Asmaa BENAISSA, Réda DJEBBAR, Ahmed ABDERRAHMANI

Abstract. Antagonistic rhizobacteria play an important role in biological control by producing lytic enzymes and antibiotics and then inhibiting the growth of a large number of pathogenic agents. The present work is in a perspective of antagonists’ strains exploration among sixty Plant Growth Promoting Rhizobacteria isolated from Rhus tripartita’s rhizosphere, characterized in a previous study. Therefore, six bacterial strains are tested: Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Proteus mirabilis, Enterococcus faecalis and Klebsiella pneumoniae. Different techniques were used: direct inoculation of bacterial cultures, diffusion discs impregnated with the supernatant and the use of bioactive substances extracted. The hydrolytic activity of carbohydrates, lipids and proteins of the positives strains was evaluated. In the present study, the antagonism activity proved to be more relevant for bacterial products than for bacterial culture. Moreover, out of the 60 PGPR strains utilized, 12 showed antagonistic potential against Gram positive and negative bacterial strains tested. Furthermore, the majority (66.66%) of the isolates assayed in our experiment were Gram-positive and belonged to Bacillus genera, compared to only 33.33% Gram-negative. The maximum zone inhibition was 20 mm, and the minimum zone inhibition was 12 mm. In the same way, the tested strains could produce at least two hydrolytic enzymes. The antagonistic effect of selected PGPR suggests the possibility of directly including these microorganisms in preventive control program against plant microbial infections or indirectly through the application of active substances as a curative treatment.

Keywords: PGPR; antagonism; antibiosis; hydrolytic enzymes



Svetlana BOORTSEVA, Maxim BYRSA, Olga BOUEVA, Irina STARODUMOVA, Ludmila EVTUSHENKO, Elena IURCU-STRAISTARU

Abstract. Three strains with antifungal, antibacterial, and plant growth-promoting activities were isolated from soils of the Republic of Moldova. Taxonomic study of these strains showed that strain 33 belongs to the species Streptomyces plicatus, while strains 9 and 66 could not be assigned to any known species and most likely represent two novel species of the genus Streptomyces. Streptomyces plicatus completely inhibited growth of A. alternata, Streptomyces sp. 9 inhibited growth of three species of genus Fusarium (growth inhibition zones between 28.0-34.0 mm), S. plicatus 33 – only F. graminearum (30.2 mm) and antifungal activity of strain Streptomyces sp. 66 was lower. All studied strains inhibited growth of phytopathogenic bacterium C. michiganensis (22.7-30.0 mm), strains Streptomyces spp. 9 and 33 – X. campestris (16.2-30.0 mm). Aqueous solutions of exometabolites of the studied strains actively increased the length of roots (by 271.32-348.84 %) and gained its weight (by 18.98-80.75 %) in dependence of concentration and belonging to strain.

Keywords: streptomycetes, antifungal and antibacterial activity, exometabolites, winter wheat, length of roots, weight of roots.



Rabab Waheed MARAEI, Gihan Mostafa HAMMOUD

Abstract. The objective of this study is to investigate the effect of treatment of three varieties of date (Bondoky, Sakkoty and Kaboshy) with gamma rays (0, 2.5, 5 and 10 kGy) on the chemical components and bioactive compounds of seeds and maximizing the benefit of these compounds, especially phenolic compounds, which have an important role as antioxidants as well as antimicrobial activity of seed extracts. Also, the fatty acids composition of seeds oil was assessed. The data indicated that most of the chemical components of the seeds were affected by irradiation in all varieties, as the content of protein and fat increased while the moisture content decreased by increasing the radiation dose compared with the control (untreated seeds). The content of sugars differed according to the variety, since Sakkoty variety has the highest content of sugars, followed by Kaboshy and Bondoky varieties. Moreover, the observed increase in antioxidant and antimicrobial activity was parallel to increase in phenolic compounds and flavonoids content due to irradiation treatment. There was an increase in saturated fatty acids and a decrease in polyunsaturated fatty acids with irradiation. Our experimental trial revealed that date seeds are rich source of bioactive compounds such as phenolic compounds and flavonoids and have antioxidant and antimicrobial activities which enhanced by irradiation treatment that may help develop antimicrobial drugs.

