Background
The production of indole-3-acetic acid (IAA) is an essential tool for rhizobacteria to stimulate and facilitate plant growth. For this, eighty rhizobial bacteria isolated from root nodules ...of
Acacia cyanophylla
grown in different regions of Morocco were firstly screened for their ability to produce IAA. Then, IAA production by a combination of isolates and the inoculation effect on the germination of
Acacia cyanophylla
seeds was studied using the best performing isolates in terms of IAA production. The best IAA producer bacterial isolate (I69) was selected to optimize IAA production using response surface methodology based on the central composite design.
Results
Results showed that the majority of tested isolates were able to produce IAA with a relatively higher concentration of 135 μg/ml for the isolate I69, followed by isolates I22 and I75 with respective concentrations of 116 μg/ml and 105 μg/ml IAA. The IAA production and the seed germination rate were relatively increased by the synergistic effect of I69 and I22. Later, response surface methodology was used to determine optimal operating conditions leading to IAA production optimization. Thus, an incubation temperature of 36 °C, a pH of 6.5, an incubation time of 1 day, and respective tryptophan and NaCl concentrations of 1 g/l and 0.1 g/l were optimal parameters leading to 166 μg/ml IAA which was the maximal produced concentration.
Conclusion
The present study highlighted that IAA-producing rhizobacteria could be harnessed to improve plant growth. Furthermore, their production can be easily controlled using response surface methodology, which represents a very useful tool for optimization.
Background
Plant growth-promoting rhizobacteria (PGPR) are known to improve plant growth and are used as biofertilizers, thanks to their numerous benefits to agriculture such as phosphorus ...solubilization and phytohormone production. In this paper, four rhizospheric bacteria (
Phyllobacterium
sp.,
Bacillus
sp.,
Agrobacterium
sp., and
Rhizobium
sp.) isolated from surface-sterilized root nodules of
Acacia cyanophylla
were tested for their ability to solubilize inorganic phosphate and to produce indole-3-acetic acid (IAA) under laboratory conditions. Then, the best IAA producer (
Rhizobium
sp.) was selected to test optimized conditions for IAA production. Finally, the effect of the four strains on plant growth for
A. cyanophylla
was evaluated in vivo.
Results
The results showed that the totality of the tested isolates had solubilized inorganic phosphate (P) in both NBRIP (National Botanical Research Institute Phosphate) and PVK (Pikovskaya) media.
Bacillus
sp. was a high P-solubilizer and showed maximum solubilization in PVK (519 μg ml
-1
) and NBRIP (782 μg ml
-1
). The optimization of maximum phosphate solubilization was done using different sources of carbon (1%) and nitrogen (0.1%). Glucose and ammonium sulfate were selected to be the best carbon and nitrogen source for phosphate solubilization by all tested strains, except for
Phyllobacterium
sp., which recorded the highest phosphate solubilization with ammonium nitrate. The IAA production by the tested strains indicated that
Rhizobium
sp. produced the highest amount of IAA (90.21 μg ml
-1
) in culture media supplemented with L-tryptophan. The best production was observed with L-Trp concentration of 0.2% (116.42 μg ml
-1
) and at an initial pH of 9 (116.07 μg ml
-1
). The effect of NaCl on IAA production was tested at concentrations of 0 to 5% and the maximum production of 89.43 μg ml
-1
was found at 2% NaCl. The extraction of crude IAA from this strain was done and purity was confirmed with Thin Layer Chromatography (TLC) analysis. A specific spot from the extracted IAA production was found to correspond with a standard spot of IAA with the same Rf value. Finally, the tested PGPR demonstrated growth stimulatory effects on
Acacia cyanophylla
seedlings in vivo, with a great increase of shoots’ and roots’ dry weights, and shoot length compared to control.
The rhizobacterial isolates were identified by 16S rDNA sequence analysis as
Agrobacterium
sp. NA11001,
Phyllobacterium
sp. C65,
Bacillus
sp. CS14, and
Rhizobium
sp. V3E1.
Conclusion
This study highlights the importance of the use of phosphate solubilizing and IAA producer microorganisms as biofertilizers to increase crop yields. The studied strains showed a significant phosphate solubilization potential and IAA production. The use of selected strains as inoculants would be interesting, in particular with a view of promoting sustainable agriculture. However, further studies to verify the efficacy of the best isolates in situ is certainly required.
