Displaying publications 21 - 40 of 61 in total

Abstract:
Sort:
  1. P(3HB-co-4HB) as high value polyhydroxyalkanoate: its development over recent decades and current advances
    Huong KH, Sevakumaran V, Amirul AA
    Crit Rev Biotechnol, 2021 Jun;41(4):474-490.
    PMID: 33726581 DOI: 10.1080/07388551.2020.1869685
    Polyhydroxyalkanoate (PHA) is a biogenic polymer that has the potential to substitute synthetic plastic in numerous applications. This is due to its unique attribute of being a biodegradable and biocompatible thermoplastic, achievable through microbial fermentation from a broad utilizable range of renewable resources. Among all the PHAs discovered, poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] stands out as a next generation healthcare biomaterial for having high biopharmaceutical and medical value since it is highly compatible to mammalian tissue. This review provides a critical assessment and complete overview of the development and trend of P(3HB-co-4HB) research over the last few decades, highlighting aspects from the microbial strain discovery to metabolic engineering and bioprocess cultivation strategies. The article also outlines the relevance of P(3HB-co-4HB) as a material for high value-added products in numerous healthcare-related applications.
    Matched MeSH terms: Hydroxybutyrates
  2. Fulltext Neutron-activated biodegradable samarium-153 acetylacetonate-poly-L-lactic acid microspheres for intraarterial radioembolization of hepatic tumors
    Wong YH, Tan HY, Kasbollah A, Abdullah BJJ, Acharya RU, Yeong CH
    World J Exp Med, 2020 Mar 30;10(2):10-25.
    PMID: 32266125 DOI: 10.5493/wjem.v10.i2.10
    BACKGROUND: Liver cancer is the 6th most common cancer in the world and the 4th most common death from cancer worldwide. Hepatic radioembolization is a minimally invasive treatment involving intraarterial administration of radioembolic microspheres.

    AIM: To develop a neutron-activated, biodegradable and theranostics samarium-153 acetylacetonate (153SmAcAc)-poly-L-lactic acid (PLLA) microsphere for intraarterial radioembolization of hepatic tumors.

    METHODS: Microspheres with different concentrations of 152SmAcAc (i.e., 100%, 150%, 175% and 200% w/w) were prepared by solvent evaporation method. The microspheres were then activated using a nuclear reactor in a neutron flux of 2 × 1012 n/cm2/s1, converting 152Sm to Samarium-153 (153Sm) via152Sm (n, γ) 153Sm reaction. The SmAcAc-PLLA microspheres before and after neutron activation were characterized using scanning electron microscope, energy dispersive X-ray spectroscopy, particle size analysis, Fourier transform infrared spectroscopy, thermo-gravimetric analysis and gamma spectroscopy. The in-vitro radiolabeling efficiency was also tested in both 0.9% sodium chloride solution and human blood plasma over a duration of 550 h.

    RESULTS: The SmAcAc-PLLA microspheres with different SmAcAc contents remained spherical before and after neutron activation. The mean diameter of the microspheres was about 35 µm. Specific activity achieved for 153SmAcAc-PLLA microspheres with 100%, 150%, 175% and 200% (w/w) SmAcAc after 3 h neutron activation were 1.7 ± 0.05, 2.5 ± 0.05, 2.7 ± 0.07, and 2.8 ± 0.09 GBq/g, respectively. The activity of per microspheres were determined as 48.36 ± 1.33, 74.10 ± 1.65, 97.87 ± 2.48, and 109.83 ± 3.71 Bq for 153SmAcAc-PLLA microspheres with 100%, 150%, 175% and 200% (w/w) SmAcAc. The energy dispersive X-ray and gamma spectrometry showed that no elemental and radioactive impurities present in the microspheres after neutron activation. Retention efficiency of 153Sm in the SmAcAc-PLLA microspheres was excellent (approximately 99%) in both 0.9% sodium chloride solution and human blood plasma over a duration of 550 h.

    CONCLUSION: The 153SmAcAc-PLLA microsphere is potentially useful for hepatic radioembolization due to their biodegradability, favorable physicochemical characteristics and excellent radiolabeling efficiency. The synthesis of the formulation does not involve ionizing radiation and hence reducing the complication and cost of production.

    Matched MeSH terms: Hydroxybutyrates
  3. N-terminal truncation of PhaCBP-M-CPF4 and its effect on PHA production
    Neoh SZ, Tan HT, Trakunjae C, Chek MF, Vaithanomsat P, Hakoshima T, et al.
