Lebanese Soil Research Articles

Characterization of Actinobacteria strains in Lebanese soil with an emphasis on investigating their antibacterial activity.

With the alarming rise of drug resistant pathogens, the quest for new bioactive compounds from natural habitats has increased. Actinobacteria are Gram-positive bacteria, considered prominent natural antibiotic synthesizers. This study aimed at isolating Actinobacteria from agricultural soil samples of Tamnine El Tahta and Haddatha, with an emphasis on the physicochemical soil characteristics. It also aimed at screening and identifying the antibacterial-producing Actinobacteria, with a determination of the chemical composition of the extract. Forty-six Actinobacteria were isolated from six soil samples. Actinobacteria load exhibited a positive correlation with moisture content, and a negative correlation with pH, salinity, and organic matter content. Primary screening for antibacterial activity was performed against various Gram-positive and Gram-negative bacteria by cross-streak method. Fourteen Actinobacteria isolates were potent against the test microorganisms, and the most effective isolate (T25) was selected for identification, and extract preparation. The antibacterial activity of the extract was tested using secondary screening, in addition to minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) determination. T25 isolate exhibited a 92% similarity with Micrococcus luteus/lylae. MIC recorded was 12.5mg/ml and the MBC was higher than 100mg/ml against all test microorganisms. Total phenol content was estimated to be 18.5 ± 0.0015mg GAE/g dry weight using Folin-Ciocalteu method, and total flavonoid content recorded 2.3 ± 0.02mg RE/g dry weight using aluminum nitrate colorimetric method. This study revealed that the physicochemical parameters in soils impact the distribution of Actinobacteria. Moreover, it focuses on Micrococcus luteus/lylae strain, considered a promising antibacterial resource for further potential clinical investigations.

Biochemical limitations of Bacillus thuringiensis based biopesticides production in a wheat bran culture medium

Bacillus thuringiensis, a gram-positive sporulating bacteria found in the environment, produces, during its sporulation phase, crystals responsible for its insecticidal activity, constituted of an assembly of pore-forming δ-endotoxins. This has led to its use as a biopesticide, an eco-friendly alternative to harmful chemical pesticides. To minimize production cost, one endemic Bacillus thuringiensis sv. kurstaki (Btk) strain Lip, isolated from Lebanese soil, was cultivated in a wheat bran (WB) based medium (IPM-4-Citrus project EC n° 734921). With the aim of studying the biochemical limitations of Btk biopesticide production in a wheat bran based medium, the WB was sieved into different granulometries, heat treated, inoculated with Btk Lip at flask scale, then filtered and separated into an insoluble and a permeate fractions. Several biochemical analyses, ie. bio performances, starch, elemental composition, total nitrogen and ashes, were then conducted on both fractions before and after culture. On a morphological level, two populations were distinguished, the fine starch granules and the coarse lignocellulosic particles. The biochemical analyses showed that both the raw and sieved WB have a similar proteins content (0.115 g/gdm WB), water content (0.116 g/gdm WB) and elemental composition (carbon: 45%, oxygen: 37%, nitrogen: 3%, hydrogen: 6%, ashes: 5%). The starch content was 17%, 14% and 34% and the fermentable fraction was estimated to 32.1%, 36.1% and 51.1% respectively for classes 2, 3 and 4. Both the elemental composition and Kjeldahl analyses showed that the nitrogen is the limiting nutrient of the culture.

Biodegradation of chlorpyrifos by bacterial strains isolated from Lebanese soil and its association with plant growth improvement

