1.Characterization of cellulase, hemicellulase and lipase and its use in deinking of laser printed paper
Lee Chee Keong ; Darah Ibrahim ; Ibrahim Che Omar
Malaysian Journal of Microbiology 2013;9(1):84-92
Aims: It is recognized that laser printed paper are difficult to deink using conventional method. This had lead to the suggestion of enzymatic approach to overcome the problem encountered by commonly employed deinking techniques.
The present study aimed to investigate 7 commercially available enzymes for their suitability use in deinking of laser printed paper.
Methodology and results: 3 cellulases, hemicellulases, xylanase and 2 lipases were used in enzymatic deinking of
laser-printed wastepaper. Cellulase A “Amano”3 (C), Hemicellulase (H) and lipase (L) were selected for used in deinking because they possess either highest activity or broad pH stability compared to others enzymes. Different combination of enzymes was carried out to evaluate their effectiveness in deinking process. CH enzymes sequence was determined to be the most effective sequence in toner removal with 1.90% of brightness increment. However, only 0.95% of brightness increment was gained by enzyme sequence L. Highest deinking efficiency obtained was not proportional to the highest total reducing sugar produced.
Conclusion, significance and impact of study: Enzyme (cellulase and hemicellulase) can be used to de-ink laserprinted wastepaper, which are difficult to be deinked by conventional chemical deinking process. Thus, enzyme deinking has high possibility as alternative method to current chemical deinking process which is not environmental friendly.
2.Enhancement of cellulolytic enzymes and xylanase production via classical mutational techniques under solid-state fermentation condition
Tai Wan Yi ; Lee Chee Keong ; Darah Ibrahim2
Malaysian Journal of Microbiology 2016;12(1):91-101
Aims: High cost of cellulases remains the most significant barrier to the economical production of bio-ethanol from
lignocellulosic biomass (LB). The present study aims at developing a local cellulolytic fungal strain through random
mutagenesis coupled with the feasibility of solid-state fermentation (SSF) by utilizing agricultural wastes such as oil palm
frond (OPF) as the substrate.
Methodology and results: Out of 95 wild isolates tested, native fungal strain Aspergillus niger, designated DWA8 was
isolated as the top enzymatic secretor. For quantitative enzyme analysis, SSF was conducted using 1x106 spore/mL
inoculated onto 5 g of ground OPF, incubated at room temperature for 7 days, with 70% moisture content and an initial
medium pH of 7. Random mutagenesis has always been tempting in the enhancement of enzyme production. In this
work, the compounded treatment of microwave, ultraviolet (UVC) and Ethyl Methanesulfonate (EMS) have generated an
Aspergillus niger MUE3.06 mutant with an overall increase of 114% in CMCase activity, approximately 70% in FPase
and Xylanase activity respectively compared with the parental DWA8 strain. Thus this finding is capable to be fully
developed as an established mutational scheme to create highly productive filamentous fungus in a cheap, simple and
sustainable way.
Conclusion, significance and impact of study: It was the first attempt to explore the combine effect of the three
popular mutagens upon cellulases and xylanases. It is believed that more diversified of mutagen types induce more
diversified mutation pattern (with instructive planning), which is very desirable in creating new enzymes with novel
abilities.
Cellulases
3.Optimization of bioethanol production process using oil palm frond juice as substrate
Maya Emira Mad Saad ; Abdul Halim Farah Amani ; Lee Chee Keong
Malaysian Journal of Microbiology 2016;12(4):308-314
Aims: Bioethanol is an environmental friendly energy source with a lot of great prospective and become an alternative to
fossil fuels .Oil palm frond juice (OPFJ) is a potential sources of sugars for bioethanol production. The present study
aimed to optimize bioethanol production.
Methodology and results: Bioethanol fermentation was carried out by Saccharomyces cerevisiae HC10 using OPFJ as
substrate in bioreactor with 1.5 L working volume. Growth profile was performed for 42 h with sampling every 3 h
interval. Effect of agitation speed (rpm) and volume of OPFJ were screened to select significant factor for high production
of bioethanol. Agitation speed at 175 rpm and volume of oil OPFJ; 40% gave 5.25 g/L and 4.52 g/L of ethanol and
biomass concentration, respectively. These parameters were further investigated via central composite design (CCD) of
Response Surface Methodology (RSM) to maximize bioethanol production. The suggested optimum conditions for
bioethanol production were agitation speed at 152 rpm and volume of OPFJ at 39.71% in which giving ethanol
concentration of 4.79 g/L. Growth profile after optimization indicated that the highest ethanol concentration (5.75%) was
achieved after 15 h of fermentation. Kinetic studies indicated that ethanol yield coefficient (Yp/s) due to consumption of
OPFJ and productivity of ethanol was 3.5 fold and 25% increased compared to before optimization, respectively. While,
in term of ethanol yield about 9% increased was observed.
