MOSP - Macao Scientific Publishers

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Osmoadaptation and plant growth promotion by salt tolerant bacteria under salt stress

Aisha Waheed Qurashi* and Anjum Nasim Sabri

Abstract: Establishment of biofilm, production of exopolysacharides (EPS) and accumulation of endogenous osmolytes under varying stress conditions are significant strategies adopted by bacterial strains for their successful survival in plant rhizosphere. Our studies focus on determining the osmoadaptation strategies used by two native salt-tolerant strains Oceanobacillus profundus (Pmt2) and Staphylococcus saprophyticus (ST1) and their plant growth promoting abilities. The ability of these strains to be used as inoculants for Lens esculenta Var. masoor 93 under salt stress was tested in the laboratory. We found that unlike the bacterial growth, biofilm formation, exopolysaccharide production and endogenous osmolyte (proline and glycine betaine) accumulation increased at higher salt stress. Biofilm formation and endogenous osmolytes increased with increasing salt concentrations. The maximum increase in EPS accumulation was observed at maximum NaCl stress for ST1. Bacterial inoculation improved growth parameters and endogenous osmolytes accumulation of plants under salt stress compared to noninoculated control plants. The ST1 strain in this work efficiently produced biofilm and exopolysacharide and accumulated osmolytes in response to NaCl stress. It could be speculated that these strategies reverse the detrimental effects of high osmolarity in soil and helpful for improving crop under salt stress.[...] Read More.

Keywords: Biofilm, exopolysaccharide, endogenous osmolytes, Lens esculenta, salinity.

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The use of a high resolution melt real-time polymerase chain reaction (PCR) assay for the environmental monitoring of Vibrio cholerae

Wouter Jacobus le Roux* and Gerhardus Nicolas van Blerk

Abstract: A real-time polymerase chain reaction (PCR) assay utilizing high resolution melt (HRM) curve analysis was developed and tested for the monitoring of Vibrio cholerae in water samples. The assay utilized previously published primers that are specific to regions of the V. cholerae ompW and ctxAB genes, allowing it to differentiate between toxigenic and non-toxigenic strains. The ompW and ctxAB primers amplify target regions of 588 and 564 bp in length (respectively) and the amplicons could be accurately identified using HRM curve analysis. High resolution melt curve analysis provided additional accuracy for the determination of amplicon melting temperatures, and allowed amplification of the two targets in a multiplex reaction. Two laboratories employed the assay to analyse 178 water samples obtained from diverse environmental water sources, for the presence of V. cholerae. The assay was found to be a rapid, highly accurate, sensitive and cost effective method for the detection and distinction between toxigenic and non-toxigenic V. cholerae strains in water.[...] Read More.

Keywords: Vibrio cholerae, high resolution melt, real-time polymerase chain reaction (PCR).

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In vitro larvicidal action of Paecilomyces marquandii crude extract

Filippe E. F. Soares, Fabio R. Braga, Hugo L. A. Geniêr, Jackson V. Araújo, Lucas B. Campos and José H. Queiroz*

Abstract: The aim of this present work is to produce Paecilomyces marquandii crude extract and its in vitro larvicidal action. Saccharose, glucose, coffee residue, soluble starch, insoluble starch, soybean meal and wheat bran were the carbon sources tested. NaNO3, NH4Cl, soybean meal, (NH4)2SO4, yeast extract, casein peptone, tryptone and NH4NO3 were the nitrogen sources tested. Central composite design was applied to determine the optimal concentration of the tested significant variables. The best carbon sources were glucose and soybean meal, while the best nitrogen source observed was tryptone. The greatest value for proteolytic activity was 246.58 U/ml due to the concentration of tryptone and pH value. Results showed that the optimum pH was 8.0, while the optimum temperature was 60°C. The optimized extract obtained from P. marquandii exhibited in vitro larvicidal activity with 60.1% reduction. Tryptone and pH optimized the production of proteases by fungus P. marquandii.[...] Read More.

Keywords: Nematophagous fungi, Paecilomyces marquandii, crude extract, larvicidal action, surface response.

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Isolation and characterization of a biosurfactant-producing bacterium from Daqing oil-contaminated sites

Tong Liu, Jumei Hou, Yuhu Zuo*, Sining Bi and Jing Jing

Abstract: Biosurfactants are biodegradable, non-toxic and ecofriendly compounds released by microorganisms. Most of the microorganisms were isolated from contaminated sites by petroleum hydrocarbon and industrial wastes. In this study, a biosurfactant-producing strain was isolated from Daqing oil-contaminated sites in China by enrichment culture, hemolytic activity assay, hydrolyzing oil activity assay, improved degreasing effect assay, and emulsification activity measurement. The strain was identified as Pseudomonas sp. BS1 based on its physiological characteristics and analysis of its 16S rRNA gene sequence. The identified isolate is capable of producing glycolipids or other anionic surfactants as determined in our analysis of a phenotypic assay using CTAB. The biosurfactant was isolated from the culture supernatant and identified as dirhamnolipids (Rha-Rha-C10-C10) by high-performance liquid chromatography–mass spectrometry. The culture filtrate and cell-free supernatant produced by this isolate were found to be highly effective in oil displacement from oil sand, suggesting that the isolate has potential use in enhanced oil recovery.[...] Read More.

