Beyond tradition: a novel approach for edible bird nest cleaning and its processing.

An edible bird nest is a product of the solidified saliva secretion from a few different swiftlet's species, during the breeding season. But the high impurities in A. maximus and C. esculent nests make them less ideal to be consumed. Eggshells and guano are the major contaminants contributing to the nitrite and nitrates contents. However, recent studies have shown significant medicinal and cosmetic applications of edible bird nest like anti-viral, anti-inflammatory, enhancing bone strength, and anti-aging. Thus, the high demand for edible bird nest in the global market to explore its potential application has improved from swiftlet farming activities to the cleaning process. Recent studies have shown the use of immobilized enzymes like keratinase for the removal of contaminants. The current review discusses the importance of Swiftlet bird nest, its application, and commercialization.

Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase and maltogenic amylase from Bacillus lehensis G1 for maltooligosaccharides synthesis.

Maltooligosaccharides (MOS) are functional oligosaccharides that can be synthesized through enzymatic cascade reaction between cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1. To address the problems of low operational stability and non-reusability of free enzymes, both enzymes were co-immobilized as combined cross-linked enzyme aggregates (Combi-CLEAs-CM) with incorporation of bovine serum albumin (BSA) and Tween 80 (Combi-CLEAs-CM-add). Combi-CLEAs-CM and Combi-CLEAs-CM-add showed activity recoveries of 54.12 % and 69.44 %, respectively after optimization. Combi-CLEAs-CM-add showed higher thermal stability at higher temperatures (40 °C) with longer half-life (46.20 min) as compared to those of free enzymes (36.67 min) and Combi-CLEAs-CM (41.51 min). Both combi-CLEAs also exhibited higher pH stability over pH 5 to pH 9, and displayed excellent reusability with >50 % of initial activity retained after four cycles. The reduction in Km value of about 22.80 % and 1.76-fold increase in starch hydrolysis in comparison to Combi-CLEAs-CM attested the improvement of enzyme-substrate interaction by Tween 80 and pores formation by BSA in Combi-CLEAs-CM-add. The improved product specificity of Combi-CLEAs-CM-add also produced the highest yield of MOS (492 mg/g) after 3 h. Therefore, Combi-CLEAs-CM-add with ease of preparation, excellent reusability and high operational stability is believed to be highly efficacious biocatalyst for MOS production.

Microbial biotechnology approaches for conversion of pineapple waste in to emerging source of healthy food for sustainable environment.

One of the most significant and difficult jobs in food sustainability, is to make use of waste in the vegetable and fruit processing sectors. The discarded fruits along with their waste materials, is anticipated to have potential use for further industrial purposes via extraction of functional ingredients, extraction of bioactive components, fermentation. As a result of its abundant availability, simplicity and safe handling, and biodegradability, pineapple waste is now the subject of extensive research. It is regarded as a resource for economic development. This vast agro-industrial waste is being investigated as a low-cost raw material to produce a variety of high-value-added goods. Researchers have concentrated on the exploitation of pineapple waste, particularly for the extraction of prebiotic oligosaccharides as well as bromelain enzyme, and as a low-cost source of fibre, biogas, organic acids, phenolic antioxidants, and ethanol. Thus, this review emphasizes on pineapple waste valorisation approaches, extraction of bioactive and functional ingredients together with the advantages of pineapple waste to be used in many areas. From the socioeconomic perspective, pineapple waste can be a new raw material source to the industries and may potentially replace the current expensive and non-renewable sources. This review summarizes various approaches used for pineapple waste processing along with several important value-added products gained which could contribute towards healthy food and a sustainable environment.

A porous-cross linked enzyme aggregates of maltogenic amylase from Bacillus lehensis G1: Robust biocatalyst with improved stability and substrate diffusion.

