Evaluation of Sterilization Performance for Vaporized-Hydrogen-Peroxide-Based Sterilizer with Diverse Controlled Parameters.

Hydrogen-peroxide-based low-temperature sterilization is a new sterilization technology for temperature-dependent medical devices. The effect of the process parameters of hydrogen-peroxide-based sterilizer on the sterilization performance of process challenge devices (PCDs) needs to be investigated. Sterilant amount, operating temperature, vacuum pressure, diffusion time, and chamber loading of the sterilizer on the sterilization performance of PCDs were adjusted. Seven PCDs with various morphologies and material containing biological indicators (BI) (EZTest, Geobacillus stearothermophilus) were used to evaluate the sterilization performance. The sterilization success rates of PCDs were 86, 71, and 57% with controlled temperature and pressure, diffusion time, and sterilant volume injection, respectively. The PCD material and structure also obviously affected sterilization performance. The sterilization of PCD A is the least successful for all parameters. Meanwhile, the sterilization of PCD B was influenced by the diffusion time and the sterilant injection volume. PCD B and PCD C were successfully sterilized by controlling the temperature and pressure. The weights and volume of the sterilization loading chamber resulted in a different sterilization performance. Sterilization performances of PCD 1, PCD 2, and PCD 3 were <70, <90, and 100%, respectively. Sterilant volume, sterilant diffusion time, pressure, temperature, PCD types, and chamber loading were proven to be important process parameters of sterilizer that affect the sterilization performance of vaporized-hydrogen-peroxide-based sterilizers.

Nitrate-contaminated groundwater remediation by combined autotrophic and heterotrophic denitrification for sulfate and pH control: batch tests.

Groundwater remediation was evaluated for combined autotrophic and heterotrophic denitrification under high (154 mg/L as CaCO3) and low (95 mg/L as CaCO3) alkaline conditions. Two levels of acetate (47 and 94 mg/L) and ethanol (24 and 48 mg/L) were added to the reactors. Obtained denitrification rates were 2.89, 2.58, 3.55, 1.96, and 2.0 mg-N/L · h for high alkaline conditions, whereas under low alkaline conditions has given 2.36, 1.94, 2.47, 2.74, and 2.29 mg-N/L · h for control, 47 and 94 mg/L acetate, and 24 and 48 mg/L ethanol, respectively. Nitrite was accumulated for controls but reactors with acetate and ethanol did not accumulate nitrite. Acetate and ethanol addition decreased sulfate to nitrate ratios in the range of 4.5-7.58 for high alkaline conditions (12.77 for control) and 4.43-6.78 for low alkaline conditions (7.90 for control). Acetate was more efficient compared with ethanol in controlling sulfate production and pH maintenance.

Heterologous expression of polygalacturonase genes isolated from Galactomyces citri-aurantii IJ-1 in Pichia pastoris.

ABSTACT: The objective of this work was to isolate the polygalacturonase genes of Galactomyces citri-aurantii IJ-1 harvested from rotten citrus peels and to heterologously express these genes in Pichia pastoris. Two polygalacturonase (PG) genes from G. citri-aurantii IJ-1 were obtained and tentatively named PG1 and PG2. The genes were cloned into pPICZαC, and expressed in Pichia pastoris strain GS115 with a native signal peptide or the α-factor secretion signal peptide of Saccharomyces cerevisiae. All of the recombinant proteins were successfully secreted into the culture media and confirmed as a single band with a molecular weight of 35 to 38 kDa by SDS-PAGE. The specific enzyme activities of recombinant PG1 and PG2 purified by His-tag affinity resin were 4,749 and 6,719 U/mg, respectively, with an optimal pH and temperature of pH 4.0 and 50°C. The Michaelis-Menten kinetic constants for PG1 and PG2, K (m), were confirmed to be 0.94 and 0.84 mM, respectively. In the presence of Mn(2+), the activity of PG1 and PG2 were increased to 160.8 and 146.4% of normal levels, respectively. In contrast, Cu(2+) and Fe(3+) acted as strong inhibitors to the PGs.

Characterization of Lactic Acid Bacteria Isolated from Sauce-type Kimchi.

This study was carried out to investigate the isolation and characterization of lactic acid bacteria (LAB) from naturally fermented sauce-type kimchi. Sauce-type kimchi was prepared with fresh, chopped ingredients (Korean cabbage, radish, garlic, ginger, green onion, and red pepper). The two isolated bacteria from sauce-type kimchi were identified as Pediococcus pentosaceus and Lactobacillus brevis by 16S rDNA sequencing and tentatively named Pediococcus sp. IJ-K1 and Lactobacillus sp. IJ-K2, respectively. Pediococcus sp. IJ-K1 was isolated from the early and middle fermentation stages of sauce-type kimchi whereas Lactobacillus sp. IJ-K2 was isolated from the late fermentation stage. The resistance of Pediococcus sp. IJ-K1 and Lactobacillus sp. IJ-K2 to artificial gastric and bile acids led to bacterial survival rates that were 100% and 84.21%, respectively.

[Comparison of liver abscess between diabetic patients and non-diabetic patients].

BACKGROUND/AIMS: Klebsiella pneumoniae is emerging as the leading cause for liver abscess although the most common pathogen was Escherichia coli in the past. Patients with diabetes mellitus are more likely to have a pyogenic liver abscess with gas forming infection; a gas forming pyogenic liver abscess carries a higher morbidity and mortality than the non-gas forming group. This study was conducted to clarify the clinical presentation and prognostic factors for pyogenic liver abscess in diabetic patients compared with non-diabetic patients. METHODS: Medical records of 140 cases of patients treated for pyogenic liver abscess from January 1995 through January 2004 were reviewed retrospectively in detail. RESULTS: Among 140 cases of pyogenic liver abscess, underlying diabetes was present in 26.4% (37/140). The clinical presentation between the two groups was not significantly different. The most common organism for the pyogenic abscess was K. pneumoniae in both groups. A gas forming liver abscess was discovered in only the diabetic liver abscess group, 6 of 37 patients (16%). CONCLUSIONS: K. pneumoniae was the most common organism cultured in both diabetic and non-diabetic liver abscess. Gas forming liver abscess was more common in diabetic patients than non-diabetic patients. Diabetic patients had more complications than non-diabetic patients.