| Poly-hydroxy fatty acid esters(PHA)is a kind of biological polyester polymer which is widely present in the microbial cell,usually mainly as carbon and energy storage material.It is generated in the carbon-nitrogen ratio imbalance condition.Belonging biodegradable,environmentally friendly alternatives to chemical plastic.Poly-3-hydroxybutyrate(PHB)is the simplest structure PHA members.It has mechanical properties similar to conventional plastics such as polypropylene or polyethylene,such as extrusion,molding,spun into fibers,formed into a film.PHA can be used with other synthetic polymers to form heteropolymers.it can not only replace petrochemical plastics production supplies,but also used as medicine or tissue engineering scaffolds excellent clone organs.Rhizobium symbiosis with legume,rod-shaped bacteria which not only can form nodules and further fixed nitrogen for plant nutrition.This article screened from the rhizosphere soil bacterium and Rhizobium to obtain PHA producing strain,through the cell wall breaking method condition,extracting the optimum conditions to improve the yield of PHB.Extract product use of pyrolysis GC-MS,GC,NMR,X-diffraction methods to identify structure and properties.Test results are as follows:1 By gram staining and Sudan black staining method,from the collected from hainan,guangdong,guangxi,fujian and other places of aqueous 50 rhizobium strains were isolated in root nodules,from the collection of south yunnan Lu Feng alfalfa in root nodules of 6rhizobium strains were isolated,got 18 strains PHA producing bacteria2 By 16 s r DNA sequence phylogenetic analysis to determine the 18 strains of PHA producing bacteria respectively belong to Bacillus genus(Bacillus),greedy copper species(Cupriavidus)and Burkholderia bacteria genera(Burkholderia).3 Through the carbon source of fermentation medium optimization,to a large increase objective product.The results showed that the medium with glucose carbon source than sucrose,fructose,mannitol as carbon source of fermentation product purpose of yield increased by 142.1%,142.1% and 246.6%,respectively,to determine the glucose for cheap high quality carbon source.4 Experiments show that this study optimized the SDS-Na Cl O wall-breaking method than liquid nitrogen grinding method and ultrasonic wall-breaking method the purpose of the wall can be better to get more products.Furthermore,the optimization of SDS-Na Cl O wall-breaking method to extract obtained 18 strains of PHA fermented product.Among them,5 kinds of extracts show thin film shape,13 kinds of extract powder.5 To commercially available genetic engineering bacteria fermentation production of PHA for comparison,18 kinds of nuclear magnetic resonance(NMR)method is used to extract the chemical structure of the preliminary analysis,the analysis found that: extract thin layers with control sample spectrum diagram of hydrogen is consistent,while the powder extract more than the control sample of hydrogen spectrogram a hydrogen element.Thin layers and powder extract and control sample spectra of carbon on the carbon element types are basically identical,but there are many differences between its carbon content,and the film extract with the carbon content of powder extract has certain differences.6 To commercially available genetic engineering bacteria fermentation production of PHA for comparison,testing the thermal stability of 18 kinds of extracts,such as soil degradation and vitrification properties,and material properties of 18 kinds of extracts the preliminary comparison and contrast samples,the results show that the two morphological types of 18 kinds of extracts of thermal stability,soil degradation and glass transition temperature and so on material properties are better than the control sample.Through the soil degradation experiment found that all the PHA extract soil degradability of similar to the sample... |
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