Shamim Ahmad

Aligarh Muslim University, Koil, Uttar Pradesh, India

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Publications (9)13.3 Total impact

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    ABSTRACT: of Cd(II), Ni(II), Cr(VI), Cr(III) ions from aqueous solution. All experiments were conducted with the dried and non growing biomasses of S. gallinarum W-61 under varying conditions of pH, contact time, and initial concentration of the metal ion. The pH of the solution considerably altered the biosorption capacity of metal ions by the test isolate. Biosorption of Cd and Ni was maximum at pH 6.5, pH 4.5 was found optimum for Cr(III) whereas S. gallinarum W-61 adsorbed Cr(VI) maximum at pH 2.5. The removal of metal ions was conspicuously rapid; most of the total adsorption occurred within 30 min of reaction time. The sorption data was analyzed with the Langmuir and Freundlich isotherm models. The highest Qmax and Kf value was found for the biosorption of Cd(II) with 48.8 mg/g and 6.78 mg/g respectively when the experiment was conducted with the non growing biomass of S. gallinarum W-61. Recovery of metal ions (Cr(VI), Cr(III) Cd(II) and Ni(II)) through desorption was found better with the dried biomass compared with the non growing biomass of the isolate. The isolate was further tested for its bioaccumulation potential under actively growing conditions. .The results of bioaccumulation shows that S. gallinarum W-61 has accumulated varying amount of test metals intracellularly. The isolate could be employed for the removal of heavy metals from spent industrial effluents before discharging it into the environment.
    Journal of Pure and Applied Microbiology 06/2014; 8(3):1961-1972. · 0.05 Impact Factor
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    ABSTRACT: This study reports the occurrence of antibiotic resistance and production of β-lactamases including extended spectrum beta-lactamases (ESβL) in enteric bacteria isolated from hospital wastewater. Among sixty-nine isolates, tested for antibiotic sensitivity, 73.9% strains were resistant to ampicillin followed by nalidixic acid (72.5%), penicillin (63.8%), co-trimoxazole (55.1%), norfloxacin (53.6%), methicillin (52.7%), cefuroxime (39.1%), cefotaxime (23.2%) and cefixime (20.3%). Resistance to streptomycin, chloramphenicol, nitrofurantoin, tetracycline, and doxycycline was recorded in less than 13% of the strains. The minimum inhibitory concentration (MIC) showed a high level of resistance (800-1600 μg/mL) to one or more antibiotics. Sixty three (91%) isolates produced β-lactamases as determined by rapid iodometric test. Multiple antibiotic resistances were noted in both among ESβL and non-ESβL producers. The β-lactamases hydrolyzed multiple substrates including penicillin (78.8% isolates), ampicillin (62.3%), cefodroxil (52.2%), cefotoxime (21.7%) and cefuroxime (18.8%). Fifteen isolates producing ESβLs were found multidrug resistant. Four ESβL producing isolates could transfer their R-plasmid to the recipient strain E. coli K-12 with conjugation frequency ranging from 7.0 × 10(-3) to 8.8 × 10(-4). The findings indicated that ESβL producing enteric bacteria are common in the waste water. Such isolates may disseminate the multiple antibiotic resistance traits among bacterial community through genetic exchange mechanisms and thus requires immediate attention.
    Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]. 01/2013; 44(3):799-806.
  • Mohammad Zubair Alam, Shamim Ahmad
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    ABSTRACT: The present work deals with the biosorption performance of dried and non-growing biomasses of Exiguobacterium sp. ZM-2, isolated from soil contaminated with tannery effluents, for the removal of Cd2+, Ni2+, Cu2+, and Zn2+ from aqueous solution. The metal concentrations studied were 25 mg/l, 50 mg/l, 100 mg/l, 150 mg/l and 200 mg/l. The effect of solution pH and contact time was also studied. The biosorption capacity was significantly altered by pH of the solution. The removal of metal ions was conspicuously rapid; most of the total sorption occurred within 30 min. The sorption data have been analyzed and fitted to the Langmuir and Freundlich isotherm models. The highest Qmax value was found for the biosorption of Cd2+ at 43.5 mg/g in the presence of the non-growing biomass. Recovery of metals (Cd2+, Zn2+, Cu2+ and Ni2+) was found to be better when dried biomass was used in comparison to non-growing biomass. Metal removal through bioaccumulation was determined by growing the bacterial strain in nutrient broth amended with different concentrations of metal ions. This multi-metal resistant isolate could be employed for the removal of heavy metals from spent industrial effluents before discharging them into the environment.