The scope of this review gives an insight into the inclusion complex of essential oil (EO) using cyclodextrins (CDs), including mechanism, preparation and characterization. It also mentioned that ...this process was influenced by the size of the inner cavity of CDs and the chemical profile of EOs. The scope has looked forward to derivative CDs, which are further modifications of native CDs to achieve more solubility and efficiency by adding hydroxyl, sulfobutylether, and methyl groups, and by using an esterification process. Subsequently, the cyclodextrin metal organic frameworks, which correspond to native CDs connected via a metal cation, were anticipated as a biocompatible porous material demonstrating a more sustained release of EOs. Indeed, supramolecular cyclodextrins obtained through the covalent binding between cyclodextrins and cross-linked reagents led to higher water solubility, stability, and sustained release. It then moves on to combining CD with biopolymer by grafting or dual encapsulation, which was studied to modulate the profile of EO release. It then moves on experimental designs used to optimize the encapsulation efficiency to reduce the amount of CD and EO added, minimize energy and time, and optimize the medium efficacy.
Human mycotic infections are one of the major health problems worldwide. Prolonged use of antimycotic drugs has contributed to the development of resistance in pathogenic fungi. This study was ...conducted to examine antioxidant and anticandidal activities of Moroccan propolis.
Two ethanolic extracts of Moroccan propolis from the Fez-Meknes region were evaluated regarding the following physicochemical parameters: Yield, pH, total carbohydrates, total proteins, total lipids, minerals, total phenolic content, total flavonoid content, and antioxidant activity using ferric reducing antioxidant power (FRAP) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. In addition, we assessed the
anticandidal activity against vulvovaginal candidiasis strains, that is,
,
,
, and
, using the broth micromethod according to the CLSI/M27-A3 reference guidelines.
The propolis samples exhibited a mean yield of 16%, with an acidic pH ranging from 4.8 to 5.9; the sample from the Oued Amlil area (OAPEE) contained high levels of resin, balsam, moisture, total carbohydrates, and total lipids: 59.8%, 0.71%, 2%, 1.01 gGlcEq/g, and 120 mg/g, respectively. Moreover, the sample from the Sefrou area (SFPEE) was richer in total proteins and minerals, with values of 2.5 g/100 g and 1.84%, respectively. The total polyphenol and flavonoid content in the propolis extracts were 117.38 and 194.68 mg of gallic acid equivalent/g, and 17.45-27.79 mg of quercetin equivalent/g, respectively. Regarding the antioxidant activity, the most effective propolis extract was the sample from the Sefrou area, at 72.5 μg/mL and 118.78 μmoL Fe
/g for ABTS-half-maximal inhibitory concentration and FRAP-half maximal effective concentration, respectively. The analysis of phenolic compounds using high-performance liquid chromatography with a diode-array detector revealed the presence of 13 polyphenols. The main compound in the OAPEE sample was epicatechin (310 mg/g), whereas in the SFPEE sample was apigenin (410 mg/g). Regarding the antifungal activity against
species, the minimum inhibitory concentration and minimum fungicidal concentration of the Moroccan propolis ethanolic extracts ranged between 31.2 and 62.5 μg/mL and 62.5 and 125 μg/mL, respectively, comparable with fluconazole (as a reference antimycotic).
This study suggests that Moroccan propolis (31.2 and 125 μg/mL) may be an important source of bioactive molecules with anticandidal activity. Propolis may be a promising naturally-occurring candidate for the development of antimycotic drugs.
This study was designed to optimize the ultrasound-assisted extraction of phenolic compounds and the antioxidant activity of Moroccan Retama sphaerocarpa extracts using response surface methodology ...(RSM). A central composite design has been conducted to investigate the effects of three factors: extraction period (X1), solvent concentration (X2), and solvent-to-material ratio (X3) on extraction yield, total phenolic content (TPC), flavonoids content (TFC), and antioxidant activity. The obtained results showed that the experimental values agreed with the predicted ones, confirming the capacity of the used model for optimizing the extraction conditions. The best extraction conditions for the simultaneous optimization were an extraction time of 38 min, a solvent concentration of 58%, and a solvent-to-material ratio of 30 mL/g. Under these conditions, the optimized values of yield, TPC, TFC, and DPPH-radical scavenging activity (DPPHIC50) were 18.91%, 154.09 mg GAE/g, 23.76 mg QE/g, and 122.47 μg/mL, respectively. The further HPLC/ESI-MS analysis of the obtained optimized extract revealed the presence of 14 phenolic compounds with piscidic acid, vitexin, and quinic acid as major compounds. These research findings indicate promising applications for efficiently extracting polyphenolic antioxidants, especially in the food industry.
