The production of vinegar on an industrial scale from different raw materials is subject to constraints, notably the low tolerance of acetic acid bacteria (AAB) to high temperatures and high ethanol concentrations. In this study, we used 25 samples of different fruits from seven Moroccan biotopes with arid and semi-arid environmental conditions as a basic substrate to isolate thermo- and ethanol-tolerant AAB strains. The isolation and morphological, biochemical and metabolic characterization of these bacteria allowed us to isolate a total number of 400 strains with characters similar to AAB, of which six strains (FAGD1, FAGD10, FAGD18 and GCM2, GCM4, GCM15) were found to be mobile and immobile Gram-negative bacteria with ellipsoidal rod-shaped colonies that clustered in pairs and in isolated chains. These strains are capable of producing acetic acid from ethanol, growing on peptone and oxidizing acetate to CO2 and H2O. Strains FAGD1, FAGD10 and FAGD18 show negative growth on YPG medium containing D-glucose > 30%, while strains GCM2, GCM4 and GCM15 show positive growth. These six strains stand out on CARR indicator medium as isolates of the genus Acetobacter ssp. Analysis of 16S rDNA gene sequencing allowed us to differentiate these strains as Acetobacter fabarum and Acetobacter pasteurianus. The study of the tolerance of these six isolates towards pH showed that most of the six strains are unable to grow at pH 3 and pH 9, with an ideal pH of 5. The behavior of the six strains at different concentrations of ethanol shows an optimal production of acetic acid after incubation at concentrations between 6% and 8% (v/v) of ethanol. All six strains tolerated an ethanol concentration of 16% (v/v). The resistance of the strains to acetic acid differs between the species of AAB. The optimum acetic acid production is obtained at a concentration of 1% (v/v) for the strains of FAGD1, FAGD10 and FAGD18, and 3% (v/v) for GCM2, GCM4 and GCM15. These strains are able to tolerate an acetic acid concentration of up to 6% (v/v). The production kinetics of the six strains show the highest levels of growth and acetic acid production at 30 °C. This rate of growth and acetic acid production is high at 35 °C, 37 °C and 40 °C. Above 40 °C, the production of acid is reduced. All six strains continue to produce acetic acid, even at high temperatures up to 48 °C. These strains can be used in the vinegar production industry to minimize the load on cooling systems, especially in countries with high summer temperatures.

In order to improve the germination rate of carob seeds (Ceratonia siliqua L.), we studied the morphological characteristics of the fruits (pod and seeds, integumentary hardness and tolerance to abiotic stress of the seeds) of seven ecotypes of carob trees from four regions of Morocco. The fruits of its seven populations were studied according to seven discriminative characteristics relating to the pods (length, width, thickness, total number of seeds, total weight of the pulp, seeds  per pod and yield of pods per tree) and four discriminative characteristics relating to the seeds namely length, width, thickness and total fresh weight of seeds. Integumentary hardness was evaluated by pretreating the seeds with boiling water and 95% sulfuric acid. Similarly, we also followed the evolution of water absorption by the seeds during 4 days and we evaluated on these seeds pre-treated, effects of different incubation temperatures (10°C, 25°C and 40°C), their tolerance to different concentrations of NaCl, PEG6000 (0MPa, -0.5MPa, -1MPa and -1.5MPa ) and their reversibility. The morphological characterization of the fruits allowed us to group the populations studied into three groups. Soaking the carob seeds in sulfuric acid for 20 minutes improved the germination rate and time. The evolution of water absorption makes it possible to distinguish two phases. The first phase is obtained during the first 24 hours and characterized by a rapid penetration of water, and second phase which lasts over the last 72 hours and which is characterized by a slow entry of water. The optimum temperature for germination of seeds from all provenances is 25°C. The germination behavior of carob under conditions of osmotic stress demonstrated a highly significant treatment effect (concentration of PEG6000) on the rate and mean time of germination and revealed that this species is very resistant to drought. This study also showed that, salt has a depressive effect on the average germination rate, time and length of radicles. The results of the reversibility test showed that the germination of seeds transferred from osmotic stress and salt stress (-0.5, -1 and -1.5MPa) and from the temperature of 40°C. is totally inhibited. On the other hand, seeds transferred from a temperature of 15°C resume germination under optimal conditions. This study allowed us to select a variety with high yield and tolerant to various biotic constraints.

Morphological characterization was investigated by agro-morphological criteria related to carob seed size in four different moroccan regions collected in 2018 and 2019. There was no significant difference (p ≤ 0.05) on the seeds lengths and widths. However, a significant difference between seeds thickness and total seeds weight per pod (p ≤ 0.05) were observed between these four populations. The fatty acid, sterol, tocopherol, hydrocarbon, and the unoxygenated composition of carob seed extracts (Ceratonia siliqua L.) were studied. The mean fat yield of the seeds obtained is 1.53%-2.17%, 2.14%-2.15%, 1.61%-1.62%, 1.71%-1.75% for, respectively, the P1 (Meknes), P2 (Fez), P3 (Khemisset), and P4 (Marrakech) in 2018 and 2019. The seed oil was extracted with hexane and the analysis of the fatty fraction was performed by gas chromatography-mass spectrometry (GC-MS). Results show that the major fatty acids for 2018 and 2019 are linoleic acid (61.48%-61.