فصلنامه زیست فناوری میکروبی
پیاپی 5 (تابستان 1389)

Currently there is an interest to use natural antibacterial compounds, Ziziphora clinopodioides, which is widely used in Iranian traditional medicine for treatment of common cold, gastrointestinal disorders and inflammations, is a member of Labiatae family. Several effects such as antibacterial, antifungal, antioxidant and anti-inflammatory have been reported as the effects of this plant. The antibacterial activity of methanolic extract and essential oil of Ziziphora clinopodioides was determined in this study. The aerial parts of Z. clinopodioides were collected. Plant materials were identified in the herbarium of the department of agricultural faculty of Jiroft Islamic Azad University. The dried and powdered plant materials were extracted by maceration method. Air dried plant material was hydro distilled using a Clevenger type apparatus to produce essential oil. The antibacterial activity of essential oil and methanolic extract were evaluated against Pseudomonas aeroginosa, Salmonella enterica, Enterobacter aerogenes, Staphylococcus aureus, Listeria monocytogenes and Bacillus cereus. MICs and MBCs were determined by the broth micro dilution method. The growth of all bacteria except Pseudomonas aeroginosa was inhibited by the essential oil and methanolic extracts of Z. clinopodioides. Minimum inhibitory concentration of essential oil for Listeria monocytogenes was 0.125 μg/ml and for Salmonella enterica and Enterobacter aerogenes was 0.25 μg /ml. MIC of methanolic extract of Z.clinopodioides for Listeria monocytogenes 1 μg/ml and for Salmonella enterica, Enterobacter aerogenes and Staphylococcus aureus was observed 2 μg/ml. The essential oil and methanolic extract of Z. clinopodioides had a strong and broad spectrum of antibacterial activity against many pathogenic bacteria especially Listeria monocytogenes.

The Consumption of dairy products, especially yoghurt, which is a fermented product, resulted and; microorganism's activity called Lactobacillus delbrueckii ssp.bulgaricu and Streptococcus thermophilus, can have beneficial effects on the body. Reducing cholesterol and triglycerides in the host is one of the effects of probiotic bacteria. In this study, the effects of probiotic yoghurt and Pegah yoghurt with 1.5% and 3% fat in in-vivo conditions were investigated. First a pure culture was obtained from the bacterial strains used in the preparation of probiotic yoghurt. Then diagnostic tests were employed to identify the bacteria and used them in producing yoghurt as well as to determine the stability of the bacteria in probiotic yoghurt. Then cholesterol and triglycerides levels were measured in the yoghurt samples. This study used 65 male White Wistar rats weighing 250±16g in seven groups. After gavage and separating the serum, using cholesterol, TG, HDL and LDL kits, the amount of each was calculated. It was observed that in yoghurts prepared with different levels of the Lactobacillus GG and S.thermophilus bacteria, after incubation the number of these bacteria reached 108 cfu / ml and was almost constant during the storage, which is an indication of bacteria stability in the produced probiotic yoghurt. Moreover, optimal pH in the probiotic yoghurt was 4.2 – 4.6. The results evaluation revealed that cholesterol and triglycerides levels in the probiotic yoghurt sample as well as in mice under gavage with probiotic yoghurt had significantly decreased compared to Pegah yoghurt especially 3% in the serum of mice under gavage with Pegah yoghurt. It was observed that the reduction in cholesterol was more than triglycerides and LDL more than HDL. The results indicate that the presence of probiotic bacterium of Lactobacillus GG in probiotic yoghurt reduced the lipid metabolites especially cholesterol in the mice, which is the main factor of low cholesterol and triglyceride compounds in probiotic yoghurt compared to common yoghurt.

