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Studies on the microbial synthesis and characterization of polyhydroxyalkanoates containing 4-hydroxyvalerate using γ-valerolactone

Muzaiyanah AR, Amirul AA

Appl Biochem Biotechnol, 2013 Jul;170(5):1194-215.
PMID: 23649305 DOI: 10.1007/s12010-013-0247-6

In this study, the ability of Cupriavidus sp. USMAA2-4 to synthesize polyhydroxyalkanoates (PHA) containing 4-hydroxyvalerate monomer (4HV) was studied through one-stage cultivation using γ-valerolactone as the carbon precursor. The presence of 4HV monomer unit in the polymer was detected through gas chromatography analysis, proving the capability of this wild strain bacterium to produce poly(3-hydrxybutyrate-co-3-hydroxyvalerate-co-4-hydroxyvalerate) [P(3HB-co-3HV-co-4HV)] terpolymer. Existence of a 4HV monomer unit in the PHA produced was further confirmed through (13)C and (1)H NMR analysis. P(3HB-co-88 % 3HV-co-1 % 4HV) terpolymer with the highest PHA content of 63 wt% was obtained through combination of 0.14 wt% C of γ-valerolactone with 0.42 wt% C of oleic acid. Various compositions of P(3HB-co-3HV-co-4HV) terpolymer with 3HV and 4HV compositions ranging from 11 to 94 mol% and from 1 to 4 mol%, respectively, were acquired by manipulating γ-valerolactone and oleic acid concentrations. The molecular weight and the thermal and mechanical properties of four different compositions of terpolymers-P(3HB-co-91 % 3HV-co-1 % 4HV), P(3HB-co-55 % 3HV-co-2 % 4HV), P(3HB-co-27 % 3HV-co-2 % 4HV), and P(3HB-co-9 % 3HV-co-1 % 4HV)-were characterized. Among these terpolymers, P(3HB-co-27 % 3HV-co-2 % 4HV) terpolymer with a molecular weight of 5.7 (10(5) Da) exhibited the highest elongation to break (264 %). The monomer unit compositional distributions of these terpolymers were investigated through acetone-water fractionation analysis. The results suggested that these produced terpolymers had broad 3HV compositional distribution and narrow 4HV compositional distribution.

Matched MeSH terms: Valerates/isolation & purification; Valerates/metabolism*; Valerates/chemistry
Fulltext Penerimaan sajian ikan air tawar dalam kalangan pelajar Universiti Kebangsaan Malaysia

Razalee Sedek, Nor Farhana Mohd Samwil

Jurnal Sains Kesihatan Malaysia, 2014;12(1):57-66.
MyJurnal

Pelbagai usaha dan kempen telah dijalankan oleh kerajaan untuk meningkatkan penerimaan orang ramai terhadap pengambilan ikan air tawar sebagai menu harian. Objektif kajian ini adalah untuk menilai penerimaan terhadap sajian ikan air tawar serta menentukan faktor-faktor yang mempengaruhi pengambilannya dalam kalangan pelajar Universiti Kebangsaan Malaysia (UKM). Seramai 232 pelajar dipilih secara rawak daripada pelbagai fakulti di UKM (kampus Bangi). Di samping pelajar, pengendali makanan di kafeteria UKM turut terlibat dalam kajian ini. Soal selidik digunakan bagi menentukan tahap kefahaman dan penerimaan pelajar terhadap ikan air tawar, kekerapan pengambilan sajian ikan air tawar serta faktor-faktor yang mempengaruhi pengambilannya. Kebolehdapatan dan kepelbagaian menu sajian ikan air tawar dikenal pasti melalui tinjauan di kafeteria UKM terpilih. Majoriti responden (95.7%) mengetahui ikan air tawar secara umum tetapi hanya 55.6% responden yang mengetahui jenis atau spesies ikan air tawar. Kebanyakan responden (63.3%) memilih ikan air tawar sebagai sajian. Ujian Khi Kuasa Dua menunjukkan terdapat perkaitan yang signifikan antara agama dan bangsa dengan pemilihan ikan air tawar sebagai sajian (p < 0.05). Ikan Keli merupakan ikan yang paling digemari oleh sejumlah 51.9% responden. Sajian yang paling digemari oleh majoriti responden (36.2%) ialah sajian ikan goreng. Bagi kebanyakan responden (43.2%), sajian ikan air tawar diambil atas faktor rasanya yang sedap. Kebanyakan kafeteria di UKM yang dikaji menjual sajian ikan air tawar dan hal ini didorong terutamanya oleh faktor mempelbagaikan menu di kafeteria mereka. Sejumlah 69.2% kafeteria melaporkan bahawa pelajar dapat menerima dengan baik sajian ikan air tawar yang disediakan tetapi hanya bagi jenis sajian ikan air tawar terpilih. Hasil kajian ini dapat memberi maklumat kepada kerajaan berkenaan penerimaan dan kesedaran pelajar universiti terhadapikan air tawar serta membantu pihak-pihak tertentu khususnya pengendali makanan di kafeteria UKM dalam menyediakan sajian ikan air tawar yang bersesuaian dengan kegemaran pelajar.

