Production of Poly(3-hydroxybutyrate) (P(3HB)) from Different Agroindustry Byproducts by Bacillus megaterium

Abstract

The use of plastics, replacing materials such as paper and glass, has become a staple of modern society. A possible alternative is the production of biopolymers, in which case polyhydroxyalkanoates (PHAs) tend to be the most studied class. Among the PHAs, poly(3-hydroxybutyrate) (P(3HB)) is one of the most studied. Bacillus megaterium can utilize a wide range of carbon sources to produce P(3HB) and display high resistance to osmotic pressure and temperature. There are few studies regarding the viability of confectionery wastewater (CWW) and rice parboiling water (RPW) in PHA production; however, data suggests they might be successfully used as culture media for microorganisms. Cultures of B. megaterium were conducted under a 22-factorial design of experiments with different agitation and airflow conditions using mineral medium added with CWW and RPW. Under maximized conditions, it was possible to obtain 7.55 g/L of dry cell biomass, with 50.1% P(3HB) content (3.78 g/L). Kinetic parameters of the maximized culture were also assessed, with the highest productivity (0.146 g/L·h) being found after 20 h of culture. Results found in the tests indicate that CWW and RPW can be used as culture media in P(3HB) production; however further studies are necessary to fully optimize the process, as well as to find alternatives to reduce the amount of residual total organic carbon (TOC) still present in the cultures.