The increasing concentration of organic matters, nitrogen and phosphorous cause an unbalanced growth of planktonic life and create serious environmental problems. The aim of this study is evaluation of phosphate uptake ability by bacterium isolated from soils contaminated with coal tar to remove phosphate from over plus phosphate in wastewaters. The first stage, sampling was performed from soils contaminated with coal tar in around of Esfahan coal tar refinery by nutrient agar plates. This study was done in order to isolate a bacterium with high ability to degrade coal tar but in during of identification, this bacterium was indicated with high ability to consume phosphate. To determine optimal P-uptake conditions, different variations were examined including pH, temperature, carbon source, phosphate and nitrogen concentration. P-uptake ability was compared with Acinetobacter calcoaceticus and E.coli. Finally, the growth and phosphate uptake were studied under the aerobic and anaerobic conditions. biochemical tests and 16S rDNA analysis for this bacterium showed similarity to Pseudomonas genus. The results obtained from optimization tests including pH of 7.5, temperature of 35˚ c and sodium acetate as the carbon source under the aerobic conditions. The most p-uptake was determined 4.8% under the optimal conditions. with regard to results obtained, this bacterium has a favorable ability to phosphate uptake and its store. Therefore, because high growth rate of this bacterium is useful for Phosphate removal on sludge.

Industrial importance of Lactic Acid Bacteria (LAB) is widely known. LAB are the greatest former of Probiotics and have numerous applications in health and industry. The aim of this study was to identify LAB from the raw milks of virgin heights of Alborz and introduce local species with industrial potential to be replaced for imported species. Also survey of present LAB diversity, preservation of local LAB in a microbial bank and looking for new species were the other goals of the study. Raw milk samples were collected from 14 selected areas of Alborz Heights and transported to the laboratory under standard terms. LAB colonies were isolated by macroscopic and microscopic observations and differential tests. DNAs of the 64 isolates were extracted and grouped by High Resolution Melting-Real Time PCR using 16SrDNA universal primers. Finally 1 sample was chosen from each group and sent for sequencing after performing PCR. Alignment of the resulted sequences with NCBI GeneBank identified 6 genuses, 9 species and 2 potentially new species. Streptococcus vestibularis, Enterococcus faecalis, Lactococcus lactis, Streptococcus infantarius, Leuconostoc argentinum, Lactobacillus brevis, Pediococcus pentosaceus, Lactobacillus rhamnosus, Lactobacillus plantarum and two bacteria from genuses Pediococcus and Enterococcus were identified by 16SrDNA analysis. The results show an amazing diversity of LAB in raw milks of Central Alborz. Most of the isolates have industrial potential and can be replaced for imported strains. Also due to 16SrDNA analysis, there is a chance for presence of two new species. The important point is that application of High Resolution Melting-Real Time PCR in this study resulted in a great decrease in time and expenses which proves the importance of using molecular techniques in microbiology and their combination with classic methods.

Salmonellosis is an infectious disease of all animals species caused by a number of different species of Salmonellae and manifested clinically by preacute septicemia or enteritis. Much recent investigation suggested that some probiotics such as Saccharomayces boulardii can prevent pathological changes caused by Salmonellae in vivo. This study was conducted to investigate the protective effects of Saccharomyces boulardii on intestine pathologic lesions of Salmonella typhimurium in rat. Thirty Conventional male rats were divided in to three group (A,b,C).Rats in group B and C received 1 ml of saline contained 107 ¬and 108 CFU of Saccharomyces boulardii orally for 5 days. Respectively animals in group A (as control) received only 1 ml saline as experiment groups on day five all animals were challenged orally with 107 Salmonella typhimurium on day 10, firstly all rats challenged with bacterium then all animals were euthanised. specimens of intestine were fixed in 10% buffered formalin solution for histological examinations and translated to pathologic library. The result of intestine histopathologic examinations was investigated by fisher exact test. The result indicate that all control groups show diarrhea and infilteration of inflammatory cells in mocosa compared with rat in experiment group that didn’t show any marked pathological changes in the intestine. This study indicates that sacharomyces boulardii hase protective effect on Salmonella typhimurium infection in rat and histological examination confirm this results.

