The Cell Division Gene Ftsz2 of Sinorhizobium Meliloti is Expressed At High Levels in Host Plant Medicago Truncatula Nodules in the Absence of Sini

In this study, we investigated the role of quorum sensing (QS) in expression of the Sinorhizobium meliloti cell division gene ftsZ2 in free-living cells and within nodules of its host plant, Medicago truncatula. Using a ftsZ2 promoter reporter fusion, we were able to track the expression of this gene in wild-type S. meliloti cells and QS mutant backgrounds in planta. Our findings revealed that expression of ftsZ2 in free-living cells was changed or reduced in sinI mutant cells compared with wild-type cells while expression in planta was substantially higher in the absence of sinI. The results further clarify the involvement of quorum sensing in the control of bacterial cell division during the symbiosis in planta

In vivo dynamics of the quorum sensing-related interplay during symbiotic interaction between the nitrogen fixing bacterium, Sinorhizobium meliloti, and its eukaryotic host, Medicago truncatula

Quorum sensing has been shown to play a role in the symbiosis between Sinorhizobium meliloti and its host plant Medicago truncatula. Quorum sensing (QS)-mediated gene regulation is central to the interactions of bacteria with their eukaryotic hosts. The ExpR/Sin quorum-sensing system of the Gram-negative bacterium Sinorhizobium meliloti plays a significant role in the establishment of symbiotic interaction with its host plant Medicago truncatula. This bacterial signaling mechanism and plant responses to bacterial QS signals are important to the success of plant-bacteria interaction. Eukaryotes, in turn, can recognize and manipulate bacterial QS. While hundreds of Sinorhizobium genes are now known to be QS-regulated in laboratory shake cultures, less is known about QS regulation in natural environments or during symbiosis. In this study, we investigated the role of quorum sensing in expression of two important Sinorhizobium meliloti genes: the AHL synthase gene sinI and the bacterial cell division gene ftsZ2 in free-living bacteria and nodules of its host plant, Medicago truncatula and the role of cell-to-cell signaling (Quorum Sensing) during these interactions in vivo. Red-fluorescent protein reporters (Rfp) were constructed in promoters of these genes and by using sinI::tdRfp and ftsZ2::tdRfp promoter reporter fusions we were able to track the expression of these genes in wild-type S. meliloti cells and QS mutant backgrounds in planta using Confocal Laser Scanning Microscopy (CLSM). The overall goal of this work was to characterize the in vivo dynamics of the QS-related interplay during symbiotic interactions between the nitrogen fixing bacterium, Sinorhizobium meliloti, and its legume host, Medicago truncatula. We have shown that the Rfp reporter genes survived infection and were expressed in the host, further they were differentially expressed in vitro in contrast to the in vivo. The production of AHL mimics by plants suggests that bacteria and plants utilize this method of bacterial communication as a control point for influencing the outcome of their interactions. Our results revealed that mexpression of ftsZ2 in free-living cells was changed or reduced in sinI mutant cells in contrast to the wild type cells in vitro while its expression in planta was substantially higher in the absence of sinI. The addition of ethyl acetate extracts prepared from bacteroids of nodules infected with wild type or sinI mutant cells to free-living cells had no effect on ftsZ2 expression in wild-type or sinI background. For sinI expression in vitro study, it was found that the addition of AHLs did no affect the levels of sinI expression. In addition, it was determined that sinI expression in vivo was the highest in wild type background and there was a high expression of sinI in sinI mutant cells

Microbial community analysis of the hypersaline water of the Dead Sea using high-throughput amplicon sequencing

