فصلنامه دنیای میکروب ها
سال هفتم شماره 4 (پیاپی 21، زمستان 1393)

Infectious bronchitis virus (IBV) is the prototype of the family Coronaviridae, which is the causative agent of infectious bronchitis (IB). This disease is highly contagious, which causes massive damages to the poultry industry. This study aimed to investigate the prevalence of IBV serotypes of broiler chicken in Gilan Province.

This cross-sectional study was carried out on trachea and lung tissue samples collected from 50 broiler chicken flocks in Gilan province. First, the IBV positive samples were identified by RT-PCR. Thereafter, The serotypes of these isolates was determined by Nested-PCR reaction specified for Massachusetts and B/793 serotypes.

Overall 32 out of 50 (64%) poultry chicken flocks were infected to IBV. Specific nested PCR on IBV positive RT-PCR products revealed that 10 (31.25%) of IBV positive samples were infected by 793/B type and 22 (68.75) were identified as Massachusetts type.

Massachusetts type vaccines such as H120 are only partially effective against other serotypes of virus. Because of the presence of 793/B type of virus in Gilan poultry farms, the addition of this strain in combination with Massachusetts strain seems necessary to stimulate better protective immunity.

Salmonellosis is a one of zoonotic diseases and Salmonella enterica is the most frequent agent of this disease. Some serotypes of Salmonella sp. harbour a plasmid which contains spv operon on it. This operon consists of five genes, namely spvRABCD. The aim of this study was to determine frequency of plasmid genes spvB, spvC and spvR in Salmonellaisolated from poultry industry in Chaharmahal va Bakhtiari province.

This cross – sectional study was carried out on 305 stool samples  obtained from poultries located at Charmahal va Bakhtiari province. Following identification of Salmonella based on routine biochemical tests. Polymerase chain reaction (PCR) assay was used for distinguish the strains and to determine the prevalence of the gene spvB, spvC and spvR.

Salmonella were identified in 160 (45.52%) samples, among them 94 cases (75.58%) were identified as Salmonella enteritidis after sefA amplification test. The prevalence of the genes spvB, spvC and spvR were 7.45, 60.76 and 14.69 %, respectively.

Due to the prevalence of Salmonella in poultries and to limitation of biochemical and serological tests, employment of molecular tests are very critical for identification of strains of Salmonella enterica and for distinguishing from other strains all around the country. Furthermore, the high prevalence of the plasmid genes involved in systemic infections can be reduced using Antibiotics.

The increases in the microbial antibiotic resistance and decreases in the sensitivity of bacteria to antimicrobial chemical compounds are some concerns of the researchers who look for herbal compounds as antimicrobial properties. The purpose of this study is to investigate the antibacterial and antioxidant properties of leaf and stem extracts of Dendrostellera lesserti against 10 human pathogenic bacteria.

Dendrostellera lesserti was collected from the Alvand Mountain (1961 m height) located at Hamedan province. After identification, the extracts were prepared using maceration method. In this sectional study, antibacterial activity was determined by agar well diffusion method, MIC (serial dilution method) and MBC. The antioxidant properties of these extracts was determined by DPPH method. Also, the amounts of phenol and flavonoid was assayed by Folin-ciocalteu and Aluminum chloride methods, respectively.

The largest growth inhibition zone with 27.3±0.6 mm diameter was observed on Micrococcus luteus culture exposed to ethanolic extract of the stem. The MIC and MBC of the extracted obtained from stem were lower than the leaf extract. Methanolic extract of stem in concentration of 1 mg/ml had the highest scavenging percentage of free radical. The methanol extracts of stem and leaf achieved the highest amount of phenol and flavonoid, 79.4±0.5 (mgGAE/g) and 2.1±0.1(mgQ/g), respectively.

The results of present study showed that alcoholic extract, especially methanol extract, of Dendrostellera lesserti showed antibacterial ability. Since the phenolic and flavonoids compounds have anti bacterial and anti-oxidant properties, the property showed in this study can be because of the presence of these compounds in the tissues studied.

Lantibiotics are small peptide antibiotics that produced by a large number of gram positive bacteria to limit growth of other bacteria. This study was performed with the aim of isolation and molecular identification of lantibiotic producer Bacilli from soil, also to optimize the production conditions and antibacterial activity of the product.

In this basic research, soil samples were collected from green bean fields located at Kazerun. The vegetative cells were killed by pasteurization method and the Gram positive spore former colonies were selected for further studies. These bacteria were grown in the broth media and their culture extracts were examined for lantibiotic production by well diffusion method. Appropriate colonies with high ability for lantibiotic production were selected and identified by biochemical and molecular methods. Also lantibiotic production at different temperatures and pH values was investigated.

The isolated strain was identified as Bacillus toyonensis based on DNA sequencing. Maximum lantibiotic production was determined after 24h incubation at 30°C and pH 7. These results showed that the addition of 1% glucose and pepton can improve lantibiotic production. The purified lantibiotic showed inhibitory effects on some gram positive bacteria.

