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T L Hu

Publications and source records attributed to T L Hu.

9 recordsLinked to original sources
PubMed2003

Color removal ability of a streptomycin resistant decolorizing strain Rhodococcus erythropolis (ATCC:4277.1).

Rhodococcua erythropolis (ATCC 4277.1) is a streptomycin resistant mutant of ATCC 4277, which can decolorize the sulfonated azo dye of Orange II and Amido Black. Pseudomonaes luteola is a decolorizing strain, which was isolated from sludge resulting from the treatment of dyeing wastewater. This study had two purposes: 1) to determine the color removal capacity of R. erythropolis (ATCC 4277.1) for Red 22, V2RP and RP2B dyes; and 2) to compare the decolorization capability of R. erythropolis (ATCC 4277.1) to that of P. luteola, a wild type decolorizing strain. R. erythropolis (ATCC 4277.1) grew well in broth containing the azo dyes of Red 22, V2RP or RP2B, and the color of azo dyes could be removed within five days of incubation. The total percentage of color removal was 70%, 30% and 23%, respectively. Color removal by R. erythropolis occurred through a process of degradation, since after five day's incubation in a dye containing broth, the color of R. erythropolis cells remained the same as their original pinkish white color. Comparison of the color removing ability between R. erythropolis and P. luteola showed that the specific color removal (SCR) of R. erythropolis was 1.52 mg of RP2B degraded per gram of dried cells, and that of SCR of P. luteola was 31.7 mg, which was 30 fold higher than that of R. erythropolis.

Azo Compounds↗
PubMed2001

Kinetic characteristics of bacterial azo-dye decolorization by Pseudomonas luteola.

A Pseudomonas luteola strain expressing azoreductase activity was utilized to remove the color of an azo dye (reactive red 22) from contaminated solutions. The effects of substrate concentrations, medium compositions, and operation parameters (e.g., pH, temperature, dissolved oxygen, etc.) on decolorization of the azo dye by a P. luteola strain were systematically investigated to reveal the key factors that dominate the performance of azo-dye decolorization. The metabolites resulting from bacterial decolorization were analyzed by high-performance liquid chromatography (HPLC) and mass spectrometery (MS). The results show that the dissolved oxygen and glucose concentration retarded decolorization of reactive red 22 by P. luteola. The optimal azo-dye decolorization occurred at 37 degrees C, while more rapid decolorization took place over pH 7-9. Yeast extract and tryptone strongly enhanced the decolorization. The Michaelis-Menten model can satisfactorily describe the dependence of specific decolorization rate on the concentration of substrate (reactive red 22 or yeast extract). Decolorization of the azo dye by intact cells of P. luteola was essentially independent of the growth phase, whereas the azoreductase activity of the cell-free extract decreased in the order of late-stationary phase > early-stationary phase > mid-log phase. This suggests that mass transfer of the azo dye across the cell membrane may be the rate-limiting step. The HPLC and MS analyses suggest that both partial reduction and complete cleavage of the azo bond could contribute to decolorization of reactive red 22 by P. luteola.

Azo Compounds↗
PubMed2001

Assessment of the effect of azo dye RP2B on the growth of a nitrogen fixing cyanobacterium--Anabaena sp.

Certain nitrogen fixing cyanobacteria are diazotrophic, which profoundly impacts the aquatic ecosystem chemically and biologically. Although certain types are banned due to their carcinogenicity, azo dyes are commonly used in the dyeing or textile industry. This work investigates the effect of azo dye on the growth of cyanobacteria. Anabaena sp. isolated from the Da Jia Brook is an odor producing, nitrogen fixing cyanobacterium. The growth rates of Anabaena sp. in the media with or without nitrogen source were 3.56 x 10(-2) mg/ml day and 2.44 x 10(-2) mg/ml day, respectively. Anabaena sp. could not use azo dye RP2B as the nitrogen source. Experimental results indicated that the growth of Anabaena sp. was inhibited in the medium containing RP2B. The degree of inhibition increased from 50% to 81% with an increasing concentration of RP2B (0-50 mg/l). The IC-50 (inhibitory concentration) of RP2B on the growth of Anabaena sp. was 5 mg/l (as based on dry weight) or 7 mg/l (as measured by chlorophyll a).

Anabaena↗
PubMed2001

Kinetics of azoreductase and assessment of toxicity of metabolic products from azo dyes by Pseudomonas luteola.

This is a continuous study on a decolorization strain, Pseudomonas luteola, which involves treating seven azo dyes with different structures. This study focuses mainly on determining both the mechanism of decolorization by P. luteola and the activity of azoreductase from P. luteola as well as identifying and assessing the toxicity of metabolic products of azo dyes. The growth of P. luteola reached the stationary phase after shaking incubation for 24 hours. Then, while being kept static, the color of seven tested azo dyes (100 mg/l) could be removed. The proportion of color removal was between 59-99%, which figure is related to the structure of the dye. Monoazo dyes (RP2B, V2RP and Red 22) showed the fastest rate of decolorization, i.e. from 0.23-0.44 mg dye-mg cell-1 hr-1. P. luteola could remove the color of V2RP and a leather dye at a concentration of 200 mg/l, and as to the rest of the azo dyes, it could remove at a concentration of up to 100 mg/l. Decolorization of RP2B and Red 22 required activation energy of 7.00 J/mol and 6.63 J/mole, respectively, indicating that it was easier for azoreductase to decolorize structurally simple dyes. The kinetics of azoreductase towards seven azo dyes suggested a competitive inhibition model be applied. Microtox was used to analyze the toxicity of the metabolic products of azo dyes. EC50 showed differences in toxicity before and after the azo dyes had been metabolized. Analysis revealed significant differences between the results obtained by EC50 with Blue 15 and those obtained with the leather dye, indicating that the toxicities of the metabolic products were increased. The differences obtained by EC50 with Red 22, RP2P and V2RP were small, and Black 22 showed no such difference. Sulfanic acid and orthanilic acid may be the intermediate products of Violet 9 and RP2B, respectively. However, according to FT-IR analysis, aromatic amines were present in the metabolic product.