Chlorpyrifos poses a danger to the environment as a result of its toxicity and endurance in soil and water. Bioremediation of pesticide-polluted soils is one of the most promising approaches for removing contaminants from the environment. This study aimed to isolate and identify chlorpyrifos-degrading bacterial strains and test their biodegradation capabilities and their roles in plant growth. The 16S rDNA gene sequencing identified the two efficient chlorpyrifos-degrading bacterial strains as Stenotrophomonas maltophilia (RS1) and Acinetobacter calcoaceticus (RS3), which significantly (p < 0.01) degraded 71.3% and 73.5% of chlorpyrifos in the liquid medium, respectively, compared to 80% degradation (p < 0.01) when cultured as a consortium within 48 h. The bioremediation of artificially chlorpyrifos-contaminated soils varied between 84.4% and 90.11% (p < 0.01), depending on the used bacterium and soil sterilization status. Furthermore, the enzymes embroiled in the degradation mechanism were sprinkled all over the cells but with different portions. Experiments on plant growth revealed that chlorpyrifos hurt lettuce growth. The presence of RS1 and RS3, on the other hand, demonstrated considerable lettuce growth-enhancing traits in terms of germination percentages, shoot and root lengths and weights. Our isolates could be promising candidates in the bioremediation of chlorpyrifos-contaminated sites in conjunction with their contribution as biofertilizers.

Characterization and Whole Genome Sequencing of AR23, a Highly Toxic Bacillus thuringiensis Strain Isolated from Lebanese Soil

The demand for sustainable and eco-friendly control methods of pests and insects is increasing worldwide. From this came the interest in Bacillus thuringiensis, an entomopathogenic bacterium capable of replacing chemical pesticides. However, the possibility of pests developing resistance to a particular strain may impair its use, and there is a need to identify novel strains of this species as potential commercial biopesticides. B. thuringiensis sv. israelensis is one of the most successful serovars, widely commercialized for its activity against black fly and mosquito larvae. In this study, we isolated, characterized, and sequenced a new Lebanese B. thuringiensis sv. israelensis isolate, strain AR23. Compared to the commercialized reference strain AM65-52 (Vectobac®, Sumitomo), AR23 showed an increased activity against several mosquito species. The genomic analysis revealed that this strain, compared to AM65-52, possesses a simplified plasmid content and an additional functional cry4Ba coding gene that most likely accounts for the increased effectiveness of this strain in mosquito larvae killing.

Impact of Lebanese practices in industry, agriculture and urbanization on soil toxicity. Evaluation of the Polycyclic Aromatic Hydrocarbons (PAHs) levels in soil

This study was carried out in order to investigate the toxicity on Lebanese soil and to show the impact of the anthropogenic activities, industrialization and urbanization, on the release of Polycyclic Aromatic Hydrocarbons (PAHs) in Lebanese soils. Hundred soil samples of different land use were screened for 17 PAHs using a UAE/GC-MS method. Detection frequency varied between 76 and 100% for most of the PAHs, where the ΣPAHs ranged from 33.5 to 4062.9 ng g−1. Moreover, BaPeq values varied between 0.93 and 332.4 ng g−1. BaPeq values in industrial and urban soils were 777 and 256 times higher than those in rural soil, respectively. None of the soil samples showed concentrations above the safe BaPeq value of 600 ng g−1. Significant decrease in concentration levels of ΣPAHs was obtained in the following order: Industrial, urban, traffic and agricultural. Furthermore, the relative high contribution of Chrysene, Benzo(a)Anthracene and Benzo(k)Fluoranthene in agricultural soils indicates that open burning remains an adopted way in Lebanon for disposal of agricultural residues, while the predominance of Benzo(ghi)Perylene and Benzo(b)Fluoranthene in industrial soils suggests the broad use of diesel powered engines in the Lebanese industrial sector. The ratios of Low Molecular Weight/High Molecular Weight and fluoranthene/fluoranthene+pyrene (Fln/Fln+Pyr) showed that PAHs in soil samples are mainly pyrogenic and created during combustion of petrol, coal, wood and other biomasses.

Public exposure to radioactivity levels in the Lebanese environment.