    Annals of Microbiology 09/2012; · 1.55 Impact Factor
  • Mohammad Zubair Alam, Shamim Ahmad
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    ABSTRACT: Bacterial strains ZA-6, W-61, KS-2 and KS-14 were isolated from agricultural soil irrigated with tannery effluents and subsequently identified by 16S rDNA sequencing as Stenotrophomonas maltophilia, Staphylococcus gallinarum, Pantoea sp. and Aeromonas sp., respectively. All isolates were examined for their resistance to hexavalent chromium and other heavy metal ions. The bacterial isolate S. maltophilia ZA-6 and S. gallinarum W-61 were resistant to 16.5 and 12.4 mM of potassium chromate, respectively, whereas Pantoea sp. KS-2 and Aeromonas sp. KS-14 were found to be sensitive to potassium chromate. S. maltophilia ZA-6 and S. gallinarum W-61 completely reduced 500 μM Cr6+ to Cr3+ within 56 h, while chromate-sensitive isolates Pantoea sp. KS-2 and Aeromonas sp. KS-14 exhibited poor chromate-reducing activity. Chromate reduction was severely affected in the presence of the metabolic inhibitors sodium cyanide and sodium azide. Sodium cyanide completely inhibited chromate reduction in each isolate, whereas 1 mM sodium azide and 10 mM sodium sulfate affected the inhibition of chromate reduction to varying degrees. The use of 1 mM 2,4-dinitrophenol, an uncoupling agent, stimulated the chromate reduction. The cell-free extract (CFE) of chromate-resistant isolates readily reduced Cr6+ to Cr3+, with that of S. gallinarum W-61 showing a Km value of 121.7 μM chromate and a Vmax of 1.12 μmol/min per milligram protein in the presence of NADH. The chromate-resistant isolates displayed lower Michealis–Menton constant (Km) values and higher maximum velocity (Vmax) than chromate-sensitive isolates. These results suggest that chromate resistance and reduction in these bacteria are related.
    Annals of Microbiology 01/2012; · 1.55 Impact Factor
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    ABSTRACT: In the present study, a total of 198 bacteria were isolated, 88 from the tannery effluents and 110 from agricultural soil irrigated with the tannery effluents. Tannery effluents and soils were analyzed for metal concentrations by atomic absorption spectrophotometer. The tannery effluents and soil samples were found to be contaminated with chromium, nickel, zinc, copper, and cadmium. All isolates were tested for their resistance against Cr(6+ ), Cr(3+ ), Ni(2+ ), Zn(2+ ), Cu(2+ ), Cd(2+ ), and Hg(2+ ). From the total of 198 isolates, maximum bacterial isolates were found to be resistant to Cr(6+ ) 178 (89.9%) followed by Cr(3+ ) 146 (73.7%), Cd(2+ ) 86 (43.4%), Zn(2+ ) 83 (41.9%), Ni(2+ ) 61 (30.8%), and Cu(2+ ) 51 (25.6%). However, most of the isolates were sensitive to Hg(2+ ). Among the isolates from tannery effluents, 97.8% were resistant to Cr(6+ ) and 64.8% were resistant to Cr(3+ ). Most of the soil isolates were resistant against Cr(6+ ) (83.6%) and Cr(3+ ) (81.8%). All isolates were categorized into Gram-positive and Gram-negative bacteria. In a total of 114 Gram-positive isolates, 91.2% were resistant to Cr(6+ ) followed by 73.7% to Cr(3+ ), 42.1% to Zn(2+ ), 40.4% to Cd(2+ ), and 32.5% to Ni(2+ ). Among Gram-negative isolates, 88.1% were found showing resistance to Cr(6+ ), 75.0% to Cr(3+ ), and 47.6% were resistant to Cd(2+ ). Majority of these metal-resistant isolates were surprisingly found sensitive to the ten commonly used antibiotics. Out of 198 isolates, 114 were found sensitive to all antibiotics whereas only two isolates were resistant to maximum eight antibiotics at a time. Forty-one and 40 isolates which constitute 20.7% and 20.2% were resistant to methicilin and amoxicillin, respectively.
