Thermostable a-amylase is a commercial enzyme that has found several biotechnological applications in recent years. This prompts researchers to check out the hot ecosystems the least explored to find producing microorganisms. Thermal waters are a poorly studied ecological niche compared to other ecosystems. Actinobacteria are known for their unique metabolic abilities to produce the most innovative bio-molecules. In this study, the isolation by conventional microbiological methods, allowed to obtain 13 thermophilic actinobacteria from a hot spring of TLEGHMA located in the eastern Algerian. All these isolates were characterized morphologically and by physiological methods. Molecular identification by sequencing of the rRNA16s gene, allowed to assign them to the genus Streptomyces sp. Among these isolates, 9 actinobacteria showed abilities to produce a thermostable a-amylase active at a temperature of 55 degrees C. Two isolates named TA3 and TA4 are however, the most successful. They were assigned to Streptomyces albidofalvus and Streptomyces cavourensis respectively. they are able to produce a thermostable a-amylase at 55 degrees C with an activity rate of 110.33U/ml by strain TA3 and 224U/ml by strain TA4 and with an optimum of activity in a pH equal to 9. These results show that these thermophilic Streptomyces from these hot waters, are a very important source of thermostable and alkalophilic a-amylase

Glyphosate, also known as N-phosphonomethylglycine, is the herbicide that is widely used across the globe. As there are concerns over its potential toxicity to non-target soil species, there is a growing interest in identifying glyphosate-degrading microorganisms in soil. Biodegradation, by actinobacteria, is a very promising approach to eliminate this pesticide from contaminated environments. The present work isolated and identified actinobacteria capable of degrading glyphosate from Saharan agriculture, as well as determined how the application of this herbicide affects the abundance of actinobacteria present in soil. It was observed that the use of glyphosate led to an increased abundance of actinobacteria in the soil compared to the untreated soil. Among this population, an actinobacterial strain was isolated from glyphosate contaminated soil by the enrichment method, and was identified to possess the greatest capability to degrade glyphosate at 50 mg/L. The identification of this strain was achieved through a combination of cultural, morphological, biochemical, and molecular techniques. This included the use of 16S rDNA sequencing, leading to its successful classification as Streptomyces sp. strain SRH22. This strain was assigned the accession number OQ302556 by the National Center for Biotechnology Information (NCBI). A rapid, sensitive, and straightforward spectrophotometric technique was employed for the quantification of glyphosate. Results showed that the optimal biodegradation (90.2%) was obtained under a temperature of 30 degrees, a PH of 7.2, and an inoculum volume of 4% timed over six days. This work shows that the Streptomyces SRH22 presents good potentiality to be used as a bioremediation agent for agricultural soils in the Algerian Sahara.

Thiamethoxam (TMX) is an effective neonicotinoid insecticide. However, its widespread use is detrimental to non-targeted organisms and water systems. This study investigates the biodegradation of this insecticide by Labrys portucalensis F11. After 30 days of incubation in mineral salt medium, L. portucalensis F11 was able to remove 41%, 35% and 100% of a supplied amount of TMX (10.8 mg L−1) provided as the sole carbon and nitrogen source, the sole carbon and sulfur source and as the sole carbon source, respectively. Periodic feeding with sodium acetate as the supplementary carbon source resulted in faster degradation of TMX (10.8 mg L−1); more than 90% was removed in 3 days. The detection and identification of biodegradation intermediates was performed by UPLC-QTOF/MS/MS. The chemical structure of 12 metabolites is proposed. Nitro reduction, oxadiazine ring cleavage and dechlorination are the main degradation pathways proposed. After biodegradation, toxicity was removed as indicated using Aliivibrio fischeri and by assessing the synthesis of an inducible β-galactosidase by an E. coli mutant (Toxi-Chromo test). L. portucalensis F11 was able to degrade TMX under different conditions and could be effective in bioremediation strategies.

