Physical and Chemical Characteristics of Five Hot Springs in Eritrea

Eritrea has a number of hot springs whose physicochemical characteristics are not documented. This study examined the thermal and chemical features of five hot springs located in the eastern escarpment of Eritrea. Field data and water samples were collected from five hot springs namely; Akwar and Maiwooi near Gahtelai, Garbanabra and Gelti near Irafayle at the Gulf of Zula and Elegedi in Alid volcanic center. The water temperatures at source varied from 49.5°C to 100°C while pH levels ranged from 6.97 to 7.54. Elegedi had significantly higher temperature (p < 0.05) than the other four hot springs. Strong correlation was observed between electrical conductivity (EC), total dissolved solid (TDS), salinity, sodium, potassium, calcium and chloride (R2 > 0.9) as well as between temperature and sulphate levels (R2 = 0.96). Evident clustering was noted at p < 0.05, using Non-metric multidimensional scaling (NMDS), between the three locations of the hot springs. Akwar and Maiwooi, situated close to each other, clustered together, Garbanabra and Gelti, which were characterized by higher salinity levels, formed a separate cluster. Elegedi, characterized by high temperature (100°C), sulphate (979.7 mg/l) and NH4+ (196.33 mg/l) levels, clustered separately. Akwar and Maiwooi had high bicarbonate (345 mg/l and 393 mg/l) and fluoride (8.20 mg/l and 6.48 mg/l) levels which are above WHO limits. Electrical conductivity (23,133 mS/cm), total dissolved solid (15,552 mg/l), sodium (3,800 mg/l), potassium (198 mg/l), calcium (1,653 mg/l) and chloride (5,946 mg/l) levels in Garbanabra and Gelti hot springs exceeded WHO limits. Bromine (74.8 mg/l in Garbanabra and 45.2 mg/l in Gelti) and boron (2.21 mg/l in Garbanabra and 1.55 mg/l in Gelti) levels were also above standard limits set for potable water. Maiwooi (1.20) and Elegedi (1.10) were depositional while Akwar water (-0.71) was slightly corrosive. The corrosive nature of the water sample from Akwar, is a public health concern. The waters from the five Eritrean hot springs are thus not fit for human consumption. In addition, the use of thermal spring water for recreational purposes should be closely monitored. Keywords: key words, hot springs, physicochemical, Eritre

Compatibility between Calpurnia aurea leaf extract, attraction aggregation, and attachment pheromone and entomopathogenic fungus Metarhizium anisopliae on viability, growth, and virulence of the pathogen

Metarhizium anisopliae sensu stricto (ss) (Metsch.) Sorok. isolate ICIPE 07 is being developed as biopesticide for the control of ticks. In addition, leaf extracts of Calpurnia aurea Benth, and the attraction aggregation and attachment pheromone (AAAP) are being used as ticks’ attractant. The three agents are being considered for use in combination in an autodissemination approach, whereby ticks that are attracted to semiochemicals are infected with the inoculum. Experiments were therefore conducted to evaluate in vitro the compatibility between C. aurea, AAAP, and the M. anisopliae on vegetative growth, conidial production, and spore viability. Calpurnia aurea leaf extract was compatible with the fungus at all the concentrations tested, whereas AAAP inhibited all the fungal growth parameters. The virulence of M. anisopliae formulated in emulsifiable extracts of C. aurea was also tested against different developmental stages of Rhipicephalus appendiculatus in laboratory bioassays. No significant differences in virulence were observed between M. anisopliae applied alone and M. anisopliae formulated in different concentrations of C. aurea leaf extracts. These results suggest that C. aurea leaf extracts is compatible with M. anisopliae and could be mixed together for “spot-spray” treatments as low-cost and environmental-friendly technology to control ticks in grazing field, while AAAP should be used separately.Bioscience Eastern and Central Africa Network (BecANet) and the Canadian International Development Agency (CIDA).http://link.springer.com/journal/10340hb2013mn201

Hydrogen-Dependent Oxygen Reduction by Homoacetogenic Bacteria Isolated from Termite Guts

