Effects of enzyme loading, incubation time and incubation temperature on sawdust hydrolysis by locally produced bacterial xylanase

The present study aims to investigate the enzymatic hydrolysis conditions of bacterial xylanase on alternative cheaper substrate which is hardwood sawdust (SD) in order to produce reducing sugars (xylose). The bacterial xylanase was produced and secreted from the Bacillus sp. The wood industry in Malaysia has become a major source of foreign exchange across the globe for developing the countries. Therefore, more wood residues (sawdust) are produced during the logging and processing of wood. Most of the sawdust will be disposed into the landfills. In actual, the sawdust can be utilised into more valuable products such as in producing reducing sugars. Thus, previous researches have studied on xylose production from wooden sawdust using commercial xylanases, but only few with the bacterial xylanase. Therefore, a study on the best conditions of enzymatic hydrolysis in producing xylose from sawdust using bacterial xylanase is essential. Prior to the enzymatic hydrolysis, the hardwood sawdust was pre-treated by autoclave at 121°C for 20 min in order to breakdown the lignin linkage and obtain the hemicellulosic xylan (delignification). The enzymatic hydrolysis conditions such as enzyme loading, incubation time and incubation temperature were experimented by One-Factor-At-Time (OFAT) method. Based on the experiment, the fifth cycle pre-treated autoclaved sawdust showed 5.5-fold higher than the untreated sawdust. The best enzymatic hydrolysis conditions for xylose production were enzyme loading of 1.4%, incubation time of 30 min, and incubation temperature of 56.9 °C. These conditions also succeeded in producing 2.5-fold higher xylose than the one without the enzymatic hydrolysis

Cross-linked enzyme aggregates of recombinant xylanase for conversion of hemicelluloses to xylooligosaccharides

Hemicelluloses are heterogeneous branched polymers of sugars that exist abundantly in nature. Enzymatic hydrolysis is envisioned as a highly potential method in converting hemicelluloses into fuels and value-added chemicals. However, the use of free enzyme is hampered by low operational stability, difficulty in recovery and non-reusability, which requires for enzyme immobilization. Carrier-bound immobilization leads to utilization of high cost matrices, clogging of filters during downstream processing and presence of large amounts of non-catalytic ballast. Therefore, cross-linked enzyme aggregates (CLEA), a carrier-free technology that combines purification (precipitation) and immobilization into a single operation and does not require purified enzymes, is the solution to these problems. In this study, a recombinant xylanase (Xyl) from Trichoderma reesei was immobilized using three approaches: Xyl-CLEA, Xyl-CLEA-BSA (bovine serum albumin) and Xyl-CLEA-silanized maghemite. The use of ethanol as precipitant (1:9 volume ratio of enzyme to precipitant), glutaraldehyde (0.2:1 of glutaraldehyde to enzyme of 100 mM concentration) as cross-linking agent and the introduction of (3-aminopropyl) triethoxysilane (APTES) silanized maghemite (0.0075:1 of silanized maghemite to enzyme) prevailed in forming xylanase CLEAs with good enzyme activity recovery (78 %), thermal stability (50 % retained activity) and reusability (50 % retained activity). The Xyl-CLEA-silanized maghemite enhanced the activity recovery 1.66- and 1.50-fold compared to Xyl-CLEA and Xyl-CLEA-BSA, respectively. At elevated temperature of 60 °C and pHs of 3.0 and 8.0, Xyl-CLEA-silanized maghemite achieved better stability compared to the other CLEAs and free enzyme. Xyl-CLEA-silanized maghemite also successfully retained more than 50 % of its activity after 6 cycles, whereas Xyl-CLEA only retained approximately 10 % after 5 cycles. Therefore, the performance of Xyl-CLEA-silanized maghemite was further investigated by xylan hydrolysis under optimised reaction conditions. Xylooligosaccharides yield was slightly improved by 1.26- fold compared to the free enzyme. Kinetic parameters confirmed that CLEA immobilization did affect the productivity of the designed biocatalyst

Cross-linked enzyme aggregates of recombinant xylanase for conversion of hemicelluloses to xylooligosaccharides

