Pseudomonas putida A (ATCC 12633) Produces Polyhydroxyalkanoates as by Products During the Degradation of Synthetic Ammonium Compounds Commonly Found in Wastewater

Assess to production of polyhydroxyalkanoates (PHAs) by Pseudomonas putida A (ATCC 12633), when it degraded the pollutant tetradecyltrimethylammonium bromide (TTAB), a synthetic quaternary ammonium compound (QAC) commonly present in wastewater. Our ultimate purpose is to develop sustainable strategies to convert waste products into high value-added products, like PHAs.

Pseudomonas putida was cultivated in the presence of preferred carbon and nitrogen sources or solely with TTAB as a carbon and nitrogen source. PHAs presence was examined through TEM, fluorescence microscopy, and flow cytometry and quantified using gravimetric techniques. Constituent monomers were identified via GC–MS. qRT-PCR assays were performed to pinpoint genes implicated in PHAs synthesis and degradation.

Maximum accumulation (52% of the dry cell weight) was achieved at 48 h of cultivation with TTAB. The accumulated PHAs, expressed as a percentage of total mass, were medium-chain-length: 3-hydroxy-decanoate (65.1%), 3-hydroxy-octanoate (11.9%), 3-hydroxy-dodecanoate (8.4%), and 3-hydroxy-tetradecanoate (14.6%). Regarding the relative expression levels of genes involved in PHA polymerization/depolymerization, those of phaC1 peaked at 48 h, but those of phaZ were detectable only after 72 h.

Pseudomonas putida’s ability to remove a QAC and produce PHAs as a result makes it a promising candidate for the biotechnological conversion of waste into valuable biopolymers.