• Journal of Animal Science and Technology
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• 제56권5호
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• pp.20.1-20.5
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• 2014

An experiment was conducted to evaluate the effect of form and particle size of feed supplemented with L-threonine on growth performance, carcass characteristic and blood biochemical parameters of broiler chickens. The experimental design was a $2{\times}2{\times}2$ factorial arrangement of treatments evaluating two feed forms (pellet or mash), two feed particle sizes (fine or course), and two inclusion rates of dietary L-threonine (with or without) which adopted from 7 to 42 days of age. In this experiment, 360 a day old chicks in two sexes were assigned in each treatment and each experimental unit was included 15 chicks. Feed consumption and weight gain were measured weekly. At 35 days of age, blood samples were taken to analysis blood biochemical parameters. At the end of the experimental period, two birds were slaughtered in each treatment and carcass analysis was carried out. The results showed that the effect of feed form on body weight gain and feed intake in whole of experimental period was significant (P < 0.05). Broilers fed pelleted diets had more weight gain than the mash group. Growth performance parameters were not affected by feed particle size and dietary L-threonine supplementation in whole of experimental period (P > 0.05). The results of carcass analysis showed that liver and gizzard relative weights were influenced by feed form (P < 0.05). However, pancreas and liver relative weights were affected by feed particle size and dietary L-threonine supplementation, respectively (P < 0.05). Triglyceride and VLDL levels were affected by feed form and dietary L-threonine supplementation (P < 0.05). The effect of feed particle size on blood biochemical parameters was not significant (P > 0.05). In conclusion, the experimental results indicated that feed form increased feed consumption and weight gain in whole of experimental period (1 to 42 days of age) while feed particle size and dietary L-threonine had no effect on broiler performance.

• 한국미생물·생명공학회지
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• 제23권1호
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• pp.24-30
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• 1995

The effects of amino acids in growth media on the biosynthesis of Serratia marcescens biodegradative threonine dehydratase activity were examined. The enzyme activity was decreased by 44 and 34% by 10 mM isoleucine and valine, respectively, whereas it was increased approximately by 20% by 10 mM threonine. Among several metabolites tested, pyruvate increased the enzyme activity by 60% at 5 mM, but decreased the enzyme activity approximately by 20 to 70% above 20 mM. The enzyme activity was increased by 64% by 5 mM glyoxylate, whereas it decreased the enzyme activity approximately by 40 to 70% above 20 mM glyoxylate. The thiamine, monopyrrole derivative, also increased the enzyme activity by 84% at 50 $\mu $g/ml, but did not affected the enzyme activity above 300 $\mu $g/ml. cAMP increased the enzyme activity by 58% at 0.5 mM, but decreased the enzyme activity by 15% at 2 mM. These data suggested that the biosynthesis of Serratia marcescens biodegradative threonine dehydratase is regulated by concentrations of pyruvate, glyoxylate and cAMP.

• 한국식품영양과학회지
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• 제29권5호
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• pp.752-757
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• 2000

Response surface methodology was used to optimized soaking and roasting conditions and monitor organoleptic properties of roasted Platycodon grandiflorum tea. In soaking and roasting processes based on the central composite design with variations in threonine/sucrose concentration for soaking of Platycodon grandiflorum, roasting temperature and roasting time, coefficients of determination ($R^2$) of the models were above 0.86(p<0.05) in organoleptic properties. The maximum conditions predicted for each corresponding organoleptic properties of roasted Platycodon grandiflorum tea were 1.64% threonine concentration, 137.83$^{\circ}C$ and 27.76 min in aroma, 1.46% threonine concentration, 136.1$0^{\circ}C$ and 25.19 min in taste, and 1.39% threonine concentration, 136.44$^{\circ}C$ and 29.05 min in overall flavour. The optimum condition ranges for organoleptic properties of roasted Platycodon grandiflorum tea were soaking in 1.40~1.64% threonine concentration, and roasting at 136.10~137.9$0^{\circ}C$ for 25.19~29.00 min.

