Chong-Boon Ong | International University of Malaya-Wales (original) (raw)

Papers by Chong-Boon Ong

Chemical Engineering Communications , Oct 19, 2024

Immobilized Aspergillus ficuum tannase on amino-functionalized multiwalled carbon nanotubes (A-MW... more Immobilized Aspergillus ficuum tannase on amino-functionalized multiwalled carbon nanotubes (A-MWCNT) was assembled through glutaraldehyde-mediated covalent coupling to produce a stable biocatalyst nanocomposite. The effective binding of tannase on the surface of A-MWCNT was evaluated and authenticated by spectroscopic signature signals and morphological differences, before and after enzyme coupling. Both free- and immobilized tannase showed optimal catalytic activities at pH 5.0 and 35 °C, with the immobilized tannase exhibiting enhanced thermostability compared to the soluble enzyme. The immobilized tannase preparation was also found to be reusable up to five cycles, with 66% of initial enzyme activity retained thereafter. The enzyme-carbon nanotube composite preparation allows for bioconversion to be accomplished in a bioreactor with a smaller footprint.

Applied Biochemistry and Biotechnology, May 7, 2024

Green tea has garnered widespread interest in the past decades due to its content of health-benef... more Green tea has garnered widespread interest in the past decades due to its content of health-beneficial polyphenols and catechins, besides reportedly exhibiting activities for the prevention, and possibly treatment, of many modern-life-associated afflictions. Hence, the functional food potential of health-beneficial beverages such as green tea is widely and commercially promoted. Biotransformation of green tea extract using enzymes such as tannase ostensibly enhances its beneficial well-being properties and disease-preventing functionalities. The tannase-treated green tea catechins may exhibit enhanced, amongst others, antioxidant, anti-tumour, anti-wrinkle, anti-inflammatory, anti-obesity and anti-sarcopenia properties compared to native green tea extract. Nonetheless, the health benefits and therapeutic and toxicological effects associated with these compounds, before and after tannase treatment, present a scientific gap for detailed studies. Accordingly, the review surveys the literature from the late twentieth century until the year 2023 related to the aforementioned important aspects.

Journal of the Serbian Chemical Society, Mar 2, 2023

The immobilization of cross-linked tannase onto carboxyl-functionalized multi-walled carbon nanot... more The immobilization of cross-linked tannase onto carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH) was achieved via physical adsorption. Glutaraldehyde was used to cross-link the enzyme molecules. Spectroscopic and morphological characterizations of the enzyme-nanotubes composite were carried out, which authenticated the successful adsorption event. Enzyme composite is proven equal to-, or even superior than free tannase, in terms of catalytic activities and stabilities, when measured under different thermal-, pH-, and recycling conditions. Whilst both free- and immobilized tannase preparations exhibited optimum catalysis at pH 5.0 and 35 °C, tannase-nanotubes composite possesses better thermal stability. The immobilized preparation retained 75 % of its initial catalytic activity following ten consecutives use. The study demonstrated a facile method to produce catalytically-efficient nanobiocatalyst composite for biotechnological applications.

Journal of Thermoplastic Composite Materials, Feb 23, 2023

Biological elastomer i.e., medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA) and its graft co... more Biological elastomer i.e., medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA) and its graft copolymer were investigated for reactive coating application. They were composited with silver-doped zinc oxide (Ag-ZnO) to produce films with photocatalytic activities. The activities were assessed from the photodegradation efficiencies of methylene blue, Rhodamine B and Orange II dyes. The PHA composite films demonstrated sustained photocatalytic activities over repeated usage compared to neat PHA. The presence of Ag also inhibits microbial growth on the film surface. The composite film exhibited negligible toxicity effect when tested against Ceriodaphnia dubia. Potential and advantages of Ag-ZnO−PHA composite film in reactive coating applications are discussed.

Biocatalysis and Biotransformation, Oct 19, 2024

The tannase enzyme was successfully purified to homogeneity from the culture broth of red yeast s... more The tannase enzyme was successfully purified to homogeneity from the culture broth of red yeast strain Rhodotorula glutinis DB2 in a three-tandem step involving ultrafiltration (5 kDa and 100 kDa systems), Sephadex G-200 gel filtration chromatography, and DEAE Sepharose CL-4B anion exchange chromatography. The purified tannase appeared to be homogeneous on sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE). The purified tannase had a specific activity of 3.33 U mg−1, with a 1.3% recovery and overall purification of 302-fold. The molecular mass of the tannase estimated by SDS-PAGE was about 73 kDa. The tannase had an optimum pH of 6.0 and an optimum temperature of 40 °C. The most stable pH was 7.0, and the enzyme was stable up to 40 °C. One mmol L−1 of Fe3+, Sr2+, Na+, and Pb2+ were found to promote tannase activity, whilst 1.0 mmol L−1 of Ba2+, Ca2+, Mg2+, Zn2+, Hg+, Ag+, Co2+, Fe2+, Mn2+, Cu2+, Cd2+, Al3+, K+, Ni2+, and Li+ inhibited tannase activity.

Polymer Science, Series B, Apr 13, 2022

Bioresponsive hydrogels are polymers with the ability to absorb a large volume of water and able ... more Bioresponsive hydrogels are polymers with the ability to absorb a large volume of water and able to response towards specific stimuli e.g., biomolecules ranging from enzymes, antigens, nucleic acids to glucose. The biorecognition events trigger changes in the form of macroscopic responses such as swelling or deswelling, degradation, or optical density variation. Surveying the literature spanning the last decade until recently, the review highlights biomedical applications for bioresponsive hydrogels, particularly in diagnostics, drug delivery, and tissue regeneration/wound healing, with responses directed towards enzyme, nucleic acid, and glucose.