    Microb Cell Fact, 2024 Feb 15;23(1):52.
    PMID: 38360657 DOI: 10.1186/s12934-024-02329-w
    BACKGROUND: Among the polyhydroxyalkanoate (PHA), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] is reported to closely resemble polypropylene and low-density polyethylene. Studies have shown that PHA synthase (PhaC) from mangrove soil (PhaCBP-M-CPF4) is an efficient PhaC for P(3HB-co-3HHx) production and N-termini of PhaCs influence its substrate specificity, dimerization, granule morphology, and molecular weights of PHA produced. This study aims to further improve PhaCBP-M-CPF4 through N-terminal truncation.

    RESULTS: The N-terminal truncated mutants of PhaCBP-M-CPF4 were constructed based on the information of the predicted secondary and tertiary structures using PSIPRED server and AlphaFold2 program, respectively. The N-terminal truncated PhaCBP-M-CPF4 mutants were evaluated in C. necator mutant PHB-4 based on the cell dry weight, PHA content, 3HHx molar composition, molecular weights, and granule morphology of the PHA granules. The results showed that most transformants harbouring the N-terminal truncated PhaCBP-M-CPF4 showed a reduction in PHA content and cell dry weight except for PhaCBP-M-CPF4 G8. PhaCBP-M-CPF4 G8 and A27 showed an improved weight-average molecular weight (Mw) of PHA produced due to lower expression of the truncated PhaCBP-M-CPF4. Transformants harbouring PhaCBP-M-CPF4 G8, A27, and T74 showed a reduction in the number of granules. PhaCBP-M-CPF4 G8 produced higher Mw PHA in mostly single larger PHA granules with comparable production as the full-length PhaCBP-M-CPF4.

    CONCLUSION: This research showed that N-terminal truncation had effects on PHA accumulation, substrate specificity, Mw, and granule morphology. This study also showed that N-terminal truncation of the amino acids that did not adopt any secondary structure can be an alternative to improve PhaCs for the production of PHA with higher Mw in mostly single larger granules.

    Matched MeSH terms: Hydroxybutyrates/metabolism
  4. Mutagenic and clastogenic characterization of poststerilized poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer biosynthesized by Delftia acidovorans
    Siew EL, Rajab NF, Osman AB, Sudesh K, Inayat-Hussain SH
    J Biomed Mater Res A, 2009 Dec;91(3):786-94.
    PMID: 19051306 DOI: 10.1002/jbm.a.32290
    Polyhydroxyalkanoates (PHA) are naturally occurring biopolyesters that have great potential in the medical field. However, the leachables resulting from sterilization process of the biomaterials may exert toxic effect including genetic damage. Here, we demonstrate that although gamma-irradiation of poly(3-hydroxybutyrate-co-50 mol % 4-hydroxybutyrate) [P(3HB-co-4HB)] did not cause any change in the morphology by scanning electron microscopy, there was a significant degradation of this copolymer where the molecular weight was reduced by 37% after sterilization indicating the generation of leachables. Therefore, further investigation on the ability of the extract of this poststerilized copolymer to induce mutagenic effect was performed using Ames test (S. typhimurium strains TA1535 and TA1537) and umu test (S. typhimurium strain TA1535/pSK1002). Additionally, the capability of the extract to induce clastogenic effect was determined using Chinese hamster lung V79 fibroblast cells. Our results showed that with and without the presence of S9 metabolic activation, no mutagenic effects were observed in both Ames and umu tests when treated with P(3HB-co-4HB) extract. Similarly, treatment of P(3HB-co-4HB) extract in V79 fibroblast cells showed no significant production of micronuclei when compared with the positive control (Mitomycin C). Together, these results indicate that leachables of poststerilized P(3HB-co-4HB) cause no mutagenic and clastogenic effects.
    Matched MeSH terms: Hydroxybutyrates/chemistry*
  5. Fulltext Molecular characterisation of phaCAB from Comamonas sp. EB172 for functional expression in Escherichia coli JM109
    Yee LN, Chuah JA, Chong ML, Phang LY, Raha AR, Sudesh K, et al.
    Microbiol Res, 2012 Oct 12;167(9):550-7.
