Purification, partial characterization, and covalent immobilization-stabilization of an extracellular α-amylase from Aspergillus niveus

Computational Insights into the Selecting Mechanism of α-Amylase Immobilized on Cellulose Nanocrystals: Unveiling the Potential of α-Amylases Immobilized for Efficient Poultry Feed Hydrolysis

The selection of an appropriate amylase for hydrolysis poultry feed is crucial for achieving improved digestibility and high-quality feed. Cellulose nanocrystals (CNCs), which are known for their high surface area, provide an excellent platform for enzyme immobilization. Immobilization greatly enhances the operational stability of α-amylases and the efficiency of starch bioconversion in poultry feeds. In this study, we immobilized two metagenome-derived α-amylases, PersiAmy2 and PersiAmy3, on CNCs and employed computational methods to characterize and compare the degradation efficiencies of these enzymes for poultry feed hydrolysis. Experimental in vitro bioconversion assessments were performed to validate the computational outcomes. Molecular docking studies revealed the superior hydrolysis performance of PersiAmy3, which displayed stronger electrostatic interactions with CNCs. Experimental characterization demonstrated the improved performance of both α-amylases after immobilization at high temperatures (80 °C). A similar trend was observed under alkaline conditions, with α-amylase activity reaching 88% within a pH range of 8.0 to 9.0. Both immobilized α-amylases exhibited halotolerance at NaCl concentrations up to 3 M and retained over 50% of their initial activity after 13 use cycles. Notably, PersiAmy3 displayed more remarkable improvements than PersiAmy2 following immobilization, including a significant increase in activity from 65 to 80.73% at 80 °C, an increase in activity to 156.48% at a high salinity of 3 M NaCl, and a longer half-life, indicating greater thermal stability within the range of 60 to 80 °C. These findings were substantiated by the in vitro hydrolysis of poultry feed, where PersiAmy3 generated 53.53 g/L reducing sugars. This comprehensive comparison underscores the utility of computational methods as a faster and more efficient approach for selecting optimal enzymes for poultry feed hydrolysis, thereby providing valuable insights into enhancing feed digestibility and quality.

Activity of Hydrolases and Their Inhibitors in Potato Plants Treated with Bacillus subtilis, Salicylic, and Jasmonic Acids and Affected by the Combined Effect of the Late Blight and the Lack of Moisture

The effect of Bacillus subtilis in combination with salicylic (SA) and jasmonic (JA) acids on the activity of amylases, cellulases, proteases, and their inhibitors in potato leaves in connection with the development of resistance to Phytophthora infestans (Mont.) de Bary in conditions of moisture deficiency have been investigated. Plants grown from microtubers were treated with Bacillus subtilis suspension (108 cells/mL) and with a mixture of bacteria with SA (10−6 M), JA (10−7 M), and SA + JA and were then infected with P. infestans (107 spores/mL) and cultivated under drought. Treatment with B. subtilis bacteria, especially in combination with signaling molecules, contributed to a decrease in the degree of pathogen infestation on plants grown with a lack of moisture. Both salicylate and jasmonate signaling pathways play an important role in the regulation of hydrolase activity and the stimulation of plant resistance. The revealed differences in the degree of hydrolase inhibitors activation under the influence of B. subtilis bacteria and signal molecules suggest different paths to the formation of resistance to P. infestans in potato under drought conditions.

Systemic Colonization of Potato Plants by Verticillium dahliae Leads to Infection of Tubers and Sprouting Buds

A green fluorescent protein (GFP)-tagged isolate of Verticillium dahliae was used to study its colonization in potato plants and tubers. Three-week-old potato plants of the highly susceptible cultivar 'Shepody' were inoculated with a conidial suspension of a GFP-tagged isolate of V. dahliae using a wound inoculation method. Colonization was studied using confocal microscopy combined with tissue sections. Conidia germinated and hyphae grew along the root hairs, elongation zones, and root caps between 24 and 96 h postinoculation (HPI). At 7 days postinoculation (DPI), the pathogen advanced to cortical tissues and grew into the root vascular bundles. At 8 weeks postinoculation (WPI), the stem epidermal cells, cortical tissues, vascular elements, and petioles were fully colonized by the mycelium of V. dahliae. At 11 WPI, the pathogen was detected in the stolon and progeny tubers, as confirmed by both GFP signals in tissues and reisolation of the pathogen on the semiselective NP-10 medium. Progeny potato tubers were harvested from the inoculated potato plants, and the GFP-signal was observed in the epidermal cells and vascular elements of sprouting buds that emerged from the harvested tubers. The infection rate of progeny tubers detected on semiselective NP-10 medium ranged from 34.55 to 55.56%, with an average of 45.31%. In conclusion, we report, for the first time, the entire progression of colonization by V. dahliae in potato plant tissues, progeny tubers, as well as of the sprouting buds that emerged from progeny tubers.

