铜绿假单胞菌NY3及其突变株好氧降解四溴双酚A特性研究

为明确铜绿假单胞菌NY3 2个烷羟化酶基因alk B1和alk B2基因在该菌代谢四溴双酚A中的作用,研究了野生NY3菌及其突变菌株(NB1D、NB2D及NB12DD)对四溴双酚A好氧降解特性.研究表明,NY3、NB1D、NB2D及NB12DD菌株均能以四溴双酚A为单一碳源和能源进行生长,并对四溴双酚A进行一定程度上的降解.NY3菌中alk B1基因和alk B2基因的缺失对NY3菌株在四溴双酚A中的生长有抑制作用,而且alk B1基因和alk B2基因在NY3菌降解四溴双酚A中起一定的作用,但不完全,说明NY3菌中还存在其他影响四溴双酚A降解的基因.缺失alk B2基因的突变株NB2D在高浓度的四溴双酚A溶液中降解转化率最少,说明alk B2基因的缺失,对NY3菌降解高浓度四溴双酚A碳源更重要.加入同一易降解共代谢碳源,野生株NY3菌及其各突变株生长特性无明显差异,然而,因共存碳源种类不同,同一菌株细胞生长量、对四溴双酚A降解及其脱溴效率等特性差别明显.加最佳共代谢碳源乳酸钠的体系内,突变株NB2D存在下易积累中间产物3,3',5-三溴双酚A和2-溴-4(异丙基-溴苯)-苯酚等直接脱溴产物,说明alk B1基因可能为NY3菌株代谢四溴双酚A脱溴时的关键基因.

Aerobic degradation characteristics of Tetrabromobisphenol A by Pseudomonas aeruginosa NY3 and its mutants

The characteristics of biodegradation of Tetrabromobisphenol A (TBBPA) by strain pseudomonas aeruginosa NY3 and its alkyl hydroxylase gene mutants (NB1D, NB2D and NB12DD) under aerobic condition were studied. The results show that all of the tested strains could grow on TBBPA as a single carbon source, and degrade TBBPA concurrently. The strain NY3 shows the best performance for TBBPA degradation. In comparison, less cell reproduction of alkB1/alkB2 gene knock-out (alkB1/alkB2) mutant exhibited lower resistance to the toxicity of TBBPA. It is shown that there were other genes within strain NY3 cells that could function as TBBPA metabolism, while genes alkB1 and alkB2 only played a certain role. The result shows that the mutant NB2D has the less ability to convert concentrated TBBPA than that of NB1D, indicating alkB2 was less important. Addition of co-metabolizing carbon sources, like sodium lactate, could greatly improve the metabolic abilities of TBBPA for the four tested strains, and their TBBPA degradation rate and de-bromination efficiencies were almost no differences. Under the presence of sodium lactate, except for strain NB12DD, all of the other three tested strains could produce the direct debromination intermediates 3,3'',5-tribromobisphenol A and 2-bromo-4-(isopropyl-bromophenyl)-phenol. Compared to NB1D, NB2D could easily accumulate the above intermediates. It is concluded that alkB1 gene may be the key gene in the debromination of TBBPA for NY3 strain.