Matched MeSH terms: Valerates
Pembangunan sel fuel mikrob untuk rawatan air sisa kilang sawit

Lim SS, Jamaliah Md. Jahim, Siti Norhana Shari, Manal Ismail, Wan Ramli Wan Daud

Sains Malaysiana, 2012;41:1253-1261.

Sel fuel mikrob (SFM) merupakan peranti yang menggunakan bakteria sebagai biomangkin untuk mengoksidakan bahan organik dan bukan organik bagi menjanakan arus elektrik. Tujuan utama kajian ini ialah menguji kebolehan SFM skala makmal dengan menggunakan enapcemar yang mengandungi kultur campuran yang hidup dalam air sisa buangan kilang pemprosesan sawit (POME). Kajian ini juga bertujuan membina reka bentuk SFM yang sesuai dan mengkaji keaktifan kultur campuran yang boleh menghasilkan kuasa elektrik. POME telah digunakan dalam bentuk yang dicairkan dengan kandungan COD bersamaan dengan 3750 mg-COD L-1. Prestasi penghasilan kuasa elektrik dan kecekapan rawatan yang dinilai daripada segi penyingkiran COD, nitrogen dan jumlah karbohidrat dalam SFM dwi-ruang telah dicatat dan dianalisis setiap hari selama 15 hari. Hasil padanan uji kaji dan model kekutuban adalah memuaskan dan telah menjelaskan ketumpatan kuasa elektrik yang dapat dihasilkan pada setiap hari. Ketumpatan kuasa didapati meningkat dari hari pertama 1.607 mW m-2 (3.816 mA m-2) ke nilai maksimum pada hari ketiga 1.979 mW m-2 (4.780 mA m-2) dan mula turun sehingga minimum pada hari ketujuh 1.311 mW m-2 (3.346 mA m-2). Peringkat rawatan air sisa kilang sawit oleh SFM boleh dibahagikan kepada tiga tahap yang berbeza. Kecekapan rawatan yang rendah walaupun ketumpatan kuasa meningkat pada tahap pertama, manakala pada tahap kedua kecekapan rawatan lebih tinggi dan akhirnya pada tahap ketiga penghasilan kuasa SFM mula turun. Kecekapan rawatan paling tinggi berlaku pada tahap ketiga semasa penghasilan kuasa elektrik yang terhasil agak malar. Kecekapan rawatan yang dinilaikan dalam bentuk penyingkiran COD, penggunaan nitrogen dan karbohidrat paling tinggi berlaku pada hari ke-15 dengan nilai masing-masing adalah 54.9, 100 dan 98.9%. Hubungan penghasilan kuasa elektrik dan kecekapan rawatan telah berjaya dimodelkan dalam persamaan linear matematik berdasarkan kepada tahap-tahap penghasilan kuasa elektrik ini.

