1株异养硝化菌胞外聚合物的研究

Characteristics of the Extracellular Polymeric Substances of a Heterotrophic Nitrifying Bacterium Strain

研究异养硝化菌(Acinetobacter sp.YY-5)在不同生长时期胞外聚合物(EPS)组成成分及其变化规律.利用热处理提取YY-5菌的EPS,分析该菌株在不同生长时期EPS组分,包括蛋白质、总糖、核酸和游离氨基酸等.并进一步把蛋白质水解成氨基酸,分析其氨基酸的变化规律及其对蛋白质理化性质的影响.结果表明,该菌株具有较高含量的EPS,且其在稳定期时EPS含量最高.在不同时期分泌的EPS组分均以蛋白质为主.EPS中各组分含量及其变化规律与该菌生长状态密切相关,在该菌株生长过程中,EPS中各组分的变化情况:蛋白质从14.599 mg.g-1增加到28.489 mg.g-1后减少为15.139 mg.g-1;总糖从6.757 mg.g-1增加到10.199 mg.g-1后减少为7.857 mg.g-1.核酸从1.56 mg.g-1一直增加到6.287 mg.g-1;游离氨基酸从3.713 mg.g-1增加到4.374 mg.g-1后减少为1.299 mg.g-1.蛋白质水解后,其中极性氨基酸呈先增加后减少的趋势,非极性氨基酸一直呈增加趋势;在生长过程中一直以带负电的氨基酸占优.

To study the variation of extracellular polymers substances（EPS） composition of the heterotrophic denitrifying bacteria（Acinetobacter sp.YY-5） at different growth stages,The EPS of YY-5 was extracted by thermal,and the composition of protein,polysaccharides,nucleic acid and free amino acids were analyzed at different growth stages.Subsequently,the proteins in extracts were hydrolyzed into amino acids,the amino acid＇s changes and effect on physical and chemical properties of proteins were investigated.The results showed the strain has a high EPS contents which mainly consist of proteins,and the EPS content achieved the highest value at stable stage.The amount of proteins increased from 14.599 mg·g-1 to 28.489 mg·g-1,then declined to 15.139 mg·g-1.Polysaccharides content increased from 6.757 mg·g-1 to 10.199 mg·g-1,then declined to 7.857 mg·g-1.The nucleic acid contents increased from 1.56 mg·g-1 to 6.287 mg·g-1 in the whole growth stages.The free amino acids contents increased from 3.713 mg·g-1 to 4.374 mg·g-1,then obviously declined to 1.299 mg·g-1.After the proteins were hydrolyzed into amino acids,the amount of polar amino acids showed the trend that increased earlier and declined later,the contents of nonpolar amino acids increased at all growth stages.The amino acids with negative charges were more than that with the positive.