Search tips
Search criteria

Results 1-10 (10)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
1.  Genes Involved in Degradation of para-Nitrophenol Are Differentially Arranged in Form of Non-Contiguous Gene Clusters in Burkholderia sp. strain SJ98 
PLoS ONE  2013;8(12):e84766.
Biodegradation of para-Nitrophenol (PNP) proceeds via two distinct pathways, having 1,2,3-benzenetriol (BT) and hydroquinone (HQ) as their respective terminal aromatic intermediates. Genes involved in these pathways have already been studied in different PNP degrading bacteria. Burkholderia sp. strain SJ98 degrades PNP via both the pathways. Earlier, we have sequenced and analyzed a ~41 kb fragment from the genomic library of strain SJ98. This DNA fragment was found to harbor all the lower pathway genes; however, genes responsible for the initial transformation of PNP could not be identified within this fragment. Now, we have sequenced and annotated the whole genome of strain SJ98 and found two ORFs (viz., pnpA and pnpB) showing maximum identity at amino acid level with p-nitrophenol 4-monooxygenase (PnpM) and p-benzoquinone reductase (BqR). Unlike the other PNP gene clusters reported earlier in different bacteria, these two ORFs in SJ98 genome are physically separated from the other genes of PNP degradation pathway. In order to ascertain the identity of ORFs pnpA and pnpB, we have performed in-vitro assays using recombinant proteins heterologously expressed and purified to homogeneity. Purified PnpA was found to be a functional PnpM and transformed PNP into benzoquinone (BQ), while PnpB was found to be a functional BqR which catalyzed the transformation of BQ into hydroquinone (HQ). Noticeably, PnpM from strain SJ98 could also transform a number of PNP analogues. Based on the above observations, we propose that the genes for PNP degradation in strain SJ98 are arranged differentially in form of non-contiguous gene clusters. This is the first report for such arrangement for gene clusters involved in PNP degradation. Therefore, we propose that PNP degradation in strain SJ98 could be an important model system for further studies on differential evolution of PNP degradation functions.
PMCID: PMC3871574  PMID: 24376843
2.  Genome Annotation of Burkholderia sp. SJ98 with Special Focus on Chemotaxis Genes 
PLoS ONE  2013;8(8):e70624.
Burkholderia sp. strain SJ98 has the chemotactic activity towards nitroaromatic and chloronitroaromatic compounds. Recently our group published draft genome of strain SJ98. In this study, we further sequence and annotate the genome of stain SJ98 to exploit the potential of this bacterium. We specifically annotate its chemotaxis genes and methyl accepting chemotaxis proteins. Genome of Burkholderia sp. SJ98 was annotated using PGAAP pipeline that predicts 7,268 CDSs, 52 tRNAs and 3 rRNAs. Our analysis based on phylogenetic and comparative genomics suggest that Burkholderia sp. YI23 is closest neighbor of the strain SJ98. The genes involved in the chemotaxis of strain SJ98 were compared with genes of closely related Burkholderia strains (i.e. YI23, CCGE 1001, CCGE 1002, CCGE 1003) and with well characterized bacterium E. coli K12. It was found that strain SJ98 has 37 che genes including 19 methyl accepting chemotaxis proteins that involved in sensing of different attractants. Chemotaxis genes have been found in a cluster along with the flagellar motor proteins. We also developed a web resource that provides comprehensive information on strain SJ98 that includes all analysis data (
PMCID: PMC3734258  PMID: 23940608
3.  Metabolism of 2-Chloro-4-Nitroaniline via Novel Aerobic Degradation Pathway by Rhodococcus sp. Strain MB-P1 
PLoS ONE  2013;8(4):e62178.
