In Vitro Assessment Of Antimicrobial Properties Of Malaysia Mangrove Plant (Rhizophora Apiculata) For The Application In Bone Replacement Materials

The aim of this study is to conduct in vitro assessment of antimicrobial (ATM) properties of Malaysia mangrove plants (Rhizophora Apiculata) barks against human pathogen bacteria for bone replacement application. Tannin extracted from Rhizophora Apiculata barks has shown a very good and significant performance as an ATM agent. In addition, development of hydroxyapatite (HA) composites with enhanced antimicrobial property are potentially attractive in of bone replacement applications. The extraction of tannin using acetone in ratio 1:5, gave practically about 33-35% of raw tannin as an ATM agent. HA/ATM composites with the ATM percentage in the range of 10-50% were used throughout the studies. Antimicrobial activity test was performed by using three human pathogen bacteria which are Staplococcus aeurus, Staplococcus epidermis and Pseudomonas aeruginosa. The disc diffusion test showed the HA/ATM agent was successfully susceptible against these three bacteria. In addition, the mean inhibition zones of antimicrobial activity were increased with the increasing of the ATM percentage in HA/ATM composites from 10 to 50%. Mechanical properties of the HA/ATM composite were also evaluated and the highest mechanical strength was given by HA/ATM composite with 40% ATM (6.65 ± 1 MPa) followed by 30% ATM (5.61 ± 1 MPa) and 50% ATM (5.46 ± 1 MPa). The results showed that the concomitant admixture of ATM to pure HA considerably increased the compressive strength of HA. Besides that, characterization on the morphology and structure of HA/ATM was done by using SEM. The presence of ATM was found to have significant effects in influencing the morphology of HA crystals. The mathematical model of ATM kinetic release was developed based on the drug release system. By refering to the kinetic release result, it has shown the Higuchi’s model is the best-fit model kinetic regarding to the highest R2 value and indicated that the ATM release from HA matrix as a square root of time dependent process based on diffusion process. Moreover, the reaction order for the reaction involved in HA kinetics growth was estimated through the integral method. Zero-order reaction is the best-fit model which showed that the reaction rate of kinetic growth for HA formation is proportional to the incubation time

Bleached kenaf microfiber as a support matrix for cyclodextrin glucanotransferase immobilization via covalent binding by different coupling agents

Enzyme immobilization via covalent binding provides a strong interaction between enzyme and support material. In this study, the effect of different coupling agents (spacer arms and ligands) in cyclodextrin glucanotransferase (CGTase) immobilization on bleached kenaf microfiber as a support matrix was investigated. The immobilized CGTase properties such as storage stability, thermal stability and reusability were evaluated. Immobilized CGTases on microfiber resulted in 0.162–0.24 U/mg-fiber when 55.6 U/mL of CGTase activity was initially added during the immobilization. The highest storage stability (60 °C) was shown by CGTase that was immobilized with ethylenediamine and o-phthalaldehyde, whereby 60% of its activity remained after 15 days. Its high stability was also confirmed by the lowest deactivation constant, kd that was obtained at 25 °C (0.0161 day−1) and 60 °C (0.0361 day−1). The CGTase immobilized using ethylenediamine and glutaraldehyde has shown the best retention of enzyme activity up to 72.72% after 12 cycles of batch reaction. The results indicate that kenaf microfiber has potential to be applied as a support for enzyme immobilization and its enzymatic properties were affected by the coupling agents

Development of cellulose nanofibre (CNF) derived from kenaf bast fibre and it's potential in enzyme immobilization support