Amplicon sequencing using next-generation technology (bTEFAP ) has been utilized in describing the diversity of Dead Sea microbiota. The investigated area is a well-known salt lake in the western part of Jordan found in the lowest geographical location in the world (more than 420 m below sea level) and characterized by extreme salinity (approximately, 34%) in addition to other extreme conditions (low pH, unique ionic composition different from sea water). DNA was extracted from Dead Sea water. A total of 314,310 small subunit RNA (SSU rRNA) sequences were parsed, and 288,452 sequences were then clustered. For alpha diversity analysis, sample was rarefied to 3,000 sequences. The Shannon-Wiener index curve plot reached a plateau at approximately 3,000 sequences indicating that sequencing depth was sufficient to capture the full scope of microbial diversity. Archaea was found to be dominating the sequences (52%), whereas Bacteria constitute 45% of the sequences. Altogether, prokaryotic sequences (which constitute 97% of all sequences) were found to predominate. The findings expand on previous studies by using high-throughput amplicon sequencing to describe the microbial community in an environment which in recent years has been shown to hide some interesting diversity

Detection of antibiotic-producing Actinobacteria in the sediment and water of Ma’in thermal springs (Jordan)

Introduction Detection of new Actinobacteria is significant to discover new antibiotics because development of new antibiotics is connected to the characterization of novel bacterial taxa. This study has focused on the identification and isolation of antibiotic-producing Actinobacteria from the sediment and the water of Ma’in thermal springs (48-59°C) situated in the center area of Jordan. Methods Samples of sediment and water were transferred to glucose yeast malt agar medium and Actinobacteria were cultivated, isolated and identified according to scanning electron microscopy and 16S rRNA gene analysis. Antibacterial activities of the isolates were then tested against different test bacteria by agar well diffusion method. Results Three different species of Actinobacteria were isolated (M1-1, M2-2, M3-2) from sediment samples. Based on 16S rRNA gene analysis, isolate M1-1 was found to have only 90% identity percentage with Nocardiopsis sp., however, isolates M2-2 and M3-2 were found to be closely related Streptomyces sp. (97%) and Nocardioides luteus (99%), respectively. The antibacterial activity showed that strain M1-1 is active against P. aeruginosa ATCC 2785 (inhibition zone, 9 mm). Strain M2-2 was found to be active against S. aureus ATCC 29213 (12 mm), B. cereus ATCC 11778 (11 mm), and E. coli ATCC 25922 (9 mm). In respect to strain M3-2, it was found to be active against S. aureus ATCC 29213 (14 mm) and B. cereus ATCC 11778 (9 mm). There were no actinobacterial isolates obtained from water samples despite their significant diversity revealed by our previous metagenomic analysis, which showed the presence of 13 different species dominated by Arthrobacter (an Actinobacterium belonging to family Actinomycetales). Conclusion There were 17 different Actinobacteria that could be detected in Ma’in thermal springs (13 unculturable species and 3 culturable species). The culturable Actinobacteria were found to have some antimicrobial activity. Further chemical analysis of the bioactive compounds is recommended

Identification, Characterization and Antibiotic Resistance of Bacterial Isolates Obtained from Waterpipe Device Hoses

The general lack of knowledge about the health effects of waterpipe smoking is among the reasons for its global spread. In this study, bacterial contamination of waterpipe hoses was investigated. Twenty hoses were collected from waterpipe cafés and screened for bacterial pathogens using standard culture and isolation techniques. Additionally, resistance of isolated bacteria to common antibiotics was determined by identifying the minimum inhibitory concentration (MIC) of each isolate. Forty eight bacterial isolates were detected. Isolates included both Gram-positive and Gram-negative pathogens from species that included Micrococcus (12), Corynebacterium (13) and Bacillus (9). In addition, some of the detected pathogens were found to be resistant to aztreonam (79%), cefixime (79%), norfloxacin, amoxicillin (47%), clarithromycin (46%) and enrofloxacin (38%). In conclusion, the hose of the waterpipe device is a good environment for the growth of bacterial pathogens, which can then be transmitted to users

Exploring the microbial diversity in Jordanian hot springs by comparative metagenomic analysis

