Bioconversion of cassava starch by-product into bacillus and related bacteria polyhydroxyalkanoates

Background: Unlike petroleum-based synthetic plastics, biodegradable biopolymer generation from industrial residue is a key strategy to reduce costs in the production process, as well as in the waste management, since efficient industrial wastewater treatment could be costly. In this context, the present work describes the prospection and use of bacterial strains capable to bioconvert cassava starch by-product into biodegradable polyhydroxyalkanoates (PHAs). Results: The first step of this study was the bacterial competence screening which was conducted with 72 strains covering 21 Bacillus and related species. The microorganism growth in a medium with a starch substrate was measured by an innovative MTT assay, while the ability of the bacteria to secrete amylase and produce PHA was evaluated by the Nile Red Dye method. Based on growth and potential for PHA production, four isolates were selected and identified as Bacillus megaterium by 16S rRNA sequencing. When cultivated in hydrolyzed cassava starch by-product, maximum production reached 4.97 g dry biomass/L with 29.7 percent of Poly-(3-hydroxybutyrate) (characterized by FTIR). Conclusions: MTT assay proved to be a reliable methodology for monitoring bacterial growth in insoluble media. Selected amylolytic strains could be used as an alternative industrial process for biodegradable plastics production from starchy residues, reducing costs for biodegradable biopolymer production and wastewater treatment operations.

[Profile of breastfeeding in children under 2 years old in the city of Itupeva, SP, Brazil]. / Perfil do aleitamento materno em menores de 2 anos na cidade de Itupeva, SP, Brasil.

The objective of this study was to estimate the frequency of breastfeeding and to identify variables associated with median breastfeeding length. It is a cross-sectional population-based study carried out in a representative sample of 261 children under 2 years old randomly selected in the urban area of Itupeva city, SP, Brazil. The breastfeeding patterns recommended by WHO were used. The frequency and the median length of breastfeeding were estimated by life tables technique. The Wilcoxon test was used to identify association between breastfeeding and the categorical variables (p<0.05) in the bivariate analysis. For the multivariate analysis, the variables associated with the breastfeeding length (Wilcoxon test; p<0.10) were inserted in a Cox Regression model. Almost 100% of the children have initiated breastfeeding and 41.0% were in breastfeeding at the moment of the interview. The median length of breastfeeding was 7.2 months and exclusive breastfeeding was only 28 days. It was observed association between the breastfeeding length and the following variables: father's schooling, mother's marital status, number of children, sequence of birth, bottle-feeding and pacifier use. The Cox regression model selected as significant variables: sequence of birth (HR=1.68; IC95%=1.03-2.73), bottle-feeding use (HR=15.20; IC95%=3.69-62.01) and pacifier use (HR=2.84; IC95%=1.95-4.19). The current pattern of breastfeeding in Itupeva is still far from the WHO recommendations; therefore, encouragement and support to breastfeeding need to be intensified. Variables influencing breastfeeding should be considered in the attempt to increase breastfeeding. Health workers should dedicate all their efforts to increase the exclusive breastfeeding period in children under 6 months of age and increase the total breastfeeding period.