Screening of degradative plasmids from Arthrobacter sp. HW08 and their ability to degrade swainsonine

Abstract

Arthrobacter sp. HW08 is capable of swainsonine (SW) degradation with high efficiency. The aim of this study was to screen the degradative plasmids from Arthrobacter sp. HW08 and investigate their ability of degrading SW. A genomic library of Arthrobacter sp. HW08 was successfully constructed by BamHI restriction digestion of genomic DNA and pUC19 vector, ligation and transformation into DH5. Five plasmids of different sizes were screened from 100 genomic library strains, and were named as pUCSW-1, pUCSW-2, pUCSW-3, pUCSW-4 and pUCSW-5, and their insertion elements had sizes of 6 684, 5 093, 136, 1 452 and 2 082 bp, respectively. They contained 7 major open reading frames. SW (400 mg l -1 ), as only carbon source, cultivated with the mixture of the five plasmid-transformants was degraded within 6 h. The degrading capability was equivalent to that of strain HW08. SW degradative ability of minimum combinations was pUCSW-2, 3, 5 > pUCSW-1, 2, 4 > pUCSW-1, 2, 5 > pUCSW-1, 3, 5, which were all slower than that of strain HW08. Any two or single transformant had no degradative ability. The results of this study support the search of the key genes of SW degradation and the investigating mechanism of SW biodegradation or exploration of its metabolic pathway, and even construction of transgene engineering bacteria to protect animals from lesion when locoweed is consumed. Key words : Swainsonine, biodegradation, degradative plasmids, Arthrobacter sp. HW08.