Entrapment of α-Amylase in Agar Beads for Biocatalysis of Macromolecular Substrate

The application of conventional or magnetic materials to support immobilization of amylolytic enzymes for batch and continuous operation of starch hydrolysis processes

In the production of ethanol, starches are converted into reducing sugars by liquefaction and saccharification processes, which mainly use soluble amylases. These processes are considered wasteful operations as operations to recover the enzymes are not practical economically so immobilizations of amylases to perform both processes appear to be a promising way to obtain more stable and reusable enzymes, to lower costs of enzymatic conversions, and to reduce enzymes degradation/contamination. Although many reviews on enzyme immobilizations are found, they only discuss immobilizations of α-amylase immobilizations on nanoparticles, but other amylases and support types are not well informed or poorly stated. As the knowledge of the developed supports for most amylase immobilizations being used in starch hydrolysis is important, a review describing about their preparations, characteristics, and applications is herewith presented. Based on the results, two major groups were discovered in the last 20 years, which include conventional and magnetic-based supports. Furthermore, several strategies for preparation and immobilization processes, which are more advanced than the previous generation, were also revealed. Although most of the starch hydrolysis processes were conducted in batches, opportunities to develop continuous reactors are offered. However, the continuous operations are difficult to be employed by magnetic-based amylases.

Effects of Formulation on the Palatability and Efficacy of In-Feed Praziquantel Medications for Marine Finfish Aquaculture

Praziquantel (PZQ) provides an effective treatment against monogenean parasitic infestations in finfish. However, its use as an in-feed treatment is challenging due to palatability issues. In this study, five formulations of PZQ beads (1−4 mm) were developed using marine-based polymers, with allicin added as a flavouring agent. All formulations attained PZQ loading rates ≥74% w/w, and the beads were successfully incorporated into fish feed pellets at an active dietary inclusion level of 10 g/kg. When tested for palatability and digestibility in small yellowtail kingfish, the PZQ-loaded beads produced with alginate-chitosan, alginate-Cremophor® RH40, and agar as carriers resulted in high consumption rates of 99−100% with no digesta or evidence of beads in the gastrointestinal tract (GIT) of fish fed with diets containing either formulation. Two formulations produced using chitosan-based carriers resulted in lower consumption rates of 68−75%, with undigested and partly digested beads found in the fish GIT 3 h post feeding. The PZQ-loaded alginate-chitosan and agar beads also showed good palatability in large (≥2 kg) yellowtail kingfish infected with gill parasites and were efficacious in removing the parasites from the fish, achieving >90% reduction in mean abundance relative to control fish (p < 0.001). The two effective formulations were stable upon storage at ambient temperature for up to 18 months, showing residual drug content >90% compared with baseline levels. Overall, the palatability, efficacy and stability data collected from this study suggest that these two PZQ particulate formulations have potential applications as in-feed anti-parasitic medications for the yellowtail kingfish farming industry.

Novel Thermotolerant Amylase from Bacillus licheniformis Strain LB04: Purification, Characterization and Agar-Agarose

This study analyzed the thermostability and effect of calcium ions on the enzymatic activity of α-amylase produced by Bacillus licheniformis strain LB04 isolated from Espinazo Hot springs in Nuevo Leon, Mexico. The enzyme was immobilized by entrapment on agar-agarose beads, with an entrapment yield of 19.9%. The identification of the bacteria was carried out using 16s rDNA sequencing. The enzyme was purified through ion exchange chromatography (IEX) in a DEAE-Sephadex column, revealing a protein with a molecular weight of ≈130 kDa. The enzyme was stable at pH 3.0 and heat stable up to 80 °C. However, the optimum conditions were reached at 65 °C and pH 3.0, with a specific activity of 1851.7 U mg⁻¹ ± 1.3. The agar-agarose immobilized α-amylase had a hydrolytic activity nearly 25% higher when compared to the free enzyme. This study provides critical information for the understanding of the enzymatic profile of B. licheniformis strain LB04 and the potential application of the microorganisms at an industrial level, specifically in the food industry.

Utilization of different polymers for the improvement of catalytic properties and recycling efficiency of bacterial maltase

Current study deals with the comparative study related to immobilization of maltase using synthetic (polyacrylamide) and non-synthetic (calcium alginate, agar-agar and agarose) polymers via entrapment technique. Polyacrylamide beads were formed by cross-linking of monomers, agar-agar and agarose through solidification while alginate beads were prepared by simple gelation. Results showed that the efficiency of enzyme significantly improved after immobilization and among all tested supports agar-agar was found to be the most promising and biocompatible for maltase in terms of immobilization yield (82.77%). The catalytic behavior of maltase was slightly shifted in terms of reaction time (free enzyme, agarose and polyacrylamide: 5.0 min; agar-agar and alginate: 10.0 min), pH (free enzyme, alginate and polyacrylamide: 6.5; agar-agar, agarose: 7.0) and temperature (free enzyme: 45 °C; alginate: 50 °C; polyacrylamide: 55 °C; agarose: 60 °C; agar-agar: 65 °C). Stability profile of immobilized maltase also revealed that all the supports utilized have significantly enhanced the activity of maltase at higher temperatures then its free counterpart. However, recycling data showed that agar-agar entrapped maltase retained 20.0% of its initial activity even after 10 cycles followed by agarose (10.0%) while polyacrylamide and alginate showed no activity after 8 and 6 cycles respectively.

Enzymatic hydrolysis of starch into sugars is influenced by microgel assembly

The use of alginate and chitosan polymer in the immobilization of Aspergillus oryzae ATCC 3940 fungal crude enzyme extract (CEE) amylase was presented. The assembly results change in the application of optimal pH and temperature hydrolysis to convert starch to sugar. Bead arrangement in three microgel supports: the internal support phase (IP), the external support phase (EP), and the internal and external support phase (UP). The best results were obtained using IP and EP. Reusing beads evaluated the stability of immobilized enzymes on IP support, remained active and bound during three cycles of reuse. For free and immobilized (IP) activity showed pH ranged from 5.0 to 7.0; optimum thermal enzymatic greater activity at 45 °C. The method of building the microgel influencing sugar reduction, in a single-step way to immobilize crude fungal amylase extracts can be used in industry.