Screening Of Polyhydroxyalkanoate And Poly-phosphorus Accumulating Bacteria And Biosynthesis Of Poly-β-hydroxybutyrate In A Strain Of Bacillus Cultured In Dairy Wastewater

Various kinds of prokaryotic microorganisms can accumulate intracellular polyhydroxyalkanoate (PHA), which is usually synthesized when excessive carbon exists along with relatively limited other nutrients in the surroundings. PHA, hasing some traditional plastic properties, such as:biocompatible, and it is a kind of biodegradable material, becoming popular in the novel polymer materials researches feilds in recent years. The main method for PHA production is the use of microbial fermentation, but cost highly, impeding the widely using of PHA. To solve this problem, the screening of high yield strain and the fermentation in cheap raw materials are the main applicable pathways.Phosphorus accumulating organisms (PAOs) is a kind of organisms, which can absorb soluble phosphate beyond the physical needs from the living environment, and form polyphosphate (inorganic polyphosphate, polyP), thereby reducing the phosphorus content in the environment and bioremediating the water eutrophication.Major bacteria accumulating PHA and polyP are derived from aquatic ecosystems. Many lakes are distributed in Inner Mongolia plateau but still lack of the researches about the PHA and polyP producing microorganisms in these lakes.In this study, water samples were collected from five lakes of Inner Mongolia plateau and isolated bacterium by pure culture, screened of PHA and polyp producing bacteria in staining methods, and one strain numbered50-47with higher PHA productivity were subjected to growth conditions optimization, preliminary test producing PHA in diary wastewater, and its PHA was qualitatively detected. The results showed that,288strains were isolated from water samples and among them,23strains were PHA producing,28phosphorus accumulating, and12accumulating both of PHA and polyp in the same cell. Out of23strains PHA producing bacteria,16belonged in α-proteobacteria,6in Bacilli, one in Actinomycetes. Bacteria accumulating polyp were divided into a-proteobacteria (6strains), Actinomycetes (8strains), Bacilli (6strains), y-proteobacteria (3strains)and Deinococci (2strains). The strain50-47belonged to Bacillus endophyticus and produced beta hydroxybutyrate (PHB). Analysis on accumulation ability in different growth stages revealed that the most favorable time of the extraction intracellular PHB was about48h cultured in1/2R2A medium; while cultured in diary wastewater, the strain still could accumulate plenty of PHB and after36h cultured the COD of the waste water declined by39.5%.