Levan is a biopolymer consisting of fructose units which usage in medical and pharmaceutical and food industries. The production of levan biopolymer from Bacillus polymyxa and surveying the growth and extraction pattern of it in optimized situation was the purpose of this research. In this research 3-5% of inoculum's culture medium of Bacillus polymyxa with PTTC1020 was added to the production medium. Samples incubated at 30-35˚C and 200 rpm for 5, 7 and 10 days. Biopolymer was extracted by ethanol (95%) in two phases, after centrifuging at 2000 rpm. Effects of agitation on biopolymer production were assessed in different intervals. Grows pattern of bacteria drown toward the amount of biopolymer production. Biopolymer type confirmed by use of determining maximum optical density, melting point, viscosity, moisture content and IR Spectrum methods. The research outcome presented maximum amount of levan biopolymer production in the situation of 3 hours of agitation for two times per day and incubation of five days as 19.5 gram per liter. Melting point, nanometer maximum optical absorption, moisture content, ash weight and viscosity in 1% density of extracted levan was appointed 200˚C, 216, 20%,50% and 1/2 respectively. Assessing IR spectrum of levan biopolymer, showed the existence of hydroxyl, hydrocarbon, carbonyl, carboxyl bonds at 1053, 3488, 292 and 1633 nanometer length waves respectively. Levan biopolymer extracted in this research was determined 19.5 g/L in optimum situation which shown 1.26% increased comparison with the other research. According to results and chemical characteristics obtained, it seems being desirable to use this biopolymer in medical, pharmaceutical and food industries.

pXO1 plasmid in Bacillus anthracis encode genes responsible for toxin production and plasmid pXO2, encode genes responsible for capsule synthesis. Plasmid size responsible for toxin synthesis is 189kb and Plasmid size responsible for capsule synthesis is 95kb. The purpose of this study is investigation of the presence of pxo genes in the Bacillus cereus, Bacillus subtilis and Bacillus thuringiensis. In first step 65 soil samples were collected throughout the country and then Bacilluses identified using standard biochemical tests. The isolation of pXO1plasmid, was performed using phenol and chloroform and its presence was confirmed in agarose gel electrophoresis. Then performed separation of proteins and was used SDS-PAGE for observation of protein bands. From the 65 soil samples, were isolated 31 Bacillus that were including 19 Bacillus cereus, 12 Bacillus subtilis and 7 Bacillus of dedicated also were including 2 Bacillus cereus and 2 Bacillus subtilis and 3 Bacillus thuringiensis. In 13 Bacillus cereus associated pXO1 plasmid bands were observed in electrophoresis. In SDS-PAGE protein bands related to the pXO1plasmid responsible for encoding Bacillus anthracis toxin was observed in the 13 Bacillus cereus, ie 34/2 percent of total bacteria, but protein band related to pXO2 plasmid responsible for encoding capsule Bacillus anthracis was not found in review bacilluses total. This study showed that transformation of pXO1 plasmid from Bacillus anthracis to Bacillus cereus has been done in Iran but transformation of pXO2 plasmid was not performed to investigate Bacilluses.

Helicobacter pylori (H. pylori) is a micro-aerophilic, Gram-negative and flagellated bacterium which was first isolated from a human gastric biopsy specimen in 1983. This organism is probably the most common chronic bacterial infection of humans, present in almost half of the world population. The high clinical relevance of H. pylori infection has stimulated the development of numerous diagnostic methods. These methods can be classified as invasive, i.e. those that detect H. pylori directly in gastric biopsy specimens, or non-invasive, i.e, based on the study of various samples (e.g. serum, urine, breath air), which indirectly indicate the presence of H. pylori. Recently, enzyme immunoassays (EIA) for direct detection of H. pylori antigens in the stool have been developed and widely used because of their full non-invasive nature. There are two groups of the EIAs including polyclonal antibody-based stool antigen tests and monoclonal antibody-based stool antigen tests. The application of specific polyclonal antibodies against H. pylori-specific antigens such as alkyl hydro peroxide reductase (AhpC) may increase the efficacy and the specificity of polyclonal antibody-based stool antigen tests.