    PMID: 22281521 DOI: 10.1016/j.micres.2011.12.006
    In this study, PHA biosynthesis operon of Comamonas sp. EB172, an acid-tolerant strain, consisting of three genes encoding acetyl-CoA acetyltransferase (phaA(Co) gene, 1182 bp), acetoacetyl-CoA reductase (phaB(Co) gene, 738 bp) and PHA synthase, class I (phaC(Co) gene, 1694 bp) were identified. Sequence analysis of the phaA(Co), phaB(Co) and phaC(Co) genes revealed that they shared more than 85%, 89% and 69% identity, respectively, with orthologues from Delftia acidovorans SPH-1 and Acidovorax ebreus TPSY. The PHA biosynthesis genes (phaC(Co) and phaAB(Co)) were successfully cloned in a heterologous host, Escherichia coli JM109. E. coli JM109 transformants harbouring pGEM'-phaC(Co)AB(Re) and pGEM'-phaC(Re)AB(Co) were shown to be functionally active synthesising 33 wt.% and 17 wt.% of poly(3-hydroxybutyrate) [P(3HB)]. E. coli JM109 transformant harbouring the three genes from the acid-tolerant Comamonas sp. EB172 (phaCAB(Co)) under the control of native promoter from Cupriavidus necator, in vivo polymerised P(3HB) when fed with glucose and volatile mixed organic acids (acetic acid:propionic acid:n-butyric acid) in ration of 3:1:1, respectively. The E. coli JM109 transformant harbouring phaCAB(Co) could accumulate P(3HB) at 2g/L of propionic acid. P(3HB) contents of 40.9% and 43.6% were achieved by using 1% of glucose and mixed organic acids, respectively.
    Matched MeSH terms: Hydroxybutyrates/metabolism
  6. Microbial-based synthesis of highly elastomeric biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) thermoplastic
    Huong KH, Teh CH, Amirul AA
    Int J Biol Macromol, 2017 Aug;101:983-995.
    PMID: 28373050 DOI: 10.1016/j.ijbiomac.2017.03.179
    This study reports the production of P(3HB-co-4HB) [Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)] in possession of high molecular weight and elastomeric properties by Cupriavidus sp. USMAA1020 in single-stage mixed-substrate cultivation system. 1,4-butanediol and 1,6-hexanediol are found to be efficient substrate mixture that has resulted in high copolymer yield, occupying a maximum of 70wt% of the total biomass and producing higher 4HB monomer composition ranging from 31mol% to 41mol%. In substrate mixtures involving 1,6-hexanediol, cleavage of the 6-hydroxyhexanoyl-CoA produces Acetyl-CoA and 4-hydroxybutyryl-CoA. Acetyl-CoA is instrumental in initiating the cell growth in the single-stage fermentation system, preventing 4-hydroxybutyryl-CoA from being utilized via β-oxidation and retained the 4HB monomer at higher ratios. Macroscopic kinetic models of the bioprocesses have revealed that the P(3HB-co-4HB) formation appears to be in the nature of mixed-growth associated with higher formation rate during exponential growth phase; evidenced by higher growth associated constants, α, from 0.0690g/g to 0.4615g/g compared to non-growth associated constants, β, from 0.0092g/g/h to 0.0459g/g/h. The P(3HB-co-31mol% 4HB) produced from the substrate mixture exhibited high weight-average molecular weight, Mwof 927kDa approaching a million Dalton, and possessed elongation at break of 1637% upon cultivation at 0.56wt% C. This is the first report on such properties for the P(3HB-co-4HB) copolymer. The copolymer is highly resistant to polymer deformation after being stretched.
    Matched MeSH terms: Hydroxybutyrates/metabolism*; Hydroxybutyrates/chemistry
  7. Microbial polyhydroxyalkanoates (PHAs): an emerging biomaterial for tissue engineering and therapeutic applications
    Sudesh K
    Med J Malaysia, 2004 May;59 Suppl B:55-6.
    PMID: 15468816
    Among the various biomaterials available for tissue engineering and therapeutic applications, microbial polyhydroxyalkanoates (PHAs) offer the most diverse range of thermal and mechanical properties. Of particular interest are the PHAs that contain 4-hydroxybutyrate such as poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB) and poly(4-hydroxybutyrate) [P(4HB)]. These polyesters can only be synthesized by a few types of bacteria, among which Comamonas acidovorans has the most efficient metabolic pathways to channel 4HB monomers. The resulting polyesters are bioabsorbable and are being developed as a new biomaterial for medical applications. By controlling the molar ratio of the monomers, it is possible to produce materials that are as tough and elastic as rubber.
