title: Inhibition or promotion of biodegradation of nitrate by Paracoccus sp. in the presence of nanoscale zero-valent iron.
abstract: To investigate the effect of nanoscale zero-valent iron (nZVI) on the growth of Paracoccus sp. strain and biodenitrification under aerobic conditions, specific factors were studied, pH, concentration of nitrate, Fe (II) and carbon dioxide. Low concentration of nZVI (50mg/L) promoted both cell growth and biodegradation of nitrate which rose from 69.91% to 76.16%, while nitrate removal fell to 67.10% in the presence of high nZVI concentration (1000 mg/L). This may be attributed to the ions produced in nZVI corrosion being used as an electron source for the biodegradation of nitrate. However, the excess uptake of Fe (II) causes oxidative damage to the cells. To confirm this, nitrate was completely removed after 20 h when 100mg/L Fe (II) was added to the solution, which is much faster than the control (86.05%, without adding Fe (II)). However, nitrate removal reached only 45.64% after 20 h, with low cell density (OD 600=0.62) in the presence of 300 mg/L Fe (II). Characterization techniques indicated that nZVI adhered to microorganism cell membranes. These findings confirmed that nZVI could affect the activity of the strain and consequently change the biodenitrification.
authors.affiliation: School of Life Science, Fujian Normal University, Fuzhou 350108, Fujian Province, China.
authors.forename: Chenghong
authors.initials: C
authors.lastname: Jiang
authors.affiliation: School of Life Science, Fujian Normal University, Fuzhou 350108, Fujian Province, China.
authors.forename: Xuping
authors.initials: X
authors.lastname: Xu
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Ravendra
authors.initials: R
authors.lastname: Naidu
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China; Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia. Electronic address: Zuliang.chen@unisa.edu.au.
authors.forename: Zuliang
authors.initials: Z
authors.lastname: Chen
mesh_terms: D001673:Biodegradation, Environmental; D007501:Iron / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism*; D010230:Paracoccus / Q000502:physiology*; D012989:Soil Pollutants / Q000737:chemistry* / Q000378:metabolism
chemical_list: D009566:Nitrates; D012989:Soil Pollutants; D007501:Iron
keywords: Biodenitrification; Cell growth; Nanotoxicity; Paracoccus sp.; nZVI