Keywords: Biosurfactant, Pseudomonas sp., dirhamnolipids, microbial enhanced oil recovery.

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Isolation and characterization of EST-SSRs in the Ramie

Jian-Hua Chen, Ming-Bao Luan, Shu-Feng Song , Zi-Zheng Zou, Xiao-Fei Wang, Ying Xu, and Zhi-Min Sun

Abstract: In order to develop the more EST-SSRs, 320 ESTs of ramie from NCBI were analyzed. 76 SSR primer-pairs developed from 320 ESTs were tested among 62 ramie individuals, and 27 SSR loci were polymorphic. Among the 27 primers, the numbers of alleles per locus ranged from two to five, in which 19 primers amplify two alleles, seven primers amplify three alleles, and only one primer amplifies five alleles. Observed heterozygosity (HO) of overall loci among the 27 primer pairs ranged from 0.16 to 0.93 and expected heterozygosity(HE) ranged from 0.21 to 0.66.Of the 27 loci, 14 displayed significant deviations from Hardy–Weinberg expectations (P < 0.05). No significant linkage disequilibrium (LD) was detected among the 27 loci. The 27 primers have been used in the ramie molecular linkage map and genetic diversity analysis successfully.[...] Read More.

Keywords: Microsatellite marker, ramie, EST, EST-SSR.

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In vitro assessment of Inula spp. organic extracts for their antifungal activity against some pathogenic and antagonistic fungi

Faten Omezzine*, Mejda Daami-Remadi, Asma Rinez, Afef Ladhari and Rabiaa Haouala

Abstract: Inula viscosa, Inula graveolens and Inula crithmoïdes (Asteraceae) leaf and flower organic extracts (hexane, chloroform and methanol) were assessed for their antifungal activity against two Trichoderma species (Trichoderma harzianum and Trichoderma viride) and three formae speciales of Fusarium oxysporum. I. viscosa organic extracts showed an important inhibitory activity against all target fungal isolates. Growth inhibition percentage ranged between 17-61, 77-100, and 55-100% in presence of hexane, chloroform and methanol I. viscosa leaf extracts, respectively. Flower organic extracts reduced mycelial growth of all fungi by 32-66, 30-75, and 8-70%, respectively. For I. graveolens, Stem + leaf organic extracts showed more or less important inhibition depending on solvent nature, though, flower organic extracts were found to be the most effective against tested fungi: a total inhibition of growth was recorded with methanol fraction against all target fungi and with hexane fraction against F. oxysporum f. sp. melonis (FOM) and T. viride. In presence of I. crithmoïdes leaf organic extracts, a total growth inhibition was noted with the three extracts against T. harzianum, with hexane and methanol fraction against T. viride and with chloroform fraction against FOM. I. crithmoïdes flower extracts caused a highly significant growth inhibition of about 57-100, 66-100, and 100-100% with hexane, chloroform and methanol extracts, respectively. Therefore, I. viscosa, I. graveolens and I. crithmoïdes could be an important source of biologically active compounds useful for developing environmentally safe antifungal products.[...] Read More.

Keywords: Antifungal activity, organic extracts, Inula, radial growth.

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Scrutiny for a disaccharide oxide reductase from filamentous extracellular pathogens

Monica A. Calderon Oropeza*, Raul A. Mendoza Martinez , Georgina Reyna Lopez, Gustavo Santoyo, Alberto Flores Garcia and Mauro M. Martinez-Pacheco

Abstract: World demand to find microorganism producers of enzymes with a potential biotechnological use is increasing daily. Therefore, the objective of this study was to find one or more microorganisms capable of oxidizing sugars. Of the thirteen strains tested AFG2 Colletotrichum lindemuthianum was the one who showed the best results concerning oxidant capacity against a variety of disaccharides. This fungus was selected for the time course of production of an extracellular oxide-reducing enzyme in liquid minimal medium. A disaccharide-oxidizing peak was obtained on the tenth day of incubation. It was found that the oxide-reducing activity is of enzymatic nature given that the extracellular extract is exposed to enzyme inhibitors and various denaturing agents. Additionally, it was possible to visualize the oxide-reducing activity by zymogram which allowed us to identify a band of enzyme activity with a calculated molecular mass of 79.43 kDa. Thus, C. lindemuthianum AFG2 wild fungal isolate is a candidate to study the production of these enzymes under optimized growth conditions that can increase performance.[...] Read More.