According to ability of this isolated strain in lantibiotic production, further studies is required for more accurate identification of produced lantibiotic in order to be employed in pharmaceutical applications.

Biosurfactants are surface active compounds that produce by microorganisms. They are used in various industries such as petroleum, chemical, petrochemical, food industry, medicine, agriculture, etc. The purpose of this study was to optimize the production of biosurfactant in different carbon sources by Bacillus laterosporus.

In this study, Bacillus laterosporus was provided from the microbial collection of Shahid Chamran University of Ahwaz. Biosurfactant production was evaluated in different carbon sources such as kerosene, glucose and sugar cane molasses at 30 and 37° C and the incubation periods of 48 and 168 hours. Screening of biosurfactant production was carried out using oil collapse and emulsification index, surface tension, and cell surface hydrophobicity.

Bacillus laterosporus showed the lowest surface tension reduction in kerosene carbon source after 168 hours incubation at 37 ° C, and decreased surface tension to 21.28 mN/m. The highest percentage of emulsification was related to medium containing molasses carbon source (43%). Bacillus laterosporus cell surface hydrophobicity in kerosene, molasses and glucose was 65, 58 and 50 %, respectively. Maximum biosurfactant production by Bacillus laterosporus obtained in kerosene carbon source around 8.4 gr/L

The results showed that 37° C, 168 hours incubation and also using kerosene as carbon sources make the optimum condition for biosurfactant production by indigenous strain of Bacillus laterosporus.

Xanthan gum is a Heteropolysaccharide at the external cell of Xanthomonas, which acts as toxin for other plants. This study aimed to isolate and identify the Xanthomonas strain from leaves of lemon trees and to evaluate its ability in production of Xanthan gum. Materials & Methods

This cross-sectional study was performed on the leaves of lemon trees infected to bacterial canker. The strain was isolated on YDC medium. The morphological characteristics colonies were compared with the colonies of Xanthomonas  campestris PTCC 1473. Xanthan gum was produced in especial medium. A 16S rRNA procedure used to confirm the identity of strains.

In this study a new strain of Xanthomonas campestris was isolated and was called as saba.ton. This strain was recorded in the gene bank with access number KF706548.1. The amount of Xanthan production was obtained 0.081 to 1.5 g/100 ml.

In this study a new strain of Xanthomonas campestris was isolated. This strain was identified as an Iranian local strain which is potentially able to produce Xanthan gum without any optimization.

Xylitol is a naturally five–carbon polyol with a high sweetening ability. The biotechnological production of xylitol by microorganisms specially yeasts is very environmentally safe and has been studied as an alternative to the chemical method. The purpose of this study was xylitol production by Candida guilliermondii that isolated from spores of Zinnia.

The xylitol producing yeast strain was isolated on Yeast extract Pepton Xylose  (YePX) medium. The identity of strains was confirmed using PCR reaction. The xylitol produced by the strains was analyzed using tine layer chromatography (TLC) and specific kits. The concentration of Xylitol produced in this experiment was quantified using HPLC method.

The xylitol producing yeast strain was isolated from pollen of Zinnia elegans flower and was identified by 16S rRNA sequence analysis as Candida guilliermondii. This strain produced 24.67 g l-1 xylitol after 72 hours in medium contained 40 g l-1 xylose.

In this study xylitol was produced by Candida guilliermondii isolated from the nature. According to the properties of xylitol and the difficulties through chemical production of this compound, the sweetener produced by biotechnological methods can be used as an attractive sugar in the nutritional supplement and pharmaceutical industries.

Bushehr province is one of the major out of season tomato growing centres in Iran. The present study aimed to identify the most important tomato viruses and to determine their frequency following observation of the massive damages in these farms.

This cross-sectional study was conducted on 250 tomato samples collected from fields in Bushehr province, which showed signs of leaf mosaic, vein clearing, mottling, and stunting. The samples were tested by DAS-ELISA using polyclonal antibodies against major known tomato viruses to identify the viruses.

The results showed that tomato fields were infected with Tomato yellow leaf curl virus (TYLCV), Zucchini yellow mosaic virus (ZYMV), Eggplant mottled dwarf virus (EMDV), Cucumber mosaic virus (CMV), Alfalfa mosaic virus (AMV), Potato virus X (PVX) and Tomato mosaic virus (ToMV) with a frequency of 94.5, 72, 65, 56.7, 27, 5.4 and 5%, respectively. No infections were observed with Squash mosaic virus (SMV), Potato virus Y (PVY), Watermelon mosaic virus (WMV) and Potato leaf roll virus (PLRV).

The results of this study showed highly contamination (50-95%) of these fields to TYLCV, ZYMV, EMDV and CMV. Therefore, application of precautionary operations, especially at the level of purchasing the spores and tracking the sings of diseases and vector insects, looks necessary to control the distribution of these viruses.