Actinobacteria have many properties that make them good candidates for the bioremediation of sites contaminated by several organic and inorganic pollutants. However, studies on the biodegradation of used motor oils by Actinobacteria, compared to other bacteria, remain little studied. Actinobacteria were isolated from soil contaminated with used motor oils and sewage sludge in order to select a species that can effectively degrade such pollutants. This study aims to assess their degradation capacity of the various hydrocarbon fractions contained in the oil by gas chromatography-mass spectrometry (GC-MS). Five Actinobacteria isolates were isolated by the enrichment method. The S1.1. A strain was considered the best biosurfactant producing strain. It presents the highest emulsification index compared to other isolated Actinobacteria (82.6%). Phenotypic and molecular identification by sequencing the 16 S rDNA gene makes it possible to assign this isolate to the species Streptomyces ginkgonis KM-1-2. Gravimetric analysis results of biodegraded used motor oil indicated that this strain is capable of degrading 76.4% of an initial 50 ml/l concentration of used motor oil after 4 weeks of incubation. The results of GC-MS analysis of the residual motor oil showed that strain S1.1. A degraded some long and intermediate chain alkanes completely or to shorter fractions. The Streptomyces ginkgonis strain KM-1-2 was also able to degrade certain alkylated mono-aromatic hydrocarbons linked to benzene, as well as certain alkylated and non-alkylated polycyclic aromatic hydrocarbons linked to anthracene, naphthalene, phenanthrene, fluorene, and azulene. This strain exhibited the highest emulsification index at 82.6%. This bacterium shows a significant biodegradation capacity and could, consequently, be used in the processes of bioaugmentation of sites contaminated by these oils.

The pollution of water resources by pesticides poses serious problems for public health and the environment. In this study, Actinobacteria strains were isolated from three wastewater treatment plants (WWTPs) and were screened for their ability to degrade 17 pesticide compounds. Preliminary screening of 13 of the isolates of Actinobacteria allowed the selection of 12 strains with potential for the degradation of nine different pesticides as sole carbon source, including aliette, for which there are no previous reports of biodegradation. Evaluation of the bacterial growth and degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam (tiam) by selected Actinobacteria strains was performed in liquid media. Strains Streptomyces sp. ML and Streptomyces sp. OV were able to degrade 45% of 2,4-DCP (50 mg/l) as the sole carbon source in 30 days and 84% of thiamethoxam (35 mg/l) in the presence of 10 mM of glucose in 18 days. The biodegradation of thiamethoxam by Actinobacteria strains was reported for the first time in this study. These strains are promising for use in bioremediation of ecosystems polluted by this type of pesticides.

In this study, we tested the ability of Streptomyces to use for their growth benzene, toluene, ethylbenzene, and o-, m-, p-xylenes as sole source of carbon and energy. These bacteria were isolated from agricultural soils and activated sludge samples from a wastewater treatment plant. The results show that Streptomyces are capable of degrading at least one of the BTEX compounds. Among them, 3 isolates from activated sludge called (U, F and V) and a single isolate (SA13) isolated from an agricultural soil, can use as the sole source of carbon and energy, all of these BTEX compounds at concentrations of 1500 mg/L. Based on the analysis of the 16S rRNA gene sequence, two active strains were identified as Streptomyces fimicarius, Streptomyces cavourensis, Streptomyces flavogriseus and Streptomyces pratensis. These strains can be excellent candidates for the bioremediation of the telluric and aquatic sites polluted by these xenobiotics.