In the framework of a National Environmental Radiation Survey Program, a total of 950 samples were collected and analyzed over 7years. The program covers different compartment of Lebanese environment, rivers, wells, marine samples, soil, and foodstuff. Air was monitored continuously through a radiation early warning network system. Data collected from 2009 to 2015 are presented in this work. Gross alpha/gross beta values in well samples were below the guidance levels stated by the WHO. Cesium-137 was detected in milk samples, whey, and jam. However, its content was much lower than the national permissible level, while its activity concentration in marine samples was lower than the values reported in studies carried out in the Mediterranean Sea. The activity concentration of 40K in food samples was comparable to studies carried out in neighboring countries and higher than the content determined in non Mediterranean countries. Concerning marine environment, the activity concentrations of natural radionuclides 238U, 232Th, and 40K were comparable to those reported in other studies carried out in different countries. As well as their content in rivers and sediments was lower than those reported in neighboring region. Potassium-40 in food and 210Po in fish were the main contributors to the internal dose. The average annual effective dose due to external exposure and internal, excluding radon gas which constitutes around 43% of the total dose, was found to be lower than the total worldwide value, 2.4mSvyear-1. Iodine-131 was detected in grass samples, collected in 2011 during Fukushima accident; its content ranged from 0.40±0.06 to 0.9±0.1Bqkg-1, as well as 137Cs was detected in some seafood samples imported from Japan and neighboring countries. Its activity concentration varied between 0.15±0.04 and 0.40±0.02Bqkg-1.

Epidemiology and clinical characteristics of traumatic brain injury in Lebanon: A systematic review.

Traumatic brain injury (TBI) is a debilitating medical and emerging public health problem that is affecting people worldwide due to a multitude of factors including both domestic and war-related acts. The objective of this paper is to systematically review the status of TBI in Lebanon - a Middle Eastern country with a weak health system that was chartered by several wars and intermittent outbursts of violence - in order to identify the present gaps in knowledge, direct future research initiatives and to assist policy makers in planning progressive and rehabilitative policies. OVID/Medline, PubMed, Scopus databases and Google Scholar were lastly searched on April 15, 2016 to identify all published research studies on TBI in Lebanon. Studies published in English, Arabic or French that assessed Lebanese patients afflicted by TBI in Lebanon were warranting inclusion in this review. Case reports, reviews, biographies and abstracts were excluded. Throughout the whole review process, reviewers worked independently and in duplicate during study selection, data abstraction and methodological assessment using the Downs and Black Checklist. In total, 11 studies were recognized eligible as they assessed Lebanese patients afflicted by TBI on Lebanese soils. Considerable methodological variation was found among the identified studies. All studies, except for two that evaluated domestic causes such as falls, reported TBI due to war-related injuries. Age distribution of TBI victims revealed two peaks, young adults between 18 and 40 years, and older adults aged 60 years and above, where males constituted the majority. Only three studies reported rates of mild TBI. Mortality, rehabilitation and systemic injury rates were rarely reported and so were the complications involved; infections were an exception. Apparently, status of TBI in Lebanon suffers from several gaps which need to be bridged through implementing more basic, epidemiological, clinical and translational research in this field in the future.

Overshadowed Crisis: The Carter Administration and the Conflict in Southern Lebanon

Building on the recent declassification of several documents in the United States, this analysis examines the policies of the Carter administration and their effects on the conflict in southern Lebanon. During President Jimmy Carter’s efforts to mediate a peace process between Israel and Egypt, Israeli military retaliation against the PLO threatened a conflagration between Israel, Syria and the Palestinians on Lebanese soil. For Carter, the troubles in southern Lebanon were a nuisance to his plans for an Egyptian-Israeli settlement. Thus, he failed to devote sufficient attention to the conflict but rather subordinated it to the need to keep Israelis and Egyptians at the negotiating table.

Hizbullah’s De-Radicalization through Performing Arts

The Lebanese Hizbullah is infamous for its terrorist global reach and militant face. In the 1980s and early 1990s, Hizbullah abducted Westerners in Lebanon and battled the Israeli Army until it withdrew in 2000. In the Arab Uprisings, Hizbullah is fighting alongside the Syrian regime and lending logistical support to the Iraqi and Yemeni Shi‘ite armed militias. Employing political disenfranchisement discourse and tactics, Hizbullah seems to shift within the parameters of pan-Islamism and pan-Arabism, while maintaining its Lebanese national identity at the centre. Notwithstanding this, Hizbullah’s resilience and assertiveness allows it to move between militancy (hard power) and integration (soft/smart power). The former exemplifies its hawkish policy during the Arab Uprisings, while the latter illustrates its dovish domestic face of being an integral part of the Lebanese state, from which it derives its legitimacy. This shift fuelled Sunni–Shi‘a discord (fitna), threatening a serious spillover of the Syrian civil war into Lebanon after al-Qa‘ida affiliates –ISIL and Nusra Front –battled Hizbullah and the Lebanese Army on Lebanese soil. In spite of that, Hizbullah exploits the concepts of cultural citizenship and cultural politics to promote, in mixed gender spaces, purposeful performing arts such as music, dance, revolutionary theatre, and satire (soft power). To my knowledge, Hizbullah is the only Islamic party that has an orchestra of more than 100 musicians who play more than 44 instruments. Many Islamists –such as the Taliban and ISIL –classify these as ‘instruments of the Devil’.

