Pollution of soil with heavy metals, herbicides, antibiotics and other chemicals is known to have a negative effect on microbial activities. Therefore, the aim of this study was to isolate cultures of Azotobacter sp. from polluted and unpolluted soils and to study the effect of these pollutants on their growth. A total of 120 Azotobacter sp. were isolated from soils irrigated with wastewater (contaminated soils) and groundwater (uncontaminated soils). These isolates were screened for resistance to heavy metals, herbicide and antibiotics. Also, the soils from which the cultures were isolated were analyzed for the concentrations of Zn 2C , Cd 2C , Cu 2C , Pb 2C and Mn 2C they contained. Contaminated soil showed high levels of heavy metals as compared to uncontaminated soil. The size of the Azotobacter population in contaminated soil was lower than that in uncontaminated soil. Of the Azotobacter isolates, 64 that were recovered from contaminated soil exhibited high resistance to heavy metals (Hg 2C , Cd 2C , Cu 2C , Cr 3C , Co 2C , Ni 2C , Zn 2C and Pb 2C ) and herbicide 2,4-D compared to 56 isolates from uncontaminated soil. Also, isolates from contaminated soil showed high resistance to chloramphenicol, nitrofurantoin and co-trimoxazole compared to those isolated from uncontaminated soil. The majority of Azotobacter isolates from contaminated soil showed multiple-resistance to different metal ions and antibiotics. All isolates failed to grow at pH less than 6. Salt concentration (5%) was found to be inhibitory to all isolates. The most potent isolates from contaminated soil that showed multiresistance to all substances tested were identified on the basis of morphological and biochemical characteristics, and 16S rRNA as A. chroococcum. These resistant isolates could be employed in contaminated soils and/or bioremediation.

Water is necessary to life so when supplied as drinking water to consumers, a satisfactory quality must be maintained. In Egypt, infectious intestinal diseases are the major cause of hospitalization in almost all regions. The purpose of this study was to evaluate the microbiological quality of treated and untreated water samples from urban and rural communities. Thirty-five samples of treated (chlorinated) water from taps, 25 samples of bottled water and 15 samples of hand pump (untreated) water collected from different cities alongside the River Nile during the winter of 2007 were bacteriologically tested for safety as drinking water. This study indicated good quality of tap water and bottled water. The untreated water samples (hand pumps) were, however, slightly contaminated by faecal coliforms, faecal enterococci, Clostridium perfringens, Salmonella and Shigella. Consequently, the consumers in the villages receiving water through hand pumps are often exposed to the risk of water-borne diseases due to inadequate treatment of the raw water. Therefore, there are guidelines necessary to protect groundwater quality. Moreover, PCR-amplified by some functional gene fragments such as dctA, dcuB, frdA, dcuS and dcuR genes of the E. coli was adapted for use as a non-cultivation-based molecular approach for detection of E. coli populations from water samples without the need for pure and identified cultures.

Microbiology journal is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the research across the whole spectrum of the subject. These including bacteriology, virology, mycology and parasitology. In addition, the journal promotes research on the impact of living organisms on their environment with emphasis on subjects such a resource, depletion, pollution, biodiversity, ecosystem…..etc www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.

Three hundred and fourty nine isolates belonging to ten different species of Pseudomonas were isolated and identified from soil and water samples on four selective isolation media: Modified Trypticase soy agar (TSA), ACC-agar containing ampicillin-chloramphenicol-cycloheximide, Nitrate plus organic acid agar and Tryptophan substrate agar. The fluorescent species were P. putida (21.2% of the total Pseudomonas species), P. fluorescens (15.8%), P. aeruginosa (9.7%) and P. aureobaciens (2.6%), while the nonfluorescent species were P. stutzeri (12.4%), P. alcaligenes (11.2%), P. pseudoalcaligenes (9.5%), P. mendocina (8.3%), P. lemoignei (5.7%) and P. ruhlandii (3.4%). Modified TSA and ACC media were efficient for the isolation of both fluorescent and nonfluorescent species, whereas Nitrate and Tryptophan media were more selective for the isolation of nonfluorescent species. The optimum temperature for the isolation of different species ranged between 20 degrees and 37 degrees C.