Preliminary Study Of Using Xylose For Cocultivation Of Pseudomonas Sp.and Saccharomyces Cerevisiae And To Produce 3-polyhydroxyalkanoates

Polyhydroxyalkanoates(PHAs)is a kind of an environmental-friendly plastic.PHAs are widely used in medicine package,plastic production and high polymer materials because they are biodegradable and biocompatible.A PHA-producing strain: Pseudomonas sp.TU02 was screened from waste acivated sludge in this study.The growth condition of Pseudomonas sp.was tested under different sole carbon sources.And Pseudomonas sp.and Saccharomyces cerevisiae were co-cultured under xylose medium to test PHA accumulation.Major results of this study were listed as follows:Pseudomonas sp.was cultivated under different carbon sources,and the results showed that it grows well in glucose,sucrose,sodium lactate and yeast extract.When Pseudomonas sp.TU02 cultivated in xylose and sodium acetate,there was no obvious phenomenon of growth,and Pseudomonas sp.can not grow on citric acid either.Among all these substrates,glucose was the most suitable for Pseudomonas sp.TU02.Pseudomonas sp.TU02 was cultivated in flasks using glucose as sole carbon source to produce PHA,and the cultivation condition was preliminary optimized.After comparison,it was founded out that when lacking phosphorus,Pseudomonas sp.TU02 could hardly grow.And the growth of Pseudomonas sp.was seriously restriceted when lacking ammonium and Mg2+.The OD600 and PHA accumulation declined obviously at 72 h compared with 48 h.The optimum PHA accumulation was achieved under following conditions: glucose 20g/L,pH 8 and cultivation time 48 h,and the optimum PHA yield was 38%(PHA/Biomass).Total PHA accumulation reached 1.62g/L.Xylose-utilizing strain Recombinant Saccharomyces cerevisiae and PHA producer Pseudomonas sp.TU02 were co-cultured in xylose medium.And the highest PHA accumulation 14%(PHA/Biomass)was achieved under following condition: inoculation ratio(Pseudomonas sp.: Saccharomyces cerevisiae)2:1,inoculation time of Pseudomonas sp.12 h.And the maximum PHA accumulation was 0.37g/L.Though the maximum PHA accumulation of microbial consortium 0.37g/L was much lower than that of the single strain,but this study made it possible to convert xylose to PHA,and further study could be performed to improve PHA yield of microbial consortia.