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BACKGROUND: In several countries, the cactus plant (Opuntia ficus‐indica (L). Mill.) has received renewed attention because of its ecological, socio‐economic and environmental role. In this study, prickly pear vinegar was produced employing two types of acetification processes: surface and submerged culture. Both acetification processes were performed at different temperatures (30, 37, 40 °C) by using two different species of thermotolerant acetic acid bacteria (Acetobacter malorum and Gluconobacter oxydans). Polyphenols and volatile compounds analyzed by ultra‐performance liquid chromatography with diode array detection and stir bar sorptive extraction–gas chromatography–mass spectrometry, respectively, were considered as the main variables to determine the effect of the acetification process on the quality of the vinegar. RESULTS: As a result, 15 polyphenols and 70 volatile compounds were identified and quantified in the vinegar samples produced by both acetification processes. The results showed that the surface acetification method led to an increase in the concentration of phenolic components, which was higher than that in the submerged process. However, a significant increase in volatile compounds predominated by esters and acids was observed when submerged culture acetification was employed, whereas alcohols were predominant in surface culture vinegars. Moreover, multivariate statistical analysis showed that the components that mostly contributed to the differentiation between all vinegar samples were the volatile compounds. CONCLUSION: It has been proved that prickly pear vinegar could be successfully produced at higher temperatures than usual, by employing thermotolerant bacteria, and that the type of acetification method significantly affects the final quality of the vinegar produced. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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%–61.52%, 52.12%–52.14%, 57.76%–58.15%, 61.33%–61.52%), palmitic acid (15.78%–15.81%, 16.44%–16.45%, 19.11%–18.37%, 20.24%–20.32%), oleic acid (11.03%–11.04%, 8.72%–8.82%, 8.51%–8.61%, 8.41%–8.53%), stearic acid (4.35%–3.14%, 5.40%–5.43%, 3.12%–3.13%, 0.96%–1.56%), and cerotic acid (0.62%–0.53%, 4.51%–4.52%, 4.03%–4.06%, 3.84%–3.87%). The unsaturated fatty acids (69.39% in 2018 and 69.68% in 2019) are the most dominant in the four seed extracts compared to the saturated fatty acids. In addition, the oil carob seeds analysis revealed the presence of γ‐tocopherol, α‐tocopherol and four sterols that included campesterol, stigmasterol, and β‐sitosterol. Moreover, the determination of hydrocarbon and un‐oxygenated compounds confirmed the existence of major compounds such as heptadecane, 2‐methyltriacontane, 1‐iodo hexadecane and 1‐iodo octadecane. The hierarchical analysis based on the morphological and chromatographic characterization of the seeds allowed the identification of three groups. Consequently, the first group consisted of populations from Marrakesh (P4) and Khemisset (P3), the second group consisted of the P1 from Meknes, and the P2 from Fez constituted the third group. [ABSTRACT FROM AUTHOR]

Industrially, the sensitivity of acetic acid bacteria (AAB) to the high temperatures and the high ethanol concentrations is the major concerns for manufacturers. This study was conceived and designed to isolate and identify new thermo‐ and ethanol‐tolerant AAB from Opuntia ficus‐indica L. fruits. As a result, among 140 isolated bacterial strains, five selected strains (CR1, CR5, CR23, CZ2, and CZ15) exhibited important acetic acid production until 40 °C. The use of 16S rDNA gene analysis was insufficient to identify selected bacteria. Indeed, except CR5 that presented 100% similarity to A. cerevisiae, the other strains presented similar homology rates simultaneously to the 16S rDNA sequences of A. cerevisiae and A. malorum. The reidentification by 16S‐23S rDNA gene sequencing showed that CR1, CR23, and CZ15 were A. malorum, which were shown tolerance to the highest concentration of ethanol (12%) and produced elevated amount (40 g/L) of acetic acid at 37 °C. In summary, we showed the thermotolerance and ethanol tolerant character of new A. malorum strains, which can be used as a starter for vinegar production. Furthermore, during the molecular characterization of the isolated strains, we concluded that 16S‐23S rDNA internal transcribed spacer sequence is of great importance for discriminating between AAB species as a complement to the identification by 16S rDNA sequencing. [ABSTRACT FROM AUTHOR]

Plant growth promoting rhizobacteria (PGPR) are beneficial bacterial that colonize plant roots and enhance plant growth by a wide variety of mechanisms. Seven isolates of bacteria were successfully isolated and phenotypically, biochemically, physiological and molecular characterized. Subsequently to investigate the effect of PGPR isolates on the growth of carob tree, a pot culture experiement was conducted as Centre for Innovation and Technology Transfer (CITT), Meknes, Morocco. All the isolates were gram negative, rods, motile, able to grow on YDC medium and citrate simmons positive, degrade glucose, fructose and mannitol, capable of hydrolyzing esculin and starch. All strains are able to produce (74-150µgml-1) of indole acetic acid, nitrogen fixatin and all isolate are unable to produce ammonia, chitinase and cellulase, the strains 2018-3, 2018-4 and 2018-5 showed protease activity. The pecentage of solibilization of phosphate varied between 15% to 45%, the maximum phosphate solubilization was identified by stain 2018-4. Sequencing of 16SrRNA genes led to the identification of two family of bacteria: Bacillaceae and Pseudomonadaceae. The species of bacteria are: Bacillus thuringiensis, two of Bacillus flexus, two of Pseudomonas gessardii, Bacillus cereus and Bacillus thaonhiensis. The analysis the result showed that the highest vegetative growth was obtained from stain 2018-4 such as plant height (13.6cm), root length (13.65cm), fresh weight of the aerial part (1.09g) and fresh weight of the root part (0.42g) in comparison to untreated plant. [ABSTRACT FROM AUTHOR]

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.