Decomposition of olive-mill waste compost, goat manure and Medicago sativa in Lebanese soils as measured using the litterbag technique

Organic amendments, green manure and plant residues are the main sources of nutrients under organic farming. The decomposition of compost from olive-mill waste, aged goat manure and lucerne (alfalfa, Medicago sativa) shoots was studied in subhumid Mediterranean conditions. The locations of Abdeh, Lebaa and Sour were distinguished by their respective clay (521, 315 and 260 g kg–1 soil) and calcium carbonate (42, 591 and 269 g kg–1 soil) contents. Nutrients release was evaluated over 1 year by using litter bags buried at 10 cm depth. Despite close initial total nitrogen (N) contents, shoots lost 50–60% of N, whereas the stable compost and manure mineralised 20–26% after 30 days of incubation. Calculated coefficients of decomposition for organic carbon (OC) were significantly higher for shoots (0.0061 day–1) than for manure (0.0020 day–1) and compost (0.0011 day–1). Coefficients for total N were very similar to those for OC: shoots (0.0050 day–1) &gt; manure (0.0018 day–1) and compost (0.0017 day–1). OC was the parameter most discriminating between fresh residue and decomposed products, and potassium the least. Of the soil properties, the calcium carbonate rather than the clay content affected decomposition. Coefficients of decomposition of OC were significantly different with Sour (0.0036 day–1) &gt; Abdeh (0.0030 day–1) &gt; Lebaa (0.0026 day–1). Coefficients for total N were also different with Abdeh ≡ Sour &gt; Lebaa. Fresh and stable products could be a source of nutrients even during winter in Mediterranean conditions.

Characterization of Bacillus thuringiensis parasporal crystals using laser speckle technique: effect of crystal concentration and dimension

In this paper, we report experimental results where laser speckle grain size and degree of light polarization are used to distinguish different sizes of Bacillus thuringiensis spherical crystals and different concentration within fermentation products. Three strains of Bacillus thuringiensis, isolated from the Lebanese soil, are selected. After fermentation, crystals and spores are separated using a technique based on flotation in order to obtain large quantities of relatively pure crystals. Crystals are then embedded in an agarose matrix gel and illuminated by a laser. Speckle patterns are recorded and analyzed. Results show that when crystal concentrations increase in the sample, the values of the degree of light linear polarization and speckle grain size decrease, and the negative values of light circular polarization degree increase. A transition from a Rayleigh scattering regime to a Mie regime is also observed. Furthermore, when the diameter of spherical crystals increases, the normalized value of the light linear polarization degree and the grain size diminish drastically for a given concentration of crystals in the matrix, whereas the normalized value of light circular polarization degree increases. This optical characterization constitutes an unambiguous signature of spherical crystals produced by fermentations of different Bacillus thuringiensis strains and shows that speckle may potentially be used at an industrial scale as a low-cost and noninvasive technique in order to characterize crystal geometry and to evaluate the yield of crystal production within fermentation.

Trauma-related infections due to cluster munitions

Trauma-related infections remain a concerning and potentially avoidable complication of conflict-related injuries. During the Israeli conflict in South Lebanon, more than four million sub-munitions were dropped over South Lebanese soil. In this study, we will explore the different types of infection caused by sub-munitions and penetrating agents. This prospective study took place from 2006 to 2012 at the Lebanese University within the Faculty of Medical Sciences' departments. This study sample consisted of 350 injured casualties. Patients suffered from blast injuries with fragmentations targeting the head, face, torso, abdomen, pelvis and extremities. Of the 350 causalities studied, 326 (93.1%) were males, and 24 (6.9%) were females. Ages varied between 10 and 70 years, with the average age being 27 years. Of the 350 patients studied, 68 (19.4%) developed infections. Infections varied between pseudomonas, Escherichia coli, Candida and fungus and sometimes led to necrosis. Vaccinations, antibiotic therapies and proper wound irrigation must be performed at appropriate emergency units. Excision and complete debridement of necrotic and contaminated tissue should also be performed. The Convention on Cluster Munitions of 2008 should be adhered to, as these weapons indiscriminately and disproportionately harm civilians, thereby violating the well-established international principles governing conflict.