This research mainly focuses on developing a natural cellulose nanofibre (CNF) from kenaf bast fibre and its potential for enzyme immobilization support. CNF was isolated by using a combination between chemical and mechanical treatments such as alkaline process and high-intensity ultrasonication process to increase the efficiency of hemicellulose and lignin removal, and to reduce its size into nano-order. The morphological study was carried out by using scanning electron microscope (SEM), indicating most of CNF diameter in range of 50-90 nm was obtained. The result of chemical analysis shows that cellulose content of raw bast fibre, bleached pulp fibre and CNF are 66.4 %, 83.7 % and 90.0 %, respectively. By decreasing the size of cellulose fibre, it increases the number of (O–H) group on the surface that plays as important role in enzyme immobilization. Covalent immobilization of cyclodextrin glucanotransferase (CGTase) onto CNF support resulted in about 95.0 % of protein loading with 69.48 % of enzyme activity, indicating high immobilization yield of enzyme. The enzymatic reaction of immobilized CGTase was able to produce more than 40 % yield of α-CD. Reusability profile of immobilized CGTase resulted in more than 60 % of retained activity up to 7 cycles. Therefore, the CNF is highly potential to be applied as enzyme immobilization support

Covalent immobilization of cyclodextrin glucanotranferase on kenaf cellulose nanofiber and its application in ultrafiltration membrane system

Cellulose nanofiber (CNF) from kenaf bast fiber has potential to be used in enzyme immobilization. This study discloses the preparation of CNF, immobilization of cyclodextrin glucanotranferase (CGTase) on CNF via chemical coupling and its application using ultrafiltration membrane. Morphological analysis shows the diameter distribution of CNF in nano-order scale (<100. nm), which upon higher ultrasonication output power resulted in smaller size of CNF. FTIR analysis confirms successful immobilization of CGTase on CNF through spacer arm-ligand interaction. The efficiency of immobilized CGTase shows more than 62% of binding yield and more than 45% of its residual activity were obtained. Reusability profile of immobilized CGTase that fouled on the surface of membrane could retain up to 50-60% of CGTase activity at 10th cycle. This study reveals the successful of CGTase immobilization on CNF via covalent binding. A novel approach technique in the application of ultrafiltration membrane was disclosed, which is beneficial to the industrial biocatalyst due to its excellent enzymatic performance and it is able to be reused for multiple times

Mass transfer with reaction kinetics of the biocatalytic membrane reactor using a fouled covalently immobilised enzyme layer (α–CGTase–CNF layer)

A dynamic mathematical model was used in this study to describe the mass transfer and reaction kinetics of a fouled α–CGTase–CNF layer in a biocatalytic membrane reactor (BMR) system. BMR performance was evaluated based on the effect of substrate concentration and pneumatic gauge pressure on the permeate flux, total permeate volume, starch conversion, and α-CD production. A model is introduced based on the layer of mass limit as the resistance blocking mechanism with reaction kinetics on the fouled α–CGTase–CNF layer. Important unknown parameters of the constants describing the layer resistance, KML0 and the kinetic constant of Michaelis-Menten, kcat, for mass transfer and its reaction kinetics, were successfully estimated at 3.9 × 107 min/mL and 216.18 mg-starch/cm3⋅U⋅min, respectively, using the proposed models. The study found that the kcat value corresponding to the maximum efficiency of the enzyme on starch cyclisation was a critical parameter in the prediction of the BMR dynamic profiles. Thus, the proposed model in this study can be used for further development of the BMR system, with excellent hydrodynamic and reaction performance

First report of Bacillus pumilus causing trunk bulges of rubber tree (Hevea brasiliensis) in Malaysia

