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Chua H, Zhou W, Cowling B, Lau E. Detection of Increased Scarlet Fever Incidence Using Digital Surveillance Data. Int J Infect Dis 2022. [DOI: 10.1016/j.ijid.2021.12.235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Chua H, Loh L, Mok M. Transnasal sphenopalatine ganglion block for post-dural puncture headache and associated tinnitus. Anaesth Rep 2021; 9:37-40. [PMID: 33681809 DOI: 10.1002/anr3.12101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 01/31/2021] [Indexed: 11/08/2022] Open
Abstract
Lumbar epidurals are frequently inserted for women in labour as they provide excellent analgesia. One of the more common procedural complications is post-dural puncture headache which can be associated with auditory symptoms such as hearing loss and tinnitus and can be treated with an epidural blood patch. Sphenopalatine ganglion blocks have also been used to treat post-dural puncture headache but have not been previously shown to resolve the associated tinnitus. We report a case where postural neck pain and tinnitus from an accidental dural puncture during lumbar epidural insertion for labour analgesia was treated successfully with a sphenopalatine ganglion block. Further, we explore the literature on the cause of tinnitus in post-dural puncture headache and the possible mechanism by which a sphenopalatine ganglion block relieves both post-dural puncture headache and the associated tinnitus.
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Affiliation(s)
- H Chua
- SingHealth Anaesthesiology Residency Program Singapore
| | - L Loh
- Division of Anaesthesiology and Perioperative Sciences Singapore General Hospital Singapore
| | - M Mok
- Division of Anaesthesiology and Perioperative Sciences Singapore General Hospital Singapore
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Chua H, Peh K, Hon F, Koh E, Cheong P, Ng W. CARE MANAGEMENT IN COMSA: SHIFTING FROM A HOSPITAL-CENTRED TO A PROACTIVE, COMMUNITY-BASED APPROACH. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- H. Chua
- Tsao Foundation, Singapore, Singapore
| | - K. Peh
- Tsao Foundation, Singapore, Singapore
| | - F. Hon
- Tsao Foundation, Singapore, Singapore
| | - E. Koh
- Tsao Foundation, Singapore, Singapore
| | - P. Cheong
- Tsao Foundation, Singapore, Singapore
| | - W. Ng
- Tsao Foundation, Singapore, Singapore
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Ng W, Peh K, Chua H, Hon F, Koh E, Cheong P. THE DEVELOPMENT OF A SYSTEM OF CARE FOR THE AT-RISK ELDERS IN COMSA. Innov Aging 2017. [DOI: 10.1093/geroni/igx004.448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- W. Ng
- Tsao Foundation, Singapore, Singapore
| | - K. Peh
- Tsao Foundation, Singapore, Singapore
| | - H. Chua
- Tsao Foundation, Singapore, Singapore
| | - F. Hon
- Tsao Foundation, Singapore, Singapore
| | - E. Koh
- Tsao Foundation, Singapore, Singapore
| | - P. Cheong
- Tsao Foundation, Singapore, Singapore
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Kan CW, Pan YN, Chua H. Effect of Electric Voltage on the Photocatalytic Oxidation Disinfection of Water Used in Real Estate. ACTA ACUST UNITED AC 2015. [DOI: 10.7763/ijesd.2015.v6.572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Larson DW, Lovely JK, Cima RR, Dozois EJ, Chua H, Wolff BG, Pemberton JH, Devine RR, Huebner M. Outcomes after implementation of a multimodal standard care pathway for laparoscopic colorectal surgery. Br J Surg 2014; 101:1023-30. [PMID: 24828373 DOI: 10.1002/bjs.9534] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2014] [Indexed: 12/13/2022]
Abstract
BACKGROUND The aim of the study was to assess which aspects of an enhanced recovery programme are associated with better outcomes following laparoscopic colorectal surgery. METHODS A database of laparoscopic colorectal procedures performed in 2011 was reviewed. Elements of the enhanced recovery programme and compliance were evaluated for short-term (30-day) outcomes. Individual elements included gabapentin, celecoxib, intrathecal analgesia, diet, postoperative fluids, and paracetamol/non-steroidal anti-inflammatory drug pain management. RESULTS Five hundred and forty-one consecutive procedures were included. Compliance with the enhanced recovery programme elements ranged from 82.4 to 99.3 per cent. Median length of hospital stay was 3 (i.q.r. 2-5) days, with 25.9 per cent of patients discharged within 48 h. Patients without complications had a median length of stay of 3 (i.q.r. 2-4) days if compliant and 3 (3-5) days if not (P < 0.001). Low oral opiate intake (oral morphine equivalent of less than 30 mg) (odds ratio (OR) 1.97, 95 per cent confidence interval 1.29 to 3.03; P = 0.002), full compliance (OR 2.36, 1.42 to 3.90; P < 0.001) and high surgeon volume (more than 100 cases per year) (OR 1.50, 1.19 to 1.89; P < 0.001) were associated with discharge within 48 h. Compliance with the elements of oral intake and fluid management in the first 48 h was associated with a reduced rate of complications (8.1 versus 19.6 per cent; P = 0.001). Median oral opiate intake was 37.5 (i.q.r. 0-105) mg in 48 h, with 26.2 per cent of patients receiving no opiates. CONCLUSION Compliance with an enhanced recovery pathway was associated with less opiate use, fewer complications and a shorter hospital stay.