Selenium levels in Lebanese environment

Very limited research has been conducted on selenium (Se) in Lebanese soils and forage crops but no work has been done on Se in water and locally produced vegetables and grains. This research was conducted in order to quantify Se levels and its availability in agricultural soils, vegetables and grains in Lebanon. Sixty-six (66) soil samples were collected from 33 selected sites in Lebanon: the Bekaa Valley, coastal and mountainous regions. Thirteen (13) different plant types (86 samples) were sampled from the same locations. Also, 13 spring water and 10 bottled water samples were collected. Soil samples were analyzed for their physical and chemical properties. Selenium was extracted from soils with: deionized–distilled water (Soluble-Se), KH 2PO 4-0.1 M (MKP-Se) and concentrated (HNO 3 + HCl) mixture (acid-Se). Plant Se was extracted by acid digestion on a hotplate. Selenium concentrations were measured by the inductively coupled plasma-mass spectrophotometer (ICP-MS). The values of Soluble-Se, MKP-Se and acid-Se ranged between 47 and 142, 147 and 400, and 1749 and 4713 μg/kg, respectively, with average values of 95, 306, and 3118 μg/kg and at a ratio of 1:3:30. Thus, Se extracted with deionized–distilled water is a good indicator for Se availability in the studied soils. The average Se concentration in plants was in the following order: radish > lettuce > cucumber > cabbage > parsley > alfalfa > onion (leaves) > broccoli > tomato > mint > chickpeas > wheat > onion (bulbs). The Se levels in water samples were in the safe range (less than 50 μg/L) and ranged between 2.14 and 17.6 μg/L. The levels of Se in the three soil extractants were positively correlated with each other and with organic matter content, salinity and phosphorus (P). Selenium levels in plant samples were positively correlated at a 0.01 significance level with clay and P content.

Analysis of radiocaesium in the Lebanese soil one decade after the Chernobyl accident

Fallout from the Chernobyl reactor accident due to the transport of a radioactive cloud over Lebanon in the beginning of May 1986 was studied 12 years after the accident for determining the level of 137Cs concentration in soil. Gamma spectroscopy measurements were performed by using coaxial high sensitivity HPGe detectors. More than 90 soil samples were collected from points uniformly distributed throughout the land of Lebanon in order to evaluate their radioactivity. The data obtained showed a relatively high 137Cs activity per surface area contamination, up to 6545 Bq m −2 in the top soil layer 0–3 cm. The average activity of 137Cs in the top soil layer 0–3 cm in depth was 59.7 Bq kg −1 dry soil ranging from 15 to 119 Bq kg −1 dry soil. The horizontal variability was found to be about 45% between the sampling sites. The depth distribution of total 137Cs activity in soil showed an exponential decrease. Estimation of the annual effective dose due to external radiation from 137Cs contaminated soil for selected sites gave values ranging from 19.3 to 91.6 μSv y −1.

Liban 2005 : décompositions et recompositions

The year 2005 in Lebanon was a year of great upheavals both as regards its relationship with neighboring Syria and its internal political equilibrium. Since the summer of 2004, Syrian influence has been in the West’s sights, particularly those of France and the United States. Damascus has been enjoined to stop interfering in Lebanon and to help disarm the Hizbollah and Palestinian factions operating on Lebanese soil. The assassination of Prime Minister Rafik Hariri, after his resignation, hastened the evacuation of Syrian troops. The following months unleashed popular mobilization unprecedented in the country’s history, but the hopes opened by this era of political emancipation were soon tarnished by the usual maneuvers of alliance-forging during the Spring elections of 2005. In the bellicose regional environment, the persistence of communitarian and political cleavages and vital questions such as the presidency of the Republic, continuing resistance and the future of Lebanese-Syrian relations perpetuate alarming scenarios for the future of Lebanon.