Benzene and its derivatives, toluene, ethylbenzene and xylenes (BTEXs) are volatile monocyclic aromatic compounds which are widely distributed in nature and highly hazardous to human and animal health. The species belonging to the genus Nocardia are filamentous bacteria widely present in the flocs of activated sludge. They lead to the formation of foams and bulking sludge, which disrupt the sludge settling properties and thus reduce the quality of the purified water. The aim of our study is to isolate from these filamentous bacteria in the activated sludge, indigenous strains of Nocardia able to use the BTEX as the sole source of carbon and energy. Two isolation media were used to isolate the Nocardia species found in the activated sludge samples taken from the Ibn Ziad (Constantine-Algeria) wastewater treatment plant. The results show that five strains that morphologically resemble Nocardia have been isolated. The strain named (S) was identified by the sequencing of its 16S rRNA gene as Nocardia nova. This strain was the only isolate capable of growing under laboratory conditions, on BTE (m-o-p) X added at concentrations of 1500 mg/L each. Such a result can be used in the bioremediation of aquatic or terrestrial ecosystems contaminated by these compounds, using this bacterium as a bio-augmentation agent.

Wastewater can be defined as water degraded mainly by human activities. This water must be treated before being reintroduced into the supply circuits. Wastewater from the agricultural sector can be difficult to process because of the presence of many persistent pesticides. The Ortiva fungicide has been used for several years worldwide since 1996. It is very toxic for aquatic organisms and can lead to long-term adverse effects in aquatic environments. Different biological treatment techniques are necessary to overcome the devastating effects of this pollutant. The micro-organisms present in the wastewater sludge are the major players in the suppression of these effects. In this study, we isolated nine actinomycetes strains which are able to degrade the fungicide Ortiva at a concentration of 500mg/L and at a temperature of 30 degrees C within 21d of incubation when supplied as a sole carbon source. The molecular identification by 16S rRNA was possible for only seven actinomycetes under laboratory conditions. These isolates showed a homology to Nocardia sp. and Streptomyces sp. The biodegradation ability of these strains reveals its potential for further study as a biological agent for the remediation water contaminated with Ortiva.

Volatile organic compounds are considered as major sources of air pollution. They cause toxicity problems, bad odors, global warming, etc. Methyl ethyl ketone (MEK) is used in the formulation of lacquer type paints, varnishes, cleaners, thinners, etc. and in many other industries such as the manufacture of synthetic leather and in the decaffeination of coffee. Released into the environment, it causes respiratory, eye, and skin health problems. At high concentrations, it poses a potential threat to public health. In recent years, effective, very environmentally sound, and economical organic biological waste gas treatment processes have emerged. The sources of degrading micro-organisms are diverse and activated sludge suspensions are widely used. Actinomycetes are known for their ability to degrade various polymers. In this study, we are interested in isolating actinobacteria from activated sludge from the wastewater treatment plant of El Athmania, Mila. Thus, five actinomycetes were isolated on ISP4 medium supplemented with nystatin at 100 μg/ml and nalidixic acid at 10 μg/ml. These isolates proved to degrade efficiently MEK in batch reactors. Growth kinetics were determined for each isolate. The time course of MEK consumption was also measured by gas chromatography. A strain named A5.7 stood out as the best degrading bacterium. Indeed, complete degradation of the substrate was achieved after only 72 h of incubation. The A5.7 isolate was assigned by morphological and cultural methods to the genus Streptomyces.

Two wood decay fungi have been isolated from the Pinus halepensis wood. They have been identified by their cultural and morphological aspects as: Tramates sp and Memnoniella sp . The isolation of the actinomycetes from different ecosystems has allowed us to obtain 80 pure strains. The agar disks technique has been employed to study the antifungal activity of these actinomycetes against the two fungi, which degrades the Pinus halepensis wood. Among all the isolated actinomycetes, 17 strains have presented an activity against at least one xylophage fungus tested. Among the 17 bacteria of actinomycetes, only one has shown a strong antifungal activity against the two fungal isolates. This actinomycete has been identified by the morphological and the chimio-taxonomical characters of the cellular wall as Streptomyces.

