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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 15, No. 3, 2012, pp. 1-13
Bioline Code: ej12025
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 15, No. 3, 2012, pp. 1-13

 en Bioconversion of cassava starch by-product into Bacillus check for this species in other resources and related bacteria polyhydroxyalkanoates
Krueger, Cristhiane L.; Radetski, Claudemir M.; Bendia, Amanda G.; Oliveira, Ida M.; Castro-Silva, Marcus A.; Rambo, Carlos R.; Antonio, Regina V. & Lima, André O.S.


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 check for this species in other resources 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 check for this species in other resources by 16S rRNA sequencing. When cultivated in hydrolyzed cassava starch by-product, maximum production reached 4.97 g dry biomass/L with 29.7% 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.

Bacillus megaterium; biodegradable plastics; biopolymer; MTT assay; starch substrates

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