Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan NSW 2308, Australia, and CRC CARE, Newcastle University LPO, PO Box 18, Callaghan, NSW 2308, Australia.
Formerly Department of Microbiology, Sri Krishnadevaraya University, Anantapur 515055, India.
Sci Total Environ. 2019 Feb 15;651(Pt 1):813-821. doi: 10.1016/j.scitotenv.2018.09.192. Epub 2018 Sep 18.
A Gram-positive bacterium, Rhodococcus wratislaviensis strain 9, completely degraded 280 μM of phenanthrene, 40% of 50 μM pyrene or 28% of 40 μM benzo[a]pyrene (BaP), each supplemented in M9 medium, within 7 days. PCR screening with gene-specific primers indicated that the strain 9 harbors genes which code for 2,3-dihydroxybiphenyl 1,2-dioxygenase (bphC), 4-nitrophenol 2-monooxygenase component B (npcB) as well as oxygenase component (nphA1), 4-hydroxybenzoate 3-monooxygenase (phbH), extradiol dioxygenase (edo), and naphthalene dioxygenase (ndo), all of which are largely implicated in biodegradation of several aromatic hydrocarbons. An orthogonal design experiment revealed that BaP biodegradation was greatly enhanced by surfactants such as Tween 80, Triton X-100 and linoleic acid, suggesting that bioavailability is the major limiting factor in bacterial metabolism of BaP. Both pyrene and BaP induced the overexpression of amidohydrolase, a metallo-dependent hydrolase, possibly involved in their biodegradation by strain 9. The up-regulation of amidohydrolase gene induced by BaP, in particular, was also confirmed by semi-quantitative RT-PCR. Catechol 2,3-dioxygenase and the large subunit of ndo, but not amidohydrolase, accumulated when the strain 9 was grown on phenanthrene. To our knowledge, this is the first report on overexpression of amidohydrolase and its possible implication in bacterial degradation of high-molecular weight PAHs.
一株革兰氏阳性菌，即罗得西亚棒杆菌 9 株，可在 7 天内完全降解 M9 培养基中添加的 280µM 菲、50µM 芘的 40%或 40µM 苯并[a]芘（BaP）的 28%。用基因特异性引物的 PCR 筛选表明，该菌株 9 携带有编码 2,3-二羟基联苯 1,2-双加氧酶（bphC）、4-硝基苯酚 2-单加氧酶 B 亚基（npcB）以及加氧酶亚基（nphA1）、4-羟基苯甲酸 3-单加氧酶（phbH）、外二醇双加氧酶（edo）和萘二氧合酶（ndo）的基因，这些基因在多种芳香烃的生物降解中起主要作用。正交设计实验表明，表面活性剂如吐温 80、Triton X-100 和亚油酸极大地促进了 BaP 的生物降解，表明生物可利用性是细菌代谢 BaP 的主要限制因素。芘和 BaP 均诱导了酰胺水解酶（一种金属依赖的水解酶）的过度表达，这可能与它们被 9 株菌生物降解有关。特别是，BaP 诱导的酰胺水解酶基因的上调也通过半定量 RT-PCR 得到了证实。当 9 株菌在菲上生长时，积累了儿茶酚 2,3-双加氧酶和 ndo 的大亚基，但没有酰胺水解酶。据我们所知，这是关于酰胺水解酶的过度表达及其在细菌降解高分子量 PAHs 中的可能作用的首次报道。