• 약학회지
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• 제36권4호
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• pp.315-320
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• 1992

The amino acid threonine was produced from glycine and ethanol in a reaction mixture using resting cells of a newly isolated gram-negative methylotrophic bacterium, capable of growth on methanol. The isolate could utilize $C_1$ compounds and a variety of multicarbon substrates as sole carbon and energy source. To obtain cells of isolate with high threonine producing activity, we investigated optimum cultural conditions. Optimal growth was at the initial concentration of 0.5%(v/v) methanol, at $30^{\circ}C$ and pH 7.0. The growth was not affected by antibiotics inhibiting cell wall synthesis, but was completely suppressed by those inhibiting protein synthesis. The optimum reaction conditions from threonine production by resting cells of this strain were found.

• Journal of Microbiology and Biotechnology
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• 제2권4호
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• pp.243-247
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• 1992

The thr operon of Escherichia coli TF427, an $\alpha$-amino-$\beta$-hydroxyvaleric acid (AHV)-resistant threonine overproducer, was cloned in a pBluescriptII $KS^＋$ plasmid by complementation of E. coli mutants. All clones contained a common 8.8 kb HindIII-generated DNA fragment and complemented the thrA, thrB, and thrC mutants by showing that these clones contained the whole thr operon. This thr operon was subcloned in the plasmid vectors pBR322, pUC18, and pECCG117, an E. coli/Corynebacterium glutamicum shuttle vector, to form recombinant plasmids pBTF11, pUTF25 and pGTF18, respectively. The subcloned thr operon was shown to be present in a 6.0 kb insert. A transformant of E. coli TF125 with pBTF11 showed an 8~11 fold higher aspartokinase I activity, and 15~20 fold higher L-threonine production than TF125, an AHV-sensitive methionine auxotroph. Also, it was found that the aspartokinase I activity of E. coli TF125 harboring pBTF11 was not inhibited by threonine and its synthesis was not repressed by threonine plus isoleucine.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.748-755
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• 2014

In the genome annotation of Escherichia coli MG1655, the orf382 (1,149 bp) is designated as a gene encoding an alcohol dehydrogenase that may be Fe-dependent. In this study, the gene was amplified from the genome by PCR and overexpressed in Escherichia coli BL21(DE3). The recombinant $6{\times}$His-tag protein was then purified and characterized. In an enzymatic assay using different hydroxyl-containing substrates (n-butanol, $\small{L}$-threonine, ethanol, isopropanol, glucose, glycerol, $\small{L}$-serine, lactic acid, citric acid, methanol, or $\small{D}$-threonine), the enzyme showed the highest activity on $\small{L}$-threonine. Characterization of the mutant constructed using gene knockout of the orf382 also implied the function of the enzyme in the metabolism of $\small{L}$-threonine into glycine. Considering the presence of tested substrates in living E. coli cel ls and previous literature, we believed that the suitable nomenclature for the enzyme should be an $\small{L}$-threonine dehydrogenase (LTDH). When using $\small{L}$-threonine as the substrate, the enzyme exhibited the best catalytic performance at $39^{\circ}C$ and pH 9.8 with $NAD^+$ as the cofactor. The determination of the Km values towards $\small{L}$-threonine (Km = $11.29{\mu}M$), ethanol ($222.5{\mu}M$), and n-butanol ($8.02{\mu}M$) also confirmed the enzyme as an LTDH. Furthermore, the LTDH was shown to be an ion-containing protein based on inductively coupled plasma-atomic emission spectrometry with an isoelectronic point of pH 5.4. Moreover, a circular dichroism analysis revealed that the metal ion was structurally and enzymatically essential, as its deprivation remarkably changed the ${\alpha}$-helix percentage (from 12.6% to 6.3%).

• BMB Reports
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• 제28권2호
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• pp.124-128
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• 1995

Biodegradative threonine dehydratase purified from Serratia marcescens ATCC 25419 was inactivated by the arginine specific modification reagent, phenylglyoxal (PGO) and the lysine modification reagent, pyridoxal 5'-phosphate (PLP). The inactivation by PGO was protected by L-threonine and L-serine. The second order rate constant for the inactivation of the enzyme by PGO was calculated to be 136 $M^{-1}min^{-1}$. The reaction order with respect to PGO was 0.83. The inactivation of the enzyme by PGO was reversed upon addition of excess hydroxylamine. The inactivation of the enzyme by PLP was protected by L-threonine, L-serine, and a-aminobutyrate. The second order rate constant for the inactivation of the enzyme by PLP was 157 $M^{-1}min^{-1}$ and the order of reaction with respect to PLP was 1.0. The inactivation of the enzyme by PLP was reversed upon addition of excess acetic anhydride. Other chemical modification reagents such as N-ethylmaleimide, 5,5'-dithiobis (2-nitrobenzoate), iodoacetamide, sodium azide, phenylmethyl sulfonylfluoride and diethylpyrocarbonate had no effect on the enzyme activity. These results suggest that essential arginine and lysine residues may be located at or near the active site.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.293-297
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• 2018