Matched MeSH terms: Valerates
Biosynthesis and native granule characteristics of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Delftia acidovorans

Loo CY, Sudesh K

Int J Biol Macromol, 2007 Apr 10;40(5):466-71.
PMID: 17207850

The ability of Delftia acidovorans to incorporate a broad range of 3-hydroxyvalerate (3HV) monomers into polyhydroxyalkanoate (PHA) copolymers was evaluated in this study. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] containing 0-90 mol% of 3HV was obtained when a mixture of sodium 3-hydroxybutyrate and sodium valerate was used as the carbon sources. Transmission electron microscopy analysis revealed an interesting aspect of the P(3HB-co-3HV) granules containing high molar ratios of 3HV whereby, the copolymer granules were generally larger than those of poly(3-hydroxybutyrate) [P(3HB)] granules, despite having almost the same cellular PHA contents. The large number of P(3HB-co-3HV) granules occupying almost the entire cell volume did not correspond to a higher amount of polymer by weight. This indicated that the granules of P(3HB-co-3HV) contain polymer chains that are loosely packed and therefore have lower density than P(3HB) granules. It was also interesting to note that a decrease in the length of the side chain from 3HV to 4-hydroxybutyrate (4HB) corresponded to an increase in the density of the respective PHA granules. The presence of longer side chain monomers (3HV) in the PHA structure seem to exhibit steric effects that prevent the polymer chains in the granules from being closely packed. The results reported here have important implications on the maximum ability of bacterial cells to accumulate PHA containing monomers with longer side chain length.

Matched MeSH terms: Valerates/metabolism
Statistical optimization and operational stability of Rhizomucor miehei lipase supported on magnetic chitosan/chitin nanoparticles for synthesis of pentyl valerate

Rahman INA, Attan N, Mahat NA, Jamalis J, Abdul Keyon AS, Kurniawan C, et al.

Int J Biol Macromol, 2018 Aug;115:680-695.
PMID: 29698760 DOI: 10.1016/j.ijbiomac.2018.04.111

The chemical-catalyzed transesterification process to produce biofuels i.e. pentyl valerate (PeVa) is environmentally unfriendly, energy-intensive with tedious downstream treatment. The present work reports the use of Rhizomucor miehei lipase (RML) crosslinked onto magnetic chitosan/chitin nanoparticles (RML-CS/CH/MNPs). The approach used to immobilize RML onto the CS/CH/MNPs yielded RML-CS/CH/MNPs with an immobilized protein loading and specific activity of 7.6 mg/g and 5.0 U·g-1, respectively. This was confirmed by assessing data of field emission scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis and Fourier transform infrared spectroscopy. A three-level-four-factor Box-Behnken design (incubation time, temperature, substrate molar ratio, and enzyme loading) was used to optimize the RML-CS/CH/MNP-catalyzed esterification synthesis of PeVa. Under optimum condition, the maximum yield of PeVa (97.8%) can be achieved in 5 h at 50 °C using molar ratio valeric acid:pentanol (1:2) and an enzyme load of 2 mg/mL. Consequently, operational stability experiments showed that the protocol adopted to prepare the CS/CH/MNP nanoparticles had increased the durability of RML. The RML-CS/CH/MNP could catalyze up to eight successive esterification cycles to produce PeVa. The study also demonstrated the functionality of CS/CH/MNP nanoparticles as an eco-friendly support matrix for improving enzymatic activity and operational stability of RML to produce PeVa.