    Matched MeSH terms: Hydroxybutyrates/analysis*; Hydroxybutyrates/metabolism*
  8. Isolation of palm oil-utilising, polyhydroxyalkanoate (PHA)-producing bacteria by an enrichment technique
    Alias Z, Tan IK
    Bioresour Technol, 2005 Jul;96(11):1229-34.
    PMID: 15734309
    In early attempts to isolate palm oil-utilising bacteria from palm oil mill effluent (POME), diluted liquid samples of POME were spread on agar containing POME as primary nutrient. 45 purified colonies were screened for intracellular lipids by staining with Sudan Black B. Of these, 10 isolates were positively stained. The latter were grown in a nitrogen-limiting medium with palm olein (a triglyceride) or saponified palm olein (salts of fatty acids) as carbon source. None of the isolates grew in the palm olein medium but all grew well in the saponified palm olein medium. Of the latter however, only one isolate was positively stained with Nile Blue A, indicating the presence of PHA. This method did not successfully generate bacterial isolates which could metabolise palm olein to produce PHA. An enrichment technique was therefore developed whereby a selective medium was designed. The latter comprised minerals and palm olein (1% w/v) as sole carbon source to which POME (2.5% v/v) was added as the source of bacteria. The culture was incubated with shaking at 30 degrees C for 4 weeks. Out of seven isolates obtained from the selective medium, two isolates, FLP1 and FLP2, could utilise palm olein for growth and production of the homopolyester, poly(3-hydroxybutyrate). FLP1 is gram-negative and is identified (BIOLOG) to have 80% similarity to Burkholderia cepacia. When grown with propionate or valerate, FLP1 produced a copolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate).
    Matched MeSH terms: Hydroxybutyrates/metabolism*
  9. In vitro genotoxicity tests for polyhydroxybutyrate--a synthetic biomaterial
    Ali AQ, Kannan TP, Ahmad A, Samsudin AR
    Toxicol In Vitro, 2008 Feb;22(1):57-67.
    PMID: 17892925
    The aims of this study are to determine the mutagenicity of a locally produced polyhydroxybutyrate (PHB) using Salmonella mutagenicity test and to find out if PHB altered the expression of p53 and c-myc proto-oncogenes and bcl-xl and bcl-xs anti-apoptotic genes in the human fibroblast cell line, MRC-5. Different concentrations of PHB were incubated with special genotypic variants of Salmonella strains (TA1535, TA1537, TA1538, TA98 and TA100) carrying mutations in several genes both with and without metabolic activation (S9) and the test was assessed based on the number of revertant colonies. The average number of revertant colonies per plate treated with PHB was less than double as compared to that of negative control. For the gene expression analyses, fibroblast cell lines were treated with PHB at different concentrations and incubated for 1, 12, 24 and 48 h separately. The total RNA was isolated and analysed for the expression of p53, c-myc, bcl-xl and bcl-xs genes. The PHB did not show over or under expression of the genes studied. The above tests indicate that the locally produced PHB is non-genotoxic and does not alter the expression of the proto-oncogenes and anti-apoptotic genes considered in this study.
    Matched MeSH terms: Hydroxybutyrates/administration & dosage; Hydroxybutyrates/toxicity*
  10. In vitro cytotoxicity evaluation of biomaterials on human osteoblast cells CRL-1543; hydroxyapatite, natural coral and polyhydroxybutarate
    Shamsuria O, Fadilah AS, Asiah AB, Rodiah MR, Suzina AH, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:174-5.
    PMID: 15468874
    The aim of this study was to evaluate the in vitro cytotoxicity of biomaterials; Hydroxyapatite (HA), Natural coral (NC) and Polyhydroxybutarate (PHB). Three different materials used in this study; HA (Ca10(PO4)6(OH)2), NC (CaCO3) and PHB (Polymer) were locally produced by the groups of researcher from Universiti Sains Malaysia. The materials were separately extracted in the complete culture medium (100mg/ml) for 72h and introduced to the osteoblast cells CRL-1543. The viability of osteoblast CRL-1543 cultivated with these extraction materials after 72h incubation period was compared to negative control with neutral red assay by using spectrophotometer at 540nm. The results showed the non-cytotoxicity of the materials. After 72h of incubation period, HA showed 123% viable cells, NC was 99.43% and PHB was 176.75%. In this study, cytotoxicity test dealt mainly with the substances that leached out from the biomaterial. The results obtained showed that the materials were not toxic and also promoted cells growth in the sense of biofunctionality.