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Affiliation(s)
- D W Larson
- Division of Colon and Rectal Surgery, Department of Surgery, Mayo Clinic, Rochester, Minnesota
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Richardson J, Nelson A, Bertaso A, Wong D, Cunnington M, Azarisman S, Chua H, Baillie T, Glenie T, Koschade B, Williams K, Teo K, Worthley M, Worthley S. Cardiac Magnetic Resonance-Derived Coronary Sinus Flow Reserve Can Accurately Determine Global Myocardial Perfusion. Heart Lung Circ 2012. [DOI: 10.1016/j.hlc.2012.05.472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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8
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Richardson J, Cunnington M, Wong D, Bertaso A, Nelson A, Azarisman S, Chua H, Williams K, Koschade B, Worthely M, Teo K, Worthley S. Cardiac Magnetic Resonance Imaging After Transcatheter Aortic Valve Implantation. Heart Lung Circ 2012. [DOI: 10.1016/j.hlc.2012.05.468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Albright JB, Bonatti H, Stauffer J, Dickson RC, Nguyen J, Harnois D, Jeanpierre C, Hinder R, Steers J, Chua H, Aranda-Michel J. Colorectal and anal neoplasms following liver transplantation. Colorectal Dis 2010; 12:657-66. [PMID: 19508543 DOI: 10.1111/j.1463-1318.2009.01840.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Liver transplantation (LT) is the treatment of choice for end-stage liver disease. The required immunosuppression increases the risk for developing malignancies. Some viruses play a crucial role. Data on neoplasms of the colon, rectum and anus in LT are limited. METHOD A retrospective evaluation of the incidence and clinical course of colorectal and anal malignancies and colonic polyps in a series of 467 consecutive LTs in 402 individuals between 1998 and 2001 was performed. Standard immunosuppression included Tacrolimus, Mycophenolic acid and steroids. RESULTS During a median follow up of 5.2 years, three colon adenocarcinomas, one EBV associated cecal posttransplant lymphoproliferative tumour and two HPV associated anal tumours were identified. Pre-LT colonoscopy was performed in 161 patients (40%), and of 153 evaluable individuals, 53 (34.9%) had polyps. Colonoscopy was performed in 186 patients (46.3%) median 14.8 (range 0.2-77.8) months post-LT and 55 (29.3%) had polyps. Post-LT adenomatous polyps were detected in 47.3% of patients with pre-LT polyps vs 6.7% of patients without pre-LT polyps (P < 0.001). Patients with alcoholic liver disease had a significantly higher rate of adenoma formation (50.0% vs 11.1%, P < 0.001). No patient died from colorectal/anal malignancy. CONCLUSION The incidence of metachronous and new polyp formation in our study is similar to people who are not immunocompromised, but subgroups are at increased risk. Viral-associated malignancies, including post-transplant lymphoproliferative disorders and anal cancer, are important entities in the LT population suggesting that complete screening of the colon, rectum and anus including pre-LT and post-LT colonoscopy should be utilized.
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Affiliation(s)
- J B Albright
- Department of Surgery, South Bay Medical Center, Harbor City, California, USA
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Abstract
The usage of plastics in packaging and disposable products, and the generation of plastic waste, have been increasing drastically. Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. In the authors' laboratories, various carbohydrates in the growth media, including sucrose, lactic acid, butyric acid, valeric acid, and various combinations of butyric and valeric acids, were utilized as the carbon (c) sources for the production of bioplastics by Alcaligenes eutrophus. As the first step in pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesize bioplastics, the authors investigated the usage of malt wastes from a beer brewery plant as the C sources for the production of bioplastics by microorganisms. Specific polymer production yield by A. Latus DSM 1124 increased to 70% polymer/cell (g/g) and 32 g/L cell dry wt, using malt wastes as the C source. The results of these experiments indicated that, with the use of different types of food wastes as the C source, different polyhydroxyalkanoate copolymers could be produced with distinct polymer properties.
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Affiliation(s)
- P H Yu
- Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong.
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Tsang YF, Sin SN, Chua H. Nocardia foaming control in activated sludge process treating domestic wastewater. Bioresour Technol 2008; 99:3381-8. [PMID: 17888655 DOI: 10.1016/j.biortech.2007.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/08/2007] [Accepted: 08/09/2007] [Indexed: 05/17/2023]
Abstract
In this study, filamentous bacteria (Nocardia amarae) were identified as the major causal microorganism in foaming sludge. The results of growth kinetics study indicated that N. amarae had a relatively strong affinity for non-readily biodegradable fatty acids. N. amarae was able to consume various fatty acids at a constant growth yield from 0.413 to 0.487 g/gCOD. Under common F/M ratio (less than 0.5 g BOD/gMLSS/d) used in activated sludge processes, specific growth rate of N. amarae was found to be more significant than that of non-filamentous bacteria. Based on this feature, a novel technique feast-fast operation (FFO) was developed for the foaming control. The sludge volume index (SVI) rapidly decreased from 300 to 80 mL/g and further stabilized at about 70 mL/g and the system was free from stable foam, while the BOD removal efficiency was maintained above 95%. This control technology effectively suppressed the overgrowth of filaments and improved the settleability of activated sludge without adverse effects on the treatment performance and the process stability.
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Affiliation(s)
- Y F Tsang
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
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Chan SY, Tsang YF, Chua H, Sin SN, Cui LH. Performance study of vegetated sequencing batch coal slag bed treating domestic wastewater in suburban area. Bioresour Technol 2008; 99:3774-81. [PMID: 17709244 DOI: 10.1016/j.biortech.2007.07.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 07/06/2007] [Accepted: 07/06/2007] [Indexed: 05/16/2023]
Abstract
A practical and affordable wastewater treatment system serving small community in suburban areas was studied. The system was a vegetated sequencing batch coal slag bed integrated with the rhythmical movement of wastewater and air like that of a sequencing batch reactor. The removal mechanisms capitalized on the pollutant removal process in conventional constructed wetland. Cyperus alternifolius was planted into the coal slag bed to form a novel plant-soil-microbial interactive system. Nutrients in the domestic wastewater, which cause environmental nuisance like eutrophication, were targeted to be eliminated by the process design. Operated with the contact time of 18 h, the treatment systems achieved around 60% removal efficiency for carbonaceous matters. The removals of ammonia nitrogen and phosphorus were about 50% and 40%, respectively, while the removal of total suspended solids was approaching 80%. From the current study, the construction cost of the vegetated sequencing batch coal slag bed was 256 RMB/m3 and the operation cost was 0.13 RMB/m3. With the advantages of ease of operation, low costs, desirable treatment efficiency and aesthetic value, the vegetated sequencing batch coal slag bed is proposed to be an alternative for onsite domestic wastewater treatment in suburban areas.
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Affiliation(s)
- S Y Chan
- Civil and Structural Engineering Department, The Hong Kong Polytechnic University, Hong Kong SAR, China.
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Chan S, Tsang Y, Cui L, Chua H. Domestic wastewater treatment using batch-fed constructed wetland and predictive model development for NH3-N removal. Process Biochem 2008. [DOI: 10.1016/j.procbio.2007.12.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Tsang YF, Chua H, Sin SN, Chan SY. Treatment of odorous volatile fatty acids using a biotrickling filter. Bioresour Technol 2008; 99:589-95. [PMID: 17321131 DOI: 10.1016/j.biortech.2006.12.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 12/21/2006] [Accepted: 12/23/2006] [Indexed: 05/14/2023]
Abstract
In this study, a novel fibrous bioreactor was developed for treating odorous compounds present in contaminated air. The first stage of this work was a preliminary study which aimed at investigating the feasibility of using the fibrous bioreactor for the removal of malodorous volatile fatty acids (VFA) that is a common odorous contaminant generated from anaerobic degradation of organic compounds. The kinetics of microbial growth and VFA degradation in the selected culture, and the performance of the submerged bioreactor at different VFA mass loadings were studied. Above 95% of VFA removal efficiencies were achieved at mass loadings up to 22.4 g/m(3)/h. In the second stage, the odour treatment process was scaled up with system design and operational considerations. A trickling biofilter with synthetic fibrous packing medium was employed. The effects of inlet VFA concentration and empty bed retention time (EBRT) on the process performance were investigated. The bioreactor was effective in removing VFA at mass loadings up to 32 g/m(3)/h, beyond which VFA started to accumulate in the recirculation liquid, indicating the biofilm was unable to degrade all of the VFA introduced. Although VFA accumulated in the liquid phase, the removal efficiency remained above 99%. This suggested that the biochemical reaction rather than gas-liquid mass transfer was the limiting step of the treatment process. In addition, the biotrickling filter was stable for long-term operation with relatively low and steady pressure drop, no clogging and degeneration of the packing material occurred during the four-month study.
