3D micromorphology evaluation of kefir microbial films loaded with extract of Amazon rainforest fruit Cupuaçu.

We performed qualitative and quantitative analysis of surfaces of kefir biofilms loaded with Amazon rainforest fruit extract. Scanning electron microscopy and atomic force microscopy were used to evaluate the micromorphology of the biofilms. The films surface displayed a lower density of microorganisms (∼ 0.061 microorganisms/µm2) for the lowest concentration of fruit extract, however, a greater density (∼0.220 microorganisms/µm2) was observed for the higher concentration. Height stereometric parameters revealed that the biofilms with the highest concentration presented the highest roughness. However, almost all the stereometric parameters related to texture showed no significant difference. Furthermore, the Hurst coefficients of the average power spectrum density were similar for all biofilms. Fractal parameters confirmed that higher concentrations of fruit extract induced a superior topographic irregularity. However, fractal lacunarity does not show any significant difference confirming the similarity of the microtextures. Moreover, fractal succolarity and surface entropy exhibited values that suggested ideal percolation and strong topographic uniformity, respectively, indicating that these films can uniformly adhere to other surfaces. Our results confirm that the stereometric and fractal parameters can be relevant for the surface characterization of microbial films, which can be of great importance to the biomedical field.

Structural evaluation of polymeric microbial films grown on kefir loaded with Maytenus rigida extract.

Kefir is a probiotic that has several health promising properties. Its grains can form microbial films on different types of substrates. In the present work, the surface characteristics of kefir biofilms associated with Maytenus rigida Mart. extract were minutely studied. Three different concentrations of plant extract were included in the biofilm forming solutions, where fresh grains of kefir were inoculated. The results showed that the plant extract was successfully incorporated into the exopolysaccharide matrix of the biofilm. The main chemical components found linked to the plant extract were triterpenes. The crystallinity of biofilms increased with the addition of the plant extract. The morphology revealed that at low concentrations of the extract there was a prevalence of lactobacilli, while at high concentrations yeasts were more observed. Adhesion and wettability were higher for biofilm with less extract. These results revealed that a combination of plant extract and kefir's exopolysaccharide could form biofilms with chemical and topographic properties of great interest in regenerative medicine.

Encapsulation of Piper aduncum and Piper hispidinervum essential oils in gelatin nanoparticles: a possible sustainable control tool of Aedes aegypti, Tetranychus urticae and Cerataphis lataniae.

BACKGROUND: The encapsulated essential oils (EOs) of Piper aduncum L. and Piper hispidinervum C. DC. in gelatin nanoparticles were evaluated against Aedes aegypti Linn., Tetranychus urticae Koch and Cerataphis lataniae Boisd. RESULTS: Encapsulation efficiency of the EOs was measured for absolute concentrations of 500 µg mL-1 (79.2 and 72.7%) and 1000 µg mL-1 (84.5 and 82.2%). The loaded nanoparticles were nearly spherical and well dispersed. The nanoparticles loaded with P. hispidinervum EO had an average size of 100 ± 2 nm, while the nanoparticles containing P. aduncum EO ranged from 175 ± 4 to 220 ± 4 nm. According to zeta potential analysis, the nanoparticles loaded with P. hispidinervum and P. aduncum EOs presented values around -43.5 ± 3 and -37.5 ± 2 mV respectively. The controlled release of EOs was described by the anomalous mechanism of Korsmeyer-Peppas. Both encapsulated EOs reached lethal dosages within 24 h of exposure and total mortality of the tested pests. CONCLUSION: The present work successfully developed gelatin-based nanoparticles that served as carriers for the EOs of P. aduncum and P. hispidinervum to be applied as a sustainable control tool of A. aegypti, T. urticae and C. lataniae. The developed loaded nanoparticles presented high encapsulation efficiency and EO concentration release higher than lethal dosages. This indicates that it is feasible to use gelatin-based nanoparticles loaded with P. aduncum and P. hispidinervum EOs to control the tested pests. © 2018 Society of Chemical Industry.