RESUMO
Phytase increases the availability of phosphate and trace elements by hydrolyzing the phosphomonoester bond in phytate present in animal feed. It is also an important enzyme from an environmental perspective because it not only promotes the growth of livestocks but also prevents phosphorus contamination released into the environment. Here we present a novel phytase derived from Turicimonas muris, TmPhy, which has distinctive structure and properties compared to other previously known phytases. TmPhy gene expressed in the Pichia system was confirmed to be 41 kDa in size and was used in purified form to evaluate optimal conditions for maximum activity. TmPhy has a dual optimum pH at pH3 and pH6.8 and exhibited the highest activity at 70°C. However, the heat tolerance of the wildtype was not satisfactory for feed application. Therefore, random mutation, disulfide bond introduction, and N-terminal mutation were performed to improve the thermostability of the TmPhy. Random mutation resulted in TmPhyM with about 45% improvement in stability at 60°C. Through further improvements, a total of three mutants were screened and their heat tolerance was evaluated. As a result, we obtained TmPhyMD1 with 46.5% residual activity, TmPhyMD2 with 74.1%, and TmPhyMD3 with 66.8% at 80°C heat treatment without significant loss of or with increased activity.
Assuntos
6-Fitase , Estabilidade Enzimática , Temperatura Alta , 6-Fitase/genética , 6-Fitase/metabolismo , 6-Fitase/química , Concentração de Íons de Hidrogênio , Mutação , Pichia/genética , Pichia/metabolismo , Temperatura , Ração Animal/análise , Cinética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/químicaRESUMO
We aimed to describe the frequency of treatment failure and associated risk factors for treatment failure amongst neonates with skin and soft tissue infections (SSTIs). We conducted a retrospective cohort study of neonates 0 to 28 days old with uncomplicated SSTIs presenting to the emergency department of a quaternary care children's hospital from 2009 to 2017. Data were collected via chart review. Skin and soft tissue infections included the following: cellulitis, abscess, mastitis, perirectal SSTI, carbuncle, and furuncle. Of the 202 neonates in the study, most were term, afebrile with mastitis, or perirectal SSTI. Treatment failure occurred in 8% (17/202) of neonates receiving oral antibiotics; 10 of these neonates had perirectal SSTIs and 2 had clindamycin and methicillin-resistant Staphylococcus aureus. Neonates with treatment failure had increased odds of having perirectal SSTIs (odds ratio [OR] = 4.08, 95% confidence interval [CI] = 1.46-11.31). Further studies are needed to identify strategies to prevent treatment failure in neonates with perirectal SSTIs.