Isolation and identification of a Staphylococcus warneri strain with anti-mycobacterial activity

Tuberculosis is the principal cause of death from infection in the world. The resurgence of tuberculosis and the increase in mycobacterial infections, as well as multidrug-resistance of mycobacteria to available antibiotics, has incentivized research on new antimycobacterial agents. Therefore, research based on water and soil samples from the Moroccan biotopes, has led to the isolation of a bacterial strain capable of inhibiting mycobacterial growth (Mycobacterium smegmatis and Mycobacterium aurum A+). The effect was due to an active substance secreted into the culture medium. Sequencing of the 16S rRNA gene identified the strain as belonging to the species Staphylococcus warneri. The active substance precipitated using ammonium sulfate, maintained its inhibitory properties, which were lost when treated with proteinase K. These results indicated that the active substance was protein. Study of the activity of the metabolite revealed its effect on M. smegmatis cell wall, facilitating genomic DNA extraction.Keywords: Tuberculosis, mycobacteria, anti-mycobacterial agents, Staphylococcus warneri, DNA extraction.African Journal of Biotechnology Vol. 12(42), pp. 611

Isolation and identification of Bacillus strains with antimycobacterial activity

Tuberculosis is the principal cause of death worldwide due to an infectious disease. The resurgence of tuberculosis, followed by the increase in prevalence of infections caused by nontuberculous mycobacteria (NTM), as well as the multi-drug resistance of mycobacteria to the majority of currently available antibiotics, have encouraged research for new antimycobacterial agents. Soil and water samples from different Moroccan biotopes, have led to the isolation of four bacterial strains (M, R, G and S), showing an inhibitory effect on mycobacterial growth. This effect was shown to be due to secreted substances in the growth medium. From subsequent analysis it was concluded that these strains produced different active substances. Sequencing of the 16S rRNA showed that these isolates belong to the genus Bacillus. The active substance from isolate M, showed the more important inhibitory effect on mycobacterial growth. It is precipitated with ammonium sulfate and lost all activity when treated with Proteinase K, revealing its protein nature

In vitro and intracellular antimycobacterial activity of a Bacillus pumilus strain

Despite the declaration of tuberculosis (TB) as a global emergency by the world health organization (WHO) about 20 years ago, the worldwide problem of this disease has worsened due to increased drug resistance of tuberculosis bacilli and acquired immune deficiency syndrome (AIDS) pandemic. Consequently, fight against multidrug and extensively drug-resistant TB is a high priority for public health and research. The present work describes the isolation of a Bacillus pumilus strain secreting a metabolite of protein nature capable of inhibiting mycobacterial growth (Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium bovis BCG). This metabolite is not toxic, accumulates within the macrophage and inactivates the bacilli with a comparable efficiency to that of the pure commercial antimycobacterial substance Amikacin

Characterization of plant growth-promoting mechanisms of rhizobacteria from the rhizosphere of date palms in tafilalet oases

Tafilalet is the largest oases in Morocco, but it is threatened by climatic and environmental stress like drought, soil degradation as well as plant diseases, in particular Fusarium wilt of date palm caused by Fusarium oxysporum f.sp albedinis (Foa). Soils are poor in terms of organic matter, nutrient concentrations and biological activity resulting in a dramatic decrease in date palm growth. Improving date palm productivity is regularly achieved by the excessive application of chemical fertilizers, which are harmful for human health and environment. In this work, we aimed at screening the plant growth-promoting rhizobacteria (PGPRs) and at the same time acting as biocontrol agents against Foa. Rhizobacteria associated with date palm and spontaneous plants in Tafilalet oases have been isolated and functionally characterized. Several plant growth promoting and biocontrol traits were investigated, including nutrients solubilization, and the production secondary metabolites and enzymes. Results showed that 97 % of strains was effective in N-fixation, 36 % in ammonia production, 90 % in P-solubilization. The Siderophores and Indol 3-acetic acid production were observed at 30 and 32 strains respectively. Besides, 78 % of strains had an inhibitory effect against Foa, in which 42 % completely inhibited the mycelia growth on PDA medium. Several strains produced cellulase, protease, amylase, chitinase and other secondary metabolites like hydrogen cyanide. Based on these results, consortia of efficient PGPRs could be selected and used as efficient microorganisms for future greenhouse and field experiments

Effect of PGPR and mixed cropping on mycorrhizal status, soil fertility, and date palm productivity under organic farming system