Production, immobilization and application of invertase from new wild strain Cunninghamella echinulata PA3S12MM

AIMS

The objective of this study was to determine the best conditions to produce invertase by Cunninghamella echinulata PA3S12MM and to immobilize and apply the enzyme.

METHODS AND RESULTS

The maximum production was verified in 8 days of cultivation at 28°C supplemented with 10 g L^-1 apple peel, reaching 1054.85 U ml^-1 . The invertase was purified from the DEAE-Sephadex column. The derivative immobilized in alginate-gelatin-calcium phosphate showed reusability >50% for 19 cycles. The derivative immobilized in glutaraldehyde-chitosan showed greater thermostability and at a different pH. The hydrolysis of 15 ml of sucrose 500 g L^-1 in a fixed bed reactor (total volume of 31 ml) produced 24.44 µmol min^-1 of glucose and fructose at a residence time of 30 min and a conversion factor of 0.5.

CONCLUSIONS

The new wild strain C. echinulata PA3S12MM presents high invertase production in medium supplemented with an agro-industrial residue and the immobilized enzyme showed high thermal stability and resistance at a different pH.

SIGNIFICANCE AND IMPACT OF THE STUDY

The fungus C. echinulata PA3S12MM is an excellent producer of invertases in Vogel medium supplemented with apple peel. The enzyme is promising for industrial application since it has good performance in reusability and inverted sugar production.

Influence of the genus Bacillus bacteria on the content of H2O2 and the activity of hydrolases and their inhibitors in potato plants during Phytophthora infestans Mont. de Bary infection

The authors studied the effect of treatment with bacteria Bacillus subtilis Cohn (strains 26D) and B. thuringiensis Berliner (strain B-6066) on the hydrogen peroxide (H2O2) content, the activity of hydrolytic enzymes and their protein inhibitors in potato plants (Solanum tuberosum L.) in connection with development of resistance to the late blight pathogen - oomycete Phytophthora infestans Mont. de Bary. Studies were carried out on potato plants of the susceptible Early Rose potato cultivar that were treated with a suspension of B. subtilis and B. thuringiensis bacteria (108 cells/ml) and infected with P. infestans (107 spores/ml). A decrease in the degree of leaf damage by oomycete was revealed under the influence of the genus Bacillus bacteria, depending on the strain. The increase in potato resistance to P. infestans infection was mediated by the stimulating effect of the B. subtilis 26D and the B. thuringiensis B-6066 bacteria on the concentration of H2O2, the modulating effect on the activity of hydrolytic enzymes and the enhancement of the transcriptional activity of protease and amylase inhibitor genes in plant tissues. Differences in the degree of activation of the transcriptional activity of hydrolase inhibitor genes by the B. subtilis 26D and the B. thuringiensis B-6066 bacteria were revealed, which suggests differential ways of forming the potato resistance to P. infestans under their influence.

Directly mining a fungal thermostable α-amylase from Chinese Nong-flavor liquor starter

BACKGROUND

Chinese Nong-flavor (NF) liquor is continuously and stably produced by solid-state fermentation technology for 1000 years, resulting in enrichment of special microbial community and enzymes system in its starter. Based on traditional culture-dependent methods, these functional enzymes are hardly obtained. According to our previous metatranscriptomic analysis, which identifies plenty of thermostable carbohydrate-active enzymes in NF liquor starter, the aim of this study is to provide a direct and efficient way to mine these thermostable enzymes.