In order to define the isolation conditions of actinomycetes from desert soils, the soils of the town of Biskra, situated at the gate of the Algerian Sahara was analyzed. Two types of samples have been prepared; the firt one was heated up at 110 °C during 10 minutes and the second did not undergo any heat processing. The isolation was carried out from these two types of soils on the starch casein medium added to a combination of several antifungal and antibacterial agents. Five different isolation mediums have been tested in this study. The results showed that the pretreatment of the soil with heat is not recommended. Indeed, the number of isolated actinomycetes was 38. 104 cfu.g-1 when the soil samples were heated up and 92.104 cfu.g-1 when no heating was used. The thermic processing reduces then the actinomycetes by more than 50 %. The antifungal and antibacterian which permit the elimination of undesirable germs are the nystatin and the nalidixic acid with respective concentrations of 50 µg/ml and 10 µg/ml. According to these results, the most favorable isolation medium for actinomycetes of desert soils studied is Glucose-yeast extract-malt (GLM).

Une souche d’actinomycetes isolee d’un echantillon de sol aride de Biskra, caracterisee comme appartenant a la serie rouge du genre Streptomyces, active contre trois bacteries a coloration de Gram positive (Staphylococcus aureus, Bacillus cereus et Streptococcus feacalis) et deux bacteries a coloration de Gram negative (Eschericha coli et Pseudomonas aeruginosa) a fait l’objet de cette etude. L’etude cinetique de la croissance et de la production d’antibacteriens a montre que l’activite antibacterienne est maximale au neuvieme jour de fermentation. Les molecules bioactives du surnageant de culture sont extraites par trois solvants de differentes polarites. Les plus grandes zones de lyse ont ete observees avec l’extrait d’acetate d’ethyle. Les substances antibacteriennes, extraites du mycelium, resistent a differents pH (de 2 a 8), gardent leur stabilite apres 30 min de chauffage a 100°C et meme apres congelation a –20°C. La chromatographie sur papier, de l’extrait du mycelium, selon la technique de Betina revele la presence de deux composes bioactifs differents

Sur un lot de cinquante-cinq souches d’actinomycètes isolées à partir d’échantillons de sol aride prélevés dans la région de Biskra, dix souches à structure filamenteuse ont été purifiées.

The study of the biodegradability of organic substances is essential in determining the behaviour of volatile organic compounds in natural environments or a biological system for effluent treatment. The present study contributes to the comprehension of the biological phenomena controlling the degradation of methanol in a series of batch-mode operated reactors. Methanol was subject to biodegradation experiments by five different inocula taken from the wastewater treatment station of El Menia. The consortia used to inoculate liquid batch cultures consisted in bacteria, actinomycetes, fungi and yeasts. The fifth consortium consisted in the mixed culture of the activated sludge sample. Substrate biodegradation and biomass growth kinetics were studied. The concentration of substrate in the liquid phase was determined by injecting 1 mu l in a Shimadzu gas chromatograph Model GC-17A, equipped with a DB-5 capillary column (30 in long, 0.25 mm internal diameter). Biomass growth was determined by direct reading of the optical density at 543 nm on a visible spectrophotometer Model Jenway 6300. Bacteria and yeasts proved to be the most efficient methanol-degrading strains. Complete elimination of initial methanol concentration (1000 ppm w/v) required 7 hours for both consortia. Substrate concentrations dropped to 610 ppm and 630 ppm, respectively, one hour after the start of degradation experiments. At t = 1 hour, methanol concentrations reached 850 ppm, 710 ppm, and 800 ppm for fungi, actinomycetes and activated sludge, respectively.

Fifty-five colonies are preleved following the catacteriticalaspect of Actinomycetales, from isolation mediums ensemenced by soil samples collected from desert region of Biskra. Ten strains were purified on selective medium with antifungal and anti negative Gram antibiotics. These strains produce bioactive substances against positive Gram and / or negative Gram bacteria. The strain A1with important spectrum of activity was identified with the cultural, morphological, physiological and biochemical characterisation as a member of Streptomycesgenera. It was considering belonging near to Streptomyces antibioticusand Streptomyces rochei.

