Papers by Keyword: Biotransformation

Abstract: Isoeugenol (2-methoxy-4-[(E)-prop-1-enyl] phenol) is a compound resulting from the isomerization of eugenol contained in clove oil (Syzygium aromaticum). Isoeugenol can be used as a precursor for vanillin biosynthesis through the biotransformation pathway. In this research, the biotransformation of isoeugenol was carried out using Pseudomonas aeruginosa as an enzyme- biocatalyst agent. The parameters used in this research include the effect of substrate concentrations of 0.5; 1; 1.5; and 2% v/v, incubation times of 24; 48; 72; and 96 hours, as well as extracting solvents with ethyl acetate and chloroform. The determination of substrate concentration was carried out at an incubation time of 24 hours, and then the characterization results with the best product concentration were used to determine the incubation time. The results of qualitative identification and characterization show that with increasing the substrate concentration, it can cause decreasing the target biotransformation results. The 1% concentration treatment with the most concentrated magenta-purple color intensity from the Schiff reagent test and the most concentrated intensity of the TLC stain has more potential to produce vanillin products with an area of 0.51% (ethyl acetate) and 0.36% (chloroform), as well as vanillyl methyl ketone with an area of 1.38% (ethyl acetate) and 4.91% (chloroform). On the other hand, increasing the incubation time can reduce the target biotransformation product. The 72 hours incubation time treatment produced vanillin 0.19% (ethyl acetate) and 0.74 (chloroform), as well as vanillyl methyl ketone 1.96% (ethyl acetate), and no vanillyl methyl ketone was produced in the chloroform solvent. In the biotransformation carried out, the substrate concentration was 1% and the incubation time was 24 hours in the chloroform extracting solvent, which became a more potential condition to produce the target biotransformation product with a substrate conversion of 5.27%, which was selective for vanillyl methyl ketone at 93.17% and vanillin at 6.83%.

Abstract: Microbial transformation of androst-4-en-3,17-dione (AD; 1) using Colletotrichum lini AS3. 4486 resulted in the production of two metabolites 2 and 3. The structures of these compounds were elucidated by spectroscopic analysis (LC-MS, FTIR and NMR) as 15α-hydroxyandrost-4-en-3,17-dione (15α-OH-AD; 2) and 11α,15α-dihydroxyandrost-4-en-3,17-dione (11α,15α-diOH-AD; 3). AD underwent regioselective hydroxylation at 15α position, subsequently hydroxylated at 11α position and converted to compound 3. 11α,15α-diOH-AD as an important metabolic product was pharmaceutical intermediate and the yield was up to 97.58% when the concentration of substrate was 4 g L^-1.

Abstract: Thirteen strains of lactic acid bacteria were isolated from the local traditional fermented yoghurt. One of them showed the highest GABA-producing ability in MRS broth with 1% L-glutamate. The strain was identified Streptococcus thermophilus QYW-LYS1 based on morphological characteristics and 16S rDNA sequence determination. The single factor design was applied to optimize culture conditions. The optimal initial cell density, temperature and reaction time were 0.2OD·mL^-1, 34°C and 72h respectively. Under the optimized reaction conditions, the production of GABA was 2.905g/L.The result may contribute to the development of traditional fermented dairy product with functional properties.

Abstract: The fungus Phanerochaete chrysosporium has been proven to biotransform refractory gold ores, leading to increase in gold recovery. This transformation has been attributed to enzymes secreted by the microbe. This paper reports the findings of preliminary investigations aimed at assessing the use of hydrogen peroxide and cell-free extracts from the fungus, P. chrysosporium, to effect biotransformation of sulphidic refractory gold ores. The investigations show that the total dissolved arsenic, iron and sulphur in solution were up to 5.2 wt%, 0.9 wt% and 6.0 wt% respectively from flotation concentrate after 72 hrs of treatment. Analysis for sulphide sulphur in the residual solids of the gold concentrate indicated about 25 wt% oxidation within 24 hours of treatment. In general, cell-free decomposition of the samples did not increase beyond 24 hours of contact time, possibly due to exhaustion of the active components. Gold extraction by cyanidation increased by 24% after 24-hr treatment with the cell-free extracts. Comparatively, cell-free (in vitro) treatment recorded 66% overall gold recovery as against 61% for whole cell (in vivo) after 72 hours of treatment. These initial results indicate clearly that in vitro processing is a promising alternative to in vivo processing of refractory gold ores using P. chrysosporium.

Abstract: Detection of 9а-OH-AD prepared by biotransformation by RP-HPLC directly was studied.The detection is performed on a Kromasil 100-5C18(4.6×250mm) column, using methanol:water(7:3,v/v)as mobile phase,0.8mL•min^-1 flow rate and external standard method,deteced at 242nm.There is a good line correlaction between peak and content in range of 0.01-0.20g/L,the correlation coefficient is 0.9942,the average recovery is 99.09% with a relative stand deviation of 0.89%(n=5).The method is simple,stable,accurate and reliable for quality control of 9а-OH-AD.

Abstract: Paecilomyces victoriae was selected to transform androstenedione (AD). Two products were obtained and identified as 7α-Hydroxyandrostenedione, 7α-Hydroxy-17α-methyltestosterone, respectively, by MS and NMR.

Abstract: Resting cells of Pseudomonas sp. SY031 were used for the direct transformation of adiponitrile to 5-cyanovaleramide (5-CVAM), which is an important intermediate of azafenidin, a new kind of herbicide with high efficiency, low toxicity and non-pollution. In this study, reaction conditions for this nitrile hydratase mediated conversion were optimized. It was observed that the maximum conversion of adiponitrile to 5-CVAM was in a solution containing 50 mM phosphate buffer (pH 6.4), 10 mM adiponitrile at 35 °C. 10 mM adiponitrile was completely converted into 5-CVAM and adipamide in shaking flasks with 5-CVAM as the main product (9.004 mM) and adipamide as a low yield (0.896 mM), indicating high regio-selectivity of the nitrile hydratase in Pseudomonas sp. SY031.

Abstract: Microbial hydroxylation of progesterone occurred in the biotransformation by Phomopsis sp.. The conversion products were purified by column chromatography with ether/EtOAc and characterized by spectroscopic methods including ¹HNMR, ¹³C NMR, IR, UV and MS. Those conversion products were identified as 11α-hydroxyprogesterone (2), 11α,15β-dihydroxy progesterone (3),11α-dihydroxypreg-1,4-dien-3,20-dione (4), 6β,15βdihydroxypregesterone (5) and 7β,15βdihydroxypregesterone (6).

Abstract: Side chain cleavage of progesterone occurred in the biotransformation by Aspergillus versicolor. The conversion products were purified by column chromatography with ether/EtOAc and characterized by spectroscopic methods including ¹H NMR, ¹³C NMR, IR, UV, MS and physical constants such as melting point and optical rotation. Those conversion products were identified as testosterone, androstenedione and androstenediendione.

Abstract: Lindane (γ-hexachlorocyclohexane) was used as the substrate for a degradation experiment with the white rot fungi Phlebia brevispora TMIC34596 and Phlebia lindtneri GB1027, which are capable of degrading DDT. Pure culture of both fungi showed that about 40% of lindane was degraded after 7 days of incubation, while over 70% of lindane was degraded after 28 days of incubation. Eight metabolic products such as pentachlorocyclohexanol, dihydroxytetrachlorocyclohexane and trihydroxytrichlorocyclohexane were detected from both fungal cultures using gas chromatography/mass spectrometry (GC/MS). This is the first report of the biodegradation of lindane through successive Cl/OH substitution pathway by microorganisms.