Azo Compounds↗
PubMed2000

Comparison of colony lift with direct spotting methods of blot preparation on the effect of colony hybridization in the detection of environmental organisms.

Nucleic acid probes are used on site to detect or to identify individual microbial cells without cultivation. This molecular technique can avoid some limitations of traditional identification methods including time consuming and imprecise. This study examined the factors affecting colony hybridization and compared the effectiveness of membrane prepared by colony lifting with direct spotting procedures using the universal probe Eub 338. The results of hybridization varied depending on the type of colony morphology. For dry and rough colonies, colony hybridization was not suitable for detecting Acinetobactersp. (CK2A, CK2B), Alcaligenes sp. (TH11 B), Xanthomonas sp. (TH7B), Arthrobacter globiformis (CCRC 10598) and Microbacterium sp. (CCRC 11036). Colonies of Acinetobacter sp. (CCRC 15425) and Alcaligenes spp. (CCRC 10828, H) on agar and membrane were thick and raised, and their detection signals of hybridization were diffused or blank. Colonies of Alcaligenes sp. (CM7A, ANV2) and Acinetobacter sp. (ANV8) isolated from the sludge of biological processes treating ABS wastewater were flat and smooth, and their hybridization signals were clear. For those strains suitable for colony hybridization, the colony blots prepared by colony lift and direct spotting procedures gave the same sensitivity for colony hybridization.

Bacteria↗
PubMed2000

A model and its implications for denitrification in soil environment.

We analyzed the mechanisms of a soil nitrogen (N) sub-model, which is a subroutine of the Crop-Environment Resources Synthesis (CERES)-maize; a model which was originally designed to simulate crop yield and has been calibrated and validated in Taiwan. Some experiments designed specifically for testing the N sub-model proved the capability of the model in reflecting field observations. With the mechanisms, we could write computer programs for calculating the relative sensitivities of major parameters in the model, and for simulating different treatments of organic matter. The purposes were to find how they affected N transformations, especially the processes of denitrification, which are considered to be responsible for N losses in upland soils and are an important environmental issue related to human disturbance of the N cycle. The results implied that soil water content and temperature were, respectively, the first and second dominant factors. They were much more sensitive than any other parameters, such as the decomposition rate coefficients, soil pH and bulk density. Decomposition of organic matter could slow down if organic matter with different carbon/nitrogen (C/N) ratios were treated in fractions. This treatment could also decrease the process of denitrification unless the organic matter was extremely large in quantity and has a high C/N ratio.

Calibration↗
PubMed1998

Tuberculum sellae meningiomas: clinical manifestation, radiologic diagnosis, surgery and visual outcome.

BACKGROUND: Most patients with tuberculum sellae meningioma (TSM) present with visual symptoms mimicking a pituitary macroadenoma. Accurate preoperative differentiation is important because TSM requires a craniotomy, whereas the transsphenoidal route is preferred for removal of most pituitary macroadenomas. METHODS: From 1989 to 1994, five patients with TSM were treated at Taichung Veterans General Hospital. All were female, ranging in age from 20 to 60 years. This paper is a retrospective review of clinical features, diagnostic methods, treatment and postoperative visual recovery. RESULTS: The most common symptom, with a duration of one month to two years, was asymmetrical visual loss. Abnormal endocrine levels were found in one patient (prolactin: 47.91 ng/ml). Another patient was misdiagnosed as having a pituitary adenoma by coronal view computed tomography (CT) and underwent a transsphenoidal operation. Later, an accurate diagnosis was made using magnetic resonance imaging (MRI). She then underwent another operation--unilateral subfrontal craniotomy with total removal of the tumor. The other patients were preoperatively diagnosed as having meningioma by MRI. They also underwent unilateral subfrontal craniotomy with total removal of tumor. All patients showed good visual improvement after their operation. The extent of visual improvement was closely related to the duration of preoperative visual loss. There was no tumor recurrence after a follow-up period of six months to five years (mean, two years and six months). CONCLUSIONS: It should be emphasized that the diagnosis of TSM must first be based on clinical symptoms and signs, or "chiasma-syndrome". It can be accurately diagnosed preoperatively by sagittal view MRI. Early diagnosis will increase the chances of a good postoperative visual outcome.

Adult↗
PubMed1989

The utilization of yeast in heavy wastewater treatment.

Wastewater discharged from vermicelli factories has high concentration of COD and BOD, it is considered to be heavy wastewater. Strach degrading yeast was isolated and applied to treat the vermicelli wastewater. A semicontinuous yeast dominant activated sludge method and an immobilized yeast cells system were used in treating the clarified vermicelli wastewater. When the solid retention time and hydraulic retention time were kept at 7.14 days, using a semicontinuous culture, the solid loading was 0.48 g COD/g MLSS.day, volumetric loading was 1.03 kg COD/m3.day, and the COD removal was about 92%. When the yeast cells were immobilized with 1% Na-alginate solution, in the batch culture system, the COD removal of the immobilized cells was about 73% in 12 hours; with the air bubble system, the immobilized cells had the ability to remove COD of 90%. It indicated that the immobilized cells can treat heavy wastewater directly, and the hydraulic retention time could be reduced from 7.14 days to 24 hours.

Industrial Waste↗