Although homoacetogenic bacteria are generally considered to be obligate anaerobes, they colonize the intestinal tracts of termites and other environments that are not entirely anoxic in space or time. In this study, we investigated how homoacetogenic bacteria isolated from the hindguts of various termites respond to the presence of molecular oxygen. All strains investigated formed growth bands in oxygen gradient agar tubes under a headspace of H(2)-CO(2). The position of the bands coincided with the oxic-anoxic interface and depended on the O(2) partial pressure in the headspace; the position of the bands relative to the meniscus remained stable for more than 1 month. Experiments with dense cell suspensions, performed with Clark-type O(2) and H(2) electrodes, revealed a large capacity for H(2)-dependent oxygen reduction in Sporomusa termitida and Sporomusa sp. strain TmAO3 (149 and 826 nmol min(−1) mg of protein(−1), respectively). Both strains also reduced O(2) with endogenous reductants, albeit at lower rates. Only in Acetonema longum did the basal rates exceed the H(2)-dependent rates considerably (181 versus 28 nmol min(−1) mg of protein)(−1)). Addition of organic substrates did not stimulate O(2) consumption in any of the strains. Nevertheless, reductive acetogenesis by cell suspensions of strain TmAO3 was inhibited even at the lowest O(2) fluxes, and growth in nonreduced medium occurred only after the bacteria had rendered the medium anoxic. Similar results were obtained with Acetobacterium woodii, suggesting that the results are not unique to the strains isolated from termites. We concluded that because of their tolerance to temporary exposure to O(2) at low partial pressures (up to 1.5 kPa in the case of strain TmAO3) and because of their large capacity for O(2) reduction, homoacetogens can reestablish conditions favorable for growth by actively removing oxygen from their environment

Evaluation of prokaryotic diversity of five hot springs in Eritrea

Abstract Background Total community rDNA was used to determine the diversity of bacteria and archaea from water, wet sediment and microbial mats samples of hot springs in the Eastern lowlands of Eritrea. The temperatures of the springs range from 49.5 °C to 100 °C while pH levels varied from 6.97 to 7.54. Akwar and Maiwooi have high carbonate levels. The springs near the seashore, Garbanabra and Gelti, are more saline with higher levels of sodium and chlorides. Elegedi, situated in the Alid volcanic area, has the highest temperature, iron and sulfate concentrations. Results The five hot springs shared 901 of 4371 OTUs recovered while the three sample types (water, wet sediment and microbial mats) also shared 1429 OTUs. The Chao1 OTU estimate in water sample was significantly higher than the wet sediment and microbial mat samples. As indicated by NMDS, the community samples at genus level showed location specific clustering. Certain genera correlated with temperature, sodium, carbonate, iron, sulfate and ammonium levels in water. The abundant phyla included Proteobacteria (6.2–82.3%), Firmicutes (1.6–63.5%), Deinococcus-Thermus (0.0–19.2%), Planctomycetes (0.0–11.8%), Aquificae (0.0–9.9%), Chlorobi (0.0–22.3%) and Bacteroidetes (2.7–8.4%). Conclusion There were significant differences in microbial community structure within the five locations and sample types at OTU level. The occurence of Aquificae, Deinococcus-Thermus, some Cyanobacteria and Crenarchaeota were highly dependent on temperature. The Halobacterium, unclassified Thaumarchaeota, Actinobacteria and Cyanobacteria showed significant correlation with salinity occurring abundantly in Garbanabra and Gelti. Firmicutes and unclassified Rhodocylaceae were higher in the microbial mat samples, while Archaea were prominent in the wet sediment samples

Phenotypic and genetic characterization of vibrio cholerae O1 isolated from various regions of Kenya between 2007 and 2010

Introduction: Cholera, a disease caused by Vibrio cholerae O1 and O139 remains an important public health problem globally. In the last decade, Kenya has experienced a steady increase of cholera cases. In 2009 alone, 11,769 cases were reported to the Ministry of Public Health and Sanitation. This study sought to describe the phenotypic characteristics of the isolated V. cholerae isolates.Methods: This was a laboratory based cross-sectional study that involved isolates from different cholera outbreaks. Seventy six Vibrio cholerae O1 strains from different geographical areas were used to  represent 2007 to 2010 cholera epidemics in Kenya, and were characterized by serotyping, biotyping, polymerase chain r(PCR), pulsed-field gel electrophoresis (PFGE) and ribotyping along with antimicrobial susceptibility testing. Results: Seventy six Vibrio cholerae O1 strains from different geographical areas were used to represent 2007 to 2010 cholera epidemics in Kenya. Serotype Inaba was dominant (88.2%) compared to Ogawa.  The isolates showed varying levels of antibiotic resistance ranging from 100% susceptible to tetracycline, doxycycline, ofloxacin, azithromycin, norfloxacin and ceftriaxone to 100% resistant to furazolidone, trimethoprim-sulfamethoxazole, polymyxin-B and streptomycin. The isolates were positive for ctxA, tcpA (El Tor), rtxC genes and were biotype El Tor variant harboring classical ctxB gene. All the isolates were classified as cholera toxin (CT) genotype 1 as they had mutation in the ctxB at positions 39 and 68. All the isolates had genetically similar NotI PFGE and BglI ribotype patterns. The absence of any observed variation is consistent with a clonal origin for all of the isolates. Conclusion: Kenya experienced cholera numerous outbreak from 2007-2010. The clinical Vibrio cholerae O1 isolates from the recent cholera epidemic were serotypes Inaba and Ogawa, Inaba being the  predominant serotype. The Vibrio cholerae O1 strains were biotype El Tor variants that produce cholera toxin B (ctx B) of the classical type and were positive for ctxA, tcpA El Tor and rtxC genes.Key words: Cholera, characterization, Kenya, serotype, epidemics, pulsed-field gel electrophoresis

