ISSN 2736-1756
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-005, January, 2019. © International Scholars Journals
Full Length Research Paper
Effect of salinity on free living - diazotroph and total bacterial populations of two saline soils
Azam Moradi1, Arezoo Tahmourespour2*, Mehran Hoodaji3 and Farhad Khorsandi4
1Department of Soil Science, Faculty of Agriculture, Islamic Azad University, Khorasgan Isfahan Branch, Esfahan, Iran.
2Department of microbiology, Islamic Azad University khorasgan Isfahan branch, Iran.
3Department of soil science, Islamic Azad University khorasgan Isfahan branch, Iran.
4Department of soil science, Islamic Azad University Darab branch, Iran.
Accepted 12 January, 2019
Abstract
Salinization of soil is a serious problem and is increasing steadily in many parts of the world. Recently, soil biotechnology application can improve the potential of saline soils land use in agriculture. The aim of this research was determining the salinity effect on free-living diazotroph and total bacterial populations in two saline soils. Soil samples with salinity of 35 and 70 dS/m selected. The heterotrophic and free-living diazotrophic bacterial populations were counted on nutrient agar and free-nitrogen medium. The salinity effect on population of each soil was determined on same media supplemented with 0.44 and 1.02 M NaCl (equal with EC 35 and 70 dS/m of each soil). The results showed that, the free- living diazotrophic and total heterotrophic bacterial populations in soil sample 1 was significantly (P < 0.05) more than soil sample 2. Also the heterotrophic and diazotrophic bacterial population in each soil sample were significantly less in the presence of salt. Soil salinity is a stress factor relating to microbial selection process and can reduce bacterial diversity and control microbial abundance, composition and functions. Use of soil halotolerant or halophyl bacterial strains which can either fix atmospheric nitrogen will be environmentally begin approach for nutrient management and ecosystem function for saline soils.
Key words: Salinity, bacterial population, diazotrophic, heterotrophic.
Mehran Hoodaji and Farhad Khorsandi, Azam Moradi, Arezoo Tahmourespour*
Page: 1 - 5
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-006, January, 2019. © International Scholars Journals
Full Length Research Paper
Isolation and identification of endophytic bacterium W4 against tomato Botrytis cinerea and antagonistic activity stability
Cong-Jun Yang1,2, Xin-Gang Zhang1,2, Guan-Ying Shi1,2, Hao-Yu Zhao1,2, Long Chen1,2, Ke Tao1,2* and Tai-Ping Hou1,2*
1College of Life Sciences, Sichuan University, Chengdu 610064, China.
2Key Laboratory of Bio-resources and Eco-environment, Ministry of Education, Sichuan University, Chengdu 610064, China.
Accepted 21 December, 2018
Abstract
Of the 72 endophytic bacteria isolated from healthy tomato stems and leaves from field-grown plants, the strain W4 gave strongly inhibitory effect on Botrytis cinerea Pers, with the inhibition rate 78% in dual culture assay and 100% using fermentation filtrate diluted 20 times. Based on morphological, physiological and biochemical properties, 16S rDNA gene sequences and Biolog system analysis, the isolate W4 was identified and named as Brevibacillus brevis W4. The activity determination demonstrated that the antagonistic effect of W4 fermentation filtrate on B. cinerea was fairly stable to temperature, pH, ultraviolet light. Only heated at 90°C for 30 min or at 100°C or above for 10 min, the inhibitory effect was significantly reduced. The inhibitory rate remained above 90% at pH 2-11 and above 95% under ultraviolet light radiation for 5-240 min. These stability characteristics of antagonistic activity were conducive to future applications in the field.
Key words: Botrytis cinerea, Brevibacillus brevis W4, endophytic bacteria, antagonistic activity.
Ke Tao* and Tai-Ping Hou*, Long Chen, Xin-Gang Zhang, Guan-Ying Shi, Cong-Jun Yang, Hao-Yu Zhao
Page: 1 - 6
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-008, January, 2019. © International Scholars Journals
Full Length Research Paper
Antibiotic resistance in Escherichia coli strains isolated from water springs in Al-Ahsa Region
Abdullah M. Alzahrani1 and Youssuf A. Gherbawy2,3*
1Department of Biology, Faculty of Science, King Faisal University, Saudi Arabia.
2Department of Biology, Faculty of Science, Taif University, Saudi Arabia.
3Department of Botany, Faculty of Science, South Valley University, Qena, Egypt.
Accepted 30 December, 2018
Abstract
In Saudi Arabia, water resources are largely limited to groundwater, which is used both for drinking and agriculture. There is no surface water except for a few oases and no permanent streams. The contamination of this source possibly through wastewater, agriculture activities and wild birds as well as amphibians and reptiles that have access to wells and springs. Twenty six strains of Escherichia coli, isolated from water springs in Al-Ahsa Region of Saudi Arabia were analyzed for their antimicrobial susceptibility. Fifteen strains, representing 57.74% of the total twenty six strains, showed multidrug resistance phenotypes. RAPD -PCR with two random primers produced different DNA fingerprinting profiles with varied number of bands. The dendrogram obtained from the RAPD-PCR results discriminated the isolates into 26 single isolates and 3 clusters at the level of 40% similarity.
Key words: Escherichia coli, antibiotic resistance, water springs, RAPD-PCR.