    Matched MeSH terms: Hydroxybutyrates/toxicity*
  11. In vitro biocompatibility evaluation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer in fibroblast cells
    Siew EL, Rajab NF, Osman AB, Sudesh K, Inayat-Hussain SH
    J Biomed Mater Res A, 2007 May;81(2):317-25.
    PMID: 17120221
    Among the various biomaterials available for tissue engineering and therapeutic applications, microbial polyhydroxyalkanoates offer the most diverse range of thermal and mechanical properties. In this study, the biocompatibility of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB); containing 50 mol % of 4-hydroxybutyrate] copolymer produced by Delftia acidovorans was evaluated. The cytotoxicity, mode of cell death, and genotoxicity of P(3HB-co-4HB) extract against V79 and L929 fibroblast cells were assessed using MTT assay, acridine orange/propidium iodide staining, and alkaline comet assay, respectively. Our results demonstrate that P(3HB-co-4HB) treated on both cell lines were comparable with clinically-used Polyglactin 910, where more than 60% of viable cells were observed following 72-h treatment at 200 mg/mL. Further morphological investigation on the mode of cell death showed an increase in apoptotic cells in a time-dependent manner in both cell lines. On the other hand, P(3HB-co-4HB) at 200 mg/mL showed no genotoxic effects as determined by alkaline comet assay following 72-h treatment. In conclusion, our study indicated that P(3HB-co-4HB) compounds showed good biocompatibility in fibroblast cells suggesting that it has potential to be used for future medical applications.
    Matched MeSH terms: Hydroxybutyrates/pharmacology*; Hydroxybutyrates/toxicity
  12. High PHA density fed-batch cultivation strategies for 4HB-rich P(3HB-co-4HB) copolymer production by transformant Cupriavidus malaysiensis USMAA1020
    Norhafini H, Huong KH, Amirul AA
    Int J Biol Macromol, 2019 Mar 15;125:1024-1032.
    PMID: 30557643 DOI: 10.1016/j.ijbiomac.2018.12.121
    P(3HB-co-4HB) with a high 4HB monomer composition was previously successfully produced using the transformant Cupriavidus malaysiensis USMAA1020 containing an additional copy of the PHA synthase gene. In this study, high PHA density fed-batch cultivation strategies were developed for such 4HB-rich P(3HB-co-4HB). The pulse, constant and mixed feeding strategies resulted in high PHA accumulation, with a PHA content of 74-92 wt% and 4HB monomer composition of 92-99 mol%. The pulse-feed of carbon and nitrogen resulted in higher PHA concentration (30.7 g/L) than carbon alone (22.3 g/L), suggesting that a trace amount of nitrogen is essential to support cell density for PHA accumulation. Constant feeding was found to be a more feasible strategy than mixed feeding, since the latter caused a drastic fluctuation in the C/N ratio, as evidenced by higher biomass formation indicating more carbon flux towards the competitive TCA pathway. A two-times carbon and nitrogen pulse feeding was the most optimal strategy achieving 92 wt% accommodation of the total biomass, with the highest PHA concentration (46 g/L) and yield (Yp/x) of 11.5 g/g. The strategy has kept the C/N at optimal ratio during the active PHA-producing phase. This is the first report of the production of high PHA density for 4HB-rich P(3HB-co-4HB).
    Matched MeSH terms: Hydroxybutyrates/metabolism*
  13. Genetic incorporation of oil-utilizing ability in Cupriavidus malaysiensis USMAA2-4 for sustainable polyhydroxyalkanoates production from palm olein and 1-pentanol
    Jeremy Wong HS, Huong KH, Shafie NAH, Amirul AA
    J Biotechnol, 2021 Aug 20;337:71-79.
    PMID: 34233208 DOI: 10.1016/j.jbiotec.2021.07.001
    The sustainability in polyhydroxyalkanoates (PHA) production is drawing increasing attention as the effort to increase the economic feasibility for commercialization pursues. Oleic acid is widely preferred by bacteria but its employment for PHA production makes sustainability rather dubious. This study showed promising poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] content of 68 wt % by lipase genes-harbouring Cupriavidus malaysiensis USMAA2-4 transformant from palm olein and 1-pentanol. High oleic acid content and low oil saturation caused palm olein to outperform crude palm oil, crude palm kernel oil and soybean oil due to its preference for oleic acid shown by previous screening. The transformant showed 8-fold and 40-fold higher lipase activity compared to C. necator H16 and its wild-type respectively. The transformant was unaffected by Co2+ but the growth of C. necator H16 was inversely proportional to Co2+ concentration and the employment of 1-pentanol also ceased its growth and PHA accumulation. Although the inhibitory effect of Fe2+, Cu2+ and Zn2+ at high molarity on LipA decreased PHA content of C. malaysiensis USMAA2-4 transformant by 23-24 wt %, the lipase activity was restorable with high molarity of Ca2+, thus resulted in higher PHA content. The transformant enabled the employment of low-cost 1-pentanol as the precursor for cost-effective PHA production and its preference for palm olein contributed to higher sustainability.
