title: Global changes in the proteome of Cupriavidus necator H16 during poly-(3-hydroxybutyrate) synthesis from various biodiesel by-product substrates.
abstract: Synthesis of poly-[3-hydroxybutyrate] (PHB) by Cupriavidus necator H16 in batch cultures was evaluated using three biodiesel-derived by-products as the sole carbon sources: waste glycerol (REG-80, refined to 80 % purity with negligible free fatty acids); glycerol bottom (REG-GB, with up to 65 % glycerol and 35 % free fatty acids), and free fatty acids (REG-FFA, with up to 75 % FFA and no glycerol). All the three substrates supported growth and PHB production by C. necator, with polymer accumulation ranging from 9 to 84 % cell dry weight (cdw), depending on the carbon source. To help understand these differences, proteomic analysis indicated that although C. necator H16 was able to accumulate PHB during growth on all three biodiesel by-products, no changes in the levels of PHB synthesis enzymes were observed. However, significant changes in the levels of expression were observed for two Phasin proteins involved with PHB accumulation, and for a number of gene products in the fatty acid β-oxidation pathway, the Glyoxylate Shunt, and the hydrogen (H2) synthesis pathways in C. necator cells cultured with different substrates. The glycerol transport protein (GlpF) was induced in REG-GB and REG-80 glycerol cultures only. Cupriavidus necator cells cultured with REG-GB and REG-FFA showed up-regulation of β-oxidation and Glyoxylate Shunt pathways proteins at 24 h pi, but H2 synthesis pathways enzymes were significantly down-regulated, compared with cells cultured with waste glycerol. Our data confirmed earlier observations of constitutive expression of PHB synthesis proteins, but further suggested that C. necator H16 cells growing on biodiesel-derived glycerol were under oxidative stress.
authors.affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6, Canada.
authors.forename: Parveen K
authors.initials: PK
authors.lastname: Sharma
authors.affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6, Canada.
authors.forename: Jilagamazhi
authors.initials: J
authors.lastname: Fu
authors.affiliation: Department of Physics and Astronomy, University of Manitoba, Winnipeg, Canada.|Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Canada.
authors.forename: Victor
authors.initials: V
authors.lastname: Spicer
authors.affiliation: Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, Winnipeg, Canada.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Krokhin
authors.affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6, Canada.
authors.forename: Nazim
authors.initials: N
authors.lastname: Cicek
authors.affiliation: Department of Microbiology, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Sparling
authors.affiliation: Department of Biosystems Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6, Canada. david.levin@umanitoba.ca.
authors.forename: David B
authors.identifier: http://orcid.org/0000-0003-4533-500X
authors.initials: DB
authors.lastname: Levin
keywords: Biodiesel-derived free fatty acids; Biodiesel-derived glycerol; Biodiesel-derived glycerol bottom; Metabolism; Poly(3-hydroxybutyrate); Proteomes; Short chain length polyhydroxyalkanoates; scl-PHAs; β-oxidation