Enzymatic synthesis of maltooligosaccharides is hampered due to lack of stability of soluble enzyme. This limitation can be tackled by cross linked enzyme aggregates (CLEAs) immobilization approach. However, substrate diffusion is a major bottleneck in cross linking technology. Herein, CLEAs of maltogenic amylase from Bacillus lehensis G1 (Mag1) was developed with addition of porous agent (Mag1-p-CLEAs). Comparison of thermal, pH and kinetic analysis with CLEAs without porous agent (Mag1-CLEAs) and free Mag1 was performed. Mag1-p-CLEAs with porous structure prepared at 0.8% (w/v) of citrus pectin (porous agent), 0.25% (w/v) of chitosan (cross linker) and cross linked for 1.5 h yielded 91.20% activity. 80% of activity is retained after 30 min of incubation at 40 °C and showed longer half-life than free Mag1 and Mag1-CLEAs. Mag1-p-CLEAs also showed pH stability at acidic and alkaline pH. The 1.68-fold increase in Vmax value in comparison to Mag1-CLEAs showed that the presence of pores of Mag1-p-CLEAs enhanced the beta-cyclodextrin accessibility. The increase in high catalytic efficiency (Kcat/Km) value, 1.90-fold and 1.05-fold showed that it also has better catalytic efficiency than free Mag1 and Mag1-CLEAs, respectively. Mag1-p-CLEAs not only improved substrate diffusibility of CLEAs, but also leads to higher thermal and pH stability of Mag1.

Comparative structural analysis of fruit and stem bromelain from Ananas comosus.

Cysteine proteases in pineapple (Ananas comosus) plants are phytotherapeutical agents that demonstrate anti-edematous, anti-inflammatory, anti-thrombotic and fibrinolytic activities. Bromelain has been identified as an active component and as a major protease of A. comosus. Bromelain has gained wide acceptance and compliance as a phytotherapeutical drug. The proteolytic fraction of pineapple stem is termed stem bromelain, while the one presents in the fruit is known as fruit bromelain. The amino acid sequence and domain analysis of the fruit and stem bromelains demonstrated several differences and similarities of these cysteine protease family members. In addition, analysis of the modelled fruit (BAA21848) and stem (CAA08861) bromelains revealed the presence of unique properties of the predicted structures. Sequence analysis and structural prediction of stem and fruit bromelains of A. comosus along with the comparison of both structures provides a new insight on their distinct properties for industrial application.

Computational docking, molecular dynamics simulation and subsite structure analysis of a maltogenic amylase from Bacillus lehensis G1 provide insights into substrate and product specificity.

Maltogenic amylase (MAG1) from Bacillus lehensis G1 displayed the highest hydrolysis activity on ß-cyclodextrin (ß-CD) to produce maltose as a main product and exhibited high transglycosylation activity on malto-oligosaccharides with polymerization degree of three and above. These substrate and product specificities of MAG1 were elucidated from structural point of view in this study. A three-dimensional structure of MAG1 was constructed using homology modeling. Docking of ß-CD and malto-oligosaccharides was then performed in the MAG1 active site. An aromatic platform in the active site was identified which is responsible in substrate recognition especially in determining the enzyme's preference toward ß-CD. Molecular dynamics (MD) simulation showed MAG1 structure is most stable when docked with ß-CD and least stable when docked with maltose. The docking analysis and MD simulation showed that the main subsites for substrate stabilization in the active site are -2, -1, +1 and +2. A bulky residue, Trp359 at the +2 subsite was identified to cause steric interference to the bound linear malto-oligosaccharides thus prevented it to occupy subsite +3, which can only be reached by a highly bent glucose molecule such as ß-CD. The resulted modes of binding from docking simulation show a good correlation with the experimentally determined hydrolysis pattern. The subsite structure generated from this study led to a possible mode of action that revealed how maltose was mainly produced during hydrolysis. Furthermore, maltose only occupies subsite +1 and +2, therefore could not be hydrolyzed or transglycosylated by the enzyme. This important knowledge has paved the way for a novel structure-based molecular design for modulation of its catalytic activities.