Amin Laglaoui

Chemical composition and antimicrobial activity of essential oils of Thymus algeriensis, Eucalyptus globulus and Rosmarinus officinalis from Morocco

BACKGROUND The present study reports on the antimicrobial activity and chemical composition of the essential oils (EOs) of Thymus algeriensis, Eucalyptus globulus and Rosmarinus officinalis from Morocco. RESULTS The composition of these species was analysed by GC-MS, and 65 components were identified. Eucalyptus globulus EO showed a great similarity with EOs from other regions, with 1,8-cineole (79.85%) the major component. Also rich in this constituent was Rosmarinus officinalis (43.99%). However, the chemical profile of Thymus algeriensis was rather different, and for the first time such a high content of borneol (23.48%) has been described in this EO. The antimicrobial activity of these species has also been studied against seven pathogenic and spoiling bacteria of significant importance. According to the results, Thymus algeriensis showed the best bacteriostatic and bactericidal effect, followed by Eucalyptus globulus and Rosmarinus officinalis. CONCLUSIONS As far as we know this is the first time that minimum inhibitory and bactericidal concentration values have been reported for Eucalyptus globulus EO. Our data support the possible use of this EO as well as Thymus algeriensis EO, as potential natural agents in preservatives for food and pharmaceutical products.

Chemical composition and antioxidant properties of Laurus nobilis L. and Myrtus communis L. essential oils from Morocco and evaluation of their antimicrobial activity acting alone or in combined processes for food preservation

BACKGROUND This study describes the antioxidant and antimicrobial activity of Laurus nobilis L. and Myrtus communis L. essential oils (EOs). This is the first report of the synergistic antimicrobial effect of these EOs in combination with physical food preservation treatments. RESULTS EOs obtained by steam distillation from aerial parts of Laurus nobilis and Myrtus communis were analysed by using gas chromatography-mass spectrometry. The main compounds were 1,8-cineole and 2-carene (L. nobilis EO); and myrtenyl acetate, 1,8-cineole and α-pinene (M. communis EO). L. nobilis EO showed higher antioxidant activity than M. communis EO in three complementary antioxidant tests. Although antimicrobial activity tests demonstrated the effectiveness of L. nobilis EO and the lack of bactericidal effect of M. communis EO, synergistic lethal effects were observed when combining each EO (0.2 µL mL(-1)) with mild heat (54°C for 10 min) or high hydrostatic pressure (175-400 MPa for 20 min). In contrast, combination of EOs with pulsed electric fields (30 kV cm(-1) for 25 pulses) showed no additional effects. CONCLUSION This study shows the great potential of these EOs in combined treatments with mild heat and high hydrostatic pressure to obtain a higher inactivation of foodborne pathogens, which might help in the design of safe processes applied at low intensity.

Synergistic combinations of high hydrostatic pressure and essential oils or their constituents and their use in preservation of fruit juices.

This work addresses the inactivation achieved with Escherichia coli O157:H7 and Listeria monocytogenes EGD-e by combined processes of high hydrostatic pressure (HHP) and essential oils (EOs) or their chemical constituents (CCs). HHP treatments (175-400 MPa for 20 min) were combined with 200 μL/L of each EO (Citrus sinensis L., Citrus lemon L., Citrus reticulata L., Thymus algeriensis L., Eucalyptus globulus L., Rosmarinus officinalis L., Mentha pulegium L., Juniperus phoenicea L., and Cyperus longus L.) or each CC ((+)-limonene, α-pinene, β-pinene, p-cymene, thymol, carvacrol, borneol, linalool, terpinen-4-ol, 1,8-cineole, α-terpinyl acetate, camphor, and (+)-pulegone) in buffer of pH 4.0 or 7.0. The tested combinations achieved different degrees of inactivation, the most effective being (+)-limonene, carvacrol, C. reticulata L. EO, T. algeriensis L. EO and C. sinensis L. EO which were capable of inactivating about 4-5 log(10) cycles of the initial cell populations in combination with HHP, and therefore showed outstanding synergistic effects. (+)-Limonene was also capable of inactivating 5 log(10) cycles of the initial E. coli O157:H7 population in combination with HHP (300 MPa for 20 min) in orange and apple juices, and a direct relationship was established between the inactivation degree caused by the combined process with (+)-limonene and the occurrence of sublethal injury after the HHP treatment. This work shows the potential of EOs and CCs in the inactivation of foodborne pathogens in combined treatments with HHP, and proposes their possible use in liquid food such as fruit juices.