The rubber industry is projected to increase to RM53 billion or USD1.3 billion of gross national income by 2020 in Malaysia (Malaysian Rubber Board 2009). Introductions of superclones with high yield potential such as RRIM 3001 are among the efforts to improve latex yield as well as timber yields. Superclone RRIM 3001, mostly cultivated by smallholders, yields about 3 tons of natural rubber latex per hectare per year. During September 2017, trunk bulging occurrences were observed in rubber trees (Hevea brasiliensis) RRIM 3001 superclone in Serdang, Selangor, Malaysia. These bulges appeared in different sizes and were similar to tumor-like bacteriosis on the whole trunk. Other symptoms were also observed, including depressed canker wounds with different sizes at the tapping zone and large bleeding lesions on the trunk and branches of the rubber trees. Symptomatic bark tissue of various rubber trees was collected at 1.52 m by using a sterile knife. The infected tissues were cut approximately at 0.5 × 0.5 cm, surface sterilized in 10% sodium hypochlorite, and washed two times in sterilized water. The tissues were mashed using pestle and mortar, shaken for 15 min in sterilized water, streaked onto nutrient agar (NA) medium, and incubated at 30°C for 24 h. From 15 putative strains, three potential strains (SM1, SM2, and SM3) were chosen for further characterization. Bacterial colonies were gram-positive, motile, endospore formers, catalase-positive and oxidase-negative, and produced a whitish pigment on NA medium. Polymerase chain reaction (PCR) amplification with 16S rRNA and Bsub-specific primers (Wattiau et al. 2001) was performed, and the products were sequenced. BLASTn analysis of both genes revealed that all strains were 99% identical to Bacillus pumilus strains M3 (GenBank accession no. MF461325) and PS23 (GenBank accession no. KP89557). The nucleotide sequences were later deposited in GenBank (accession nos. MH401100 to MH401102 for 16 rRNA gene and MH428001 to MH428003 for Bsub-specific gene). Phylogenetic analysis of Bsub-specific gene sequences showed all three strains were closely related to B. pumilus AGERI-PB1 reference strain in GenBank database with 99% similarity (accession no. LC385524). A pathogenicity test was carried out on 3-month-old superclone RRIM 3001 seedlings by inoculating 200 μl of 108 CFU/ml bacterial suspensions of all three strains to the upper part of the stem using a sterilized syringe. Parafilm was used to cover the inoculation sites. Six replicates were used for each treatment. Control seedlings were inoculated with sterilized water. Within 21 to 28 days postinoculation, rubber seedlings inoculated with B. pumilus strains produced symptoms such as necrosis on the leaves, cankers, exhibiting ooze, and tumor-like bacteriosis as observed naturally in the field. Control seedlings remained asymptomatic. Reisolation of the bacterium from the symptomatic tissues confirmed the presence of B. pumilus based on phenotypic characteristics and molecular characterization. To the best of our knowledge, this is the first official report of B. pumilus causing trunk bulges on rubber trees in Malaysia. Recent reports revealed that B. pumilus is pathogenic by causing disease to various type of plants including muskmelon (Song et al. 2018), ginger (Peng et al. 2013), and Scots pine (Kovaleva et al. 2015)

Covalent immobilization of α-CGTase on cellulose nanofiber derived from kenaf bast for enzymatic membrane reactor

