The damaging effects of short chain fatty acids on Escherichia coli membranes

Carboxylic acids are an attractive biorenewable chemical. However, like many other fermentatively produced compounds, they are inhibitory to the biocatalyst. An understanding of the mechanism of toxicity can aid in mitigating this problem. Here, we show that hexanoic and octanoic acids are completely inhibitory to Escherichia coli MG1655 in minimal medium at a concentration of 40 mM, while decanoic acid was inhibitory at 20 mM. This growth inhibition is pH-dependent and is accompanied by a significant change in the fluorescence polarization (fluidity) and integrity. This inhibition and sensitivity to membrane fluidization, but not to damage of membrane integrity, can be at least partially mitigated during short-term adaptation to octanoic acid. This short-term adaptation was accompanied by a change in membrane lipid composition and a decrease in cell surface hydrophobicity. Specifically, the saturated/unsaturated lipid ratio decreased and the average lipid length increased. A fatty acid-producing strain exhibited an increase in membrane leakage as the product titer increased, but no change in membrane fluidity. These results highlight the importance of the cell membrane as a target for future metabolic engineering efforts for enabling resistance and tolerance of desirable biorenewable compounds, such as carboxylic acids. Knowledge of these effects can help in the engineering of robust biocatalysts for biorenewable chemicals production. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00253-013-5113-5) contains supplementary material, which is available to authorized users

Factors Associated with Medication Adherence to Long-Acting Injectable Antipsychotics: Results from the STAR Network Depot Study

Introduction Long-acting injectable (LAI) antipsychotics are prescribed to people with severe psychiatric disorders who show poor adherence to oral medication. The present paper examined factors potentially associated with medication adherence to LAI treatment.Methods The STAR (Servizi Territoriali Associati per la Ricerca) Network Depot Study was a multicenter, observational, prospective study that enrolled 461 subjects initiating a LAI from 32 Italian centers. After 6 and 12 months of treatment, we evaluated differences between participants with high ( >= 5 points) and low ( < 5 points) medication adherence using Kemp's 7-point scale in sociodemographic, clinical, psychopathological, and drug-related variables. Factors that differed significantly between the two groups were entered for multivariate logistic regression.Results Six months after enrollment, participants with high medication adherence were younger, living with other people, had lower Brief Psychiatric Rating Scale ( BPRS) total scores, lower adverse events, and a more positive attitude toward medication than participants with low adherence. Multivariate regression confirmed lower BPRS resistance and activation scores, absence of adverse events, and positive attitude toward medication as factors significantly associated with good adherence. After 12 months, all BPRS subscales were significantly lower in the high adherence group, which also showed a more positive attitude toward medication. BPRS resistance and attitude toward medication were confirmed as factors associated with medication adherence.Discussion Our findings suggest that adherence to LAI is principally related to attitude toward medication and traits of suspiciousness/hostility. Quality of patient- clinician relationship and tailored psychoeducational strategies may positively affect adherence in people undergoing psychopharmacological treatment, including LAI