applicable in industrial processes

The Aspergillus niger NRC1ami pectinase was evaluated according to its hydrolysis efficiency of dry untreated orange peels (UOP), HCl-treated orange peels and NaOH-treated orange peels (HOP and NOP). Pectinase was entrapped in polyvinyl alcohol (PVA) sponge and the optimum pH and temperature of the free and immobilized enzymes were shifted from 4, 40 °C to 6, 50 °C respectively. The study of pH stability of free and immobilized pectinase showed that the immobilization process protected the enzyme strongly from severe alkaline pHs. The immobilization process improved the enzyme thermal stability to great instant. The unique feature of the immobilization process is its ability to solve the orange juice haze problem completely. Immobilized enzyme was reused 12 times in orange juice clarification with 9% activity loss from the original activity. Maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) of the partially purified form were significantly changed after immobilization.