Biodegradation of naphthalene-2-sulfonic acid present in tannery wastewater by bacterial isolates Arthrobacter sp. 2AC and Comamonas sp. 4BC.
Two bacterial strains, 2AC and 4BC, both capable of utilizing naphthalene-2-sulfonic acid (2-NSA) as a sole source of carbon, were isolated from activated sludges previously exposed to tannery wastewater. Enrichments were carried out in mineral salt medium (MSM) with 2-NSA as the sole carbon source. 16S rDNA sequencing analysis indicated that 2AC is an Arthrobacter sp. and 4BC is a Comamonas sp. Within 33 h, both isolates degraded 100% of 2-NSA in MSM and also 2-NSA in non-sterile tannery wastewater. The yield coefficient was 0.33 g biomass dry weight per gram of 2-NSA. A conceptual model, which describes the aerobic transformation of organic matter, was used for interpreting the biodegradation kinetics of 2-NSA. The half-lives for 2-NSA, at initial concentrations of 100 and 500 mg/l in MSM, ranged from 20 h (2AC) to 26 h (4BC) with lag-phases of 8 h (2AC) and 12 h (4BC). The carbon balance indicates that 75-90% of the initial TOC (total organic carbon) was mineralized, 5-20% remained as DOC (dissolved organic carbon) and 3-10% was biomass carbon. The principal metabolite of 2-NSA biodegradation (in both MSM and tannery wastewater) produced by Comamonas sp. 4BC had a MW of 174 and accounted for the residual DOC (7.0-19.0% of the initial TOC and 66% of the remaining TOC). Three to ten percent of the initial TOC (33% of the remaining TOC) was associated with biomass. The metabolite was not detected when Arthrobacter sp. 2AC was used, and a lower residual DOC and biomass carbon were recorded. This suggests that the two strains may use different catabolic pathways for 2-NSA degradation. The rapid biodegradation of 2-NSA (100 mg/l) added to non-sterile tannery wastewater (total 2-NSA, 105 mg/l) when inoculated with either Arthrobacter 2AC or Comamonas 4BC showed that both strains were able to compete with the indigenous microorganisms and degrade 2-NSA even in the presence of alternate carbon sources (DOC in tannery wastewater = 91 mg/l). The results provide information useful for the rational design of bioreactors for tannery wastewater treatment.
Song
Zhi
Z
Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
Edwards
Suzanne R
SR
Burns
Richard G
RG
D001173:Arthrobacter / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D020585:Comamonas / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D007700:Kinetics; D008954:Models, Biological; D009282:Naphthalenesulfonates / Q000378:metabolism*; D010802:Phylogeny; D012722:Sewage / Q000382:microbiology; D021241:Spectrometry, Mass, Electrospray Ionization; D013633:Tanning; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D004269:DNA, Bacterial; D009282:Naphthalenesulfonates; D012722:Sewage; D014874:Water Pollutants, Chemical; D002244:Carbon