Nanobiocatalyst is a new frontier of emerging nano-sized material support in enzyme immobilization application. This approach provides an innovative strategy between enzyme technology and utilization of natural nano-cellulose support in nanobiotechnology. This research work was focused on the covalent immobilization of α-cyclodextrin glucanotranferase (α-CGTase) on the cellulose nanofiber (CNF) support from kenaf bast fiber. The obtained immobilized α- CGTase-CNF was applied in stirred-cell ultrafiltration (UF) membrane system as enzymatic membrane reactor (EMR). Chemical-physical treatment (e.g. delignification, 3-stage of bleaching and high-intensity ultrasonication) were firstly performed to isolate the CNF from kenaf bast fiber. The combination of this treatment contributes to the efficiency of hemicellulose and lignin removal, and reduce its size from micro to nano-order. SEM and TEM analysis show the size distribution of fiber in a range of nano-order scale (<100 nm), which higher ultrasonication output power resulted in smaller size of CNF. Chemical composition analysis reveals the cellulose content increased up to 90% after the treatment. FTIR analysis reveals the changes in the surface functional group of CNF, contributes successful in removal of lignin and hemicellulose in the fiber. FTIR analysis also confirms successful immobilization of α-CGTase on CNF through ligand–spacer arm interaction (α-CGTase–GA–1,12-diaminododecane– CNF), where there is no significant damages on the dimensional structural of fiber after went through these treatments process. The efficiency of immobilized α-CGTase shows more than 62% of binding yield and more than 45% of its residual activity were obtained. The membrane fouling of α-CGTase-CNF layer using UF membrane indicated to the higher permeate flux declined when applying higher pneumatic pressure to the system, but it decreased in production yield of α-CD. Reusability profile of fouled α-CGTase-CNF layer is able to retain up to 50-60% of α-CGTase activity at 10th cycle and α-CD productivity that represent for each operation cycle was slightly decreased from its initial cycle. Substrate concentration and pneumatic pressure contribute to the major effect of fouled α-CGTase-CNF layer toward the performance of membrane operation and enzymatic production yield. Permeate flux profiles indicate the lowest substrate concentration with high pneumatic pressure showed the best performance of membrane operation with lowest permeate flux declined. Meanwhile, enzymatic production of α-CD profiles indicate that higher substrate concentration with lowest pneumatic pressure contributed to the highest value of α-CD production. Mass transfer and reaction kinetic of fouled α-CGTase-CNF layer were evaluated using gPROMS software. This software was used to study the mechanism and behavior of fouled α-CGTase- CNF layer toward the effect of substrate concentration and pneumatic pressure for the performance of membrane operation and its effectiveness during enzymatic reaction. The application of enzymatic membrane reactor (EMR) module system with accuracy of mathematical modelling is beneficial for further development of continuous membrane operation system with excellent enzymatic performance and it is able to be reused for multiple times

Study on the Preparation of Cellulose Nanofibre (CNF) from kenaf bast fibre for enzyme immobilization application

This paper discussed on the preparation of natural CNF from kenaf bast fibre for the application as a support structure in enzyme immobilization. The treatments involved for this preparation were delignification, bleaching and high-intensity ultra-sonication process to obtain nanofibre with high cellulose content and less than 100 nm diameter. Chemical composition analysis showed the influence of each process treatment on cellulose content of raw bast fibre, bleached pulp fibre and CNF(63.67, 81.12 and 91.97%, respectively). By increasing the cellulose content and decreasing the size of cellulose fibre, it resulted in a greater number of –OH functional group on its surface that plays as important role in enzyme immobilization. FTIR spectroscopy confirms that the removal of lignin and hemicellulose from the fibre after the treatments, as well as its interaction with coupling agents and CGTase enzyme. About 62.10% of enzyme loading and 45.62% of its activity yield were obtained after immobilization. Enzymatic reaction of immobilized CGTase on CNF indicates about more than 60% relative production yield of α-CD was achieved and its reusability was able to retain about 67.0% from its initial activity after 8 cycles of reaction. Therefore, the CNF is a good potential as a support for enzyme immobilization

Groundhook control of semi-active suspension for heavy vehicle

Active vibration isolation systems are not commonly used due to their associated cost and power requirements. In principle, semi-semi active isolation systems can deliver adaptability, good performance and less power consumption compared with fully active control. This paper presents a semi-active concept of a 7-degree of freedom (DOF) full vehicle model for heavy vehicle. To develop suspension control system that can improve road holding and improve ride comfort, dynamic modeling of passive and semi-active suspension for heavy vehicle model was constructed. The simulation model was developed using MATLAB Simulink software. Passive heavy vehicle model was validated using vehicle dynamics simulation software known as TruckSim. The validation was done by comparing the simulation results. The primary focus of this paper is on ride quality control and road holding. The paper investigates analytically, the use of passive and semi-active suspension for ride quality and road holding on heavy vehicle. The control scheme of the semi-active suspension system is based on the groundhook control. A ride test was conducted at constant speed, and the simulation results of passive and semi-active suspension consist of roll, pitch, vehicle body heave and tire forces are compared and analyzed. The results show that the semi-active system controlled by groundhook strategy provides better isolation than a conventional passive damped system