Effect of Thymus vulgaris and Origanum compactum essential oils on the shelf life of fresh goat cheese

We have carried out our study on the chemical composition and antimicrobial activity of Thymus vulgaris and Origanum compactum essential oils that were harvested in the northeast of Morocco. Carvacrol was the major component in the two investigated essential oils. A high antimicrobial activity has been shown on all tested bacterial strains. The effect of the incorporation of these two essential oils at concentrations of 0.05% and 0.1% on physicochemical, microbiological and sensorial characteristics of goat fresh cheese stored at 8°C has also been studied. No significant differences have been showed between control and aromatized cheeses with respect to pH, titrable acidity, dry matter, lactic acid bacteria and aerobic mesophylic flora. However, coliforms were completely inhibited by the presence of both essential oils from the first storage day. Shelf life estimation has been determined by the reparameterized Gompertz equation by monitoring the growth of molds and yeasts. Origanum compactum essential oil was more effective on extending the shelf life of fresh goat cheese than Thymus vulgaris essential oil. Nevertheless, the aromatized cheese with Thymus vulgaris essential oil was the most appreciated by the tasting panel.

Characterization of bottom ash from two hospital waste incinerators in Rabat, Morocco

The uncontrolled disposal of bottom ash generated by the incineration units of hazardous and infected wastes in developed countries are the main cause of significant damage, such as contamination of the soil, as well as surface and underground waters, which may put both the environment and public health at risk. In Morocco, little information is available on the chemical properties of the resulting ashes. In this study, 16 hospital waste ash samples were collected from the incinerators of the two main hospitals in Rabat: Ibn Sina and Cheikh Zayd. A series of tests was conducted, including particle size distribution, mineralogical and chemical composition, and heavy metal leaching behaviour. The results showed that the samples were composed mainly of P2O5 (18%), SiO2 (17%), Na2O (16%), CaO (14%) and SO3 (10%). Moreover, chemical analysis clearly demonstrated that medical waste (MW) contains large amounts of waste generated by domestic activities in the hospital, with a lack of sorting system in the monitoring of MW. Furthermore, the ashes contained high concentrations of heavy metals such as zinc, lead, chromium and nickel with a vast range of 0.5–25071 mg/kg. Leaching tests showed that the extracted amounts of all the heavy metals were lower, with concentrations < 2.85 mg/kg. Comparison of the corresponding heavy metal concentrations with the limit values set by the Council Decision 2003/33/EC allowed us to conclude that bottom ashes meet the waste acceptance criteria regarding these heavy metals.

Effect of harvest time on yield, chemical composition, antimicrobial and antioxidant activities of Thymus vulgaris and Mentha pulegium essential oils.

Department of Food Technology, Research Unit of Nuclear Technology, Environment and Quality Laboratory of Food Technology, National Institute of Agronomic Research (INRA), Tangier, Morocco. Department of Animal Production and Food Science, Veterinary Faculty, Universidad de Zaragoza, Spain. 3 Department of Chemistry, Faculty of Science and Technology, Universite Abdelmalek Esaâdi, Morocco. 4 Department of Biology, Faculty of Science and Technology, Universite Abdelmalek Esaâdi, Morocco. Department of Biology, Polydisciplinary Faculty of Larache, Universite Abdelmalek Esaâdi, Morocco.

Effect of Essential Oils on Cell Viability, Membrane Integrity and Membrane Fluidity of Listeria innocua and Escherichia coli

Abstract Listeria innocua LRGIA 01 and Escherichia coli CECT 471 cells were exposed to five essential oils (EOs) at different concentrations to determine their minimal inhibitory concentrations and minimal bactericidal concentrations. Since bacterial membranes are considered as a target of antimicrobial EOs, the membrane fluidity and integrity of bacteria were monitored respectively after 280 minutes or 24 hours exposure to Laurus nobilis or Satureja calamintha EOs. Measuring fluorescence anisotropy of two probes revealed that these two EOs rigidified the surface of membrane but increased the fluidity of its core. Application of the Live/Dead® BacLightTM kit after 24 hours contact with EOs at their MIC at the bacterial optimal temperature allowed observing that they damaged the membranes of bacteria and the persistence of Viable But Non Culturable (VBNC) bacteria. These observations should both be taken into account when considering addition of EOs to control the growth of certain important food-borne pathogenic bacteria.