Youssuf A. Gherbawy*, Abdullah M. Alzahrani
Page: 1 - 8
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-006, January, 2019. © International Scholars Journals
Full Length Research Paper
Actinopolyspora egyptensis sp. nov., a new halophilic actinomycete
Wael N. Hozzein1,2* and Michael Goodfellow3
1Chair of Advanced Proteomics and Cytomics Research, College of Science, King Saud University, Riyadh, Saudi Arabia.
2Department of Botany, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
3Division of Biology, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK.
Accepted 22 December, 2018
Abstract
A halophilic actinomycete, designated HT371T, was isolated from a soil sample collected from the shore of the salty Lake Qaroun, Egypt, and was the subject of a polyphasic study. Analysis of 16S rRNA indicated that the isolate belonged to the genus Actinopolyspora and constituted a separate clade in the Actinopolyspora 16S rRNA gene tree with similarity values of 96.5 and 96.2% with Actinopolyspora halophila DSM43834T and Actinopolyspora mortivallis DSM44261T, respectively. Isolate HT371T had chemotaxonomic and morphological properties consistent with its classification in the genus Actinopolyspora and could grow on agar plates at NaCl concentrations of up to 25% (w/v). The isolate was readily differentiated from the type strains of genus Actinopolyspora using a range of phenotypic characters. On the basis of polyphasic evidence, the strain HT371T represents a novel species for which the name Actinopolyspora egyptensis sp. nov. is proposed. The type strain is HT371T (=CGMCC 4.2041T).
Key words: Actinopolyspora egyptensis sp. nov., halophilic isolate, polyphasic taxonomy.
Wael N. Hozzein*, Michael Goodfellow
Page: 1 - 6
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 13 (1), pp. 001-006, January, 2019. © International Scholars Journals
Full Length Research Paper
-lactam antibiotic resistance in Escherichia coli commensal faecal flora of healthy population in Taif, Saudi Arabia
Eman Mohammed Halawani
Department of Biology, Faculty of Science, Taif University, Taif, Saudi Arabia. E-mail: [email protected]. Tel: 00966505708387. Fax: 009667433699.
Accepted 10 December, 2018
Abstract
One hundred and twenty faecal sample of commensal Escherichia coli strains were collected from different healthy persons and tested for their susceptibility to 12 -lactam antibiotics by disc diffusion and minimum inhibitory concentration methods. Colonization with strains resistant to ampicillin (Amp), amoxicillin, carbenicillin and peperacillin was detected in 36.7% of the tested isolates. Resistance patterns to 3-6 -lactams was observed in 91.7% of the tested E. coli isolates. Transfer of Amp resistance marker by conjugation was usually associated with Strepomycin (Stm) and sulfonamise (Sul) in 100% of tested isoletes and with chloramphenicol (Clm) and tetracycline (Tet) in 63.3 and 45.6% of the isolates, respectively. This suggests that resistance markers to Amp, Stm, Sul, Tet and Clm existed as cossets on cojugative plasmids. Therefore, resistance to these antibiotics could rapidly disseminate and persist in the Saudi Society. All Amp resistant isolates produced one or two types of -lactamases with molecular weights of 28.9 and 28.8 KDa, which indicated TEM-1 and SHV-1. Both types of - lactamases are known to be plasmid-mediated in enteric bacterial species and are common in E. coli commensal faecal flora. Extended-spectrum -lactamases (ESBLs) were not detected in any of the tested strains and therefore, these types of -lactamases are uncommon in commensal E. coli in citizens of Taif. Measures should be taken to prevent the misuse of -lactams and the spread of antibiotic resistance in Saudi Society.
Key words: Antibiotic resistance, -lactams, -lactamases, commensal Escherichia coli.
Eman Mohammed Halawani
Page: 1 - 6
Research Article
Advanced Journal of Microbiology Research ISSN 2241-9837 Vol. 12 (12), pp. 001-010, December, 2018. © International Scholars Journals
Full Length Research Paper
Identification of clusters in tissue samples in gene expression data with Principal Component Analysis based on relative variance matrix
Uzma Nawaz* and Asghar Ali
Department of Statistics, Bahauddin Zakariya University, 60800, Multan, Pakistan.
Accepted 04 December, 2018
Abstract
Principal Component Analysis (PCA) has been in use as a preprocessing step to clustering for long. We have focused on the clustering of tissue samples in gene expression data. Different clustering techniques and algorithm are available in literature on gene expression data but with the existing ambiguity on the number of clusters, apart from relying on biologically known groups. A consensus is needed to reach on the number of clusters in the wide variety of existing clustering techniques based on different similarity or dissimilarity metrics. The conventional usage of PCA for clustering is either by forcing the unit variance to each variable or the high magnitude of variance of an individual variable is allowed to dominate the entire results of PCA. We propose the use of relative variance covariance method in PCA, so as to give due consideration to the joint and individual variances in the dataset and identify clusters with principal component loadings. We emphasize empirically that the proposed approach of PCA is conclusively more informative than the available approaches to identify cluster structure in tissue samples (sample expression profiles). Clusters formed are valid with the existing results on the data set under study and with valid biological background.
Key words: Clustering methods, gene expression analysis, principal component analysis, the relative variance covariance matrix, principal component loadings.
Uzma Nawaz*, Asghar Ali
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