Conclusion, Significance and Impact of study: This showed that OPFJ can be an alternative new feedstock for
bioethanol production using S. cerevisiae HC10.
4.Minimally Invasive Spinal Stabilization Using Fluoroscopic-Guided Percutaneous Screws as a Form of Palliative Surgery in Patients with Spinal Metastasis.
Mun Keong KWAN ; Chee Kean LEE ; Chris Yin Wei CHAN
Asian Spine Journal 2016;10(1):99-110
STUDY DESIGN: Prospective cohort study. PURPOSE: To report the outcome of 50 patients with spinal metastases treated with minimally invasive stabilization (MISt) using fluoroscopic guided percutaneous pedicle screws with/without minimally invasive decompression. OVERVIEW OF LITERATURE: The advent of minimally invasive percutaneous pedicle screw stabilization system has revolutionized the treatment of spinal metastasis. METHODS: Between 2008 and 2013, 50 cases of spinal metastasis with pathological fracture(s) with/without neurology deficit were treated by MISt at our institution. The patients were assessed by Tomita score, pain score, operation time, blood loss, neurological recovery, time to ambulation and survival. RESULTS: The mean Tomita score was 6.3+/-2.4. Thirty seven patients (74.0%) required minimally invasive decompression in addition to MISt. The mean operating time was 2.3+/-0.5 hours for MISt alone and 3.4+/-1.2 hours for MISt with decompression. Mean blood loss for MISt alone and MISt with decompression was 0.4+/-0.2 L and 1.7+/-0.9 L, respectively. MISt provided a statistically significant reduction in visual analog scale pain score with mean preoperative score of 7.9+/-1.4 that was significantly decreased to 2.5+/-1.2 postoperatively (p=0.000). For patients with neurological deficit, 70% displayed improvement of one Frankel grade and 5% had an improvement of 2 Frankel grades. No patient was bed-ridden postoperatively, with the average time to ambulation of 3.4+/-1.8 days. The mean overall survival time was 11.3 months (range, 2-51 months). Those with a Tomita score <8 survived significantly longer than those a Tomita score > or =8 with a mean survival of 14.1+/-12.5 months and 6.8+/-4.9 months, respectively (p=0.019). There were no surgical complications, except one case of implant failure. CONCLUSIONS: MISt is an acceptable treatment option for spinal metastatic patients, providing good relief of instability back pain with no major complications.
Back Pain
;
Cohort Studies
;
Decompression
;
Fractures, Spontaneous
;
Humans
;
Neoplasm Metastasis*
;
Neurology
;
Palliative Care*
;
Prospective Studies
;
Visual Analog Scale
;
Walking
5.Ultra Long Construct Minimally Invasive Spinal Stabilization Using Percutaneous Pedicle Screws in the Treatment of Symptomatic Multicentric Spinal Metastasis.
Chee Kean LEE ; Chris Yin Wei CHAN ; Mun Keong KWAN
Asian Spine Journal 2015;9(6):962-965
Managing multiple level spinal metastases is challenging. We report the case of a 58-year-old female with advanced lung cancer who presented with multiple pathological fractures of the thoracic spine (T5, T6, T7, and T8 vertebrae). She was treated with palliative radiotherapy. Her resting pain improved, but the instability pain persisted. One month later, she had a trivial fall leading to a pathological fracture of the L2 vertebra with cauda equine syndrome. The patient was treated surgically with minimally invasive decompression of the L2 and with percutaneous instrumented stabilization using an ultra-long construct from T3 to L5 (15 spinal levels), spanning the previously radiated zone and the decompression site. Postoperatively, she had significant improvements in pain and neurology. There were no surgical complications. Ultra long construct minimally invasive spinal stabilization is the ideal approach for symptomatic multicentric spinal metastasis with poor prognostic scores. Using this technique, the goals of spinal stabilization and direct neural decompression can be achieved with minimal morbidity.
Decompression
;
Female
;
Fractures, Spontaneous
;
Humans
;
Lung Neoplasms
;
Middle Aged
;
Neoplasm Metastasis*
;
Neurology
;
Radiotherapy
;
Spinal Cord Compression
;
Spine
6.Surgical Morphometry of C1 and C2 Vertebrae: A Three-Dimensional Computed Tomography Analysis of 180 Chinese, Indian, and Malay Patients.
