![]() The industrial sectors that exploit these biopolymers include food, textile, agriculture, biomedicine, and electronics ( Raza et al., 2018). These biopolymers possess physical and mechanical properties similar to oil-based plastics displaying thermal malleability and elasticity and having suitable breaking points for thermoforming ( Laycock et al., 2013). To this end, commercial substitutes of petrochemical plastics are the biodegradable poly(3-hydroxyalkanoates) (PHAs). This phenomenon is detrimental to preserving natural environments and human health ( Smith et al., 2018), demanding actions to move toward a circular bioproduction economy. Factors like temperature and radiation decompose the polymers in small particles (<5 mm), entering now into the food chain ( Law and Thompson, 2014). 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). Crude glycerol has emerged as a suitable feedstock for the biotechnological production of various industrial chemicals given its high surplus catalyzed by the biodiesel industry. ![]()
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