Ni, Cu, Zn and Pb background values determination in representative Lebanese soil using the thick target PIXE technique

Soil contamination by heavy metal ions is one of the most serious environmental problems. The determination of the natural levels or background values of heavy metals in agricultural soils is the first step for soil contamination assessment. The background values of heavy metals should constitute the base serving to evaluate the impact of land use on soil pollution and to determine the trigger values and intervention levels, which is very important for decision makers and planners in the field of land management and land use. In this paper 104 agricultural soil samples collected from the North Lebanon region, covering the soil surface and subsoil horizons and originating from 46 soil profiles, were analyzed using the thick target PIXE (TT-PIXE) technique. The background values for Ni, Cu, Zn and Pb were determined and discussed in relation to their horizon depths and to the soil lithological classes characterizing the studied region. This study is the first attempt to lay the basis for soil assessment based on land quality.

DDT Residues in Lebanese Soils

The present study was conducted to evaluate the levels of residual DDT in Lebanese soils. A total of 113 surface soil samples were collected for analysis from three major agricultural regions in the country: Mount Lebanon, Beqa’a valley and the coastal plain. The values of residual DDT in soils ranged between 0 and 1190 ng g−1. The majority of the analyzed soil samples were free or contained very low concentrations of DDE. Only two surface soil samples, which were collected from urban areas with high human activities, contained relatively high concentrations of residual DDT. The levels of residual DDT in all of the analyzed soil samples were within the permissible limits for agricultural soils.

Availability and Transformation of Applied Phosphorus In Calcareous Lebanese Soils

AbstractThough the initial reactions of P in soils are important with respect to plant growth and efficient fertilizer use, the reactions that occur with time have received less research attention, and may have even more important implications for these aspects. In order to monitor changes in applied P after fertilization, six calcareous soils were incubated up to 200 d with P solutions and periodically extracted with NaHCO3, and inorganically fractioned. Soil batches were equilibrated with P solutions ranging from 0 to 40 mg P L−1 for adsorption isotherm data after 0, 60, and 200‐d incubation. Desorption curves were obtained by water extraction for eight consecutive days. Extractable P values declined rapidly within the first day, and uniformly thereafter. The amounts of P retained against NaHCO3 extraction were closely related to citrate‐dithionite‐bicarbonate (CDB)‐Fe. With the longer incubation period, generally less P was released in the water extraction. Similarly, desorbed P was inversely related to CDB‐Fe. While P additions mainly enriched the NH4Cl‐ and NaOH‐P fractions, the amounts recovered decreased with time. Increasing prior soil‐P contact time also caused a shift in the adsorption isotherms, reflecting changes in retained P and the soils' retention capacity. Thus, free Fe oxides may modify longer‐term P reactions and residual P availability in CaCO3‐rich soils.

Significance of Iron Oxides and Calcium Carbonate Particle Size in Phosphate Sorption by Calcareous Soils

AbstractThough many soil components are involved in reactions whereby soluble fertilizer P is converted to less soluble and therefore less available forms, the relative influence of each phase in this process is not clearly defined. While both crystalline and amorphous Fe oxides readily react with P in noncalcareous soils, the contribution of these forms to P sorption in calcareous soils has received little attention. Thus, in this study, samples of 20 mainly calcareous Lebanese soils, ranging widely in relevant properties, were equilibrated for 6 d with 25 mL P solutions ranging from 12.5 to 62.5 mg kg−1. The data did not conform to the conventional Langmuir isotherm. Correlations and regression coefficients with actual P rentention from solution indicated an involvement of oxalate Fe, but there was no effect of CaCO3 particle size. Removal of Fe prior to equilibration had an inconsistent effect on P retention. The P behavior of calcareous soils may be modified by Fe oxides in such soils.

Potassium lebanese soils as reflected by electro-ultrafiltration,chemical extraction and cropping

Potassium lebanese soils as reflected by electro-ultrafiltration,chemical extraction and cropping