Matched MeSH terms: Valerates/chemical synthesis*
Ternary biogenic silica/magnetite/graphene oxide composite for the hyperactivation of Candida rugosa lipase in the esterification production of ethyl valerate

Jacob AG, Wahab RA, Mahat NA

Enzyme Microb Technol, 2021 Aug;148:109807.
PMID: 34116744 DOI: 10.1016/j.enzmictec.2021.109807

Oil palm leaves (OPL) silica (SiO2) can replace the energy-intensive, commercially produced SiO2. Moreover, the agronomically sourced biogenic SiO2 is more biocompatible and cost-effective enzyme support, which properties could be improved by the addition of magnetite (Fe3O4) and graphene oxide (GO) to yield better ternary support to immobilize enzymes, i.e., Candida rugosa lipase (CRL). This study aimed to optimize the Candida rugosa lipase (CRL immobilization onto the ternary OPL-silica-magnetite (Fe3O4)-GO (SiO2/Fe3O4/GO) support, for use as biocatalyst for ethyl valerate (EV) production. Notably, this is the first study detailing the CRL/SiO2/Fe3O4/GO biocatalyst preparation for rapid and high yield production of ethyl valerate (EV). AFM and FESEM micrographs revealed globules of CRL covalently bound to GL-A-SiO2/Fe3O4/GO; similar to Raman and UV-spectroscopy results. FTIR spectra revealed amide bonds at 3478 cm-1 and 1640 cm-1 from covalent interactions between CRL and GL-A-SiO2/Fe3O4/GO. Optimum immobilization conditions were 4% (v/v) glutaraldehyde, 8 mg/mL CRL, at 16 h stirring in 150 mM NaCl at 30 °C, offering 24.78 ± 0.26 mg/g protein (specific activity = 65.24 ± 0.88 U/g). The CRL/SiO2/Fe3O4/GO yielded 77.43 ± 1.04 % of EV compared to free CRL (48.75 ± 0.70 %), verifying the suitability of SiO2/Fe3O4/GO to hyperactivate and stabilize CRL for satisfactory EV production.

Matched MeSH terms: Valerates
Metabolic phenotyping of urine for discriminating alcohol-dependent from social drinkers and alcohol-naive subjects

Mostafa H, Amin AM, Teh CH, Murugaiyah V, Arif NH, Ibrahim B

Drug Alcohol Depend, 2016 12 01;169:80-84.
PMID: 27788404 DOI: 10.1016/j.drugalcdep.2016.10.016

BACKGROUND: Alcohol-dependence (AD) is a ravaging public health and social problem. AD diagnosis depends on questionnaires and some biomarkers, which lack specificity and sensitivity, however, often leading to less precise diagnosis, as well as delaying treatment. This represents a great burden, not only on AD individuals but also on their families. Metabolomics using nuclear magnetic resonance spectroscopy (NMR) can provide novel techniques for the identification of novel biomarkers of AD. These putative biomarkers can facilitate early diagnosis of AD.
OBJECTIVES: To identify novel biomarkers able to discriminate between alcohol-dependent, non-AD alcohol drinkers and controls using metabolomics.
METHOD: Urine samples were collected from 30 alcohol-dependent persons who did not yet start AD treatment, 54 social drinkers and 60 controls, who were then analysed using NMR. Data analysis was done using multivariate analysis including principal component analysis (PCA) and orthogonal partial least square-discriminate analysis (OPLS-DA), followed by univariate and multivariate logistic regression to develop the discriminatory model. The reproducibility was done using intraclass correlation coefficient (ICC).
RESULTS: The OPLS-DA revealed significant discrimination between AD and other groups with sensitivity 86.21%, specificity 97.25% and accuracy 94.93%. Six biomarkers were significantly associated with AD in the multivariate logistic regression model. These biomarkers were cis-aconitic acid, citric acid, alanine, lactic acid, 1,2-propanediol and 2-hydroxyisovaleric acid. The reproducibility of all biomarkers was excellent (0.81-1.0).
CONCLUSION: This study revealed that metabolomics analysis of urine using NMR identified AD novel biomarkers which can discriminate AD from social drinkers and controls with high accuracy.

Matched MeSH terms: Valerates/urine