2-chloro-4-nitroaniline (2-C-4-NA) is used as an intermediate in the manufacture of dyes, pharmaceuticals, corrosion inhibitor and also used in the synthesis of niclosamide, a molluscicide. It is marked as a black-listed substance due to its poor biodegradability. We report biodegradation of 2-C-4-NA and its pathway characterization by Rhodococcus sp. strain MB-P1 under aerobic conditions. The strain MB-P1 utilizes 2-C-4-NA as the sole carbon, nitrogen, and energy source. In the growth medium, the degradation of 2-C-4-NA occurs with the release of nitrite ions, chloride ions, and ammonia. During the resting cell studies, the 2-C-4-NA-induced cells of strain MB-P1 transformed 2-C-4-NA stoichiometrically to 4-amino-3-chlorophenol (4-A-3-CP), which subsequently gets transformed to 6-chlorohydroxyquinol (6-CHQ) metabolite. Enzyme assays by cell-free lysates prepared from 2-C-4-NA-induced MB-P1 cells, demonstrated that the first enzyme in the 2-C-4-NA degradation pathway is a flavin-dependent monooxygenase that catalyzes the stoichiometric removal of nitro group and production of 4-A-3-CP. Oxygen uptake studies on 4-A-3-CP and related anilines by 2-C-4-NA-induced MB-P1 cells demonstrated the involvement of aniline dioxygenase in the second step of 2-C-4-NA degradation. This is the first report showing 2-C-4-NA degradation and elucidation of corresponding metabolic pathway by an aerobic bacterium.
PMCID: PMC3629101  PMID: 23614030
4.  Draft Genome Sequence of the 2-Chloro-4-Nitrophenol-Degrading Bacterium Arthrobacter sp. Strain SJCon 
Genome Announcements  2013;1(2):e00058-13.
We report the 4.39-Mb draft genome sequence of the 2-chloro-4-nitrophenol-degrading bacterium Arthrobacter sp. strain SJCon, isolated from a pesticide-contaminated site. The draft genome sequence of strain SJCon will be helpful in studying the genetic pathways involved in the degradation of several aromatic compounds.
PMCID: PMC3593328  PMID: 23516196
5.  Genome Sequence of the Halotolerant Bacterium Imtechella halotolerans K1T 
Journal of Bacteriology  2012;194(14):3731.
We report the 3.087-Mb genome sequence of Imtechella halotolerans K1T, isolated from an estuarine water sample collected from Kochi, Kerala, India. Strain K1 was recently reported as a novel genus of the family Flavobacteriaceae.
PMCID: PMC3393483  PMID: 22740661
6.  Draft Genome Sequence of the Nitrophenol-Degrading Actinomycete Rhodococcus imtechensis RKJ300 
Journal of Bacteriology  2012;194(13):3543.
We report the 8.231-Mb genome sequence of Rhodococcus imtechensis RKJ300, isolated from pesticide-contaminated soil in Punjab, India. The genome sequence of the strain RKJ300 will be helpful in exploring the molecular pathways involved in the degradation of nitrophenols.
PMCID: PMC3434742  PMID: 22689233
7.  Genome Sequence of the Nitroaromatic Compound-Degrading Bacterium Burkholderia sp. Strain SJ98 
Journal of Bacteriology  2012;194(12):3286.
We report the 7.85-Mb genome sequence of Burkholderia sp. strain SJ98, isolated from agricultural fields of Assam, India. The draft genome of this strain will be helpful in studying the genetic pathways involved in the degradation of aromatic compounds.
PMCID: PMC3370847  PMID: 22628512
8.  Branching of the p-nitrophenol (PNP) degradation pathway in burkholderia sp. Strain SJ98: Evidences from genetic characterization of PNP gene cluster 
AMB Express  2012;2:30.
Aerobic microbial degradation of p-nitrophenol (PNP) has been classically shown to proceed via ‘Hydroquinone (HQ) pathway’ in Gram-negative bacteria, whereas in Gram-positive PNP degraders it proceed via ‘Benzenetriol (BT) pathway’. These pathways are characterized by the ring cleavage of HQ and BT as terminal aromatic intermediates respectively. Earlier reports on PNP degradation have indicated these pathways to be mutually exclusive. We report involvement of both ‘HQ’ and ‘BT’ ring cleavage pathways in PNP degradation by Burkholderia sp. strain SJ98. Genetic characterization of an ~41 Kb DNA fragment harboring PNP degradation gene cluster cloned and sequenced from strain SJ98 showed presence of multiple orfs including pnpC and pnpD which corresponded to previously characterized ‘benzenetriol-dioxygenase (BtD)’ and ‘maleylacetate reductase (MaR)’ respectively. This gene cluster also showed presence of pnpE1 and pnpE2, which shared strong sequence identity to cognate sub-units of ‘hydroquinone dioxygenase’ (HqD). Heterologous expression and biochemical characterization ascertained the identity of PnpE1 and PnpE2. In in vitro assay reconstituted heterotetrameric complex of PnpE1 and PnpE2 catalyzed transformation of hydroquinone (HQ) into corresponding hydroxymuconic semialdehyde (HMS) in a substrate specific manner. Together, these results clearly establish branching of PNP degradation in strain SJ98. We propose that strain SJ98 presents a useful model system for future studies on evolution of microbial degradation of PNP.