Chee Kean LEE ; Tiam Siong TAN ; Chris Yin Wei CHAN ; Mun Keong KWAN
Asian Spine Journal 2017;11(2):181-189
STUDY DESIGN: Clinical imaging study. PURPOSE: To study the surgical morphometry of C1 and C2 vertebrae in Chinese, Indian, and Malay patients. OVERVIEW OF LITERATURE: C1 lateral mass and C2 pedicle screw fixation is gaining popularity. However, there is a lack of C1–C2 morphometric data for the Asian population. METHODS: Computed tomography analysis of 180 subjects (60 subjects each belonging to Chinese, Indian, and Malay populations) using simulation software was performed. Length and angulations of C1 lateral mass (C1LM) and C2 pedicle (C2P) screws were assessed. RESULTS: The predicted C1LM screw length was between 23.2 and 30.2 mm. The safe zone of trajectories was within 11.0°±7.7° laterally to 29.1°±6.2° medially in the axial plane and 37.0°±10.2° caudally to 20.9°±7.8° cephalically in the sagittal plane. The shortest and longest predicted C2P screw lengths were 22.1±2.8 mm and 28.5±3.2 mm, respectively. The safe trajectories were from 25.1° to 39.3° medially in the axial plane and 32.3° to 45.9° cephalically in the sagittal plane. CONCLUSIONS: C1LM screw length was 23–30 mm with the axial safe zone from 11° laterally to 29° medially and sagittal safe zone at 21° cephalically. C2P screw length was 22–28 mm with axial safe zone from 26° to 40° medially and sagittal safe zone from 32° to 46° cephalically. These data serve as an important reference for Chinese, Indian, and Malay populations during C1–C2 instrumentation.
Asian Continental Ancestry Group*
;
Humans
;
Pedicle Screws
;
Spine*
7.Proximate and biochemical analysis for marine and freshwater algae
Soopna PUSPANADAN ; Wan Maznah Wan Omar ; Lee Chee KEONG
Malaysian Journal of Microbiology 2018;14(2):137-144
Aims:In this study, ten indigenous microalgae samples from freshwater and marine waters from Malaysia, cultured and analysed on proximate and biochemical analysis. The proximate and biochemical analysis consists of starch, carbohydrates, lipid, protein, ash and moisture contents. This study was more focused on screening of starch accumulation in marine and freshwater microalgae cultures. Methodology and results:Based on screening, the results showed that Chlorella salinacontents highest starch of 4.92±0.33%, followed by Spirulinasp. 2.58±1.18%, Isochrysis maritime 0.99±0.33%, and lastly for Nitzschiapanduriformisand Naviculadistanscontents similar percentage of starch (0.44±0.10 and 0.40±0.07%, respectively). Besides starch analysis, proximate analyses(ash, moisture, lipid, protein, and carbohydrates) have been conducted. The results obtained indicated that all the cultures contain more than 4.50% of carbohydrates in average, followed by lipid and protein <1%. The results demonstrate that further optimization and various harvesting stages (early of exponential phase, early of stationary phaseand late stationary phase) may increase lipid, carbohydrates, starch, and protein accumulation. Chlorella salinaand Spirulinasp. will be used to further study on optimization of physical and chemical factors for high starch accumulation. Conclusion, significance and impact of study:In conclusion, this experiment focused more on preliminary screening for further application of starch uses in food and food packaging indust
8.Optimization of polyhydroxyalkanoate (PHA) production by Burkholderia cepacia BPT1213 utilizing waste glycerol as the sole carbon source
Nor Fauziah Mohd Zain ; Wan Nadiah Wan Abdullah ; Tan Joo SHUN ; Lee Chee KEONG ; Mohammed Razip SAMIAN
Malaysian Journal of Microbiology 2018;14(2):164-171
Aims:This study was carried out to optimize the fermentation conditions using statistical approach for polyhydroxyalkanoate(PHA) production by a local isolate, Burkholderia cepaciaBPT1213, in the shake flask system.Methodology and results:Throughout this study, B. cepaciaBPT1213 was grown in minimal salt medium (MSM) supplemented with 2% of waste glycerol (86.70% purity).The strain can produce up to 1.33 g/L cell dry weight (CDW) with 22.21% of PHA content, thus giving a total PHA concentration 0.30 g/L before optimization. A factorial design experiment that was carried out showed all parameters KH2PO4, Na2HPO4·2H2O, carbon-to-nitrogen ratio (C/N), initial pH of medium, and temperature significantly affected the growth (cell dry weight, CDW) and PHA content. Response surface methodology (RSM) using central composite design (CCD) was then applied to optimize these parameters. The optimum conditions suggested were at 2.5 g/L KH2PO4, 4.5 g/L Na2HPO4·2H2O, 30 (g/g) C/N ratio, initial medium pH of 8.5 and 37 °C cultivation temperature, with a predicted CDW of 3.43 g/L and PHA content of 45.71% contributing to 1.57 g/L total PHA concentration. The verification experiment resulted in 3.60 g/L of CDW with 48.08% of PHA content contributing to 1.73 g/L total PHA concentration.Conclusion, significance and impact of study:The statistical approach using factorial design and RSM have succeeded in increasing the production of PHA by B. cepaciaBPT1213 using waste glycerol as the sole carbon source which is a promising renewable and cheaper feedsto
9.Femoral head diameter in the Malaysian population.