    Matched MeSH terms: Hydroxybutyrates
  14. Factors influencing the release of Mitragyna speciosa crude extracts from biodegradable P(3HB-co-4HB)
    Chee JW, Amirul AA, Majid MI, Mansor SM
    Int J Pharm, 2008 Sep 1;361(1-2):1-6.
    PMID: 18584978 DOI: 10.1016/j.ijpharm.2008.05.007
    Copolyesters of 3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB) were produced by Cupriavidus sp. (USMAA2-4) (DSM 19379) from carbon sources of 1,4-butanediol and gamma-butyrolactone. The composition of copolyesters produced varied from 0 to 45 mol% 4HB, depending on the combination of carbon sources supplied. The P(3HB-co-4HB) films containing Mitragyna speciosa crude extract were prepared with the ratio varying from 10 to 40% (w/w). The in vitro crude extract release of the films was studied in 0.1M phosphate buffer (pH 7.4) at 37 degrees C. Although the release rate was slow, it was maintained at a constant rate. This suggests that the crude extract release was due to the polymer degradation because the amount of crude extract released was consistent. The amount of degradation was based on the films' dry weight loss, decrease in molecular weight and surface morphology changes. The degradation rate increased with the 4HB content. This showed that the polymer degradation is dependant on the molecular weight, crystallinity, thermal properties and water permeability. The different drug loading ratio which led to surface morphology changes also gave an effect on polymer degradation.
    Matched MeSH terms: Hydroxybutyrates/chemistry*
  15. Fulltext Factors affecting poly(3-hydroxybutyrate) production from oil palm frond juice by Cupriavidus necator (CCUG52238(T))
    Mohd Zahari MA, Ariffin H, Mokhtar MN, Salihon J, Shirai Y, Hassan MA
    J Biomed Biotechnol, 2012;2012:125865.
    PMID: 23133311 DOI: 10.1155/2012/125865
    Factors influencing poly(3-hydroxybutyrate) P(3HB) production by Cupriavidus necator CCUG52238(T) utilizing oil palm frond (OPF) juice were clarified in this study. Effects of initial medium pH, agitation speed, and ammonium sulfate (NH(4))(2)SO(4) concentration on the production of P(3HB) were investigated in shake flasks experiments using OPF juice as the sole carbon source. The highest P(3HB) content was recorded at pH 7.0, agitation speed of 220 rpm, and (NH(4))(2)SO(4) concentration at 0.5 g/L. By culturing the wild-type strain of C. necator under the aforementioned conditions, the cell dry weight (CDW) and P(3HB) content obtained were 9.31 ± 0.13 g/L and 45 ± 1.5 wt.%, respectively. This accounted for 40% increment of P(3HB) content compared to the nonoptimized condition. In the meanwhile, the effect of dissolved oxygen tension (DOT) on P(3HB) production was investigated in a 2-L bioreactor. Highest CDW (11.37 g/L) and P(3HB) content (44 wt.%) were achieved when DOT level was set at 30%. P(3HB) produced from OPF juice had a tensile strength of 40 MPa and elongation at break of 8% demonstrated that P(3HB) produced from renewable and cheap carbon source is comparable to those produced from commercial substrate.
    Matched MeSH terms: Hydroxybutyrates/metabolism*
  16. Expression of His-tagged NADPH-dependent acetoacetyl-CoA reductase in recombinant Escherichia coli BL-21(DE3)
    Kee PE, Chiang YC, Ng HS, Lan JC
    J Biosci Bioeng, 2023 Oct;136(4):312-319.