PMCID: PMC3485097  PMID: 22681853
P-nitrophenol; Hydroquinone dioxygenase; PNP pathway; Burkholderia sp SJ98
9.  Isolation and Growth Characteristics of Chromium(VI) and Pentachlorophenol Tolerant Bacterial Isolate from Treated Tannery Effluent for its Possible Use in Simultaneous Bioremediation 
Indian Journal of Microbiology  2011;51(1):61-69.
The bacterial strains resistant to pentachlorophenol (PCP) and hexavalent chromium [Cr(VI)] were isolated from treated tannery effluent of a common effluent treatment plant. Most of the physico-chemical parameters analyzed were above permissible limits. Thirty-eight and four bacterial isolates, respectively were found resistant to >50 μg/ml concentration of [Cr(VI)] and the same level of PCP. Out of the above 42 isolates, only one was found simultaneously tolerant to higher levels of both PCP (500 μg/ml) and Cr(VI) (200 μg/ml), and hence was selected for further studies. To the best of our knowledge, this is the first report in which a native bacterial isolate simultaneously tolerant to such a high concentrations of Cr(VI) and PCP has been reported. The culture growth was best at 0.4% (w/v) glucose as an additional carbon source and 0.2% (w/v) ammonium chloride as a nitrogen source. The growth results with cow urine as a nitrogen source were comparable with the best nitrogen source ammonium chloride. The isolate exhibited resistance to multiple heavy metals (Pb, As, Hg, Zn, Co & Ni) and to antibiotics nalidixic acid and polymixin-B. The efficacy of bacterial isolate for growth, PCP degradation (56.5%) and Cr(VI) bioremediation (74.5%) was best at 48 h incubation. The isolate was identified as Bacillus sp. by morphological and biochemical tests. The 16S rDNA sequence analysis revealed 98% homology with Bacillus cereus. However, further molecular analysis is underway to ascertain its likelyhood of a novel species.
PMCID: PMC3209868  PMID: 22282630
Chromium; Heavy metals; Pentachlorophenol; Simultaneous bioremediation
10.  An antibiotic, heavy metal resistant and halotolerant Bacillus cereus SIU1 and its thermoalkaline protease 
Many workers have reported halotolerant bacteria from saline conditions capable of protease production. However, antibiotic resistance and heavy metal tolerance pattern of such organisms is not documented very well. Similarly, only a few researchers have reported the pattern of pH change of fermentation medium during the course of protease production. In this study, we have isolated a halotolerant Bacillus cereus SIU1 strain from a non-saline environment and studied its antibiotic and heavy metal resistance pattern. The isolate produces a thermoalkaline protease and changes the medium pH during the course of fermentation. Thermostability of protease was also studied for 30 min.
Seventy bacterial strains isolated from the soils of Eastern Uttar Pradesh, India were screened for protease production. All of them exhibited protease activity. However, 40% bacterial isolates were found good protease producers as observed by caseinolytic zones on milk agar plates. Among them, culture S-4 was adjudged as the best protease producer, and was identified as Bacillus cereus by morphological, biochemical and 16 S rDNA sequence analyses. The isolate was resistant to heavy metals (As2+, Pb2+, Cs1+) and antibiotics (penicillin, lincomycin, cloxacillin, pefloxacin). Its growth behavior and protease production was studied at 45°C and pH 9.0. The protease units of 88 ml-1 were noted in unoptimized modified glucose yeast extract (GYE) medium during early stationary phase at 20 h incubation period. The enzyme was stable in the temperature range of 35°-55°C.
An antibiotic and heavy metal resistant, halotolerant Bacillus cereus isolate is capable of producing thermoalkaline protease, which is active and stable at pH 9.0 and 35°-55°C. This isolate may be useful in several industrial applications owing to its halotolerance and antibiotic and heavy metal resistance characteristics.
PMCID: PMC2914678  PMID: 20646325

Results 1-10 (10)