Controlling the residual glucose concentration is important for improving productivity in $\text\tiny{L}$-threonine fermentation. In this study, we developed a procedure to automatically control the feeding quantity of glucose solution as a function of ammonia-water consumption rate. The feeding ratio ($R_{C/N}$) of glucose and ammonia water was predetermined via a stoichiometric approach, on the basis of glucose-ammonia water consumption rates. In a 5-L fermenter, 102 g/l $\text\tiny{L}$-threonine was obtained using our glucose-ammonia water combined feeding strategy, which was then successfully applied in a 500-L fermenter (89 g/l). Therefore, we conclude that an automatic combination feeding strategy is suitable for improving $\text\tiny{L}$-threonine production.

• Journal of Microbiology
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• 제41권3호
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• pp.202-206
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• 2003

A protein, exhibiting a high similarity to the major serine transporter of Escherichia coli, SstT, was found in Haemophilus influenzae Rd. A Na$\^$＋/-stimulated serine transport activity was also detected in the cells. The gene (sstT) for the Na$\^$＋//serine symporter from the chromosome of H. influenzae was cloned, and the properties of the transporter investigated. The serine transport activity was stimulated by Na$\^$＋/. The uptake of Na$\^$＋/ was elicited by the addition of serine or threonine into the cells, supporting the idea that these amino acids are transported by a mechanism of Na$\^$＋//substrate symport. No uptake of H$\^$＋/ was elicited by the influx of serine. The serine transport via the SstT of H. influenzae was inhibited by excess threonine, which was used as another substrate. The $K_{m}$ and the $V_{max}$ values for the serine transport were 2.5 ${\mu}$M and 14 nmol/min/mg protein, respectively.

• 한국식품영양학회지
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• 제23권2호
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• pp.171-177
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• 2010

Serratia marcescens catabolic threonine dehydratase는 streptomycin sulfate treatment, Sephadex G-200 gel filtration, AMP-Sepharose 4B affinity chromatography 등의 방법으로 정제하였는데, 최종 단계에서 회수율은 15.5%이었으며 50배 정제되었다. Native 분자량은 native pore gradient polyacrylamide gel electrophoresis(PAGE) 방법으로는 120,000이었다. SDS-PAGE에 의한 subunit의 분자량은 30,000이었고, 즉 S. marcescens 효소는 4개의 동일한 subunit으로 구성된 homo-tetrameric protein임이 판명되었다. S. marcescens 효소의 L-threonine에 대한 Km값은 AMP가 있는 조건에서 7.3 mM, AMP가 없는 조건에서 92 mM이었다. S. marcescens 효소는 효소 1 mole 당 각각 2 mole의 pyridoxal 5'-phosphate(PLP), 16개의 free-SH group을 가지고 있었다. S. marcescens 효소는 AMP의 존재 하에서 $\alpha$-ketobutyrate, pyruvate, glyoxylate, phosphoenol pyruvate(PEP)에 의해 효소 활성이 억제되었으며, cAMP와 ADP에 의해서는 효소 활성이 증가되었다. 효소학적 성질면에서 S. marcescens 효소는 E. coli 효소보다는 S. typhimurium 효소와 유사하였다. 한편, E. coli 효소는 cAMP에 의하여 효소 활성이 증가되고, S. typhimurium 효소는 ADP에 의해 효소 활성이 증가되는 것과 다르게, S. marcescens 효소는 cAMP와 ADP 모두 효소 활성이 증가되었다. 따라서 이상의 연구 결과들은 세 enteric bacteria의 catabolic threonine dehydratase가 서로 작은 차이점이 있다는 것을 반영하며, 이러한 사실을 규명하기 위해서는 향후 보다 심층적인 연구를 수행하여야 할 것으로 사료된다.