Keywords: Gamma rays; bioactive compounds; antioxidant and antimicrobial activity; date seeds.



Natalia CHISELIŢA, Agafia USATÎI

Abstract. The paper provides new data about the influence of ZnO nanoparticles with <50 nm dimensions in concentrations 1, 5, 10, 15, 20, 30, 50, 70 mg/L on cell viability, biomass production, total carbohydrates, proteins, β-glucans and catalase activity of Saccharomyces cerevisiae CNMN-Y-20 yeast strain. Our research has demonstrated the efficiency of ZnO nanopaticles utilization for stimulation of biosynthetic processes at studied strain. Nanoparticles stimulate cell viability, biomass production, protein content, β-glucans and insignificantly carbohydrates content, their effect depends from used concentration. A statistically significant increase was found in β-glucans content on using 10 and 15 mg/L concentrations of nanoparticles. The obtained results highlights the perspective of using <50 nm ZnO nanoparticles in yeast biotechnology for obtaining of β-glucans.

Keywords: Saccharomyces cerevisiae, ZnO nanoparticles, multiplication, biomass, cellular components.



Abir RADJAH, Hichem CHORFI, Yamina BOUATROUS

Abstract. The recent study aims to evaluate the effects of developmental stage and extraction solvent on the chemical composition, antioxidant potential, total phenolics and total flavonoids content of three southern east Algerian plant species (Limoniastrum guyonianum Boiss., Zygophyllum cornutum Coss. and Peganum harmala L.). The analyses were performed at the flowering and the vegetative stages and the extracts were obtained using three different solvent systems. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity was used to assess the antioxidant activity. For phenolic identification, high performance liquid chromatography (HPLC) was used. Extraction yields and compositions varied among species, solvents and stages. The highest yield was detected with 70% acetone and recorded for Zygophyllum cornutum Coss. (28 %). Peganum harmala L. presented the most important amounts of polyphenols and flavonoids (72.454 ± 0.214 mg GAE/g DW, 1.706 mg QE/g DW) at the vegetative stage. Limoniastrum guyonianum Boiss. exhibited the strongest DPPH radical scavenging activity (IC50 = 1.451 mg/ml) among the species at the vegetative stage with 70% ethanol. The HPLC analysis led to the identification of gallic, vanillic and ferulic acids, and catechin in the extracts of Limoniastrumn guyonianum Boiss. Gallic, 2,4-dimethoxy-trans-cinnamic acids and Kaempferol were detected in the extracts of Zygophyllum cornutum Coss. In the extracts of Peganum harmala L., gallic and caffeic acids, quercetin and berberine were identified. The efficiency of antioxidant compounds is directly related to their quality, which is influenced by several factors like the stage of development and the experimental conditions.

Keywords: Antioxidant activity; extraction solvent; medicinal plants; polyphenols; vegetative and flowering stages.



Nesrine GHERAIRIA, Soumia BOUKERCHE, Atef CHOUIKH, Selma KHOUDIR, Azzedine CHEFROUR

Abstract. The flora of Algeria enjoys a considerable biodiversity; it includes aromatic and medicinal plants endowed with many therapeutic activities. To this end, and as part of the enhancement of this flora, we were interested in studying the antibacterial activity of the essential oils from two species of genus Thymus (Thymus capitatus and Thymus hirtus ssp. algeriensis) growing wild in the Souk Ahras region (northeast Algeria). The antibacterial activity of essential oils was evaluated by the agar diffusion test and we determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against six pathogenic bacteria: Pseudomonas aeruginosa, Acinetobacter spp, Escherichia coli, Salmonella spp, Staphylococcus aureus and Enterocus faecalis. The strains tested were highly sensitive to essential oils, except Pseudomonas aeruginosa, which showed some resistance. The MIC values found ranging between 0.05 % and 0.8 %. The MBC values were equivalent or equal to double the MIC, indicating a strong bactericidal effect of various Thymus essential oils tested.