Hemicelluloses are heterogeneous branched polymers of sugars that exist abundantly in nature. Enzymatic hydrolysis is envisioned as a highly potential method in converting hemicelluloses into fuels and value-added chemicals. However, the use of free enzyme is hampered by low operational stability, difficulty in recovery and non-reusability, which requires for enzyme immobilization. Carrier-bound immobilization leads to utilization of high cost matrices, clogging of filters during downstream processing and presence of large amounts of non-catalytic ballast. Therefore, cross-linked enzyme aggregates (CLEA), a carrier-free technology that combines purification (precipitation) and immobilization into a single operation and does not require purified enzymes, is the solution to these problems. In this study, a recombinant xylanase (Xyl) from Trichoderma reesei was immobilized using three approaches: Xyl-CLEA, Xyl-CLEA-BSA (bovine serum albumin) and Xyl-CLEA-silanized maghemite. The use of ethanol as precipitant (1:9 volume ratio of enzyme to precipitant), glutaraldehyde (0.2:1 of glutaraldehyde to enzyme of 100 mM concentration) as cross-linking agent and the introduction of (3-aminopropyl) triethoxysilane (APTES) silanized maghemite (0.0075:1 of silanized maghemite to enzyme) prevailed in forming xylanase CLEAs with good enzyme activity recovery (78 %), thermal stability (50 % retained activity) and reusability (50 % retained activity). The Xyl-CLEA-silanized maghemite enhanced the activity recovery 1.66- and 1.50-fold compared to Xyl-CLEA and Xyl-CLEA-BSA, respectively. At elevated temperature of 60 °C and pHs of 3.0 and 8.0, Xyl-CLEA-silanized maghemite achieved better stability compared to the other CLEAs and free enzyme. Xyl-CLEA-silanized maghemite also successfully retained more than 50 % of its activity after 6 cycles, whereas Xyl-CLEA only retained approximately 10 % after 5 cycles. Therefore, the performance of Xyl-CLEA-silanized maghemite was further investigated by xylan hydrolysis under optimised reaction conditions. Xylooligosaccharides yield was slightly improved by 1.26- fold compared to the free enzyme. Kinetic parameters confirmed that CLEA immobilization did affect the productivity of the designed biocatalyst

Introduction to Enzyme Immobilization

Recent advances in biotechnology and bioengineering have shown an increasing trend towards the development of environmentally friendly, safe and sustainable bioprocesses using enzymes. The excellent selectivity, specificity and catalytic performance have made enzymes robust biocatalysts with a wide range of applications in biomedicine, biosensing, and biocatalysis (Bilal et al., 2021). Due to the low use of chemicals and the absence of hazardous metabolites/byproducts, the use of biocatalysts is expected to facilitate environmentally friendly processes. In addition, there is a recurring obstacle in the various industries where biocatalysis can be used: the application of enzyme catalysis in chemical processes is limited by the lack of stability of enzymes at high temperatures or in turbulent flow regimes, as well as in potentially toxic solvents (Chapman et al., 2018

Simulation of lovastatin production in solid-state fermentation via oil palm frond

Lovastatin is a potent drug for lowering the blood cholesterol. It is a competitive inhibitor of 3-hyroxy3-methyl glutaryl coenzyme A (HMG-CoA) reductase, which is a key enzyme in the cholesterol production pathway. Lovastatin increases the good cholesterol or high-density lipoproteins to prevent the formation of plaque inside the blood vessels. This study aims to develop a process model of lovastatin production, produced by Monascus purpureus under solid-state fermentation using oil palm frond. SuperPro Design V9.5 software was used to develop and simulate the process model. Three parameters which are initial moisture content, composition of peptone and potassium, were varied to investigate their effects on lovastatin production. The optimum condition simulated using the process model at pH 7 with 60% initial moisture content, 0.0075 kg/hr of potassium, and 0.0075 kg/hr of peptone was able to produce 0.0288 kg/kg of lovastatin. The simulated results show good agreement with experimental work, with low percentage error of 5.77%, and provide a good approximation on the production of lovastatin under various process operating conditions

