A comparative study of the effectiveness of β-glucosidase immobilized on CNT-nanoparticles and Ca-alginate beads

Enzymes are extensively used in various industrial, biomedical and biopharmaceutical applications. However, enzymes in their free form are unstable and expensive besides being characteristically susceptible to inhibition by high product concentrations and are highly sensitive to pH and temperature changes. Immobilization technology offers solutions to these challenges besides enhancing operational stability, longevity and ease of separation. β-glucosidase has been widely employed as model enzyme for enzymatic studies. Ca-alginate beads provide a gentle environment for immobilization, but have certain limitations such as low stability, high porosity and limitations in biocompatibility. Carbon nanotubes (CNTs) on the other hand have excellent mechanical, thermal and electrical properties, as well as dimensional and chemical compatibility with biomolecules like DNA and enzymes, suitable for biosensor design. Here, β-glucosidase was immobilized in Ca-alginate gel and multi-walled carbon nanotubes (MWCNT) using standard techniques and their activity was compared with that of free enzyme. The activity was found highest (12.53 U/mL) for the free enzyme and lowest (9.768 U/mL) for the immobilized Ca-alginate. The activity of immobilized MWCNT (12.20 U/mL) was close to the free enzyme activity. The enzyme reaction was found to follow Michaelis-Menten kinetics. The Michaelis constants, Km and Vmax, determined using Langmuir linearized plot are respectively 0.09048 μmol/mL and 0.00989 μmol/mL.min for immobilized Ca-alginate; and 0.0985 μmol/mL and 0.01237 μmol/mL.min for immobilized MWCNT. The corresponding values for the free enzyme are 0.0854 μmol/mL and 0.01263 μmol/mL.min. Thus, MWCNT appears to be a promising support material for enzyme immobilization. Keywords: β-glucosidase, immobilization, Ca-alginate, carbon-nanotube, Michaelis-Menten kinetic

Comparison of Ex-Situ and In-Situ Transesterification for the Production of Microbial Biodiesel

Microbial biodiesel is converted from microbial lipids via transesterification process. Most microbial biodiesel studies are focusing on the use of microalgal lipids as feedstock. Apart from using microalgae for lipid biosynthesis, lipids can also be extracted from other oleaginous microorganisms like fungi and yeast. However, there are gaps in the studies of lipid production from filamentous fungi, especially in-situ transesterification process. The aim of this project is to compare in-situ with the ex-situ transesterification of fungal biomass from Aspergillus oryzae. In ex-situ transesterification, two methods of lipid extraction, the Soxhlet extraction and the Bligh and Dyer extraction, were performed. For in-situ transesterification, two methods using different catalysts were investigated. Base-catalyzed in-situ transesterification of fungal biomass resulted on the highest Fatty Acid Methyl Esters (FAME) yield. The base-catalyzed in-situ transesterification was further optimized via Central Composite Design (CCD) of Response Surface Methodology (RSM). The parameters investigated were the catalyst loading, methanol to biomass ratio and reaction time. The optimization showed that the highest FAME yield was at 25.1% (w/w) with 10 minutes reaction time, 5% catalyst and 360:1 of the ratio of the methanol to biomass. Based on Analysis of Variance (ANOVA), the model was found to be significant according to the value of “Prob >F” of 0.0028. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Wastewater treatment by immobilised cell systems

The immobilization of whole cells is an important technique which provides alternative solution in the field of wastewater treatment for the purification of wastewater contaminated with various materials, such as organic compounds, inorganic compounds, metals, and so on. The immobilized cells are biocatalysts which can easily be separated from treated water without a setting step and such can be repeatedly used without washing out from the systems. The processes using immobilized cells have been studied and applied to practical treatment systems. An effective way of removing ammonia nitrogen from aqueous solutions is the utilization of immobilized cells because of high cell concentration, long retention time of biomass in the system, rapid separation of cells from liquid and ability to scale up the process. These immobilized catalyst systems are therefore proposed as potential methods for the treatment of various types of wastewater from low to high strength

Aerobic biodegradation of oil and grease in palm oil mill effluent using consortium of microorganisms

The current methods adapted for the treatment of Palm Oil Mill Effluent (POME) in most of the palm oil mills are not very effective in treating the pollutants in the POME to the stringent standards required. Furthermore the status and concentration of oil and grease after the treatment processes is given less attention and this suggests that these approaches employed are not sustainable to minimize the environmental impact of oil and grease in POME. Moreover, the range of concentration of oil and grease in POME is relatively higher than those obtained in toxic wastewaters, thus, the need for affective treatment process for POME. Treating POME through aerobic biodegradation process with consortia of microorganisms will facilitate effective conversion of the oil and grease present in POME to environmentally safe biomass thereby rendering the wastewater safe for effective reuse in the oil palm mills and eventual safe discharge

Enzyme-based biosensors for electrochemical detection of pesticides - a mini review

Despite their important contribution in increasing crops production, most pesticides are harmful to humans and living beings and can persist in the environment over long a long duration. Traditional chromatographic methods of analysis are expensive and cumbersome. Biosensor technology appears therefore as an efficient and economical alternative for fast detection of pesticides. The devices are portable, rapid, and highly sensitive. Other important features of the devices are their relatively high sensistivity and low response time. Enzymatic biosensors for pesticide detection rely either on the inhibition mechanism or on the catalytic activity of the immobilized enzyme toward a specific pesticide. Metal and carbon based nanomaterials are being widely used as immobilization support owing to novel characteristics such as biocompatibility and enhanced electron transfer ability for sensitive electrochemical detection, among others. This review focusses on the electrochemical detection of organophosphorus pesticides, delineating the limit of detection and response time of biosensors toward a wide range of organophosphorus pesticides

Assessment of extracellular activities of novel microorganisms for biodegradation of palm oil mill effluent (POME)

Palm oil mill effluent (POME) constitutes 60% of the wastes generated in typical palm oil mill and its environmental impact has been identified to be harmful to aquatic lives. This project examined the potential of degrading POME with microorganisms that are indigenous to POME. Thus, two microorganisms were isolated from POME using serial dilution (10−1 to 10−10) procedure on solid plates containing Potato Dextrose Agar (PDA), Sabouround Dextrose Agar (SDA) and Malt Extract Agar (MEA), respectively. The two microorganisms (TRQ1 and TRQ2) that consistently appeared on the three media plates were quantified and subjected to extracellular enzymatic activities such as amylolytic, gelatinolytic, cellulolytic and lipolytic. The two isolates, TRQ1 and TRQ2, showed negative response to amylolytic test and this confirmed that they are not fungi; however they are Gelatinolytic and Cellulolytic. TRQ1 showed low lipolytic activity while TRQ2 did not show any. The diameter covered by TRQ1 and TRQ2 on gelatin media were 8.5 and 8.0cm respectively, while the spread on cellulose media were 3.5 and 3.25 cm, respectively, on the seventh day. Furthermore, TRQ1 covered a diameter of 1.65cm while TRQ2 retained its initial diameter. These results show that TRQ1 and TRQ2 contain gelatinolytic and cellulolytic enzymes and can be utilized for the degradation of cellulosic substrates present in POME, in particular. The cheap and wide availability of the material (POME) used as source for the production of these microorganisms indicates their economic importance for industrial applications and environmental sustainability, particularly in converting waste to wealth. Keywords: Biodegradation; Cellulolytic; Gelatinolytic; Lipolytic; Microorganisms; POM