Keywords: Thymus; essential oils; antibacterial activity; MIC; MBC.



Dorina BONEA

Abstract: The present study was undertaken to assess the allelopathic effect of Datura inoxia Mill. in relation to the germination and initial growth of Zea mays L. Cogermination of maize with D. inoxia seeds and aqueous extracts from fresh and dry D. inoxia biomass in concentrations of 7.5%, 10% and 20% were examined under laboratory conditions using Petri dishes. The results showed that seeds cogermination had not significant effect on maize germination, but had significant effects on seedlings growth. Inhibition of root length of maize seedlings was of 61.9% and inhibition of shoot length was of 40.0%. The aqueous extracts of D. inoxia showed significantly deterioration in germination and seedlings growth of maize. The inhibitory effects of the extracts on germination ranged from 23.2% to 57.1%, on root length – from 19.8% to 92.6%, and on shoot length – from 33.2% to 69.6%. In conclusion, since this weed had strong allelopathic potential which suppressed germination and initial growth of maize. Moreover, there is an urgent need of integrated D. inoxia management strategy to stop further spread of this alien weed into cultivable areas.

Keywords: allelopathy; cogermination; Downy thorn-apple; inhibition; maize.



Lilya BOUCELHA, Réda DJEBBAR, Ouzna ABROUS-BELBACHIR

Abstract: Guaiacol peroxidase (GPX) is involved in a wide range of vital plant physiological processes primarily development and stress tolerance. However, the precise role of this enzyme in each seed part of the plant and in the various stages of development is still poorly known. Our work consisted in studying the kinetics of the activity of guaiacol peroxidase in cotyledons and embryonic axes (radicle and plumule) during the different phases of Vigna unguiculata (L.) Walp. germination. The results obtained showed that the kinetics of GPX during germination was triphasic. Indeed, it was activated after the first 30 minutes of imbibition, then decreased during the germination phase and reactivated after the 8th hour in plumule and cotyledons, but after the 20th hour in the radicle. On the other hand, our results showed that the GPX activity was extremely strong in the plumule compared to the other two seed parts. As for the cytochemical analysis, our study showed that during the germination imbibition phase, there is a slight accumulation of hydrogen peroxide H2O2, mainly in the meristematic tissues. The involvement of guaiacol peroxidase during germination of V. unguiculata (L.) Walp differs according to the seed part and the germination phase. The activation, the reduction and then the reactivation of the activity of this enzyme during germination could be explained by its multiple regulations, given that the existence of several isoenzymes. We can also conclude that during germination, GPX is mainly involved in development rather than in antioxidant activity.

Keywords: Gaïacol peroxidase; oxygen peroxide; germination; cotyledons; radicle; plumule; Vigna unguiculata.



Olga POSTOLACHI , Inna RASTIMESINA, Valentina JOSAN, Tatiana GUTU

Abstract. The aim of our study was to assess the effect of iron NPs (magnetite (Fe3O4) and zero-valent iron Fe(0)) on the formation of microbial consortia, in the presence of the herbicide trifluralin. In our researches the increase in the trifluralin concentration in the growth medium led to the decrease of both the density and the number of species of the microbial population. Addition of iron NPs to the culture medium clearly diminished the cytotoxic action of trifluralin on the microbial communities from the enrichment cultures. The effect of NPs on the formation of consortia of microorganisms depended on their chemical structure. Magnetite NPs showed a cytotoxic effect on microbial consortium, especially against bacteria. The population of bacteria in this consortium was well below the control level. Fe(0) NPs had the most favorable effect on the formation of microbial consortium; the resulting trifluralin-resistant consortium consisted of 4 strains of bacteria and 1 fungal strain.

Keywords: microbial consortia; trifluralin; iron nanoparticles.



