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- Title
Biodegradation of 4-nitrotoluene with biosurfactant production by Rhodococcus pyridinivorans NT2: metabolic pathway, cell surface properties and toxicological characterization.
- Authors
Kundu, Debasree; Hazra, Chinmay; Dandi, Navin; Chaudhari, Ambalal
- Abstract
A novel 4-nitrotoluene-degrading bacterial strain was isolated from pesticides contaminated effluent-sediment and identified as Rhodococcus pyridinivorans NT2 based on morphological and biochemical properties and 16S rDNA sequencing. The strain NT2 degraded 4-NT (400 mg l) with rapid growth at the end of 120 h, reduced surface tension of the media from 71 to 29 mN m and produced glycolipidic biosurfactants (45 mg l). The biosurfactant was purified and characterized as trehalose lipids. The biosurfactant was stable in high salinity (10 % w/v NaCl), elevated temperatures (120 °C for 15 min) and a wide pH range (2.0-10.0). The noticeable changes during biodegradation were decreased hydrophobicity; an increase in degree of fatty acid saturation, saturated/unsaturated ratio and cyclopropane fatty acid. Biodegradation of 4-NT was accompanied by the accumulation of ammonium (NH) and negligible amount of nitrite ion (NO). Product stoichiometry showed a carbon (C) and nitrogen (N) mass balance of 37 and 35 %, respectively. Biodegradation of 4-NT proceeded by oxidation at the methyl group to form 4-nitrobenzoate, followed by reduction and hydrolytic deamination yielding protocatechuate, which was metabolized through β-ketoadipate pathway. In vitro and in vivo acute toxicity assays in adult rat ( Rattus norvegicus) showed sequential detoxification and the order of toxicity was 4-NT >4-nitrobenzyl alcohol >4-nitrobenzaldehyde >4-nitrobenzoate >> protocatechuate. Taken together, the strain NT2 could be used as a potential bioaugmentation candidate for the bioremediation of contaminated sites.
- Subjects
NITROTOLUENE; RHODOCOCCUS; BIOSURFACTANTS; STOICHIOMETRY; TREHALOSE; DEAMINATION; MICROBIAL surfactants
- Publication
Biodegradation, 2013, Vol 24, Issue 6, p775
- ISSN
0923-9820
- Publication type
Article
- DOI
10.1007/s10532-013-9627-4