    PMID: 37500302 DOI: 10.1016/j.jbiosc.2023.07.001
    Poly-3-hydroxybutyrate (P(3HB)), a member of the polyhydroxyalkanoate (PHA) family, is a biodegradable polyester with diverse industrial applications. NADPH-dependent acetoacetyl-CoA reductase (phaB) is the enzyme which plays an essential role in P(3HB) synthesis by catalyzing the conversion of the intermediates. The expression of phaB enzyme using the recombinant Escherichia coli BL-21(DE3) and the purification of the synthesized enzyme were studied. The pET-B3 plasmid harbouring the phaB gene derived from Ralstonia eutropha H16, was driven by the lac promoter in E. coli BL-21(DE3). The enzyme was expressed with different induction time, temperatures and cell age. Results showed that the cell age of 4 h, induction time of 12 h at 37°C were identified as the optimal conditions for the enzyme reductase expression. A specific activity of 0.151 U mg-1 protein and total protein concentration of 0.518 mg mg-1 of dry cell weight (DCW) were attained. Affinity chromatography was performed to purify the His-tagged phaB enzyme, in which enhanced the specific activity (14.44 U mg-1) and purification fold (38-fold), despite relative low yield (44.6%) of the enzyme was obtained. The purified phaB showed an optimal enzyme activity at 30°C and pH 8.0. The findings provide an alternative for the synthesis of the reductase enzyme which can be used in the industrial-scale production of the biodegradable polymers.
    Matched MeSH terms: Hydroxybutyrates/metabolism
  17. Enhancement of stress tolerance in the polyhydroxyalkanoate producers without mobilization of the accumulated granules
    Goh LK, Purama RK, Sudesh K
    Appl Biochem Biotechnol, 2014 Feb;172(3):1585-98.
    PMID: 24233544 DOI: 10.1007/s12010-013-0634-z
    Poly(3-hydroxybutyrate) [P(3HB)], a polymer belonging to the polyhydroxyalkanoate (PHA) family, is accumulated by numerous bacteria as carbon and energy storage material. The mobilization of accumulated P(3HB) is associated with increased stress and starvation tolerance. However, the potential function of accumulated copolymer such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] remained unknown. In this study, Delftia acidovorans DS 17 was used to evaluate the contributions of P(3HB) and P(3HB-co-3HV) granules during simulated exogenous carbon deprivation on cell survival by transferring cells with PHAs to carbon-free mineral salt medium supplemented with 1% (w/v) nitrogen source. By mobilizing the intracellular P(3HB) and P(3HB-co-3HV) at 11 and 40 mol% 3HV compositions, the cells survived starvation. Surprisingly, D. acidovorans containing P(3HB-co-94 mol% 3HV) also survived although the mobilization was not as effective. Similarly, recombinant Escherichia coli pGEM-T::phbCAB(Cn) (harboring the PHA biosynthesis genes of Cupriavidus necator) containing P(3HB) granules had a higher viable cell counts compared to those without P(3HB) granules but without any P(3HB) mobilization when exposed to oxidative stress by photoactivated titanium dioxide. This study provided strong evidence that enhancement of stress tolerance in PHA producers can be achieved without mobilization of the previously accumulated granules. Instead, PHA biosynthesis may improve bacterial survival via multiple mechanisms.
    Matched MeSH terms: Hydroxybutyrates/chemistry*
  18. Fulltext Enhancement of bioplastic polyhydroxybutyrate P(3HB) production from glucose by newly engineered strain Cupriavidus necator NSDG-GG using response surface methodology
    Biglari N, Ganjali Dashti M, Abdeshahian P, Orita I, Fukui T, Sudesh K
    3 Biotech, 2018 Aug;8(8):330.
    PMID: 30073115 DOI: 10.1007/s13205-018-1351-7
    This study aimed to enhance production of polyhydroxybutyrate P(3HB) by a newly engineered strain of Cupriavidus necator NSDG-GG by applying response surface methodology (RSM). From initial experiment of one-factor-at-a-time (OFAT), glucose and urea were found to be the most significant substrates as carbon and nitrogen sources, respectively, for the production of P(3HB). OFAT experiment results showed that the maximum biomass, P(3HB) content, and P(3HB) concentration of 8.95 g/L, 76 wt%, and 6.80 g/L were achieved at 25 g/L glucose and 0.54 g/L urea with an agitation rate of 200 rpm at 30 °C after 48 h. In this study, RSM was applied to optimize the three key variables (glucose concentration, urea concentration, and agitation speed) at a time to obtain optimal conditions in a multivariable system. Fermentation experiments were conducted in shaking flask by cultivation of C. necator NSDG-GG using various glucose concentrations (10-50 g/L), urea concentrations (0.27-0.73 g/L), and agitation speeds (150-250 rpm). The interaction between the variables studied was analyzed by ANOVA analysis. The RSM results indicated that the optimum cultivation conditions were 37.70 g/L glucose, 0.73 g/L urea, and 200 rpm agitation speed. The validation experiments under optimum conditions produced the highest biomass of 12.84 g/L, P(3HB) content of 92.16 wt%, and P(3HB) concentration of 11.83 g/L. RSM was found to be an efficient method in enhancing the production of biomass, P(3HB) content, and P(3HB) concentration by 43, 21, and 74%, respectively.