Valentina JOSAN

Abstract. The aim of this study was to assess the utilization of agricultural waste as the support material for rhodococcus cells immobilization. Hazelnut (Corylus avellana L.) shell, common walnut (Juglans regia L.) shell, peanut (Arachis hypogaea L.) shell, pistachios (Pistacia vera L.) shell, pumpkin (Cucurbita pepo L.) and sunflower (Helianthus annuus L.) seeds husk were used to immobilize cells of Rhodococcus rhodochrous CNMN-Ac-05, destructor of persistent organic pollutants. The peanut shell as a support material demonstrated a good adsorption of bacterial cells – 7.95 mg dry cells per gram of carrier (34.3%), while the efficiency of cells immobilization on the sunflower’s husk was very low – 6.2%. The reduction of carrier particle size to 100–500 µm was contributed to an increase in the number of cells adsorbed on supports made from peanut and hazelnut shells. The efficiency of bacterial immobilization was in 1.5 and 3 times higher than the initial one for supports made of peanut and hazelnut shell accordingly.

Keywords: Rhodococcus rhodochrous; organic supports; immobilized cells.



Yasser KADRI, Abdallah MOUSSAOUI, Abdelmadjid BENMEBAREK

Abstract. This modest work is an attempt to give an overview of the importance of the medicinal plants used by the population in the wilaya of Adrar. To find out about these medicinal plants traditionally used by the population, ethnobotanical surveys were conducted during the 2015/2016 to 2017/2018 campaigns in the Adrar region. The purpose of this approach is the collection of data on the therapeutic uses practiced. We selected for this work sixty (60) species of medicinal plants belonging to thirty (30) botanical families, and also to show that: 1. leaves are the most used parts; 2. the decoction is the most used method; 3. the most frequent administration is the oral route; 4. the majority of species were involved in the treatment of digestive and respiratory diseases; 5. the most represented families are Asteraceae and Fabaceae.

Keywords: Ethnobotany study; herbal medicine; medicinal plants; Adrar region.



Muthik GUDA, Mikdad TAHER, Basim ALMAYAHI

Abstract. Reed plants were grown in a controlled laboratory environment. The aim of study is explain the effect of heat stress to anatomical feature of vascular system in Phragmites australis. The results show that high temperature increasing the diameter and density of xylem vessels. However, high temperature decreases the density of xylem vessels. There are differences in development of vascular bundle at 25 °C. It is represented as optimum degree for growing. When the temperature increased to 35 °C and 45 °C, the diameter of the metaxilem vessels and the diameter of the phloem are decreased over time until 18 weeks to the lower diameter. The diameter and vascular distances are showed an increase in the thickness of cell walls with increased thermal stress. Sclerenchyma cells are increased in number with increased exposure to heat stress. A comprehensive study of the temperature effects on plant vascular tissues and water can help us to understand plant responses to climate change. Thus improving breeding programs for climate-resistant types.

Keywords: Phragmites australis; stress; metaxylem; phloem; vascular bundles.



Yamina BOUATROUS, Soulef KRIKER, Boutheina KHACHAI

Abstract. As part of the discovery of new antioxidants of natural origin, we have devoted this study to the evaluation of the antioxidant activity of phenolic extracts. of Curcuma longa L. and Nigella sativa L. a medicinal plant widely used in the traditional pharmacopoeia the polyphenol compounds were obtained by maceration in ethanol with a yield of 10% of the Nigella sativa extract and 21% of the Curcuma longa extract. The total content of phenol compounds of the ethanol extracts was determined by the method of folin -ciocalteu, The highest content is found in the plant Curcuma longa, it is of the order of 251.46mg / mL (7.54mg GAE / g), and for the plant Nigella sativa, it is of the order of 167.46mg / mL (5.02mg GAE / g) .The antioxidant activity was evaluated using the free radical reduction method DPPH extract concentration needed to reduce 50% of the radical DPPH (EC50). The ethanol extract of Curcuma longa L. is estimated at 0.00596 mg / mL showing a very important activity which is practically similar to that of the ethanol extract of Nigella sativa L. which reduces stability to DPPH with an EC50 of 0.050 mg / mL. From these results it is proved that ascorbic acid remains the most effective antioxidant with an EC50 of 0.0002 mg / mL relative to the ethanol extract of the plants studied.

Keywords: Curcuma longa L.; Nigella sativa L.; antioxidant activity; Folin-Ciocalteu; phenol compounds.