Pseudomonas pseudoalcaligenes CECT5344, a cyanide-degrading bacterium with by-product (polyhydroxyalkanoates) formation capacity

Microbial Cell Factories

Research

Fernando de la Peña Moreno¹  María Auxiliadora Prieto Jiménez¹  Francisco Castillo Rodríguez²  Conrado Moreno Vivián²  Lara Paloma Sáez Melero²  María Dolores Roldán Ruiz²  Isabel Manso Cobos²  Víctor Manuel Luque-Almagro²  María Isabel Ibáñez García² 

[1] Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas (CIB-CSIC), Madrid, Spain;Departamento de Bioquímica y Biología Molecular, Campus de Rabanales, Edificio Severo Ochoa, 1ª Planta Universidad de Córdoba, 14071, Córdoba, Spain;

关键词: Alkalophile;    Bioplastics;    Cyanide degradation;    Polyhydroxyalkanoates;    Pseudomonas;   

DOI  :  10.1186/s12934-015-0267-8

 received in 2015-02-09, accepted in 2015-05-25,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundCyanide is one of the most toxic chemicals produced by anthropogenic activities like mining and jewelry industries, which generate wastewater residues with high concentrations of this compound. Pseudomonas pseudoalcaligenes CECT5344 is a model microorganism to be used in detoxification of industrial wastewaters containing not only free cyanide (CN−) but also cyano-derivatives, such as cyanate, nitriles and metal-cyanide complexes. Previous in silico analyses suggested the existence of genes putatively involved in metabolism of short chain length (scl-) and medium chain length (mcl-) polyhydroxyalkanoates (PHAs) located in three different clusters in the genome of this bacterium. PHAs are polyesters considered as an alternative of petroleum-based plastics. Strategies to optimize the bioremediation process in terms of reducing the cost of the production medium are required.ResultsIn this work, a biological treatment of the jewelry industry cyanide-rich wastewater coupled to PHAs production as by-product has been considered. The functionality of the pha genes from P. pseudoalcaligenes CECT5344 has been demonstrated. Mutant strains defective in each proposed PHA synthases coding genes (Mpha−, deleted in putative mcl-PHA synthases; Spha−, deleted in the putative scl-PHA synthase) were generated. The accumulation and monomer composition of scl- or mcl-PHAs in wild type and mutant strains were confirmed by gas chromatography-mass spectrometry (GC–MS). The production of PHAs as by-product while degrading cyanide from the jewelry industry wastewater was analyzed in batch reactor in each strain. The wild type and the mutant strains grew at similar rates when using octanoate as the carbon source and cyanide as the sole nitrogen source. When cyanide was depleted from the medium, both scl-PHAs and mcl-PHAs were detected in the wild-type strain, whereas scl-PHAs or mcl-PHAs were accumulated in Mpha− and Spha−, respectively. The scl-PHAs were identified as homopolymers of 3-hydroxybutyrate and the mcl-PHAs were composed of 3-hydroxyoctanoate and 3-hydroxyhexanoate monomers.ConclusionsThese results demonstrated, as proof of concept, that talented strains such as P. pseudoalcaligenes might be applied in bioremediation of industrial residues containing cyanide, while concomitantly generate by-products like polyhydroxyalkanoates. A customized optimization of the target bioremediation process is required to gain benefits of this type of approaches.

【 授权许可】

CC BY   
© Manso Cobos et al. 2015