Simultaneous P-Solubilizing and Biocontrol Activity of Rhizobacteria Isolated from Rice Rhizosphere Soil

Application of beneficial rhizobacteria as plant biofertilizers and biocontrol agents may be a promising alternative to chemical control. To perform this aim, the present work is an evaluation of three phosphate-solubilizing Aeromonas strains isolated from the rhizosphere of rice. These selected rhizobacteria were checked for quantitative assay of tricalcium phosphate (TCP) solubilization and P concentrations were between 119.56 and 165.85 mg l−1. Then, they were evaluated for extracellular hydrolytic enzymes production (chitinase, cellulase, amylase, lipase, and protease). The results showed that they were all able to hydrolyze different substrates apart from carboxymethyl cellulose. These test bacteria were checked in vitro as well for antagonism ability against six fungal phytopathogens, Colletotrichum acutatum, Verticillium dahliae, Phytophthora cinnamomi, Phytophthora cactorum, Botryotinia fuckheliana, and Fusarium oxysporum, and also against five phytopathogenic bacteria, Pseudomonas savastanoi, Clavibacter michiganensis, Ralstonia solanacearum, Erwinia amylovora, and Pseudomonas syringae. GT70 was the only isolate that showed antifungal effect against two fungi, V. dahliae and P. cactorum. For antibacterial activities, the best inhibition was obtained in the presence of GT70 and PT29 against R. Solanacearum. Finally, these bacteria were used for rice inoculation substituting soluble P by TCP. The results demonstrated significant increases in plant length and dry matter, especially in the presence of both strains GT70 and PT29 after 30 days under controlled conditions. However, more evaluation of these isolates under field conditions is needed before recommending them as biofertilizers.

The role of fish in the diet of swordfish ( Xiphias gladius ) in the Strait of Gibraltar

To study the diet of the swordfish ( Xiphias gladius ) in the Strait of Gibraltar, a total of 176 stomachs were examined from the Moroccan artisanal fishery targeting this species, from April to September 2015. The frequency of occurrence (FO), percentage in number and in weight of prey as well as the per cent index of relative importance of prey (%IRI) were calculated to assess the diet preferences of swordfish in relation to its body size, sex and month. Our findings confirm the opportunistic feeding behaviour of swordfish. The prey items consist primarily of fish (54.6% in number and 82.7% in weight), followed by cephalopod (43.36% in number and 17.25% in weight). The Atlantic horse mackerel ( Trachurus trachurus ) and the southern shortfin squid ( Illex coindetii ) are the most important prey, with a % IRI of 47.54 and 35.04%, respectively. The results revealed that there are no significant differences in the diet preferences among sexes and size classes. However, diet composition varied significantly among months. A significant correlation was found between the body length of predator and prey size. The remarkable decrease in the fullness index (fi) from June to August suggests that swordfish were in a spawning condition, with reduced feeding.

Performance of GenoType® MTBDRplus assay in the diagnosis of drug-resistant tuberculosis in Tangier, Morocco.

OBJECTIVES In Morocco, tuberculosis (TB) is a major public health problem with high morbidity and mortality. The main problem faced by the national TB programme is the high rate of drug-resistant (DR), particularly multi-drug resistant (MDR) strains. Diagnosis of DR-TB is mainly performed by conventional techniques that are time consuming with limited efficacy. In 2014, the GenoType® MTBDRplus assay was introduced in Morocco for drug susceptibility testing (DST). In this regard, the present study was planned to assess the diagnostic accuracy of the GenoType® MTBDRplus assay. METHODS A total of 70 samples from suspected TB cases in Tangier (Morocco) were analysed by conventional DST and GenoType® MTBDRplus assay. RESULTS Among the 70 samples, 37.1% were MDR, whereas monoresistance to isoniazid (INH) and rifampicin (RIF) was detected in 186% and 17.1% of strains, respectively, by DST. Using the GenoType® MTBDRplus approach, 12 isolates (17.1%) were identified as INH monoresistant, 9 (12.9%) as RIF monoresistant and 26 (37.1%) as MDR. rpoB531 and katG315 mutations were the most common mutations associated with resistance to RIF and INH, respectively. Significantly, all phenotypically MDR strains were also MDR by GenoType® MTBDRplus. The sensitivity of GenoType® MTBDRplus was 92.1% for RIF resistance and 97.4% for INH resistance, whereas the specificity was 100% for the two tested drugs. CONCLUSIONS GenoType® MTBDRplus assay is a rapid, reliable and accurate tool for the detection of DR-TB in clinical specimens. Its routine use will be of a great interest to prevent the dissemination of DR-TB in the community.