    Matched MeSH terms: Hydroxybutyrates
  19. Enhanced production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties
    Vigneswari S, Vijaya S, Majid MI, Sudesh K, Sipaut CS, Azizan MN, et al.
    J Ind Microbiol Biotechnol, 2009 Apr;36(4):547-56.
    PMID: 19189144 DOI: 10.1007/s10295-009-0525-z
    Cupriavidus sp. USMAA1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer with various 4HB precursors as the sole carbon source. Manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of P(3HB-co-4HB) copolymer and 4HB composition. P(3HB-co-4HB) copolymer with 4HB compositions ranging from 23 to 75 mol% 4HB with various mechanical and thermal properties were successfully produced by varying the medium aeration. The physical and mechanical properties of P(3HB-co-4HB) copolymers were characterized by NMR spectroscopy, gel-permeation chromatography, tensile test, and differential scanning calorimetry. The number-average molecular weights (M (n)) of copolymers ranged from 260 x 10(3) to 590 x 10(3)Da, and the polydispersities (M (w)/M (n)) were between 1.8 and 3.0. Increases in the 4HB composition lowered the molecular weight of these copolymers. In addition, the increase in 4HB composition affected the randomness of copolymer, melting temperature (T (m)), glass transition temperature (T (g)), tensile strength, and elongation to break. Enzymatic degradation of P(3HB-co-4HB) films with an extracellular depolymerase from Ochrobactrum sp. DP5 showed that the degradation rate increased proportionally with time as the 4HB fraction increased from 17 to 50 mol% but were much lower with higher 4HB fraction. Degradation of P(3HB-co-4HB) films with lipase from Chromobacterium viscosum exhibited highest degradation rate at 75 mol% 4HB. The biocompatibility of P(3HB-co-4HB) copolymers were evaluated and these copolymers have been shown to support the growth and proliferation of fibroblast cells.
    Matched MeSH terms: Hydroxybutyrates/metabolism*; Hydroxybutyrates/pharmacology; Hydroxybutyrates/chemistry*
  20. Fulltext Enhanced polyhydroxybutyrate (PHB) production by newly isolated rare actinomycetes Rhodococcus sp. strain BSRT1-1 using response surface methodology
    Trakunjae C, Boondaeng A, Apiwatanapiwat W, Kosugi A, Arai T, Sudesh K, et al.
    Sci Rep, 2021 01 21;11(1):1896.
    PMID: 33479335 DOI: 10.1038/s41598-021-81386-2
    Poly-β-hydroxybutyrate (PHB) is a biodegradable polymer, synthesized as carbon and energy reserve by bacteria and archaea. To the best of our knowledge, this is the first report on PHB production by a rare actinomycete species, Rhodococcus pyridinivorans BSRT1-1. Response surface methodology (RSM) employing central composite design, was applied to enhance PHB production in a flask scale. A maximum yield of 3.6 ± 0.5 g/L in biomass and 43.1 ± 0.5 wt% of dry cell weight (DCW) of PHB were obtained when using RSM optimized medium, which was improved the production of biomass and PHB content by 2.5 and 2.3-fold, respectively. The optimized medium was applied to upscale PHB production in a 10 L stirred-tank bioreactor, maximum biomass of 5.2 ± 0.5 g/L, and PHB content of 46.8 ± 2 wt% DCW were achieved. Furthermore, the FTIR and 1H NMR results confirmed the polymer as PHB. DSC and TGA analysis results revealed the melting, glass transition, and thermal decomposition temperature of 171.8, 4.03, and 288 °C, respectively. In conclusion, RSM can be a promising technique to improve PHB production by a newly isolated strain of R. pyridinivorans BSRT1-1 and the properties of produced PHB possessed similar properties compared to commercial PHB.
    Matched MeSH terms: Hydroxybutyrates/chemical synthesis; Hydroxybutyrates/metabolism; Hydroxybutyrates/chemistry*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links