In developing countries like India, there are many industrial areas discharging effluent containing large amount of polyaromatic hydrocarbon (PAH) which causes hazardous effect on the soil-water environment. The objective of this study was to isolate and characterize high-efficiency PAN-degrading microbial consortium from 3 decade old petrochemical refinery field located in Nagpur, Maharashtra with history of PAH disposal. Based on biochemical tests and 16S rDNA gene sequence analysis the consortium was identified as Sphingobacterium sp., Bacillus cereus and a novel bacterium Achromobacter insolitus MHF ENV IV with effective phenanthrene-degrading ability. The biodegradation data of phenanthrene indicates about 100%, 56.9% and 25.8% degradation at the concentration of 100 mg/l, 250 mg/l and 500 mg/l respectively within 14 days. The consortium and its monoculture isolates also utilized variety of other hydrocarbons for growth. To best of our knowledge this is the first time that Achromobacter insolitus has been reported to mineralize phenanthrene effectively. GC-MS analysis of phenanthrene degradation confirmed biodegradation by detection of intermediates like salicylaldehyde, salicylic acid and catechol. All the results indicated that the microbial consortium have a promising application in bioremediation of petrochemical contaminated environments and could be potentially useful for the study of PAH degradation and for bioremediation purposes. (C) 2011 Elsevier B.V. All rights reserved.