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Articles by Samia Ahmad
Total Records ( 5 ) for Samia Ahmad
  Sabeen Survery , Samia Ahmad , Syed Abdus Subhan , Munazza Ajaz and Sheikh Ajaz Rasool
  Sixty bacterial strains (isolated from soil near different petrol pumps of Karachi city) were screened for hydrocarbon degradation. They were identified on the basis of morpho-cultural and biochemical characteristics and were found belonging to different genera including Staphylococcus, Corynebacterium, Bacillus, Proteus, Pseudomonas, Klebsiella and Escherichia. Four solid hydrocarbons including biphenyl, camphor, phenanthrene and naphthalene and four liquid hydrocarbons i.e. benzene, toluene, octane and heptane were used in this study. In the case of solid hydrocarbons a total of 17% degraded biphenyl, 8% degraded camphor, 8% degraded naphthalene and 10% degraded phenanthrene. In case of liquid hydrocarbons about 57% were able to degraded benzene, 55% degraded toluene, 48% degraded octane and 33% degraded heptane. About 89% isolates degraded both solid and liquid hydrocarbons while 11% could not degrade any of them. In order to locate the genes responsible for hydrocarbon degradation, curing experiments were performed using physical agent i.e. elevated temperature and the chemical agent i.e. acridine orange. Results of these experiments indicated that the genes are plasmid born. In vivo direct gene transfer (bacterial conjugation) experiments were also performed and it was shown that hydrocarbon-degrading plasmid genes are stably transferable to the competent recipient cells.
  Nusrat Jabeen , Sheikh Ajaz Rasool , Samia Ahmad , Munazza Ajaz and Sadia Saeed
  Five phytopathogenic strains namely, Xanthomonas oryzae NA1, Xanthomonas citri NA2, Pseudomonas andropogonis NA3, Erwinia carotovora NA4 (isolated from diseased fruits and vegetables) and Agrobacterium radiobacter NA5 (isolated from pepper rhizophere) were identified on morpho-cultural and biochemical considerations. API 20 E and API 20 NE kits were used to confirm the identification. All isolates were screened for bacteriocinogenic activity against phytopathogenic bacteria. Accordingly, only two strains i.e. Erwinia carotovora NA4, Agrobacterium radiobacter NA5 were found to produce bacteriocin. These bacteriocins are designated as erwiniocin NA4, agrocin NA5, respectively. Both the producer strains have shown antibacterial activity against closely related strains. The activity potential of erwiniocin NA4 was calculated as 160AU mL-1 while that of agrocin NA5 was 80AU mL-1. The effect of temperature variation and pH on erwiniocin NA4 and agrocin NA5 was also checked and both were found activity resistant at 100°C for 10 min and pH range 2-14. Erwiniocin NA4 was also found resistant to autoclaving while bioactivity of agrocin NA5 was lost after similar treatment.
  Nadia Gul , Talat Y. Mujahid and Samia Ahmad
  Sixty-five bacterial strains were isolated from urine samples of patients suffering from urinary tract infection and identified by conventional methods. Eighty percent of total isolated organisms were found to be gram negative while remaining 20% were gram positive. Among gram negatives, E. coli and gram positive S. aureus and S. pyogene were the most prevalent organism. The percentage of gram negative isolates was as follows Escherichia coli (47.6%) followed by Pseudomonas aeruginosa (9.2%), Klebsiella pneumoniae (7.6%), Enterobacter aerogenes (6.1%), Proteus mirabilis and Serratia marcescens (4.6% each). The percentage of gram positive isolates includes, Staphylococcus aureus and Streptococcus pyogenes (4.6% each), Enterococcus faecalis, Staphylococcus epidermidis and Bacillus subtilis (3% each) and Staphylococcus saprophyticus (1.5%). The antibiotic resistance of identified organisms was carried out by disc-diffusion method with commercially available disc of fifteen antibiotics having different mode of actions such as cell wall synthesis inhibitors, membrane permeability alternatives, protein synthesis inhibitors and DNA synthesis inhibitors. Gram negatives showed more resistance to these antibiotics as compared to gram positive organisms. The most effective antibiotic for gram negative UTI isolates is gentamycin showing 69.2% efficacy, then sulfamethoxazole-trimethoprim (SXT-TMP) with 55% efficacy and then kanamycin having 50% efficacy. Among gram positives, chloramphenicol is most effective with 84.6% efficacy, then ofloxacin and gentamycin with 76.9% efficacy and then norfloxacin with 69.2% efficacy.
  Nadia Gul , Talat Y. Mujahid , Nayyar Jehan and Samia Ahmad
  Curcuma longa belongs to the family Zingiberaceae, commonly known as turmeric. Antibacterial activity of ionic, oil, resins and ethanolic fractions of turmeric was checked against both gram positive and gram negative Urinary Tract Infection isolates. Sixty-five bacterial strains were isolated from urine of patients suffering from urinary tract infection and identified by conventional methods. Eighty percent of total isolated organisms were found to be gram negative while remaining 20% were gram positive. Ionic, resin and ethanolic fractions of turmeric were found to possessed antibacterial activity against S. saprophyticus, S. aureus, S. epidermidis, S. pyogenes, E. faecalis and B. subtilis while oil fraction exhibited no activity against the same organisms. No activity of any of the four fractions was found against gram negative isolates. The antibacterial activity of turmeric was also compared with fifteen standard antibiotics. Comparative study of turmeric fractions with standard antibiotics showed that ionic, resin and ethanolic fractions of turmeric are 100% effective against all tested gram positive organisms, which are resistant to most of the broad-spectrum antibiotics used.
  Shahina Naz , Samia Ahmad , Sheikh Ajaz Rasool , Rahmanullah Siddiqi and Syed Asad Sayeed
  The extracts derived from Terminalia catappa leaves and fruit following antibacterial activity directed isolation, were screened for their antibacterial activity against species of corynebacteria, staphylococci, streptococci, enterococci, escherichia, salmonella and shigella. The results indicated that crude ethanolic extract, aqueous fraction of crude extract and its sub fractions (petroleum ether and ethylacetate) possessed prominent antibacterial activity, therefore supporting the medicinal uses of this species. In addition, further isolation and phytochemical analysis of the five fractions finally obtained led to the isolation of ferulic acid, vanillic acid, pelargonidin, cyanidin, myricetin, quercetin and gallic acid.
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