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Affiliation(s)
- Y F Tsang
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
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Sarraj MA, Chua H, Umbers A, Escalona R, Loveland KL, Findlay JK, Stenvers KL. 209. The absence of betaglycan affects Sox9 m RNA expression at the time of sex determination in a mouse model. Reprod Fertil Dev 2008. [DOI: 10.1071/srb08abs209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Betaglycan is a co-receptor that binds both TGF-β and inhibin, and thereby acts as a modulator of the activities of multiple members of the TGF-β superfamily. We have previously shown that the murine betaglycan gene is expressed in somatic cells within the interstitium of the fetal testis from 12.5 dpc-16.5 dpc. Betaglycan protein was predominantly localised to the interstitial cells surrounding the developing seminiferous cords which stained positive for Cyp11a (p450 Scc), a Leydig cell marker. In order to determine the impact of this receptor on fetal Leydig cell biology, RNA was extracted from two independently collected sets of betaglycan knockout and wildtype male and female gonads at 12.5 dpc and 13.5 dpc (n = 4 gonad pairs/set), and quantitative real time PCR was performed to determine changes in the expression levels of key genes involved in fetal Leydig cell differentiation and function. This analysis revealed that the levels of mRNA expression of SF1, Cyp11a and Cyp17a1 were downregulated between 12.5–13.5 dpc in the betaglycan knockout embryos compared with wildtype embryos immediately after the time of sex determination. Interestingly, the expression level of the key Sertoli cell marker SRY-(sex determining region Y)-box 9 (Sox9) was transiently decreased at 12.5 dpc by 50% in the knockout testis in comparison with that of the wildtype testis. No significant change was found one day later at 13.5 dpc. Our data show that betaglycan is predominantly expressed in the fetal Leydig cells of the murine testis and that the presence of this receptor is required for normal fetal Leydig cell differentiation. Furthermore, the transient downregulation of Sox9 expression in null testis suggests that Sertoli cell differentiation may also be affected in betaglycan knockout mice, and that this defect may precede the defect in Leydig cell development.
Supported by: the NHMRC Australia (RegKeys 338516; 241000).
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Ren NQ, Chua H, Chan SY, Tsang YF, Wang YJ, Sin N. Assessing optimal fermentation type for bio-hydrogen production in continuous-flow acidogenic reactors. Bioresour Technol 2007; 98:1774-80. [PMID: 16935495 DOI: 10.1016/j.biortech.2006.07.026] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 07/03/2006] [Accepted: 07/03/2006] [Indexed: 05/11/2023]
Abstract
In this study, the optimal fermentation type and the operating conditions of anaerobic process in continuous-flow acidogenic reactors was investigated for the maximization of bio-hydrogen production using mixed cultures. Butyric acid type fermentation occurred at pH>6, propionic acid type fermentation occurred at pH about 5.5 with E(h) (redox potential) >-278mV, and ethanol-type fermentation occurred at pH<4.5. The representative strains of these fermentations were Clostridium sp., Propionibacterium sp. and Bacteriodes sp., respectively. Ethanol fermentation was optimal type by comparing the operating stabilities and hydrogen production capacities between the fermentation types, which remained stable when the organic loading rate (OLR) reached the highest OLR at 86.1kgCOD/m(3)d. The maximum hydrogen production reached up to 14.99L/d.
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Affiliation(s)
- N Q Ren
- School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China
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Wang YJ, Hua FL, Tsang YF, Chan SY, Sin SN, Chua H, Yu PHF, Ren NQ. Synthesis of PHAs from waster under various C:N ratios. Bioresour Technol 2007; 98:1690-3. [PMID: 16844370 DOI: 10.1016/j.biortech.2006.05.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/26/2006] [Accepted: 05/26/2006] [Indexed: 05/10/2023]
Abstract
Polyhydroxyalkanoates (PHAs) production was carried out under various C:N ratios. A ratio of 100 resulted best polymer yield. C-source was an important factor in synthesis. For example, as the ratio of valeric acid (C5) to butyric acid (C4) in N-free medium was increased, the mole fraction of HV in the copolymer increased. When soy waste was used as a C-source a copolymer, a high HV mole fraction (HB:HV, 75:25) was produced while when malt waste was used, a much lower HV mole fraction (HB:HV, 90:10) was generated. It was concluded that activated sludge bacteria could be induced to produce PHAs using food wastes as C-sources and this could be the basis for production of biodegradable plastics.
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Affiliation(s)
- Y J Wang
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, PR China
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Tsang Y, Chua H, Sin S, Tam C. A novel technology for bulking control in biological wastewater treatment plant for pulp and paper making industry. Biochem Eng J 2006. [DOI: 10.1016/j.bej.2006.08.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kwek T, Chin K, Chua H. Crit Care 2006; 10:P459. [DOI: 10.1186/cc4806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Affiliation(s)
- X. Z. Li
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China, and Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Science, Guangzhou 510650, China
| | - M. F. Hou
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China, and Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Science, Guangzhou 510650, China
| | - F. B. Li
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China, and Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Science, Guangzhou 510650, China
| | - H. Chua
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China, and Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environment and Soil Science, Guangzhou 510650, China
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Abstract
Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. As the first step in our pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesise environmental-friendly bioplastics, we investigated the usage of soya wastes from a soya milk dairy, and malt wastes from a beer brewery plant as the carbon sources for the production of polyhydroxyalkanoates (PHA) by selected strain of microorganism. Bench experiments showed that Alcaligenes latus DSM 1124 used the nutrients from malt and soya wastes to biosynthesise PHAs. The final dried cell mass and specific polymer production of A. latus DSM 1124 were 32g/L and 70% polymer/cells (g/g), 18.42 g/L and 32.57% polymer/cell (g/g), and 28 g/L and 36% polymer/cells (g/g), from malt waste, soya waste, and from sucrose, respectively. These results suggest that many types of food wastes might be used as the carbon source for the production of PHA.