    Environmental Monitoring and Assessment 07/2011; 178(1-4):281-91. · 1.68 Impact Factor
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    Ecotoxicology and Environmental Safety 03/2011; 74(3):550. · 2.20 Impact Factor
  • Mohammad Zubair Alam, Shamim Ahmad
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    ABSTRACT: Four bacterial isolates (two resistant and two sensitive to chromium) were isolated from soil contaminated with tannery effluents at Jajmau (Kanpur), India, and were identified by 16S rDNA gene sequencing as Stenotrophomonas maltophilia, Exiguobacterium sp., Pantoea sp., and Aeromonas sp. Biosorption of chromium by dried and living biomasses was determined in the resistant and sensitive isolates. The effect of pH, initial metal concentration, and contact time on biosorption was studied. At pH 2.5 the living biomass of chromium resistant isolate Exiguobacterium sp. ZM-2 biosorbed maximum amount of Cr6+ (29.8 mg/g) whereas the dried biomass of this isolate biosorbed 20.1 mg/g at an initial concentration of 100 mg/L. In case of chromate sensitive isolates, much difference was not observed in biosorption capacities between their dried and living biomasses. The maximum biosorption of Cr3+ was observed at pH 4.5. However, biosorption was identical in resistant and sensitive isolates. The data on chromium biosorption were analyzed using Langmuir and Freundlich isotherm model. The biosorption data of Cr6+ and Cr3+ from aqueous solution were better fitted in Langmuir isotherm model compared to Freundlich isotherm model. Metal recovery through desorption was observed better with dried biomasses compared to the living biomasses for both types of chromium ions. Bioaccumulation of chromate was found higher in chromate resistant isolates compared to the chromate sensitive isolates. Transmission electron microscopy confirmed the accumulation of chromium in cytoplasm in the resistant isolates.
    CLEAN - Soil Air Water 02/2011; 39(3):226 - 237. · 2.05 Impact Factor
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    ABSTRACT: The tannery effluents at Kanpur (India) have been in use for irrigation since last many years, polluting soil directly while ground water and food crops indirectly. Gas chromatography-mass spectrometric analysis of the test samples revealed the presence of organic compounds including diisooctyl phthalate, phenyl N-methylcarbamate, dibutyl phthalate, bis 2-methoxyethyl phthalate, and higher alkanes. Tannery effluent extracts were prepared using XAD-4/8 resins, dichloromethane, chloroform, and hexane and tested with Ames Salmonella test and DNA repair-defective Escherichia coli K-12 mutants. In the presence of XAD-concentrated tannery effluent, TA98 found to be the most sensitive strain in terms of mutagenic index followed by TA97a whereas in terms of mutagenic potential TA102 was most responsive. The extracts were also found genotoxic as determined in terms of survival of E. coli K-12 mutants, suggesting the presence of DNA damaging compounds in the tannery effluents. In the light of results, precautious use of tannery effluents for irrigation is suggested.
    Ecotoxicology and Environmental Safety 10/2010; 73(7):1620-8. · 2.20 Impact Factor
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    ABSTRACT: It is a common practice in India to irrigate agricultural fields with wastewater originating from industries and domestic sources. At Jajmau (Kanpur), India, tannery effluent is used for irrigation purposes. This practice has been polluting the soil directly and groundwater and food crops indirectly. This study is aimed at evaluating the mutagenic impact of soil irrigated with tannery effluent. Soil extracts were prepared using four organic solvents (dichloromethane, methanol, acetonitrile, and acetone) and tested with Ames Salmonella/microsome test and DNA repair-defective E. coli k-12 mutants. Gas Chromatography-mass spectrometric analysis of soil samples revealed the presence of a large number of organic compounds including bis(2-ethylhexyl)phthalate, benzene, 1,3-hexadien-5-yne, 2,4-bis(1,1-dimethyl)phenol, Docosane, 10-methylnonadecane, and many higher alkanes. The soil extracts exhibited significant mutagenicity with Ames tester strains. TA98 was found to be the most sensitive strains to all the soil extracts, producing maximum response in terms of mutagenic index of 14.2 (-S9) and 13.6 (+S9) in the presence of dichloromethane extract. Dichloromethane-extracted soil exhibited a maximum mutagenic potential of 17.3 (-S9) and 20.0 (+S9) revertants/mg soil equivalent in TA100. Methanol, acetonitrile, and acetone extracts were also found to be mutagenic. A significant decline in the survival of DNA repair-defective E. coli K-12 mutants was observed compared to their isogenic wild-type counterparts when treated with different soil extracts. PolA mutant was found to be the most sensitive strain toward all four soil extracts.
    Archives of Environmental Contamination and Toxicology 02/2009; 57(3):463-76. · 2.01 Impact Factor