Journal of Food Biochemistry, Sep 7, 2021

Multi-walled carbon nanotubes (MWCNT)-tannase composite was investigated as an immobilized biocat... more Multi-walled carbon nanotubes (MWCNT)-tannase composite was investigated as an immobilized biocatalyst on the basis of its facile preparation, low cost, and excellent aqueous dispersibility. Cross-linked tannase enzymes, obtained in the presence of glutaraldehyde, were composited with MWCNT via physical adsorption. Multiple techniques were applied to investigate, and corroborate the successful adsorption of cross-linked tannase onto the MWCNT structure. Green tea infusion extract post-treatment using the composite preparation showed elevated radical scavenging activities relative to the control. Green tea infusion extract exhibited a markedly reduced EC50 value on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals following its treatment with the enzyme composite, which represents 20%–34% enhancement in its free radical scavenging capacity. Stoichiometry and number of reduced DPPH were determined and compared. The antioxidative potential of a widely consumed, health-beneficial green tea is elevated by the treatment with MWCNT-tannase composite.

Preparative Biochemistry & Biotechnology, Feb 20, 2018

Immobilization of cross-linked tannase on pristine multiwalled carbon nanotubes (MWCNT) was succe... more Immobilization of cross-linked tannase on pristine multiwalled carbon nanotubes (MWCNT) was successfully performed. Cross-linking of tannase molecules was made through glutaraldehyde. The immobilized tannase exhibited significantly improved pH, thermal, and recycling stability. The optimal pH for both free and immobilized tannase was observed at pH 5.0 with optimal operating temperature at 30°C. Moreover, immobilized enzyme retained greater biocatalytic activities upon 10 repeated uses compared to free enzyme in solution. Immobilization of tannase was accomplished by strong hydrophobic interaction most likely between hydrophobic amino acid moieties of the glutaraldehyde cross-linked tannase to the MWCNT.

International Journal of Food Science & Technology, Jan 9, 2017

Summary The antioxidant activities of native- and tannase-treated green tea extracts along with t... more Summary The antioxidant activities of native- and tannase-treated green tea extracts along with their major polyphenol components were investigated. The polyphenolic content and composition of the tea before and after tannase treatment were determined by liquid chromatography coupled with mass spectrometry (LC-MS). Approximately 99% of the (−)-epigallocatechin gallate (EGCG) and (−)-epicatechin gallate (ECG) in green tea extract were converted by tannase to (−)-epigallocatechin (EGC) and (−)-epicatechin (EC), respectively, after 30 min. Biotransformed green tea exhibited a significantly higher DPPH˙ radical scavenging activities than native green tea (EC50 value of 0.024 ± 0.001 and 0.044 ± 0.001 mg mL−1, respectively). Kinetic parameters such as scavenging rate and stoichiometry were calculated. The rate of DPPH˙ radical scavenging activities for tannase-treated green tea extract was shown to be higher than native green tea extract.

Brazilian Archives of Biology and Technology, Feb 1, 2014

Stevia rebaudiana Bertoni is a medicinal plants and commercially use as non-caloric sweetener for... more Stevia rebaudiana Bertoni is a medicinal plants and commercially use as non-caloric sweetener for diabetic patient. In the present study, a protocol was developed for in vitro micropropagation using 6-benzylamino purine (BAP) and Kinetin (Kn) for the formation of multiple shoot proliferation and Indole-3-acetic acid (IAA), Indole-3-butyric acid (IBA) and 1-Naphthaleneacetic acid (NAA) for the induction of roots. Maximum shoot formation (7.82 ± 0.7 shoots per explants) was observed on a Murashige and Skoog (MS) medium supplemented with 0.5 mg L-1 BAP and 0.25 mg L-1 Kn. The maximum number of roots (30.12 ± 2.1 roots per explants) was obtained on a MS medium containing 1.0 mg L-1 IBA. The well rooted plantlets were successfully weaned and acclimatized in plant soil with survival rate of 83.3 %.

Journal of Pure and Applied Microbiology, Sep 30, 2013

Present work deals with optimize the cultural condition and medium composition for enhancing the ... more Present work deals with optimize the cultural condition and medium composition for enhancing the tannase production by Rhodoforula glutinis DB2 in submerged fermentation. A tannase-producing read yeast strain R. glutinis DB2 was isolated from hydrolysable tannin solution (extracted from Rhizophora apiculate bark) that kept for a year at room temperature (30±2 0C), This yeast strain showed ability to produced extracellular tannase significantly under submerged fermentation using tannic acid as an inducer. The rapid degradation of tannic acid and production of extracellular tannase was observed in the submerged fermentation medium. R. glutinis DB2 produced maximum extracellular tannase activity at the optimum bioprocess condition with 0.75 U/ mL and the yeast growth of 8.7 g/L. These results indicate that an increment about 83% of tannase production was obtained compared to before optimizaation of cultural condition (0.41 U/ mL).

BioTechnologia, Oct 23, 2014

Aspergillus niger FBT1, a local extracellular strain for tannase production, was isolated from so... more Aspergillus niger FBT1, a local extracellular strain for tannase production, was isolated from soil collected from Matang Mangrove Forest Reserve in Perak, Malaysia. This fungus strain was cultivated in an Erlenmeyer flask under a submerged fermentation system. Medium compositions play a very important role in enhancing enzyme production during fermentation. The production of tannase by A. niger FBT1 increased significantly (95%) when the medium compositions and various process parameters were optimized. Incubation for 72 hours (30 0C, pH 7) in medium complemented with sodium nitrate was found optimal. Additional supplementation with tannic acid (2% w/v) as the sole carbon source strongly increased the yield of the enzyme.