A new PCB-degrading rhizobacterium strain named A1 was isolated from the long-term PCBs-contaminated alfalfa rhizospheric soil by enrichment culture.Through morphological observation and sequence analysis of 16S rDNA,the strain was identified as Pandoraea norimbergensis.GC-MS was used to determine the ability of resting cells degradation of PCBs,and it was found that the strain could totally remove 56.7% of the Aroclor1242 in 72 hours.The bphA1 gene core,encoding the catalytic site of the large subunit of biphenyl dioxygenase,was sequenced and its third structure was also predicted.It showed that the nucleic acid sequence of bphA1 gene had 100% homology compared with Pandoraea sp.JB1,and the third structure of protein had 99.37% identity compared with Comamonas testosteroni B356.

鹄沼枝额虫是一种淡水小型甲壳动物,主要以细菌、有机碎屑和单胞藻等为食.用豆腐、虾片、米糠、大豆、面粉、小球藻6种饵料培养鹄沼枝额虫幼体,经11d培育,结果显示,不同饵料对鹄沼枝额虫生长、成活率有显著影响.方差分析表明,虾片组的鹄沼枝额虫体长增长显著优于其他5种饵料组(P<0.05);小球藻组的鹄沼枝额虫成活率显著高于米糠、豆腐和面粉组(P<0.05),但与虾片和大豆组没有显著性差异(P>0.05).虾片培养的鹄沼枝额虫较其他5种饵料提早1-2d产卵,且初次产卵量和卵径均为最大.用虾片、大豆、米糠、虾片+米糠、大豆+米糠5种饵料投喂性腺刚开始发育的鹄沼枝额虫,经27d培育,结果表明,不同饵料组间的鹄沼枝额虫生殖力差异显著.虾片+米糠培育的鹄沼枝额虫生殖总量显著高于米糠和大豆(P<0.05),而与虾片和大豆+米糠组没有显著性差异(P>0.05).因此,虾片和虾片+米糠是培养鹄沼枝额虫的优质饵料,对其生长和种群增殖有明显的促进作用.

The protein CpcS1 encoded by gene alr0617 and the protein CpcT1 encoded by gene all5339 were proved to be the lyase of phycocyaninβsubunit of Cys-84 and Cys- 155,respectively,with which phycocyanobiln can be covalent coupled.But lyases CpcS1 plus CpcT1 could not catalyse the attachment of phycocyanobilin at the two sites at the same time.To search the possible assistant lyases,six homologous genes were tested with comparison to CpcS1 and CpcT1.These genes were constructed to fit for the experiments designed.After the coded proteins were expressed in E.coli,they were mixed together with protein CpcS1 or CpcT1,and then purified by Ni~(2+)affinity chroma-tography. The complexes among those proteins could be checked by SDS-PAGE.The experiments showed that CpcT1 interacted with CpcS1,CpcT2,PecF,forming the respective complexes.Even so,when those genes were transformed into E.coli,together with phycocyanobilin-biosynthesizing genes,cpcB,and cpcS1 or cpcT1,no native CpcB was obtained.

Genes all5292 and alr0647 were obtained by BLAST comparison from the cyanobacterium,Anabaena sp.PCC7120.They are homologous to cpcS and cpcT encoding the biliprotein lyases.According to the homology analysis,the similarity of All5292 and CpcS was up to 53.4%,and that of All0647 and CpcT up to 61.4%.The functions of All5292 and Alr0647 were analyzed in vitro with a heterologous E.coli system with plasmids conferring biosynthesis of phycocyanobilin(PCB)and of the acceptor proteins,β-phycoerythrocyanin(PecB) or β-phycocyanin(CpcB).The products were evaluated with absorption spectra and fluorescence spectra.The results showed that no lyase activity was found in any case,although all5292 and/or alr0647 expressed in the heterologous E.coli system.Via analyses of the transcription of all5292 and alr0647 in Anabaena sp.PCC7120,it was found that all5292 and alr0647 were transcribed only under N-starved conditions.