Study On Screening, Identification And Synthetic Product Determination Of A PHA Producing Bacterium

The white pollution caused by plastic products and the rising prices of non-renewable resources like petroleum have led to the development of non-oil production and the high polymer materials which can replace traditional chemically synthesized.Microbial synthetic bio-polyesters(PHA)have received much attention as a substitute for materials with similar synthetic high polymers.However,PHA cannot be widely used due to its limited synthesis of microbial synthetic bacteria,high synthesis cost and single monomer structure.In this paper,PHA synthetic strain was successfully screened from the oil stain around the No.93 soybean oil production line.The 16 S rRNA sequence analysis and phylogenetic tree analysis confirmed that the strain was Pseudomonas aeruginosa and named Pseudomonas aeruginosa93-3-1(NCBI accession number is MH426701).Optimization of culture conditions showed that Pseudomonas aeruginosa93-3-1 can produce mcl-PHA containing 3HO,3HD and 3HDD under a cultivation temperature of 37 ?,pH7,containing 2%(w/v)soybean oil and 1%(w/v)potassium nitrate.Moreover,under optimal culture conditions,the strain can produce 0.15g/L mcl-PHA containing 3HO and 3HD by using an inorganic salt medium containing 3%(w/v)waste edible oil as a carbon source.To analyze the type and synthetic pathway of the PHA synthase,we determined the genomic sequence of this strain.The results of gene sequencing indicated that the PHA synthesis gene locus of this strain is similar to the PHA synthase of other Pseudomonas sp.and is a Class II PHA synthase.It is composed of 1680bp(phaC1),858bp(phaZ)and 1683bp(phaC2),and has 70% or more high base homology with Pseudomonas sp.SG4502,Pseudomonas putida and Pseudomonas sp.61-3,and this strain utilizes the ?-oxidation pathway of fatty acids to synthesize mcl-PHA.This study not only enriches the types of PHA synthetic bacteria,but also has important reference value in reducing the synthesis cost of biopolyesters and obtaining high-value-added products by using inexpensive carbon sources.