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The biomass energy source has been a promising renewable alternative for fossil fuels and their inevitable environmental impacts on Earth's life, from which the greenhouse gas (GHG) emissions and the environment pollution followed by consequent ecosystem imbalance are major concerns. Biofuels and bioplastics are well-known examples of renewable products obtained from biomass that has shown increasing potential to succeed the conventional fuels and plastics. However, biofuels and especially bioplastics have faced their main hindrance in their uncompetitive costs. Furthermore, the "drop-in" plastics are the market leaders, which reduce the carbon footprint but continue to state the biodegradability concern attributed to most of plastic products, the packaging sector. This chapter outlines the common features and feedstocks of biofuels and bioplastics aiming to support their associated production set toward the bio-based and biodegradable poly(lactic acid) (PLA) and polyhydroxyalkanoates (PHAs) as promising models with fast-growing production capacity forecasted for the next years and biodegradable solution for short-lived and disposable plastic materials.

Pandoraea sp. MA03 wild type strain was subjected to UV mutation to obtain mutants unable to grow on propionic acid (PA) but still able to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] from glycerol and PA at high 3HV yields. In shake flask experiments, mutant prp25 was selected from 52 mutants affected in the propionate metabolism exhibiting a conversion rate of PA into 3HV units of 0.78 g g . The use of crude glycerol (CG) plus PA or valeric acid resulted in a copolymer with 3HV contents varying from 21.9 to 30 mol% and 22.2 to 36.7 mol%, respectively. Fed-batch fermentations were performed using CG and PA and reached a 3HV yield of 1.16 g g , which is 86% of the maximum theoretical yield. Nitrogen limitation was a key parameter for polymer accumulation reaching up to 63.7% content and 18.1 mol% of 3HV. Henceforth, mutant prp25 is revealed as an additional alternative to minimize costs and support the P(3HB-co-3HV) production from biodiesel by-products. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1077-1084, 2017.

Polyhydroxyalkanoate (PHA) bioplastic was synthesized by Burkholderia glumae MA13 from carbon sources and industrial byproducts related to sugarcane biorefineries: sucrose, xylose, molasses, vinasse, bagasse hydrolysate, yeast extract, yeast autolysate, and inactivated dry yeast besides different inorganic nitrogen sources. Sugarcane molasses free of pre-treatment was the best carbon source, even compared to pure sucrose, with intracellular polymer accumulation values of 41.1–46.6% cell dry weight. Whereas, xylose and bagasse hydrolysate were poor inducers of microbial growth and polymer synthesis, the addition of 25% (v/v) sugarcane vinasse to the culture media containing molasses was not deleterious and resulted in a statistically similar maximum polymer content of 44.8% and a maximum PHA yield of 0.18 g/g, at 34°C and initial pH of 6.5, which is economic and ecologically interesting to save water required for the industrial processes and especially to offer a fermentative recycling for this final byproduct from bioethanol industry, as an alternative to its inappropriate disposal in water bodies and soil contamination. Ammonium sulfate was better even than tested organic nitrogen sources to trigger the PHA synthesis with polymer content ranging from 29.7 to 44.8%. GC-MS analysis showed a biopolymer constituted mainly of poly(3-hydroxybutyrate) although low fractions of 3-hydroxyvalerate monomer were achieved, which were not higher than 1.5 mol% free of copolymer precursors. B. glumae MA13 has been demonstrated to be adapted to synthesize bioplastics from different sugarcane feedstocks and corroborates to support a biorefinery concept with value-added green chemicals for the sugarcane productive chain with additional ecologic benefits into a sustainable model.

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