فهرست مطالب a. akhavansepahi

Persian Gulf or Pars Sea is a water course which is in the direction of Oman Sea and is between Iran and Arab Peninsula. The strategic strait of Hormoz is curved shape strip which is square Iran Plateau from Saudi Arabia and connects water of Persian Gulf Oman Sea and India Ocean. The goal of this study was to investigate the present Halomonas varieties which live in beaches belonging to strait of Hormoz and which are a part of biological diversity of this strait. Twelve samples from the water and sediment of this region from different depths of striat of Hormoz were collected and sent to laboratory in sterile conditions. Enrichment of samples was done in the Alkaline Peptone Water medium and Nutrient Broth medium. Samples were incubated on 3 solid incubational environments: Endo, EMB and Mac Conkey Agar. Finally 70 isolates were obtained from these environments. Genetic test was done based on sequencing 16S rRNA. The phylogenetic analysis on the samples, based on 16S rRNA analysis, identified three Halomonas species including Halomonasvenusta, Halomonas sulfidaeris and Halomonas alkaliphila. This study shows that beaches of strait of Hormoz is a good habitat for halophile gram negative bacteria ( Halomonas) which may have biotechnical applications .

Biosurfactants are active surface components produced by some bacteria and fungi. These molecules reduce surface and interfacial tension in aqueous solutions and biphasic systems respectively. The most important application of biosurfactants is in oil industry to enhance oil recovery. The aim of this study is to isolate biosurfactant-producing bacteria and optimize the conditions such as temperature and pH for maximum biosurfactant production. Samples were collected from 8 selected points of oil-contaminated soils in the Sirri Island. Overall, 160 strains of bacteria were investigated in terms of isolation and morphological and gram stain. 59 strains had hemolytic activity and 46 strains had oil collapsing ability. Also, the results of oil displacement test were positive for 20 strains. Afterwards, 18 strains were selected and complementary tests such as foam formation and emulsification activity and surface tension were performed on them. Finally, two strains were found to be able to reduce surface tension more than 30 mNm-1 at 37 °C and a pH value of 7.0. Two strains with a high amount of biosurfactant production and emulsification ability were obtained in the present study. Regarding the high potential of the biosurfactant produced, it is suggested that it should be used in commercial applications such as enhanced oil recovery, bioremediation of soil and marine environments, and food industries.

Backgrounds and

Total and Fecal coliforms (TC and FC), heterotrophic plate count (HPC), were counted by microbiological method and E.coli O157:H7 were detected through immunological and Real time PCRmethods inwater intake and all of units of Isfahanwater treatment plant (IWTP).

The microbial profile including TC, FC, and HPC, were monitored and turbidity and total organic carbon were analyzed in 8 locations of water intake, and unit operation and processes of IWTP, including, inlet, sedimentation, ozonation, and filtration and finished water. Immunological method through anti-serum kits and molecular method of RT-PCR were used to detect E.coli O157:H7 in the 8 locations and also the sludge of the sedimentation basin and filters backwash water of IWTP.

Survival of E.coli O157:H7 in sludge sample of sedimentation basin was indicated by formation of agglutination particles in immunological method and through indicator probes in the RT-PCR method. However, E.coli O157:H7 was not detected in water samples of other units of IWTP. The removal percent of TC, FC, and HPC were: 59.5, 49, and 54.8 % in sedimentation basin; 66, 45.8, and 57 % in ozonation;: 98.8, 98, and 78.8 in the filtration; and 96, 100, 91% in disinfection, respectively.

This study approved the existence of the pathogenic coliform, E.coli O157:H7 in thesludge of sedimentation basin. Absent of E.coli O157:H7 in the finished water indicates that the existing units of IWTP could eliminate these pathogenic bacteria, before reaching the final units of the plant, including the filters and disinfection.