Isolation and characterization of n-alkane utilizing bacteria, which produce biomulsifiers

Includes bibliographical references.Bacterial strains were isolated by enrichment cultures from oil-contaminated soil samples. In the present study, several strains, capable of growing on crude oil, were isolated. Isolates were screened for their inherent abilities to produce bioemulsifiers when they were grown on hydrocarbon substrates

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

Midgut bacterial diversity analysis of laboratory reared and wild Anopheles gambiae and Culex quinquefasciatus mosquitoes in Kenya

Open Access JournalMidgut symbiotic bacteria are known to play fundamental roles in the biology of mosquitoes, however knowledge of midgut bacterial communities associated with mosquitoes is scanty due to limitation of the isolation techniques based on culturing. In this study, the composition and diversity of midgut bacteria in field collected and lab reared adult female Anopheles gambiae and Culex quinquefasciatus mosquitoes was explored using the Illumina sequencing. Deoxyribonucleic acid was isolated from the pooled midgut extracts and their 16S rRNA gene sequenced using Illumina sequencing platform. Operational taxonomic units (OTUs) were analyzed using QIIME 1.8.0; taxonomy was assigned using BLASTn against SILVA 119 and hierarchical clustering was done using R program software. Out of the total number of sequence reads obtained, 145 OTUs were realized at 3% genetic distance. The 145 OTUs spanned 12 phyla; Proteobacteria, Firmicutes, Cyanobacteria, Euryarchaeota, Gemmatimonadetes, Spirochaetae, Archeabacteria Verrucomicrobia, Chloroflexi, Bacteriodetes, Acidobacteria and Actinobacteria. Microbial community composition based on OTUs showed significant difference between field collected and lab reared mosquitoes (ᵪ2 = 45.0799, p = 3.2 × 10-5). Similarly, there was a significant difference in community composition at OTU level between Anopheles gambiae and Culex quinquefasciatus (ᵪ2 = 31.2257, p = 7.7 × 10-4). The bacterial composition and diversity appeared to be influenced by the environment and the species of the mosquitoes

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

Additional file 6: Table S4. of Evaluation of prokaryotic diversity of five hot springs in Eritrea

Abundance of bacteria at family level in various samples collected from the five hot springs in Eritrea. The first letters of the sample names refer to the five hot springs (A = Akwar, E = Elegedi, G = Garbanabra, J = Gelti and M = Maiwooi), while the second letters are for sample types (A = microbial mat, S = wet sediment, and W = water). (XLSX 30 kb

Additional file 5: Table S3. of Evaluation of prokaryotic diversity of five hot springs in Eritrea

Abundance of microbial taxa at phyla level in various samples collected from the five hot springs in Eritrea. The first letters of the sample names refer to the five hot springs (A = Akwar, E = Elegedi, G = Garbanabra, J = Gelti and M = Maiwooi), while the second letters are for sample types (A = microbial mat, S = wet sediment, and W = water). (XLSX 10 kb

Additional file 4: Figure S2. of Evaluation of prokaryotic diversity of five hot springs in Eritrea

Rarefaction curves of OTUs from amplicon samples collected from the five hot springs in Eritrea. The number of OTUs is plotted in relation to sub-sampled sequence datasets size (number of reads). The first letters of the sample names refer to the five hot springs (A = Akwar, E = Elegedi, G = Garbanabra, J = Gelti and M = Maiwooi), while the second letters are for sample types (A = Microbial mat, S = wet sediment, and W = water). (TIFF 1023 kb

Potential human pathogenic bacteria in five hot springs in Eritrea revealed by next generation sequencing

<div><p>Human pathogens can survive and grow in hot springs. For water quality assessment, <i>Escherichia coli</i> or <i>Enterococci</i> are the main thermotolerant enteric bacteria commonly used to estimate the load of pathogenic bacteria in water. However, most of the environmental bacteria are unculturable thus culture methods may cause bias in detection of most pathogens. Illumina sequencing can provide a more comprehensive and accurate insight into environmental bacterial pathogens, which can be used to develop better risk assessment methods and promote public health awareness. In this study, high-throughput Illumina sequencing was used to identify bacterial pathogens from five hot springs; Maiwooi, Akwar, Garbanabra, Elegedi and Gelti, in Eritrea. Water samples were collected from the five hot springs. Total community DNA was extracted from samples using the phenol-chloroform method. The 16S rRNA gene variable region (V4—V7) of the extracted DNA was amplified and library construction done according to Illumina sequencing protocol. The sequence reads (length >200 bp) from Illumina sequencing libraries ranged from 22,091 sequences in the wet sediment sample from Garbanabra to 155,789 sequences in the mat sample from Elegedi. Taxonomy was assigned to each OTU using BLASTn against a curated database derived from GreenGenes, RDPII, SILVA SSU Reference 119 and NCBI. The proportion of potential pathogens from the water samples was highest in Maiwooi (17.8%), followed by Gelti (16.7%), Akwar (13.6%) and Garbanabra (10.9%). Although the numbers of DNA sequence reads from Illumina sequencing were very high for the Elegedi (104,328), corresponding proportion of potential pathogens very low (3.6%). Most of the potential pathogenic bacterial sequences identified were from <i>Proteobacteria</i> and <i>Firmicutes</i>. <i>Legionella</i> and <i>Clostridium</i> were the most common detected genera with different species. Most of the potential pathogens were detected from the water samples. However, sequences belonging to <i>Clostridium</i> were observed more abundantly from the mat samples. This study employed high-throughput sequencing technologies to determine the presence of pathogenic bacteria in the five hot springs in Eritrea.</p></div

Location and physical characteristics of the five hot springs in Eritrea.

<p>Location and physical characteristics of the five hot springs in Eritrea.</p

Hierarchical clustering, based on Bray-Curtis dissimilarities, illustrating the composition of potential pathogens at species level in the five hot springs in Eritrea.

<p>The first letters of the sample names refer to the five hot springs (A = Akwar, E = Elegedi, G = Garbanabra, J = Gelti and M = Maiwooi), while the second letters are for sample types (A = Microbial mat, S = wet sediment, and W = water).</p