Roxarsone biotransformation by a nitroreductase and an acetyltransferase in Pseudomonas chlororaphis, a bacterium isolated from soil.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, Rox), a widely used organoarsenical feed additive, can enter soils and be further biotransformed into various arsenic species that pose human health and ecological risks. However, the pathway and molecular mechanism of Rox biotransformation by soil microbes are not well studied. Therefore, in this study, we isolated a Rox-transforming bacterium from manure-fertilized soil and identified it as Pseudomonas chlororaphis through morphological analysis and 16S rRNA gene sequencing. Pseudomonas chlororaphis was able to biotransform Rox to 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA), N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), arsenate [As(V)], arsenite [As(III)], and dimethylarsenate [DMAs(V)]. The complete genome of Pseudomonas chlororaphis was sequenced. PcmdaB, encoding a nitroreductase, and PcnhoA, encoding an acetyltransferase, were identified in the genome of Pseudomonas chlororaphis. Expression of PcmdaB and PcnhoA in E. coli Rosetta was shown to confer Rox(III) and 3-AHPAA(III) resistance through Rox nitroreduction and 3-AHPAA acetylation, respectively. The PcMdaB and PcNhoA enzymes were further purified and functionally characterized in vitro. The kinetic data of both PcMdaB and PcNhoA were well fit to the Michaelis-Menten equation, and nitroreduction catalyzed by PcMdaB is the rate-limiting step for Rox transformation. Our results provide new insights into the environmental risk assessment and bioremediation of Rox(V)-contaminated soils.

[High-risk human papilloma virus DNA detection kit (cervista HPV HR) should be highly validated clinically in cervical cancer screening programs].

OBJECTIVE: The aim of this study is to evaluate the clinical significance of High-risk Human Papilloma virus DNA Detection Kit (Cervista HPV HR) designed to the utilized in cervical cancer screening programs. METHODS: The investigation for Cervista HPV HR test is designed to detect 437 residual liquid-based cytology specimens collected during routine liquid-based Pap tests at standard care vistis and to identify the presence of HR HPV. We compared Cervista HPV HR Test against standard PCR, in order to examine the performance of Cervista HPV HR Test in populations with cervical intraepithelial neoplasia grade 2+ (CIN 2, CIN 3 and Cancer, CIN 2+), and the capabilities of A5/A6, A7, A9 oligonucleotides of Cervista for predicting CIN2+. RESULTS: The accuracy of Cervista compared to PCR with bi-directional sequencing was 88.26%. The positive percent of Cervista HPV HR Test and PCR were 38.96% and 29.08%, respectively. The sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) of Cervista HPV HR Test for the detection of CIN2+ were 98.46%, 58.49%, 99.54% and 29.68%, respectively. The A9 oligonucleotides positivity percent was significantly higher in CIN2 + (odds ratio: 24.037, 95% CI: 10.086 - 57.283). CONCLUSION: The Cervista HPV HR test can be clinically used for detecting HR HPV types during routine cervical cancer screening. A9 oligonucleotides were also strongly associated with CIN2+ diagnosis, which is improtant in cervical cancer screening for triage to colposcopy.