A field study was carried out for two years at an organic farm under arid climate in Morocco to investigate the effect of an integrated biofertilization approach on Arbuscular Mycorrhizal Fungal (AMF) abundance and infectivity, soil fertility, yield, and fruit quality of date palm. The biofertilization approach included three management practices namely application of compost, inoculation with a consortium of native PGPR strains originally isolated from date palms of Drâa-Tafilalet region (Pseudomonas koreensis, Serratia nematodiphila, S. marcescens, and Klebsiella sp.) and using mixed-cropping with sorghum. Accordingly, four treatments were established in this study: 1) mixed-cropping with sorghum, 2) PGPR inoculation, 3) sorghum + PGPR, and 4) control (without sorghum or PGPR). All treatments received compost as organic amendment. Results revealed that mixed-cropping with sorghum significantly increased AMF colonization intensity and spore density by more than 50% and 29%, respectively. Sorghum association also resulted in a significant increase in organic matter concentrations of up to 2.95% against 2.45% in monocropping soils. The integrated biofertilization approach resulted in the highest yield with an increase rate of 10.6% and 12.1% in the first and the second year, respectively compared to date palms receiving compost alone. Similarly, the mineral composition and quality characteristics of date fruits were significantly improved. The enhancement of soil fertility and date palm productivity under harsh environmental conditions represents a first step towards the adoption of sustainable practices in the region and in similar areas

Isolement et identification moléculaire de souches d'actinomycètes productrices de substances antimicrobiennes à partir de biotopes marocains et caractérisation partielle des principes actifs

Vingt souches d'actinomycètes ont été isolées à partir d'échantillons de sol et de bois prélevés à partir d'une vielle maison dans l'ancienne médina de Fès et d'échantillons de sol prélevés de la région de Moulay Yacoub et des rives d'Ouèd Sebbou. L'activité antimicrobienne, réalisée par la technique des cylindres d'agar et celle des stries croisées, a été déterminée contre des bactéries à Gram positif (Bacillus subtilis 5262, Bacillus cereus cip 14579, Staphylococcus aureus 7625, Staphylococcus epidermidis 6821) ; des bactéries à Gram négatif (Pseudomanas aeroginosa 76110, E.coli cip 7624) et la levure Candida albicans. Parmi les vingt isolats, douze (60 %) ont montré une activité contre au moins une des souches tests. Par ailleurs, l'analyse moléculaire des vingt isolats par amplification et séquençage partiel du gène de l'ARNr 16S a permis d'attribuer dix huit isolats au genre Streptomyces et deux aux genres Saccharothrix et Lentzea. De plus, le séquençage de la quasi-totalité de l'ADNr 16S (1460 pb) de cinq isolats (Sj32, Sj33, Sj38, Sj68 et Sj69) nous a permis d'assigner les isolats Sj38 et Sj69 à S. parvus, et Saccharothrix sp., respectivement. Les substances bioactives produites par les cinq souches d'actinomycètes sont extraites par des solvants organiques et les molécules produites sont purifiées par HPLC. Une étude de la stabilité de l'activité antibactérienne en fonction de la température et de la protéinase K a montré que les substances bioactives seraient de nature non protéique pour Sj32, Sj33, Sj68 et Sj69 et protéique pour Sj38. Une étude de la cytotoxicité de la fraction active de la souche Sj32 sur les cellules MRC-5 a montré qu'elle présente une forte cytotoxicité contre ces cellules. Enfin, l'étude de l'effet de la fraction active de la souche Sj32 sur la transcription et la traduction bactérienne in vitro, a montré que cette substance purifiée n'inhibe pas ces deux processus biologiques.Twenty strains of actinomycetes were isolated from soil and wood samples taken from an old house in the old medina of Fez and also soil samples from the region of Moulay Yacoub and banks of Sebbou River. The antimicrobial activity, carried out using the agar piece and cross striations methods, were tested against Gram-positive bacteria (Bacillus subtilis 5262, Bacillus cereus cip 14579, Staphylococcus aureus 7625, Staphylococcus epidermidis 6821); bacteria Gram-negative (Pseudomonas aeruginosa 76110, E. coli cIP 7624) and the yeast Candida albicans. Among the 20 isolates, 12 (60%) showed activity against at least one of the test strains.Molecular analysis of the twenty isolates by amplification and partial sequencing of the 16S rRNA gene allowed us to assign eighteen isolates to the genus Streptomyces and two to genera Saccharothrix and Lentzea.In addition, sequencing of nearly complete 16S rDNA (1460 bp) of five isolates (Sj32, Sj33, Sj38, Sj68 and Sj69) allowed us to assign isolates Sj38 and Sj69 to S. parvus and Saccharothrix sp., respectively.Bioactive substances produced by the five strains of actinomycetes were extracted by organic solvents and the molecules produced are purified by HPLC. A study of the stability of the antibacterial activity according to temperature and proteinase K showed that the bioactive substances are of non-protein nature for Sj32, Sj33, Sj68 and Sj69 and of protein nature for Sj38.A study of the cytotoxicity of the active fraction of the strain Sj32 on MRC-5 cells showed that it had a strong cytotoxcity against these cells.Finally, the in vitro study of the effect of the active fraction of the strain Sj32 on bacterial transcription and translation, showed that the purified substance didn't inhibit these two biological processesMONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Exploring Natural Fermented Foods as a Source for New Efficient Thermotolerant Yeasts for the Production of Second-Generation Bioethanol