RESULTS

In present study, an alpha-amylase (NFAmy13A) gene, which showed the highest expression level of enzymes in starch degradation at high temperature stage (62 °C), was directly obtained by functional metatranscriptomics from Chinese Nong-flavor liquor starter and expressed in Pichia pastoris. NFAmy13A had a typical signal peptide and shared the highest sequence identity of 64% with α-amylase from Aspergillus niger. The recombinant enzyme of NFAmy13A showed an optimal pH at 5.0-5.5 and optimal temperature at 60 °C. NFAmy13A was activated and stabilized by Ca²⁺, and its half-lives at 60 and 70 °C were improved significantly from 1.5 and 0.4 h to 16 and 0.7 h, respectively, in the presence of 10 mM CaCl₂. Meanwhile, Hg²⁺, Co²⁺ and SDS largely inhibited its activity. NFAmy13A showed the maximum activity on amylopectin, followed by various starches, amylose, glycogen, and pullulan, and its specificity activity on amylopectin was 200.4 U/mg. Moreover, this α-amylase efficiently hydrolyzed starches (from corn, wheat, and potato) at high concentrations up to 15 mg/ml.

CONCLUSIONS

This study provides a direct way to mine active enzymes from man-made environment of NF liquor starter, by which a fungal thermostable α-amylase (NFAmy13A) is successfully obtained. The good characteristics of NFAmy13A in degrading starch at high temperature are consistent with its pivotal role in solid-state fermentation of NF liquor brewing. This work would stimulate mining more enzymes from NF liquor starter and studying their potentially synergistic roles in NF liquor brewing, thus paving the way toward the optimization of liquor production and improvement of liquor quality in future.

Marine Microbiological Enzymes: Studies with Multiple Strategies and Prospects

Marine microorganisms produce a series of promising enzymes that have been widely used or are potentially valuable for our daily life. Both classic and newly developed biochemistry technologies have been broadly used to study marine and terrestrial microbiological enzymes. In this brief review, we provide a research update and prospects regarding regulatory mechanisms and related strategies of acyl-homoserine lactones (AHL) lactonase, which is an important but largely unexplored enzyme. We also detail the status and catalytic mechanism of the main types of polysaccharide-degrading enzymes that broadly exist among marine microorganisms but have been poorly explored. In order to facilitate understanding, the regulatory and synthetic biology strategies of terrestrial microorganisms are also mentioned in comparison. We anticipate that this review will provide an outline of multiple strategies for promising marine microbial enzymes and open new avenues for the exploration, engineering and application of various enzymes.

Purification and characterization of a highly efficient calcium-independent α-amylase from Talaromyces pinophilus 1-95

Alpha-amylase is a very important enzyme in the starch conversion process. Most of the α-amylases are calcium-dependent and exhibit poor performance in the simultaneous saccharification and fermentation process of industrial bioethanol production that uses starch as feedstock. In this study, an extracellular amylolytic enzyme was purified from the culture broth of newly isolated Talaromyces pinophilus strain 1-95. The purified amylolytic enzyme, with an apparent molecular weight of 58 kDa on SDS-PAGE, hydrolyzed maltopentaose, maltohexaose, and maltoheptaose into mainly maltose and maltotriose and minor amount of glucose, confirming the endo-acting mode of the enzyme, and hence, was named Talaromyces pinophilus α-amylase (TpAA). TpAA was most active at pH 4.0-5.0 (with the temperature held at 37°C) and 55°C (at pH 5.0), and stable within the pH range of 5.0-9.5 (at 4°C) and below 45°C (at pH 5.0). Interestingly, the Ca2+ did not improve its enzymatic activity, optimal temperature, or thermostability of the enzyme, indicating that the TpAA was Ca2+-independent. TpAA displayed higher enzyme activity toward malto-oligosaccharides and dextrin than other previously reported α-amylases. This highly active Ca2+-independent α-amylase may have potential applications in starch-to-ethanol conversion process.

Mini-review: Brazilian fungi diversity for biomass degradation

Brazil houses over 10% of the total number of known species on Earth, with a great diversity of plants and fungi. The collection, isolation, identification and conservation of filamentous fungi with relevance to agriculture, pharmaceutical, food and biotechnological industries in Biological Resource Centers (CRBs) is very important to the development of a nation's scientific and technological infrastructure. In Brazil, 36 fungal collections are registered in the database of International Collections. Several federal and state programs have encouraged the formation of a researcher's network in order to study natural resources and the nation's biodiversity. In this context, Brazilian researchers have been on the frontiers of knowledge, investigating the enzymatic systems from native filamentous fungi with potential for biomass degradation and biotechnological application. In this review, we address recent progress in Brazilian fungal research, focusing on the identification and study of fungi and enzymes with potential for biomass degradation and application in bioenergy.