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Affiliation(s)
- P H Yu
- Union Laboratory of Asymmetric Synthesis, Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hong Kong, China.
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Hu WF, Sin SN, Chua H, Yu PHF. Synthesis of Polyhydroxyalkanoate (PHA) from Excess Activated Sludge Under Various Oxidation–Reduction Potentials (ORP) by Using Acetate and Propionate as Carbon Sources. Appl Biochem Biotechnol 2005; 121-124:289-301. [PMID: 15917607 DOI: 10.1385/abab:121:1-3:0289] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Accumulation of poly hydroxyalkanoate (PHA) from excess activated sludge (EAS) was monitored and controlled via the oxidation-reduction potential (ORP) adjusting process. The ORP was adjusted and controlled by only regulating the gas-flow rate pumped into the cultural broth in which sodium acetate (C2) and propionate (C3) were used as carbon sources. Productivity of PHA and the PHA compositions at various C2 to C3 ratios were also investigated. When ORP was maintained at +30 mV, 35% (w/w) of PHA of cell dry weight obtained when C2 was used as sole carbon source. The PHA copolymer, poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), accumulated by EAS with different 3-hydroxyvalarate (3HV) molar fractions ranged from 8% to 78.0% when C2 and C3 was used as sole carbon source, By using ORP to monitor and control the fermentation process instead DO meter, the ORP system provided more precise control to the PHA accumulation process from EAS under low dissolved oxygen (DO) concentrations. Adjusting the C2 to C3 ratios in the media could control the composition such as the 3HV/3HB ratios of the PHBV. Furthermore, it might be an effective way to adjust the 3HV molar fractions in PHBV by controlling the DO concentration via the ORP monitoring system. The 3HV molar fractions in the PHBV declined with increasing ORP from -30 mV to +100 mV by adjusting the gas-flow rate (i.e. the DO concentration). It is concluded that the DO plays a very important role in the synthesis of 3HV subunits in PHBV co-polymer from the EAS. Therefore, a hypothetic metabolic model for PHA synthesis from EAS was proposed to try to explain the results in this study.
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Affiliation(s)
- W F Hu
- College of Food Science, South China Agricultural University, Guangzhou 510642, China.
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Wang L, Zhou Q, Chua H. Evaluation of a novel integrated bioreactor--AOS system for treating oil-containing restaurant wastewater on site in Hong Kong. J Environ Sci Health A Tox Hazard Subst Environ Eng 2005; 40:227-243. [PMID: 15663313 DOI: 10.1081/ese-200038539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
AOS system is an anaerobic digestion reactor (A-section, UASB or UBF), oxidation degradation reactor (O-section, aerobic biofilm reactor), and physical sedimentation tank (S-section) 3-in-1 integrated reactor. The compact bioreactor was applied to treat oil-containing restaurant's wastewater on site in Hong Kong. The treatment efficiency was observed at different HRT. Experimental results indicated that the AOS system for treating oil-containing restaurant wastewater on site was feasible when HRT at 0.6 days above. During the running period, the net sludge generation rate of the AOS system was only about 0.08-0.09 g g(-1)removed COD, and the utmost COD specific volumetric removal rate (SVRR) of the system reached 2.77 gL(-1) d(-1). The utmost specific biomass substrate utilization rate (SBSUR) of COD in O-section and A-section reached 1.22 d(-1) and 0.128 d(-1), respectively. In addition, the experiment results showed that the AOS system with a filter in UASB (that is UBF's AOS system) could bear much more great HLR comparing with UASB's AOS and was more efficient for treating oil-containing restaurant's wastewater on site.
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Affiliation(s)
- L Wang
- School of Environmental Science and Engineering, Tongji University, Shanghai, China.
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25
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Wang L, Zhou Q, Chua H. Determination of the optimal and economical biofilter depth in an anaerobic hybrid reactor for treating livestock industrial wastewater. J Environ Sci Health A Tox Hazard Subst Environ Eng 2005; 40:215-226. [PMID: 15663312 DOI: 10.1081/ese-200038535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A laboratory scale anaerobic hybrid reactor (AHR) being comprised of UASB and anaerobic biofilter was used to study the different biofilter depth with corresponding different critical HRT (1) and HRT (2) in treating livestock industrial wastewater, where the critical HRT (1) was defined as the HRT which resulted in the total COD in the effluent of the AHR exceeding in the influent at unsteady state, and the HRT (2) was defined as the HRT which resulted in the total COD in the effluent of the AHR exceeding the quality standard for discharging to sewer (in Hong Kong is Total COD < 1000 mg L1) at steady state. Two formulas expressing the relationship of different biofilter depth in the AHR and it's critical HRT (1) and HRT (2) in treating livestock industrial wastewater were obtained and used to design optimal and economical biofilter depth in a full scale AHR for treating livestock industrial wastewater on site. The performance of the full scale AHR indicated that using the experience formulas to design the optimal and economical biofilter depth in the full scale AHR for treating livestock industrial wastewater was successful. Experimental results also showed that the biofilter in the full scale AHR had not only physical filtration effect, but also had powerful biodegradation capability, furthermore, at unsteady state, the effect of biofilter on pollutant degrading in the full scale AHR was more great.
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Affiliation(s)
- L Wang
- School of Environmental Science and Engineering, Tongji University, Shanghai, PR China.
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Tsz-Chun M, Chan PL, Lawford H, Chua H, Lo WH, Yu PH. Microbial Synthesis and Characterization of Physiochemical Properties of Polyhydroxyalkanoates (PHAs) Produced by Bacteria Isolated from Activated Sludge Obtained from the Municipal Wastewater Works in Hong Kong. Appl Biochem Biotechnol 2005. [DOI: 10.1385/abab:122:1-3:0731] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
The effects of saturated and unsaturated fatty acids (lauric acid, palmitic acid, steric acid, oleic acid, linoleic acid, soybean oil) on Sphaerotilus natans, 0B17 (Pseudomonas sp.), and recombinant Escherichia coli DH5(/pUC19/CAB were studied. Oleic acid enhances Poly-3-hydroxybutyrate (PHB) production in these three bacterial strains, suggesting that the single double bond of the acid activates the polyhydroxylkanoate accumulation enzymatic reaction. Under the effect of lauric acid and linoleic acid, the growth of S. natans and 0B17 were totally inhibited. However, the enhanced PHB accumulation in recombinant E. coli was observed.
