Thermostable, alkaline and detergent-tolerant lipase from a newly isolated thermophilic Bacillus stearothermophilus.

Lipases are the enzymes of choice for laundry detergent industries, owing to their triglyceride removing ability from the soiled fabric, which eventually reduces the usage of phosphate-based chemical cleansers in the detergent formulation. In this study, a novel thermo-alkaline lipase-producing strain identified as Bacillus stearothermophilus was isolated from the soil samples of olive oil mill. Enhanced lipase production was observed at 55°C, pH 11 and after 48 h of incubation. Among the substrates tested, xylose (a carbon source), peptone (a nitrogen source) and olive oil at a concentration of 1% were suitable substrates for enhancing lipase production. MgSO4 and Tween-80 were suitable substrates for maximizing lipase production. The enzyme was purified to homogeneity by a single CM-Sephadex column chromatography and revealed molecular mass of 67 kDa. The enzyme (BL1) was active over a wide range of pH from 9.0 to 13.0, with an optimum at pH 11.0, exhibited maximal activity at 55°C and retained more than 70% of its activity after incubation at 70°C or pH 13 for 0.5 h or 24 h, respectively. The enzyme hydrolyzed both short and long-chain triacylglycerols at comparable rates. BL1 was studied in a preliminary evaluation for use in detergent formulation solutions. This novel lipase showed extreme stability towards non-ionic and anionic surfactants after pre-incubation for 1 h at 40°C, and good stability towards oxidizing agents. Additionally, the enzyme showed excellent stability and compatibility with various commercial detergents, suggesting its potential as an additive in detergent formulations.

Eficacia da descontaminacao de residuos biologicos infectantes de laboratorios de microbiologia apos tratamento termico por autoclavacao / Efficacy of the decontamination of biological infectious waste after thermal treatment by autoclaving

A pesquisa foi realizada no Laboratório Central de Saúde Pública de Minas Gerais com o objetivo de validar o processo de descontaminação de resíduos infectantes do subgrupo A1 e identificar possíveis falhas no procedimento preliminar à sua disposição final. Foram avaliados tanto a descontaminação dos resíduos totalmente descartáveis acondicionados em sacos plásticos termorresistentes quanto o processo de descontaminação dos resíduos reutilizáveis provenientes do Laboratório de Tuberculose, acondicionados em caixas metálicas. Enquanto os resultados obtidos no primeiro estudo indicaram uma deficiência considerável no tratamento dos resíduos, no segundo caso a eficácia foi comprovada. Medidas preventivas e corretivas foram propostas e adotadas como consequência deste trabalho, e são aqui descritas.

Laboratory studies were performed at the Central Laboratory of Public Health of Minas Gerais in order to validate the process of infectious waste decontamination (subgroup A1) from the public health service and identify possible flaws in the procedure preliminary to its final disposal. We evaluated both the decontamination of disposable waste packed in thermo-resistant plastic bags as well and the decontamination process of reusable waste from the Tuberculosis Laboratory packed in metallic boxes. The results of the first study indicated a significant deficiency in waste treatment, while in the second case efficacy was demonstrated. Preventive and corrective measures were proposed and adopted as a result of this work and are described herein.

Evaluation of a Bacillus stearothermophilus tube test as a screening tool for anticoccidial residues in poultry

A Bacillus stearothermophilus var. calidolactis C953 tube test was evaluated for its ability in detecting the residue of selected anticoccidial drugs in poultry, specically sulfamethazine, furazolidone, and amprolium. Various concentrations of each drug were injected into chicken liver and kidney tissues and these tissues were tested to determine the drug detection limits for each drug. The detection limit was defined as the drug concentration at which 95% of the test results were interpreted as positive. The limits of detection in liver tissue were 0.35 microgram/ml for furazolidone, 0.70 microgram/ml for sulfamethazine and 7.80 microgram/ ml for amprolium. In kidney tissues, they were 0.30 microgram/ml for furazolidone, 0.54 microgram/ml for sulfamethazine, and 7.6 microgram/ml for amprolium. It was concluded that this tube test could be used to screen for the residue of these three drugs in poultry.

PROPERTIES OF ?-GALACTOSIDASE FROM BACILLUS STEAROTHERMOPHILUS / 微生物学通报

A themostable intracellular ? galactosidase from a thermophilic Bacillus stearothermophilus was purified by a combination of (NH 4) 2SO 4 fractionation,ion exchange (DEAE 22)and gel filtration (Sephades G 75).The optimum temperature and pH of the enzyme acivity were 60℃and pH6.4 respectively.The ? galatosidase activity exhibited thermosttability at 50 ℃.The enzyme was significaantly activated by alkali and alkali earth metal ions.The activity was inhibited by Zn 2+ 、 Fe 3+ 、 Cu 2+ Reducing agents enhanced ? galactosidase activity.Thiol binding agents drastically decreased the enzyme activity.The enzyme was specific for ? D glycosidic linkages,and the identity of the aglycone moiety also influenced enzyme activity.At 55℃the Km for O nitrophenyl ? D galactosidase(ONPG)and lactose were 2.63mmol/L and 4.39mmol/L, respectively,and Vmax for both substrates were 1.93?10 5 mmol.min 1 .mg 1 protein6.54?10 5 mmol.min 1 .mg 1 protein,respectively.The enzyme was inhibited by glucose (the products of lactose hydrolysis,ki 2.47mmol/L),but not by galactose.In addition,the enzyme possessed transgalactosylation activity.Galacto oligosaccharides,both tri and tetrasaccharide,were involved in the products during lactose hydrolysis.