Unfortunately, synthetic plastics are not prone to biodegradation and massively accumulate in the oceans and soil ecosystems ( Zettler et al., 2013 Lau et al., 2020). The worldwide manufacture of petrochemical plastics reaches over 359 million tons annually as these materials are essential in our current lifestyle ( Poblete-Castro et al., 2020a Tournier et al., 2020). putida strains using the industrial crude glycerol, where the fed-batch process selection is essential to exploit the superior biopolymer production hallmarks of engineered bacterial strains. Here, we demonstrated that the DO-stat feeding approach in high cell density cultures enables the high yield production of mcl-PHA in P. The biosynthesized mcl-PHAs had average molecular weights ranging from 460 to 505 KDa and a polydispersity index (PDI) of 2.4–2.6. The mutant Δ phaZ amassed 38.9% of the CDW as mcl-PHA and exhibited a specific PHA volumetric productivity of 0.34 (g L –1 h –1), 48% higher than the parental KT2440 under the same growth conditions. Citric acid was the main by-product secreted by the cells, accumulating in the culture broth up to 48 (g L –1) under nitrogen limitation. putida strains using a DO-stat approach under nitrogen depletion. We next evaluated the PHA production ability of the P. During the PHA production stage, we supplied the substrate at a constant rate of 50 (g h –1), where the KT2440 and the Δ phaZ produced 9.7 and 12.7 gPHA L –1, respectively, after 60 h cultivation.
Initially, the cells grew in a batch phase (μ max 0.21 h –1) for 22 h followed by a carbon-limiting exponential feeding, where the specific growth rate was set at 0.1 (h –1), resulting in a cell dry weight (CDW) of nearly 50 (g L –1) at 40 h cultivation. putida KT2440 and the hyper-PHA producer Δ phaZ mutant in two different fed-batch modes to synthesize mcl-PHAs from raw glycerol.
putida is a suited platform to derive these polyoxoesters from crude glycerol, the attained concentrations in batch and fed-batch cultures are still low. Pseudomonas bacteria metabolize the polyol into several biopolymers, including alginate and medium-chain-length poly(3-hydroxyalkanoates) ( mcl-PHAs). 5Biosystems Engineering Laboratory, Faculty of Life Sciences, Center for Bioinformatics and Integrative Biology, Universidad Andres Bello, Santiago, ChileĬrude glycerol has emerged as a suitable feedstock for the biotechnological production of various industrial chemicals given its high surplus catalyzed by the biodiesel industry.4Departamento de Química Física, Facultad de Química y Farmacia, Pontificia Universidad Católica de Chile, Macul, Chile.3Central Facility of Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany.2Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.
1Institute for Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.José Manuel Borrero-de Acuña 1,2, Manfred Rohde 3, Cesar Saldias 4 and Ignacio Poblete-Castro 5*
0 kommentar(er)