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Affiliation(s)
- K W Lo
- State Key Lab of Chinese Med and Molecular Pharmacology, Shenzen, China
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Ma TC, Chan PL, Lawford H, Chua H, Lo WH, Yu PH. Microbial synthesis and characterization of physiochemical properties of polyhydroxyalkanoates (PHAs) produced by bacteria isolated from activated sludge obtained from the municipal wastewater works in Hong Kong. Appl Biochem Biotechnol 2005; 121-124:731-9. [PMID: 15920276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The first objective of this study was the measurement of physical properties of P(3HB-co-3HV) copolymers with different (hydroxybutyrate) HB to (hydroxyvalerate) HV ratios produced by Bacillus cereus (TRY2) isolated from activated sludge. The 3HV PHBV copolymers were 0.05, 22.6, 39.2, 54.1, and 69.1 mol%, respectively. The second objective was to study possible waste water treatment and production of PHAs at the same time by B. cereus (TRY2) and Pseudomonas spp. (TOB17) (both were isolated from activated sludge), recombinant Bacillus DH5alpha, and a combination of the above three bacteria. The results were satisfactory; the maximum COD and TOC of the sewage sludge reduced were 53.5% and 67.5%, respectively.
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Affiliation(s)
- Tsz-Chun Ma
- State Key Lab of Chinese Med and Molecular Pharmacology, Shenzen, China
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Wang L, Chua H, Sin SN, Zhou Q, Ren DM, Li ZL. A combined bioprocess for integrated removal of copper and organic pollutant from copper-containing municipal wastewater. J Environ Sci Health A Tox Hazard Subst Environ Eng 2004; 39:223-235. [PMID: 15030153 DOI: 10.1081/ese-120027380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Heavy metal-containing wastewater is difficult to treat by most of the bioprocess due to its toxicity to microorganism in activated sludge. In this study, a combined bioprocess consisting of biosorption section that contained magnetite immobilized Pseudomonas putida 5-x cell as biosorbent followed by sequence batch reactor (SBR) was developed to treat Cu(2+)-containing municipal wastewater. The production techniques of Pseudomonas putida 5-x cell as biosorbent, such as optimal cell harvest period and cell pretreatment techniques were studied. Experimental results showed, considering both cell biomass and cell adsorption capacity to Cu(2+), 36 h is the optimal harvest period in the course of culturing Pseudomonas putida 5-x cells as biosorbent, and 0.1-0.3 mol L(-1) HCl is an optimal cell pretreating eluant to improve Cu(2+) adsorption capacity. The performances of the combined bioprocess for treating Cu(2+) containing wastewater were assessed. Experimental results showed that after treatment by biosorption, the Cu(2+) level in wastewater was reduced to level that did not inhibit COD removal efficiency of subsequent SBR activated sludge process, although it still affected the COD adsorption capacity of activated sludge. In terms of COD removal, the biosorption section was efficient for reducing Cu(2+) concentration to provide biodegradable wastewater for subsequent SBR activated sludge process.
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Affiliation(s)
- L Wang
- School of Life Sciences, Fudan University, Shanghai, PR China.
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30
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Wang L, Zhou Q, Chua H. Contribution of cell outer membrane and inner membrane to Cu2+ adsorption by cell envelope of Pseudomonas putida 5-x. J Environ Sci Health A Tox Hazard Subst Environ Eng 2004; 39:2071-2080. [PMID: 15332669 DOI: 10.1081/ese-120039375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The role of outer and inner membrane in the Cu2+ adsorption process by gram-negative bacterium Pseudomonas putida 5-x, which was isolated from local electroplating effluent with high Cu2+ accumulating capability, was studied. The results indicate that both the outer and inner membrane exhibited high Cu2+ adsorption capacity. Outer and inner membrane contributed about 30-35% and 20-25% parts of adsorption capacity in Cu2+ adsorption by cell envelope of Pseudomonas putida 5-x, respectively. The total contribution of outer and inner membrane to Cu2+ adsorption by cell envelope was much greater than that of peptidoglycan layer. The relatively high phospholipid content in the outer membrane might result in its greater heavy metal ions adsorption capacity. The Cu2+ binding process by the outer and inner membrane of Pseudomonas putida 5-x is the adsorption processes and can be described with Freundlich isotherms.
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Affiliation(s)
- L Wang
- School of Environmental Science and Engineering, Tongji University, Shanghai, China.
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31
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Wang L, Zhou Q, Zhang BS, Li ZL, Chua H, Ren DM. The biodegradation of 1,3-dichlorobenzene by an adapted strain Bacillus cereus PF-11 derived from town-gas industrial effluent. J Environ Sci Health A Tox Hazard Subst Environ Eng 2003; 38:1837-1848. [PMID: 12940485 DOI: 10.1081/ese-120022882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In the present study, an adapted bacterium PF-11 with high 1,3-dichlorobenzene degradation capability was isolated from town-gas industrial effluent through continuous introducing of N-methyl-N'-nitro-N-nitrosoquanidine (NTG). In suitable condition, a degradation rate of 32 mg L(-1) d(-1) of 1,3-dichlorobenzene was obtained by strain PF-11 with effective chlorion release. Strain PF-11 was tentatively identified as gram-positive Bacillus cereus. The substrate specificity of the strain PF-11 was relatively low, and the degradation rate for different chlorobenzenes was in the order of monochlorobenzene > 1,3-dichlorobenzene > 1,2-dichlorobenzene. Initial oxidation step was molecular oxygen attacking chlorobenzene ring catalyzed by dioxygenase.
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Affiliation(s)
- L Wang
- School of Life Sciences, Fudan University, Shanghai, China.
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Wang L, Chua H, Wong PK, Lo WH, Yu PHF. Ni2+ removal and recovery from electroplating effluent by Pseudomonas putida 5-x cell biomass. J Environ Sci Health A Tox Hazard Subst Environ Eng 2003; 38:521-531. [PMID: 12680580 DOI: 10.1081/ese-120016912] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Ni2+ and Cu2+ are the major heavy metal ions in electroplating wastewater of Hong Kong. In the present study, Pseudomonas putida 5-x cell biomass was used to remove Ni2+ from electroplating effluent. Ni2+ adsorption capacity of P. putida 5-x cell biomass cultured in sulphate-limiting medium was found to be minimum in early logarithmic growth phase, and maximum of 28.1 mg g(-1) in late stationary growth phase. Pretreated cells by 0.1 mol L(-1) HCl could greatly enhance the Ni2+ adsorption capacity of cell biomass from 28.1 to 36.7 mg g(-1) and had no significant effect on biomass loss. The adsorption process of P. putida 5-x fresh cells and pretreated cell all could be expressed with Freundlich isotherm. TEM analyses indicated that acidic pretreatment degraded the superficial layer-capsule outside of the fresh cell to improve the adsorption capacity of cell to Ni2+. The Ni2+ bound by P. putida 5-x cell biomass could be efficiently recovered using 0.1 mol L(-1) HCl, and the cell biomass could be reused at least five cycles for Ni2+ removal and recovery with 93% above removal efficiency and 98% above recovery rate. Owing to the Cu2+ presented in electroplating wastewater inhibiting Ni2+ adsorption process by P. putida 5-x cell biomass, two-stage biosorption processes should be designed to remove and recover Cu2+ and Ni2+ sequentially from electroplating effluent.