Twenty-five strains of actinomycetes were isolated from samples of water, soil and tree barks collected at two sites located in the north-east of Algeria. Antimicrobial activity was tested using the agar cylinder method against three Gram-positive bacteria, three Gram-negative bacteria, three yeasts and three filamentous fungi. Among the 25 isolates 14 (56%) strains showed an activity against at least one of the test-bacteria studied and two (8%) showed antifungal activity. Ninety-three percent of the active strains were identified by the universal PCR as belonging to the Streptomyces genus and 7% to the Actinomadura genus. (c) 2005 Elsevier SAS. All rights reserved.

Dans le cadre de la recherche de nouveaux antibiotiques élaborés par des actinomycètes originaires des milieux extrêmes, l’activité antibactérienne d’une souche d’actinomycète isolée d’eau de Sebkha de Ain Mlila a été étudiée. Ses caractères morphologiques et macromorphologiques sur milieu ISP2 + 0,5 % NaCl permettent de la rapprocher de l’un des genres, Kitasatosporia, Saccharopolyspora ou. Les molécules bioactives produites par cette souche et excrétées dans le milieu de fermentation sont extraites par trois solvants de polarité différente, celles du mycélium sont retrouvées dans l’extrait méthanolique. L’étude cinétique de la croissance et de la production de substances inhibitrices, réalisée sur milieu ISP2 + 0,5 % NaCl (220 tr/ mn, 28°C), a révélé que l’activité antibactérienne de la souche A4 est maximale au quatrième jour dans le mycélium et au cinquième jour dans l’extrait butanolique du surnageant.

L'evolution constante de la resistance bacterienne aux antibiotiques et l'emergence de nouvelles maladies infectieuses justifient l'urgence de disposer de nouvelles molecules antimicrobiennes. Des echantillons d’eau et de sol environnant de Sebkha ont ete explores dans le cadre de la recherche de souches actinomycetales productrices, eventuellement, de nouveaux antibiotiques. Sur les quatre milieux d’isolement utilises, quarante deux types de colonies bacteriennes se rapprochant par leur aspect macroscopique aux actinomycetes ont ete prelevees. L’observation microscopique a l’etat frais et apres coloration de Gram a revele que parmi les quarante deux colonies trente-neuf sont a coloration de Gram positive dont cinq souches seulement presentent un aspect filamenteux, quelque fois fragmente ; ce qui les rapprochent d'une maniere certaine aux actinomycetes filamenteux. Apres purification, l'activite antibacterienne des cinq souches actinomycetales a ete mise en evidence sur deux milieux de composition differente et par deux techniques de diffusion sur gelose : technique de la double couche et technique des cylindres d'agar. Toutes les souches ont presente une activite inhibitrice a l'egard des souches bacteriennes-tests de collection a coloration de Gram positive et/ou a coloration de Gram negative et ceci quelle que soit la technique utilisee. Trois souches d'entre elles ont montre une activite vis a vis d’Aspergillus niger, d’Aspergillus oryzae et deCandida albicans. L’analyse statistique a revelee que la mise en evidence de l’activite antibacterienne et de l’activite antifongique dependent, a la fois, des souches actinomycetales etudiees, dela composition des milieux de culture et des microorganismes-tests utilises.

As part of a research program whose aim is to identify new antifungal metabolites from rare actinomycetes, three Saharan soils from south east Algeria were analyzed. Twenty-seven (27) strains of actinomycetes were isolated and tested for their antifungal activity. The soil from the region of Biskra gave the highest number of actinomycetes, i.e. 52% versus 18% and 30% for the soils from El-Oued and Ourgla, respectively. The results of this study showed the GLM medium to be the most favorable for the isolation of actinomycetes from these ecosystems, on its own providing 17 strains out of the total number of actinomycetes isolated. Two strains presented very important antifungal activity against most of the filamentous fungi and test yeasts used. Molecular identification by polymerase chain reaction using universal 16S rDNA primers allowed the two active strains to be classified in the genus Streptomyces. (c) 2005 Elsevier SAS. All rights reserved.