A culture-independent approach was utilized in this study to reveal the microbial diversity in Jordanian hot springs represented by Ma\u27in and Afra hot springs. Water samples from Ma\u27in and Afra hot springs were collected in June 2015. The in situ temperature of water samples range was 38-59°C and the pH range was 7.4-8.4. The metagenome was extracted and analyzed using the next generation technology (bTEFAP ). A total of 314,310 sequences were parsed and 288,452 were then clustered. The sequences were predominated by bacteria (\u3e84%) and the relative abundance of archaea in each sample was \u3c1%. Eukaryotic microorganisms were detected but with varying abundances (0.6%-15%). Because most of the detected sequences were found to belong to the domain of bacteria (196,936 sequences out 288,452), the bacterial sequences were utilized for further microbial analyses. With respect to alpha and beta diversity, samples were rarefied to 30,000 sequences and bootstrapped at 10,000 sequences. The Shannon-Wiener Index curve plot reaches a plateau at approximately 3,000 sequences indicating that sequencing depth was sufficient to capture the full scope of microbial diversity. By examining the relative abundance of phyla detected in each sample, it appears that the biota of both Jordanian hot springs sampled are compositionally similar, with over 50% of the microbial community of each sample being comprised of the phylum Proteobacteria. The second most abundant phylum was the phylum Bacteroidetes which represents more than 13% in each sample. The phylum Firmicutes was also detected with a significant abundance. However, lower abundance of Deinococcus, Verrucomicrobia, Planctomycetes, and Chloroflexi was detected. A principal coordinate analysis plot was generated based upon the weighted UniFrac distance matrix. By utilizing Monte Carlo simulations, we were able to determine that there were no significant differences in the microbial diversity between each sample

Microbiological analysis, antimicrobial activity, and heavy-metals content of Jordanian Ma'in hot-springs water

Ma'in hot springs are known as sites of balneotherapy. However, little is known about their microbiology and chemistry. In this study, we aim at evaluating the antimicrobial activity of Ma'in hot-springs water (MHSW), studying its microbiology, and determining its physicochemical properties including the heavy metals content. Therefore, water samples were collected from Ma'in hot springs and tested for antimicrobial activity using agar diffusion method. Water was then cultivated on nutrient agar to isolate and identify the dominant bacteria by chemical and molecular methods. The identified strains were tested by cross streak method to evaluate their antimicrobial activity against different clinical and standard strains. Finally, water samples were chemically analyzed and the heavy-metals content was assessed. Results revealed that MHSW was not active against any of the clinical isolates. Nevertheless, MHSW was found to be active against five standard bacterial strains, namely, Staphylococcus epidermidis ATCC 12228 (inhibition zone: 20 mm), Staphylococcus aureus ATCC 29213 (inhibition zone: 19 mm), Micrococcus luteus ATCC 9341 (inhibition zone: 15.3 mm), and Bacillus cereus ATCC 11778 (inhibition zone: 12.3 mm). After cultivation of MHSW, five bacterial isolates were obtained and identified based on 16S rRNA gene analysis as new strains of Anoxybacillus flavithermus (identity percentage ranges between 96–99%). Physicochemical analysis revealed that the in situ temperature was 59 °C, pH was 7.8, salinity was 1.6 ppt, and dissolved oxygen was 3.8 mg l−1. In respect to heavy-metals content in MHSW, the following metals were present in the order: Cr (0.571 ppm) > Mn(0.169 ppm) > Fe (0.124 ppm) > Zn (0.095) > Cu(0.070 ppm) > Ni(0.058 ppm) > Cd (0.023 ppm) > Pb (0 ppm). Cd, Cr, Ni and Mn were found to be higher than permissible levels set by international organizations and countries. This study highlights new chemical and microbiological data about Ma'in hot springs. Keywords: Ma'in hot springs, Antimicrobial activity, Heavy metals, Water microbiology, Thermophilic bacteria, Balneotherap