聚（3－羟基丁酸－co－4－羟基丁酸共聚酯）降解菌株的选育及其降解特性1）

摘要

从工业污水中筛选出一株可高效降解聚（3－羟基丁酸－co－4－羟基丁酸共聚酯）（ P3／4HB）的真菌菌株，经形态学鉴定和系统发育学分析，鉴定该菌株为烟曲霉，命名为Aspergillus sp．DS0906。该菌株还能够特异性降解高分子聚酯聚3－羟基丁酸酯、聚（3－羟基丁酸酯－co－4－羟基戊酸共聚酯）和聚丁二酸丁二醇酯，但是不能降解聚乳酸和聚ε－己内酯。菌株发酵粗酶液的最适反应温度为60℃，在10～50℃之间酶的温度稳定性较好，最适反应pH值为6．0，在pH ＝6．0～8．0的范围内稳定性较高。 Aspergillus sp．DS0906粗酶液降解P3／4HB的产物为羟基丁酸单体，推测降解酶以每次剪切一个羟基丁酸单元的外切酶模式发挥降解作用。%A fungus with high poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) degrading ability was isolated from industrial sewage , and it was identified as Aspergillus species and named as Aspergillus sp.DS0906 through fungal morphol-ogy observation and molecular identification of ITS sequence .Aspergillus sp.DS0906 could also degrade poly ( hydroxybu-tyrate) ( PHB) , poly ( hydroxybutyrate-co-hydroxyvalerate ) ( PHBV) and poly ( butylene succinate ) ( PBS) rather than polylactic acid (PLA) and polycaprolactone (PCL).The optimum temperature and pH of crude enzyme was 60℃and 6.0, respectively.The enzyme was stable form 10℃to 50℃and pH of from 6.0 to 8.0.The degradation products for P 3/4HB by the crude enzyme were determined as 3-hydroxybutyrate monomer or 4-hydroxybutyrate instead of dimer or trimer by GC analysis, and the depolymerase exhibited an exo-type action that cleaved the first bond in the chain end .