Nutritional values and microencapsulation techniques of fish oil from different sources: A mini review

ish oil is commonly consumed as dietary supplement due to its richness in long-chain polyunsaturated essential fatty acids, Omega-3. Omega-3 fatty acids are essential nutrients that are important in prevent- ing heart disease and also vital in human early development stage. Fish oil-based supplements can easily be found in global market and may vary in concentrations, forms, and purity. The main concerns on those available fish oil-based products are on their freshness and stability, since Omega-3 fatty acids are prone to oxidation and release unpleasant smell. In recent years, microencapsulation technology received sig- nificant increment in demand as it was continuously applied in food and pharmaceutical industries. Mechanisms of these techniques involved the formation of emulsion containing the core (fish oil) and the coating materials. The present review aims to compile findings and scientific research of nutritional values and microencapsulation techniques of fish oil. The sources of fish oil, therapeutic benefits, and bioactive compound constituents, different microencapsulation techniques, coating materials formula- tions, advantages and challenges on the current available microencapsulation techniques are also dis- cussed and reviewed

Pineapple enzyme: Beneficial poultry supplement

Pineapple waste have been reported to contain nutrients such as dietary fibres, sugars, proteins and minerals. These nurients could serve as a prominent source of growth factors to poultry. Hence, it can helps as an alternative to reduce poultry farmer’s costs to buy poultry feed

Hollow Fiber Membrane as a Carrier for Enzyme Immobilization

Cyclodextrin (CD) is produced from starch by an enzymatic conversion catalyzed by cyclodextrin glucanotransferase (CGTase). CD has been used in a wide range of industries, especially in food, cosmetic, pharmaceutical, and agrochemical industries, due to its ability to improve the physicochemical properties of organic molecules, conferring greater chemical resistance to environmental factors, higher solubility, and reduced volatility (Ching et al. 2022). The commercialization of CGTase for industrial purposes is highly challenging due to the instability of the CGTase, sensitivity to the process condition, and high cost of isolation and purification (Guzik, Hupert-Kocurek, and Wojcieszyńska 2014; Mohamad et al. 2015). The instability of CGTase during the reaction process results in low yield CD. Therefore, enzyme immobilization has been applied to improve CGTase stability and achieve higher CD yields

Intensification of phenolic content and antioxidant activity of extract from red pitaya (hylocereus polyrhzius) peel

Red Pitaya (Hylocereus polyrhizus) is widely known for number of health benefits including cholesterol- lowering effects, protection against diabetes and cancer. This paper presents the study on extraction of phenolic compound and antioxidant activity from Red Pitaya peel using ultrasonic-assisted extraction (UAE) process with water as a solvent. The amount of phenolic compound and antioxidant activity in the extracts were studied at different sonication temperatures (25�80 °C) and ultrasonic powers (200�600 W) with constant frequency of 50 kHz. The extracts were analysed using High- Performance Liquid Chromatography (HPLC) and 1, 1- Diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that the extractions yield increases with the increases of extraction temperature and power. These changes are probably due to the cavitation activity that occurred during transmission of ultrasonic waves in the solvent. Temperature of 40 oC and ultrasonic power of 200 W recorded most suitable extraction conditions with total phenolic content (TPC) of 2.5084 mg/ml and high antioxidant activity of 4.5052%. The result from this study maybe useful to identify the suitable gradient condition of ultrasonic-assisted extraction and operating conditions to extract high phenolic compound and antioxidant activity from Red Pitaya’s peel

Analysis Of Explosion Severity Of Tea Powder At Different Particle Size And Concentration In A Confined Space

Tea contains compounds rich in carbon-hydrogen bonds. When tea dust is suspended in air, across a variety of particle sizes and concentrations, in the presence of spark, it can combust, therefore presenting an explosion hazard. The explosion pressure properties of tea dust of four different dust concentrations (1000 g/m³, 1500 g/m³, 2000 g/m³ and 2500 g/m³) were conducted in a 20-L spherical explosion test vessel under five distinct particle sizes (71 µm, 125 µm, 160 µm, 180 µm and 250 µm). According to the findings, the explosion pressure characteristic is strongly related to dust concentration and particle size. Moisture content also has an effect on explosion propagation. The dried tea dust reached the maximum explosion pressure faster than undried tea dust. Among of the concentration and particle size range tested, the highest explosion pressure, 14.6 bar, was recorded at 2000 g/m³ with particle size 125 μm. The explosion index was 222 bar/s. It was shown that at higher dust concentration (≥2000 g/m3) and smaller particle sizes (≤125 μm) the explosion became more severe, whereby the flame accelerated at a higher rate and raised the explosion pressure drastically. The pressure characteristic changed as the conditions in which they occurred changed. These analyses and predictions are essential for achieving safe and optimal performance of tea manufacturing technology as well as the development of new applications