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Affiliation(s)
- L Wang
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
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Wang L, Chua H, Zhou Q, Wong PK, Sin SN, Lo WL, Yu PH. Role of cell surface components on Cu2+ adsorption by Pseudomonas putida 5-x isolated from electroplating effluent. Water Res 2003; 37:561-568. [PMID: 12688690 DOI: 10.1016/s0043-1354(02)00350-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A gram-negative bacterium Pseudomonas putida 5-x with high Cu2+ accumulating capability was isolated from electroplating effluent in Kwun Tong, Hong Kong. The pretreated cells without superficial layer-capsule, isolated cell envelopes and the separated peptidoglycan layer materials were obtained from fresh P. putida 5-x cells, their Cu2+ adsorption capacities and properties were compared with that of the fresh cells. Pretreatment by 0.1 mol L(-1) HCl enhanced Cu2+ adsorption capacity due to the degradation of cell superficial layer-capsule of P. putida 5-x cells. Isolated cell envelopes possessed five times more Cu2+ adsorption capacity than that of fresh intact cell. The Cu2+ adsorption of separated peptidoglycan layer materials indicated that the peptidoglycan layer only played 10-15% part of the Cu2+ adsorption capacity, and implied other cell surface components such as outer membrane or inner membrane might play an important role in such high Cu2+ binding of the cell envelopes. The adsorption process of fresh cells, pretreated cells and cell envelopes of P. putida 5-x could be described with Freundlich isotherm, while the adsorption of Cu2+ by separated peptidoglycan layer materials was better described with Langmuir isotherm.
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Affiliation(s)
- L Wang
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
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34
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Lo W, Chua H, Wong MF, Yu P. Bacterial biosorbent for removing and recovering copper from electroplating effluents. Water Sci Technol 2003; 47:251-256. [PMID: 12578202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Investigations were carried out to study the removal and recovery of Cu(II) ions from wastewater by Micrococcus sp. The Langmuir isotherm model described very well the equilibrium behavior of copper biosorption, with maximum biosorption capacity (q(max)) reaching 52.1 mg Cu2+/g dry cell at pH 6. Biomass prewashed with sulfuric acid (0.05 mol 1(-1)) and sodium sulfate (1 mol l(-1)) solutions were shown to increase the copper removal capabilities up to 27% and 16%, respectively. Copper uptake by cells was negligible at pH 2.0 and then increased quickly with increasing pH until 6.0. Cells of Micrococcus sp. were immobilized in 2% calcium alginate and 10% polyacrylamide gel beads. A counter-current process comprising a series of immobilized cell reactors was developed for removing and recovering copper from electroplating effluents. This process was capable of producing an effluent at low copper concentration, with only a minimum amount of desorbing agent used. The technique of scanning electron microscopy coupled with X-ray dispersion analysis shows that Cu2+ exchanged with K+ and Ca2+ on the cell wall of Micrococcus sp., thereby suggesting ion exchange as one of the dominant mechanisms of metal biosorption for this bacterial strain.
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Affiliation(s)
- W Lo
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR.
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36
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Abstract
Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined at pH 5.0 and initial metal concentration of 100 mg/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity. The lead and copper biosorption of this strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q(max)) reaching 271.7mg of Pb2+/g of dry cell and 46.8 mg of Cu2+/g of dry cell at pH 5.0. Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased with increasing pH from 2.0 to 7.0. A mutual inhibitory effect was observed in the lead-copper system because the presence of either ion affected the sorption capacity of the other. Unequal inhibitions were observed in all the nickel binary systems. The increasing order of affinity of the three metals toward P. pseudoalcaligenes was Ni < Cu < Pb. The metal biosorptive potential of these isolates, especially P. pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents.
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Affiliation(s)
- W C Leung
- Department of Applied Biology, The Hong Kong Polytechnic University, Hung Hom, China
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37
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Abstract
Studies were conducted to investigate the removal and recovery of copper (II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption followed the Langmuir isotherm model very well with a maximum biosorption capacity (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2+/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Copper uptake by cells was negligible at pH 2.0 and then increased rapidly with increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu approximate to Pb > Ni approximate to Zn. There is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO4(2-), and NO3- (0-500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recovering >90% of the initial copper sorbed. The copper capacity of Micrococcus sp. remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. may be applicable to the development of potentially cost-effective biosorbent for removing and recovering copper from effluents.
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Affiliation(s)
- M F Wong
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, SAR, China
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Law KH, Leung YC, Lawford H, Chua H, Wai-Hung L, Yu PH. Production of polyhydroxybutyrate by Bacillus species isolated from municipal activated sludge. Appl Biochem Biotechnol 2002; 91-93:515-24. [PMID: 11963881 DOI: 10.1385/abab:91-93:1-9:515] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Plastic wastes are considered to be severe environmental contaminants causing waste disposal problems. Widespread use of biodegradable plastics is one of the solutions, but it is limited by high production cost. Biologic wastewater treatment generates large quantities of biomass as activated sludge. Only a few reports focus on the potential of utilizing resident Bacillus species from activated sludge in polyhydroxbutyrate (PHB) production as well as the production of PHB from food wastes. They have attractive properties such as short generation time, absence of endotoxins, and secretion of both amylases and proteinases that can well utilize food wastes for nutrients, which can further reduce the cost of production of polyhydroxyalkanoates (PHAs). Two PHA-producing strains, HF-1 and HF-2, were isolated from activated sludge. HF-1 outperformed HF-2 in terms of growth and PHB production in hydrolyzed soy and malt wastes. The isolated bacteria was characterized by DNA sequence alignment. Cell extracts of HF-1 were also compared to Bacillus megaterium cell extracts on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The biopolymers accumulated were analyzed by gas chromatography, nuclear magnetic resonance, and Fourier transform infrared methods.