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•Phenolic compounds were obtained by ultrasound-assisted extraction from Moroccan Retama sphaerocarapa L. leaves.•Extraction yield, total phenols and flavonoids content and antioxidant activity were successfully optimized by response surface methodology.•Mathematical models were developed based on extraction period, temperature and solvent-to-sample ratio.•Extract obtained under optimal conditions was characterized by HPLC/ESI-MS.•Piscidic acid, vitexin, and quinic acid were major compounds in Retama sphaerocarapa L. leaves.
Secondary plant metabolites, in particular phenolic compounds, are characterized by great diversity in the plant kingdom and are widely used in the medical and industrial fields. The extraction of ...these compounds represents a critical step, and the differences in extraction conditions strongly affect the yields and the total concentrations of polyphenols in the extracts. In this way, the objective of the present study was to optimize the extraction parameters of the polyphenols from Lavandula stoechas using the extraction technique assisted by ultrasound. Yield and the total concentration of polyphenols have been optimized, taking into account three variables, the extraction time (min), the ethanol concentration (%), and the solvent/extract ratio (ml/g). The optimum extraction yield (31.88%) was obtained by ensuring the following parameters: an ethanol concentration of 40%, a liquid/solid ratio of 30 ml/g, and a time processing of 32.62 min. The maximum concentration of total polyphenols (190.14 mg gallic acid equivalents (GAE)/g) was obtained after 21.5 min of extraction, with a liquid/solid ratio of 30 ml/g and a concentration of ethanol at 40%. In order to obtain the maximum yield (24.9%) and the total concentration of polyphenols (190.14 mg GAE/g) simultaneously, the following parameters must be adjusted: an extraction time of 21.5 min, a liquid/solid ratio of 30 ml/g, and a concentration of ethanol at 40%. The experimental values of the yield and the total concentration of the polyphenols were in good agreement with the predicted values, which suggests that the ultrasonic extraction model adopted in this study is validated.
An entomological survey was carried out in the locality of Aichoune to conduct a study on sand flies, species composition, and monthly relative abundance. This study is essential for the ...implementation of integrated vector management control. Insects collection was carried out twice a month from January 2013 to December 2014 by means of adhesive and CDC-type light traps. A total of 5441 sand flies were collected with the predominance of males (a sex ratio = 1.89). The sampled specimens consist of seven species divided into two genera: Phlebotomus (99.55%) and Sergentomyia (0.44%). Phlebotomus sergenti was the dominant species with an average annual proportion of 47.38%, followed by P. perniciosus (37.32%), P. longicuspis (8,56%), P. papatasi (6.23%), and P. ariasi (0.05%). The genus Sergentomyia was less common (0.44%). S.minuta was represented only by 0.36% and S. fallax by 0.07%. The species dynamics showed a unimodal evolution for P. sergenti and P. papatasi. They were active from May to October. P. perniciosus presents a trimodal trend showing the most relevant peak in August. The highest number of specimens was collected in June, when the temperature reaches an annual average value of 25.5°C. The obtained results will help us better understand the leishmaniasis transmission dynamics in the Aichoune locality and will contribute to the design of a surveillance strategy.
