Background The authors hypothesized that low tidal volume (VT) would minimize ventilator-induced lung injury regardless of the degree of mechanical power. The authors investigated the impact of power, obtained by different combinations of VT and respiratory rate (RR), on ventilator-induced lung injury in experimental mild acute respiratory distress syndrome (ARDS). Methods Forty Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, 32 rats were randomly assigned to be mechanically ventilated (2 h) with a combination of different VT (6 ml/kg and 11 ml/kg) and RR that resulted in low and high power. Power was calculated as energy (ΔP,L2/E,L) × RR (ΔP,L = transpulmonary driving pressure; E,L = lung elastance), and was threefold higher in high than in low power groups. Eight rats were not mechanically ventilated and used for molecular biology analysis. Results Diffuse alveolar damage score, which represents the severity of edema, atelectasis, and overdistension, was increased in high VT compared to low VT, in both low (low VT: 11 [9 to 14], high VT: 18 [15 to 20]) and high (low VT: 19 [16 to 25], high VT: 29 [27 to 30]) power groups. At high VT, interleukin-6 and amphiregulin expressions were higher in high-power than in low-power groups. At high power, amphiregulin and club cell protein 16 expressions were higher in high VT than in low VT. Mechanical energy and power correlated well with diffuse alveolar damage score and interleukin-6, amphiregulin, and club cell protein 16 expression. Conclusions In experimental mild ARDS, even at low VT, high mechanical power promoted ventilator-induced lung injury. To minimize ventilator-induced lung injury, low VT should be combined with low power.

The filamentous fungus Mucor circinelloides URM 4182 was tested to determine its ability to produce single-cell oil suitable for obtaining biodiesel. Cell growth and lipid accumulation were investigated in a medium containing glucose as the main carbon source. A microwave-assisted ethanol extraction technique (microwave power ⩽200 W, 50-60 °C) was established and applied to lipid extraction from the fungal hyphae to obtain high lipid concentration (44%wt) of the dry biomass, which was considerably higher than the quantity obtained by classical solvent methods. The lipid profile showed a considerable amount of oleic acid (39.3%wt), palmitic acid (22.2%wt) and γ-linoleic acid (10.8%wt). Biodiesel was produced by transesterification of the single-cell oil with ethanol using a immobilized lipase from Candida antarctica (Novozym® 435) as the catalyst. (1)H NMR and HPLC analyses confirmed conversion of 93% of the single-cell oil from M. circinelloides into ethyl esters (FAEE).

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The intracellular lipase production by Mucor circinelloides URM 4182 was investigated through a step-by-step strategy to attain immobilized whole-cells with high lipase activity. Physicochemical parameters, such as carbon and nitrogen sources, inoculum size and aeration, were studied to determine the optimum conditions for both lipase production and immobilization in polyurethane support. Olive oil and soybean peptone were found to be the best carbon and nitrogen sources, respectively, to enhance the intracellular lipase activity. Low inoculum level and poor aeration rate also provided suitable conditions to attain high lipase activity (64.8 ± 0.8 U g(-1)). The transesterification activity of the immobilized whole- cells was assayed and optimal reaction conditions for the ethanolysis of babassu oil were determined by experimental design. Statistical analysis showed that M. circinelloides whole-cells were able to produce ethyl esters at all tested conditions, with the highest yield attained (98.1 %) at 35 °C using an 1:6 oil-to-ethanol molar ratio. The biocatalyst operational stability was also assayed in a continuous packed bed reactor (PBR) charged with glutaraldehyde (GA) and Aliquat-treated cells revealing half-life of 43.0 ± 0.5 and 20.0 ± 0.8 days, respectively. These results indicate the potential of immobilized M. circinelloides URM 4182 whole-cells as a low-cost alternative to conventional biocatalysts in the production of ethyl esters from babassu oil.