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Affiliation(s)
- K H Law
- Department of Applied Biology and Chemical Technology, Hong Kong Polytechnic University, Hung Hom, China
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Wilson CL, Song LM, Chua H, Ferrara M, Devine RM, Dozois RR, Nehra V. Bleeding from cavernous angiomatosis of the rectum in Klippel-Trenaunay syndrome: report of three cases and literature review. Am J Gastroenterol 2001; 96:2783-8. [PMID: 11569713 DOI: 10.1111/j.1572-0241.2001.04110.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Klippel-Trenaunay syndrome (KTS) is a congenital vascular anomaly characterized by limb hypertrophy, cutaneous hemangiomas, and varicosities. GI hemorrhage is a potentially serious complication secondary to diffuse hemangiomatous involvement of the gut. We report on three patients with KTS who presented with transfusion-dependent anemia and life-threatening bleeding due to extensive cavernous hemangiomas involving the rectum. Two patients were treated by proctocolectomy and coloanal anastomosis, which preserved anal function while controlling bleeding. The third patient required an abdominoperineal resection because of extensive rectal, perianal, and perineal angiomatosis. The literature on the evaluation and management of GI hemorrhage in KTS, particularly of colorectal origin, is reviewed.
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Affiliation(s)
- C L Wilson
- Divisions of Gastroenterology and Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA
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Abstract
Tolo Harbour is a large eutrophic land-locked estuarine embayment in Hong Kong. The rapid urbanization, commercio-industrial activities and lack of legislative control around the Tolo catchment produced large quantities of untreated or partially treated municipal sewage, agricultural wastes and cottage industrial effluents which were discharged into Tolo Harbour via rivers and watercourses. Control measures were implemented to reduce the external nutrient loading into the harbour since the early 1980s. Nutrient data for the period 1982 to 1997 were analyzed for temporal trends. Over the period of observation, the total inorganic nitrogen and total phosphorus both show an increasing trend, despite a decade of efforts in reducing nutrient loading. The release rates of potentially mobile nitrogen (N) and phosphorus (P) from the sediments collected from Tolo Harbour were determined by N and P release experiments under oxic conditions. The experimental results showed that the sediment released significant amount of nutrients, especially orthophosphates and ammonia nitrogen. The maximum release rates were 15.0 and 206.0 mg/m2/day, respectively. Although the external nutrient loading has been reduced, nutrients could gradually be released back into the water column from the contaminated sediments and delay improvement of the water quality.
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Affiliation(s)
- W F Hu
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China
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Abstract
The extent of heavy metal cation contamination in the Shing Mun River has been assessed. Sediment samples were taken at eight strategic locations along the river system. The highest concentrations of copper (Cu, 1.66 mg/g), lead (Pb, 0.354 mg/g), zinc (Zn, 2.2 mg/g) and chromium (Cr, 0.047 mg/g) were found in the Fo Tan Nullah, a major tributary of the Shing Mun River. The highest concentrations of aluminum (114 mg/g) and cadmium (Cd, 0.047 mg/g) were found in the Shing Mun Main River Channel. These contaminated sediments, accumulated over the years on the river bed, could act as secondary sources of pollution to the overlying water column in the river.
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Affiliation(s)
- S N Sin
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, People's Republic of China
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Chua H, Yu PH, Lo W, Sin SN. The degradation of xenobiotic branched carboxylic acids in anaerobic sediment of the Pearl River in Southern China. Sci Total Environ 2001; 266:221-228. [PMID: 11258820 DOI: 10.1016/s0048-9697(00)00750-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Xenobiotic branched carboxylic acids (BCAs) discharged by industries are often persistent in biological wastewater treatment systems and end up in water and sediments. In this study, the degradation of 12 typical BCAs in an anaerobic environment of river sediment was studied in vitro using enrichment shake-flask cultures. The anaerobic consortium taken from the river sediment, comprising BCA-degrading and methane-producing genera, degraded BCAs with tertiary carbons through beta-oxidation, followed by methanogenesis mechanisms. The maximum cell densities in the cultures using BCAs as the sole carbon source ranged between 5.0 and 6.0 x 10(5) cells/ml. The maximum degradation rates were between 5.0 and 8.5 x 10(-3) mmol/h. The consortium could not degrade BCAs with quaternary carbons. The degree of branching at the alpha or beta position along the carbon chain interfered with the beta-oxidation mechanisms. These BCAs would accumulate in the sediment and significantly affect the cycling of organic carbon and nutrients.
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Affiliation(s)
- H Chua
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon
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Abstract
Biological processes have become popular for odor treatment. In this study, a novel fibrous bed bioreactor was applied for treatment of odorous gas. The column reactor was packed with spirally wound fibrous sheet material on which a consortium of microorganisms selected from activated sludge was immobilized. The first stage of this work comprised a preliminary study that aimed at investigating the feasibility of the fibrous bed bioreactor for treatment of odorous volatile fatty acids (VFAs). In this stage, the performance of a fibrous bed bioreactor at increasing mass loadings ranging from 9.7 to 104.2 g/(m3.h) was studied. VFA removal efficiencies above 90% were achieved at mass loadings up to 50.3 g/(m3.h). At a mass loading of 104.2 g/(m3.h), removal efficiency was found to be 87.7%. In the second stage of the work, the process was scaled up with design and operational considerations, namely, packing medium, process condition, and configuration selections. A trickling biofilter with synthetic fibrous packing medium was selected. It was operated under countercurrent flow of gas and liquid streams. The effects of inlet concentration and empty bed retention time on bioreactor performance were studied. The bioreactor was effective in treating odorous VFAs at mass loadings up to 32 g/(m3.h), at which VFAs started to accumulate in the recirculation liquid, indicating that the biofilm was unable to degrade all the VFAs introduced. Although VFAs accumulated in the liquid phase, the removal efficiency remained above 99%, implying that the biochemical reaction rate, rather than gas-to-liquid mass transfer rate, was the limiting factor of this process. The bioreactor was stable for long-term operation; no clogging and degeneration of the packing medium was observed during the 4-mo operation.
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Affiliation(s)
- H Chua
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong
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Lei W, Chua H, Lo WH, Yu PH, Zhao YG, Wong PK. A novel magnetite-immobilized cell process for heavy metal removal from industrial effluent. Appl Biochem Biotechnol 2000; 84-86:1113-26. [PMID: 10849862 DOI: 10.1385/abab:84-86:1-9:1113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The sorption and desorption of copper (II) (Cu[II]) ions from the wastewater by magnetite-immobilized cells of Pseudomonas putida 5-x with acidic pretreatment were studied. Pretreating cells with 0.6 N HCl was found to enhance greatly the adsorption capacity of biomass up to 85.6 mg/g and had no significant effect on the loss of P. putida 5-x cells during biosorbent pretreatment. The biosorption capacity to Cu2+ of magnetite-immobilized cells of P. putida 5-x harvested during various growth phases was also investigated. The experimental results illustrated that the adsorption capacity to Cu2+ of P. putida 5-x cultured in sulfate-limiting medium reached maximum during the late stationary growth phase or early death phase, and reached minimum during the log growth phase. The mechanism of copper sequestering by this type of biomass was studied via transmission electron microscopy. A degradation of the peptidoglycan layer of the cell wall was observed in the acidic pretreatment, but no further degradation appeared after the adsorption-desorption cycle. Cu(II) accumulated mostly on the surface of the cell walls and was effectively desorbed by the acidic treatment during the desorption process.
