RESUMO
Mn(II)-oxidizing bacteria (MOB) are widely distributed in natural environments and can convert soluble Mn(II) into insoluble Mn(III) and Mn(IV). The biogenic manganese oxides (BioMnOx) produced by MOB have been considered for remediating heavy metal pollution and degrading organic pollutants in an eco-friendly manner. In this study, a manganese-oxidizing bacterium was isolated from Mn-polluted rivulet sediment and identified as Bacillus sp. strain M2 by PCR, phylogenetic tree construction, transmission electron microscopy (TEM), and physiological and biochemical indices. Strain M2 grew well under Mn(II) stress. BioMnOx with nanosized irregular geometric shapes and loose structures generated by strain M2 were found on the surface of the bacterial cells. The content of Mn in the bacteria was as high as 5.36%. Approximately 71.24% and 47.52% of Mn(II) was oxidized to Mn(III/IV) in the cell and in the deposits, respectively, within 3 d of cultivation with Mn(II). Extracellular enzymes contributed to the Mn removal and oxidation. In conclusion, Bacillus sp. strain M2 has a high potential for use in the remediation of Mn-contaminated sites.
RESUMO
In the acidic medium, hydrosulfuryl(-SH) in cysteine hydrochloride can reduce Fe3+ to Fe2+, then Fe2+ react with potassium ferricyanide to form KFe[Fe(CN)6](soluble Prussian blue). Prussian blue has a maximum absorption at 727 nm, Bill's law is observed between mass concentration of cysteine hydrochloride and absorbance of Prussian blue, the content of cysteine hydrochloride is indirectly determinated by measuring the absorbance of Prussian blue. An accurate, simple, fast spectrophotometric method for the determination of cysteine hydrochloride content by ferric chloride-potassium ferricyanide has been established. The optimal determination conditions of cysteine hydrochloride content are explored. The cysteine hydrochloride content is determinate by this method.
Assuntos
Cisteína , FerricianetosRESUMO
BACKGROUND: Human papillomavirus (HPV) vaccination and screening have been demonstrated to be effective methods for controlling cervical cancer. To provide evidence for effective targeted interventions, we investigated the HPV prevalence and genotypic distribution in women of different age groups in the Longgang community of Shenzhen, China. METHODS: A total of 29 263 women were enrolled in the Longgang District Central Hospital from January 2018 to October 2020. Cervical specimens were collected at enrolment. We used a polymerase chain reaction diagnostic kit to detect the genotypes of HPV. RESULTS: The prevalence of overall, high-risk, probable high-risk (PHR) and low-risk HPV infection was 8.2% (95% confidence interval [CI] 7.9 to 8.5), 6.9% (95% CI 6.6 to 7.2), 0.9% (95% CI 0.8 to 1.1) and 1.6% (95% CI 1.5 to 1.8), respectively. High-risk HPV genotype infections accounted for 84.4% (95% CI 82.8 to 85.8) of the overall HPV infections. The five most predominant genotypes were HPV-52, HPV-16, HPV-58, HPV-53 and HPV-51. CONCLUSION: Our study found that the prevalence of HPV infection increased with age and women 55-59 y of age presented the highest HPV prevalence. As a PHR subtype, HPV-53 has a higher infection rate in women. HPV-52, HPV-16 and HPV-58 are common infection genotypes.