This study aims to identify the volatile profile of three essential oils obtained from Eucalyptus polybractea cryptonifera (EPEO), Ormenis mixta (OMEO), and Lavandula burnatii briquet (LBEO) and to ...examine their combined antibacterial activity that affords the optimal inhibitory ability against S. aureus and E. coli using simplex-centroid mixture design and checkerboard assay. Essential oils (EOs) were isolated by hydrodistillation and characterized using gas chromatography-mass spectrometry (GC-MS) and gas chromatography coupled with flame-ionization detector (GC-FID). The antibacterial activity was performed using disc diffusion and microdilution assays. The chemical analysis revealed that 1,8-cineole (23.75%), p-cymene (22.47%), and α-pinene (11.20%) and p-menthane-1,8-diol (18.19%), α-pinene (10.81%), and D-germacrene (9.17%) were the main components detected in E. polybractea and O. mixta EOs, respectively. However, L. burnatii EO was mainly represented by linalool (24.40%) and linalyl acetate (18.68%). The EPEO, LBEO, and OMEO had a strong antibacterial effect on S. aureus with minimal inhibitory concentrations (MICs) values ranging from 0.25 to 0.5% (v/v). Furthermore, the combination of 1/2048 MICEPEO + 1/4 MICLBEO showed a synergistic antibacterial effect on S. aureus with a FIC index of 0.25, while the formulation of 1/4 MICEPEO + 1/4 MICOMEO demonstrated an antibacterial synergistic activity on E. coli with a FIC index of 0.5. Moreover, the simplex-centroid mixture design reported that the most effective combinations on E. coli and S. aureus correspond to 32%/28%/40% and 35%/30%/35% of E. polybractea, O. mixta, and L. burnatii, respectively. Presented information highlights the action of antibacterial formulations of these EOs and suggests their potential applications as alternatives to commercialized drugs to contract the development of bacteria causing serious infections and food deterioration.
In this study, experimental design approach coupled with MIC assay were used to determine the combined treatment effect of three Moroccan essential oils (EOs) derived from Ammi visnaga (AVEO), Mentha ...suaveolens (MSEO) and Lavandula stoechas (LSEO), against S. aureus, E. coli and P. aeruginosa, as well as to predict the optimal formulations of these EOs to inhibit bacterial adhesion on the stainless steel (304L SS) surface. EOs were obtained via hydrodistillation and then, their volatile content was analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). The antibacterial activity was evaluated using disc-diffusion, microdilution assays. Moreover, the anti-adhesive effect was assessed using two complementary methods, including contact angle measurements and scanning electron microscopy (SEM) analysis. The GC-MS analysis revealed the presence of various bioactive compounds in AVEO, MSEO and LSEO. The main identified components were piperitenone oxide (52.04%) and pulegone (19.78%) for MSEO; and camphor (23.97 %) and menthol (21.5%) for LSEO. Whereas, AVEO was mainly characterized by the presence of linalool (30.24 %). The antibacterial assays showed that all EOs are able to inhibit the bacterial growth at low concentration (MIC ranged from 0.015 to 4 v/v (%)). The optimization of mixtures antibacterial effect has demonstrated the synergistic effect between the three EOs. The optimal mixture predicted against E. coli, P. aeruginosa, and S. aureus corresponded to 30%/42%/28%, 50%/50%/0%, 43%/30%/27%, and AVEO, LSEO and MSEO, respectively. The contact angle assessment indicated that LSEO, MSEO, AVEO and their optimal mixtures remarkably inhibit bacterial adhesion by the alteration of the physico-chemical properties of 304L SS surface. These results are confirmed by SEM analysis, and proved that EOs formulation was able to inhibit more than 80% of bacterial adhesion to 304L SS surface. In light of these findings, EOs mixtures recommended here, can be applied as a promoting and eco-friendly agent for combating the formation of biofilms on stainless steel surface.
A controlled fermentation was conducted to develop and design a bioorganic fertilizer based on three wastes generated by the food industry: olive mill wastewater (OMW), molasses and rice hulls by ...inoculation with selected strains of lactic acid bacteria (LAB), of the species “Lactiplantibacillus plantarum” and “Levilactobacillus brevis” and of the yeast of the species “candida famata”. The fermentation with commercial yeasts and particularly the species of “saccharomyces” produced an unstable fertilizer with a high pH value (6.14).Whereas, the fermentation test with an inoculum composed of 20% yeast and 80% lactic acid bacteria showed a decrease in pH at 4.66 and a maximum enzymatic activity of 43.900 IU/l after 30 h. This combination allowed an appropriate morphological and microbiological quality of the bioorganic fertilizer. To determine with precision, the optimum conditions of this fermentation an optimization design was applied. As a result of experiments and statistical validation of the fitted model, the bioorganic fertilizer with the lowest pH value was achieved after fermentation of 53.2% OMW, 19.1% molasses, 21.3% rice hulls and 6.4% inoculum content. The final pH was able to reach a value of 4.07 with desirability of the order of 99.7%. A fertilizer with the lowest possible pH allowed farmers longer storage periods and required no special storage conditions.
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