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Affiliation(s)
- W Lei
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong
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45
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Abstract
Foaming is a common operational problem in activated sludge processes that often adversely affects the quality of the treated effluent. Overgrowth of the filamentous Nocardia spp. in the microbial ecosystem was previously identified as the cause of foaming. In the present study, the specific growth rate of Nocardia amarae was found to be much higher than that of nonfilamentous bacteria under food:microorganism (F:M) ratios lower than 0.5 mg of biological oxygen demand (BOD)/(mg of mixed liquor suspended solids [MLSS].d). This indicated that filamentous overgrowth may occur in normal activated sludge processes that are continually operated under the usual F:M range of 0.2-0.6 mg of BOD/(mg of MLSS.d). A novel two-component feast-fast operation (FFO) that capitalized on the sensitivity of filamentous bacteria to F:M ratio was designed to prevent and control foaming problems. The F:M ratio in the "feasting" aeration unit was 0.8 mg of BOD/(mg of MLSS.d) whereas that in the "fasting" aeration unit was 0.2 mg of BOD/(mg of MLSS.d). The FFO resulted in an overall process F:M ratio that still remained within the normal range, while avoiding prolonged exposure of the activated sludge ecosystem to an F:M ratio below 0.5 mg of BOD/(mg of MLSS.d). The FFO suppressed the overgrowth of filamentous bacteria without adversely affecting the organic treatment efficiency of the modified process.
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Affiliation(s)
- H Chua
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong
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46
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Abstract
Polyhydroxyalkanoates (PHAs) have been recognized as good candidates for biodegradable plastics, but their high price compared with conventional plastics has limited their use. In this study, activated sludge microorganisms from a conventional wastewater treatment process were induced, by controlling the carbon:nitrogen (C:N) ratio in the reactor liquor, to accumulate PHAs. In addition, an intermittent nitrogen feeding program was established to optimize the volumetric PHA productivity in a wastewater treatment process. The optimal overall polymer production yield of 0.111 g of polymer/g of carbonaceous substrate consumed was achieved under a C:N ratio of 96:1 by feeding nitrogen in the reactor liquor once every four cycles. At the same time, the amount of excess sludge generated from the wastewater treatment process was reduced by 22.9%.
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Affiliation(s)
- C K Ma
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, China
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Hong K, Chen GQ, Yu PH, Zhang G, Liu Y, Chua H. Effect of C:N molar ratio on monomer composition of polyhydroxyalkanoates produced by Pseudomonas mendocina 0806 and Pseudomonas pseudoalkaligenus YS1. Appl Biochem Biotechnol 2000; 84-86:971-80. [PMID: 10849851 DOI: 10.1385/abab:84-86:1-9:971] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by bacteria. In this study, the effect of C:N molar ratio on the monomer composition of PHAs was investigated, including medium chain length PHA produced by Pseudomonas mendocina 0806 and PHA blends consisting of monomers of 3-hydroxybutyrate and medium chain length hydroxyalkanoate produced by Pseudomonas pseudoalkaligenus YS1. It was observed that there were some fixed ranges of C:N molar ratio that affect the monomer composition of PHA independently of the substrate. For strain 0806, the ranges were C:N < 20, 20 < C:N < 200, and C:N > 200. The monomer composition was constant among these ranges when using glucose and octanoate as the sole substrate. For strain YS1, the ranges were C:N < 20, 20 < C:N < 45, and C:N > 45. These results are useful for controlling monomer composition in PHA production.
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Affiliation(s)
- K Hong
- Engineering School, South China University of Tropical Agriculture, Danzhou, Hainan, China
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48
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Abstract
The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5 d), the heavy metal ions in the wastewater reduced the CAC but had no significant effect on the chemical oxygen demand removal efficiency.
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Affiliation(s)
- S N Sin
- Department of Civil and Structural Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR
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49
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Abstract
Branched fatty acids (BAFs) in industrial effluents are often persistent in biological wastewater treatment systems and end up as organic contaminants in the water environment. In this study, degradation of eight characteristic BAFs in a natural anaerobic ecosystem of an eutrophic river sediment was studied in vitro by enrichment culture techniques. The anaerobic consortium, comprising of BFA-degrading and methane-producing genera, degraded BFAs with a tertiary carbon through beta-oxidation followed by methanogenesis mechanisms. The consortium could not degrade BFAs with a quaternary carbon. The degree of branching at the alpha or beta position along the carbon chain interfered with the beta-oxidation mechanisms, and hence affected the degradability of the compound.
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Affiliation(s)
- S N Sin
- Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, People's Republic of China
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50
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Abstract
A Gram-positive coccus-shaped bacterium capable of synthesizing higher relative molecular weight (M(r)) poly-hydroxybutyrate (PHB) was isolated from sesame oil and identified as Staphylococcus epidermidis (by Microbial ID, Inc., Newark, NJ). The experiment was conducted by shake flask fermentation culture using media containing fructose. Cell growth up to a dry mass of 2.5 g/L and PHB accumulation up to 15.02% of cell dry wt was observed. Apart from using single carbohydrate as a sole carbon source, various industrial food wastes including sesame oil, ice cream, malt, and soya wastes were investigated as nutrients for S. epidermidis to reduce the cost of the carbon source. As a result, we found that by using malt wastes as nutrient for cell growth, PHB accumulation of S. epidermidis was much better than using other wastes as nutrient source. The final dried cell mass and PHB production using malt wastes were 1.76 g/L and 6.93% polymer/cells (grams/gram), and 3.5 g/L and 3.31% polymer/cells (grams/gram) in shake flask culture and in fermentor culture, respectively. The bacterial polymer was characterized by 1H-nuclear magnetic resonance (NMR), 13C-NMR, Fourier transform infrared, and differential scanning calorimetry. The results show that with different industrial food wastes as carbon and energy sources, the same biopolymer (PHB) was obtained. However, the use of sesame oil as the carbon source resulted in the accumulation of PHB with a higher melting point than that produced from other food wastes as carbon sources by this organism under similar experimental conditions.
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Affiliation(s)
- A L Wong
- Open Laboratory of Chirotechnology, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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