International audienceConsidering the cost-effectiveness of bioethanol production at high temperatures, there is an enduring need to find new thermotolerant ethanologenic yeasts. In this study, a total of eighteen thermotolerant yeasts were isolated from various natural fermented products in Morocco. Ethanol production using 50 g/L glucose or 50 g/L xylose as the sole carbon source revealed potential yeasts with high productivities and volumetric ethanol productivities at high temperatures. Based on molecular identification, the selected thermotolerant fermentative isolates were affiliated with Pichia kudriavzevii, Kluyveromyces marxianus, and Kluyveromyces sp. During the simultaneous saccharification and fermentation of lignocellulosic biomass at a high temperature (42 °C), the designated yeast P. kudriavzevii YSR7 produced an ethanol concentration of 22.36 g/L, 18.2 g/L and 6.34 g/L from 100 g/L barley straw (BS), chickpea straw (CS), and olive tree pruning (OTP), respectively. It also exhibited multi-stress tolerance, such as ethanol, acetic acid, and osmotic tolerance. Therefore, the yeast P. kudriavzevii YSR7 showed promising attributes for biorefinery-scale ethanol production in the future

Dry chemo-mechanical pretreatment of chickpea straw: Effect and optimization of experimental parameters to improve hydrolysis yields

International audienceDry chemo-mechanical (DCM) pretreatment is an interesting eco-friendly approach for bioconversion of lignocellulosic biomass into sugars and other valuable molecules. In this study, different dry DCM pretreatments were developed using a combination of alkaline and vibro-milling “VBM”. High-resolution fractional factorial 2k-1 design (FFD) was applied to evaluate statistically the effects of NaOH concentration (2–10%), impregnation ratio (20–50%), milling time (10–60 min), milling frequency (15–30 Hz), and ball diameter (1 or 2.5 cm) on reducing sugars release from chickpea straw (CS). The optimal conditions ensuring the maximum concentration of reducing sugars (374.70 mg/g biomass) after 72 h of enzymatic hydrolysis were 10% of NaOH, impregnation of 50%, 60 min of VBM, frequency VBM of 30 Hz, and ball diameter of 2.5 cm. Furthermore, an ethanol concentration of 17.81 g/L was obtained after simultaneous saccharification and fermentation of the pretreated CS under the defined optimized conditions

Isolation, characterization and antimicrobial activity of a Streptomyces strain isolated from deteriorated wood

Emergence of drug resistance among pathogenic bacteria to currently used antibiotics has made the search for novel bioactive compounds from natural and unexplored habitats a necessity. In this study, we reported the isolation, characterization and antimicrobial activity of an actinomycete strain isolated from deteriorated wood of an old house located in the Medina of Fez. The isolate, named H2, was identified by 16S rDNA sequencing and was shown to belong to the genus Streptomyces. The isolate was screened for antimicrobial activity against Gram positive bacteria, Gram negative bacteria, Mycobacteria, yeasts and fungi. Partial characterization of the active substance (resistance to proteinase K and heat) showed that it would be of non-protein nature. The kinetics of production of the active substance showed that the maximum production occurs between the 7th and 10th day of fermentation. In addition, organic extract of the isolate was able to release genomic DNA of Staphylococcus aureus suggesting that it acts probably on the bacterial cell wall. Thin layer chromatography (TLC) of the ethyl acetate extract followed by bioautography has allowed localizing the active substances. This will open the way to further investigations to demonstrate their potential importance in combating pathogenic bacteria. Key words: Actinomycetes, Streptomyces, antimicrobial activity, molecular identification