Chee Kean LEE ; Mun Keong KWAN ; Azhar Mahmood MERICAN ; Wuey Min NG ; Lim Beng SAW ; Kok Kheng TEH ; Manoharan KRISHNAN ; Ramanathan RAMIAH
Singapore medical journal 2014;55(8):436-438
INTRODUCTIONHip arthroplasty is commonly performed worldwide. The objective of this study was to determine the diameter of the femoral head in the Malaysian population in relation to gender and race (i.e. among Malay, Chinese and Indian patients).
METHODSThis was a retrospective cross-sectional study performed between January 1995 and December 2006, evaluating the femoral head diameters of all patients aged 50 years and above who underwent hemiarthroplasty at two major hospitals in Malaysia.
RESULTSA total of 945 femoral heads (663 women, 282 men) were evaluated. The mean age of the patients in our cohort was 75.2 ± 9.4 (range 50-101) years. The mean femoral head diameter (with intact articular cartilage) was 44.9 ± 3.2 (range 38-54) mm. In our study, men had a significantly larger mean femoral head diameter than women (47.7 ± 2.8 mm vs. 43.7 ± 2.4 mm; p < 0.05). Patients of Chinese ethnicity were also found to have significantly larger femoral head diameters, when compared among the three races studied (p < 0.05).
CONCLUSIONMalaysians have a mean femoral head diameter of 44.9 ± 3.2 mm. Among our patients, Chinese patients had a significantly larger femoral head size than Malay and Indian patients. We also found that, in our cohort, men had significantly larger femoral head diameters than women.
Aged ; Aged, 80 and over ; Arthroplasty, Replacement, Hip ; Asian Continental Ancestry Group ; Cross-Sectional Studies ; Female ; Femur Head ; anatomy & histology ; pathology ; Humans ; Malaysia ; Male ; Middle Aged ; Reference Values ; Retrospective Studies
10.Efficiency of chitosan and eggshell on harvesting of Spirulina sp. in a bioflocculation process
Yuen Hing Lai ; Fatin Hamimi Md Azmi ; Nur Ain Fatehah ; Soopna Puspanadan ; Chee Keong Lee
Malaysian Journal of Microbiology 2019;15(3):188-194
Aims:
Microalgae were very small in size (a few μm) and have a low concentration in the medium. Due to their size, harvesting of microalgae from their growth medium remain a major obstacle in downstream processing. Efficient harvesting method must be applied to ensure it is cost effective, preserves quality and improves the culture process which is important for commercial algal production. Common harvesting methods use to harvest microalgae from their growth medium are centrifugation, filtration, flotation, sedimentation, and flocculation. Flocculation is a common method use to harvest microalgae due to low cost, save time and highly efficient method for algae biomass recovery. The purpose of this study was to investigate the effects chitosan and eggshell on flocculation of microalga Spirulina platensis. Chitosan and eggshell were chosen as flocculant due to their biodegradability, non-toxicity and safe to handle.
Methodology and results:
The efficiencies of flocculation process were examined by conducting experiments over a range of culture pH, flocculant concentrations and flocculation time using chitosan and eggshell as flocculant agent. Under optimized flocculation conditions of 50 mg/L chitosan at pH 8 culture media for 90 min of flocculation time and 4 mg/mL eggshell at pH 4 culture media for 8 min of flocculation time, the maximum flocculation efficiency obtained was 79.98±1.65% and 97.17±1.38%, respectively.
Conclusion, significance and impact of study
Therefore, it can be concluded that chitosan and eggshell could be used as flocculants for harvesting large scale microalgal biomass production. Nevertheless, eggshell is more economical and more efficient compared to chitosan in harvesting microalgae biomass.