Diversity of <em>Termitomyces</em> Associated with Fungus-Farming Termites Assessed by Cultural and Culture-Independent Methods

<div><p>Background</p><p>Fungus-cultivating termites make use of an obligate mutualism with fungi from the genus <i>Termitomyces</i>, which are acquired through either vertical transmission via reproductive alates or horizontally transmitted during the formation of new mounds. <i>Termitomyces</i> taxonomy, and thus estimating diversity and host specificity of these fungi, is challenging because fruiting bodies are rarely found. Molecular techniques can be applied but need not necessarily yield the same outcome than morphological identification.</p> <p>Methodology</p><p>Culture-dependent and culture-independent methods were used to comprehensively assess host specificity and gut fungal diversity. Termites were identified using mitochondrial cytochrome oxidase II (COII) genes. Twenty-three <i>Termitomyces</i> cultures were isolated from fungal combs. Internal transcribed spacer (ITS) clone libraries were constructed from termite guts. Presence of <i>Termitomyces</i> was confirmed using specific and universal primers. <i>Termitomyces</i> species boundaries were estimated by cross-comparison of macromorphological and sequence features, and ITS clustering parameters accordingly optimized. The overall trends in coverage of <i>Termitomyces</i> diversity and host associations were estimated using Genbank data.</p> <p>Results and Conclusion</p><p>Results indicate a monoculture of <i>Termitomyces</i> in the guts as well as the isolation sources (fungal combs). However, cases of more than one <i>Termitomyces</i> strains per mound were observed since mounds can contain different termite colonies. The newly found cultures, as well as the clustering analysis of GenBank data indicate that there are on average between one and two host genera per <i>Termitomyces</i> species. Saturation does not appear to have been reached, neither for the total number of known <i>Termitomyces</i> species nor for the number of <i>Termitomyces</i> species per host taxon, nor for the number of known hosts per <i>Termitomyces</i> species. Considering the rarity of <i>Termitomyces</i> fruiting bodies, it is suggested to base the future taxonomy of the group mainly on well-characterized and publicly accessible cultures.</p> </div

Clustering-optimization plot for the selected ITS data, using the species boundaries estimated via Fig. 1 as reference partition.

<p>Shown are the partition-agreement metrics (MRI) in dependency of the ITS sequence dissimilarity thresholds for three values of the <i>F</i> clustering parameter: light gray, <i>F</i> = 0.0; dark grey, <i>F</i> = 0.5; black, <i>F</i> = 1.0.</p

Temporal development of coverage of <i>Termitomyces</i> diversity by GenBank ITS sequences based on optimal clustering parameters (thick lines) as well as a selection of suboptimal ones (thin lines) to assess parameter sensitivity of the overall trends.

<p>As in Fig. 2, the clustering parameter <i>F</i> is indicated by color: light gray, <i>F</i> = 0.0; dark grey, <i>F</i> = 0.5; black, <i>F</i> = 1.0. The suboptimal threshold values were varied between 1% and 5% in steps of 1% and are either arranged in decreasing or increasing order, depending on the context; see the text for further details. Deposition years were extracted from the GenBank accessions; the incomplete year 2012 was coded as 2011.5. A, cumulative number of clusters; B, average number of sequences per cluster; C, average number of distinct host genera per cluster indicated in the GenBank accessions; D, average number of distinct host species per cluster indicated in the GenBank accessions; E, average number of clusters per host genus; F, average number of clusters per host species. In C and D, values below 1 may occur because host affiliations need not be indicated in GenBank entries.</p