Keywords: Colletotrichum lindemuthianum, disaccharide oxide reductase activity relative zymogram.

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Molecular cloning and extracellular expression of cyclodextrin glycosyltransferase gene from Bacillus sp. NR5 UPM

Norhayati Ramli, Suraini Abd-Aziz*, Mohd Ali Hassan, Noorjahan Banu Alitheen, Kamarulzaman Kamaruddin and Zoolhilmi Ibrahim

Abstract: The cloning of a polymerase chain reaction (PCR) gene fragment from Bacillus sp. NR5 UPM isolated from the soil in Malaysia into an Escherichia coli expression vector was successfully carried out. Analysis of the nucleotide sequences revealed the presence of an open reading frame of 2112 bp which encoded a protein containing 704 amino acids with a putative molecular weight of 78.6 kDa. The deduced amino acids sequence showed about 98% homology with the CGTase from Bacillus sp. KC201. Compared to the wild type, the CGTase that was produced in E. coli cells only required one-fourth of culture time and neutral pH to produce CGTase. After 12 h of cultivation, the CGTase activity in the culture medium reached 29.6 U/ml, which was approximately 2.5-fold higher than the CGTase from the parental strain. The CGTase was produced extracellularly by E. coli (94%) indicating the signal peptide was functional in E. coli.[...] Read More.

Keywords: Molecular cloning, nucleotide sequence, cyclodextrin glycosyltransferase, Bacillus sp. NR5 UPM.

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Bacteremia due to multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL) producing Acinetobacter baumannii

Abdollah Bazargani and Zahra Hashemizadeh*

Abstract: Bacteremia due to Acinetobacter baumannii is a common problem in hospitals worldwide. Physicians in the intensive care units (ICUs) encountered a serious challenge of finding a drug to cure the extended-spectrum beta-lactamase (ESBL) producing and multi-drug resistant (MDR) A. baumannii bacteremia. Our aim was to determine the frequency of A. baumannii bacteremia in an Iranian hospital ICUs, their antibiotic susceptibility patterns, and the frequency of ESBLs by a cross-sectional study. A total of 340 patients admitted to ICUs during a 6 month period of study were investigated for bacteremia due to A. baumannii. Bacteria isolates from blood specimens were identified as A. baumannii by API 20NE system. Antimicrobial susceptibility was studied with disk diffusion method. Detection of ESBLs was done by double disk synergy test. Of the 340 patients investigated, bacteremia was found in 114 cases (33%). A. baumannii was diagnosed as the etiological agent of bacteremia in 69 cases (60.5%). All the isolates were multi-drug resistant. Except one, all the remaining isolates (98.6%) were resistant to at least 7 of 13 tested antibiotics. Pandrug-resistance was observed in 4 isolates (5.6%). Of all the isolated A. baumannii, 49 (71%) were found to be resistant to cephalosporins by screening tests and among them 27 isolates (39%) were found to be ESBL producing. Our study showed a high frequency of A. baumannii bacteremia occurrence in our hospital ICUs. An urgent intervention is needed to reduce the MDR bacterial load in these critical units.[...] Read More.

Keywords: Acinetobacter baumannii, bacteremia, multi-drug resistant, extended-spectrum beta-lactamase.

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Identification of some Penicillium species by traditional approach of morphological observation and culture

Suhaib A. Bandh*, Azra N. Kamili and Bashir A. Ganai

Abstract: Ninety six samples of water collected from Dal Lake, Kashmir at eight different sites for a period of one year from April 2010 to March 2011 were tested for the presence of Penicillium species. Five different species of the said genus were isolated from the samples by serial dilution technique. Out of total 122 fungal colonies isolated, five species of Penicillium viz, Penicillium olivicolor, Penicillium commune, Penicillium chrysogenum, Penicillium funiculosum and Penicillium dimorphosporum were obtained. Among the isolated species P. funiculosum was the most abundant (28.7%) followed by P. chrysogenum (27.04%), P. dimorphosporum (23.77%), P. olivicolor (16.40%) and P. commune (4.09%). Maximum percentage of fungal colonies (27.7%) was observed at site PKB followed by TBN (21.13%), DLG and GB (13.15%) each, NL (8.45%), BHN (7.04%), HB (5.63%) and BD (3.76%).[...] Read More.

Keywords: Macroscopic, microscopic, Dal Lake, serial dilution, water, Penicillium.

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