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Background Oleuropein, the main bitter phenolic glucoside responsible for green olive bitterness, may be degraded by the β-glucosidase enzyme to release glucose and phenolic compounds. Results Lactobacillus plantarum FSO1 and Candida pelliculosa L18 strains, isolated from natural fermented green olives, were tested for their β-glucosidase production and activity at different initial pH, NaCl concentrations, and temperature. The results showed that strains produced extracellular and induced β-glucosidase, with a molecular weight of 60 kD. The strains demonstrated their biodegradation capacity of oleuropein, associated with the accumulation of hydroxytyrosol and other phenolic compounds, resulting in antioxidant activity values significantly higher than that of ascorbic acid. The highest production value of β-glucosidase was 0.91 U/ml obtained at pH 5 and pH 6, respectively for L. plantarum FSO1 and C. pelliculosa L18. The increase of NaCl concentration, from 0 to 10% (w/v), inhibited the production of β-glucosidase for both strains. However, the β-glucosidase was activated with an increase of NaCl concentration, with a maximum activity obtained at 8% NaCl (w/v). The enzyme activity was optimal at pH 5 for both strains, while the optimum temperature was 45 °C for L. plantarum FSO1 and 35 °C for C. pelliculosa L18. Conclusions L. plantarum FSO1 and C. pelliculosa L18 strains showed their ability to produce an extracellular and induced β-glucosidase enzyme with promising traits for application in the biological processing of table olives.

Lactic acid bacteria (LAB) are ubiquitous bacteria associated with spontaneous lactic fermentation of vegetables, dairy and meat products. They are generally recognized as safe (GRAS), and they are involved in transformation of probiotic lacto-fermented foods, highly desired for their nutraceutical properties. The antifungal activity is one of the exciting properties of LAB, because of its possible application in food bio-preservation, as alternative to chemical preservatives. Many recent research works have been developed on antifungal activity of LAB, and they demonstrate their capacity to produce various antifungal compounds, (i.e. organic acids, PLA, proteinaceous compounds, peptides, cyclic dipeptides, fatty acids, and other compounds), of different properties (hydrophilic, hydrophobic and amphiphilic). The effectiveness of LAB in controlling spoilage and pathogenic fungi, demonstrated in different agricultural and food products, can be due to the synergistic effect between their antifungal compounds of different properties; where the amphiphilic-compounds allow the contact between the target microbial cell (hydrophilic compartment) and antifungal hydrophobic-compounds. Further studies on the interaction between compounds of these three properties are to de be developed, in order to highlight more their mechanism of action, and make LAB more profitable in improving shelf life and nutraceutical properties of foods.

The objective of this work is the study of the antifungal and antibacterial activity of Lactiplantibacillus plantarum S61 strains, isolated from traditional fermenting green olives against Rhodotorula glutinis UMP 22 and Listeria monocytogenes ATCC 19117, and its application in meat as bio-preservative agent. The cell-free supernatant (CFS) of Lpb. plantarum S61 shows high inhibition zones, which are 22.45 ± 0.49 and 17.75 ± 0.35 mm, against Rhodotorula glutinis and Listeria monocytogenes. The minimum fungicidal and bactericidal concentrations of the CFS obtained are 8% (v/v) and 10% (v/v), respectively. The competition assay, realized in liquid medium by co-culture of Lpb. plantarum S61 with Rho Rhodotorula glutinis and L. monocytogenes, led to inhibition percentages of 77.72% and 89.52%, respectively. However, the antimicrobial activity of Lpb. plantarum S61 was revealed a proteinaceous nature. Lpb. plantarum S61 strain allowed the reduction of L. monocytogenes in minced poultry meat during 7 days of storage at 4 °C. In addition, Lpb. plantarum S61 improved the physicochemical and color parameters of poultry minced meat. Lpb. plantarum S61 and/or its antimicrobial compounds can be applied as bio-preservative agent in meat product and food industry.

The aim of this work was to characterize the antifungal activity of Lactobacillus strains, isolated from traditional fermented green olives. The in vitro test was carried out by eight strains of Lactobacillus in order to verify their antifungal effects on the most virulent isolate of Phytophthora infestans harvested from the Triffa plain, eastern of Morocco. 100% of the Lactobacillus tested showed an antifungal effect against P.infestans, all belonging to the genus Lactobacillus, three of them brevis and five plantarum. All Lactobacillus tested had a fungistatic effect on spore germination and mycelial growth, except L.b brevis 14 and L.b plantarum 62 which had a fungicidal effect on mycelial growth. Among 8 Lactobacillus studied, 2 strains were selected in this work for their high inhibitory effect and for their fungicidal effect on mycelial growth. Antifungal activity begins after 24 h and obtained the maximum after 48 h, with an inhibition zone of 29.13 and 28.30 mm for L.b brevis 14 and L.b plantarum 62 respectively. These two strains showed an antifungal effect at different incubation temperatures (4°C, 25°C, 37°C and 45°C), with maximum inhibition zone obtained at 37°C with 16 mm for L.b14 and 14 mm for L.b 62. The high inhibition zone was obtained at pH 3 for L.b brevis 14 and pH 4 for L.b plantarum 62, respectively 19 and 16, 66 mm. No inhibition was detected for the supernatant and neutralized supernatant, the maximum inhibition was obtained for the concentration × 4. The antifungal compounds produced by these Lactobacillus strains were heat resistant, active in large pH value, with a variable nature.

Biological preservatives are increasingly in demand as an alternative to chemicals, because of consumer’s health and environmental concerns. Lactic acid bacteria isolated from fermented olives, considered as extreme environment, may encompass significant antimicrobial activity against microorganisms involved in foodborne diseases and food spoilage. Three LAB strains (Levilactobacillus brevis S27, Lactiplantibacillus pentosus S42, and Lactiplantibacillus plantarum S62), isolated from fermented olive, were studied for their antimicrobial activity against pathogenic bacteria (Listeria innocua and E. coli) and yeast (Rhodotorula glutinis), involved in foodborne diseases and food spoilage. The microbial culture, cell-free supernatant (CFS) of all LAB strains showed inhibition zone (IZ) values ranges of 26.33-28.83 mm, 14.16-16.33 mm and 10-12.16 mm against R. glutinis, L. innocua and E. coli, respectively. The IZ values ranges obtained with NCFS (neutralized CFS at pH 7) against R. glutinis and L. innocua were respectively of 17.83-20.50 mm and 13.16-14.50 mm, whereas no inhibition was obtained against E. coli. Their bioactive molecules of proteinaceous nature showed that among the four peptide bands obtained, two bands of approximately 42 and 56 kDa are common for the three LAB strains (S27, S42 and S62). Two additional bands of 46 and 89kD are observed in S42 and S27, respectively. The minimum inhibitory concentration of 10-fold concentrated CFS (10xCFS) obtained was 5% against E. coli and 4.5% against L. innocua and R. glutinis. The 10xCFS of Lb. plantarum S62, selected as the most efficient strain against pathogens, demonstrated its effectiveness in decontamination of milk at concentrations of 0.45% (v/v) and 0.5% (v/v) against L. innocua and E. coli. The CFS allowed, at 0.5 mL/piece of 5 cm diameter, a total inhibition of R. glutinis, without affecting the color of Pastilla leaf. The CFS of Lb. plantarum S62 can be used as a bio-preservative against pathogenic bacteria (L. innocua and E. coli) in milk, and against R. glutinis in Pastilla leaf.

International audience; The aim of this work is to characterize the potential probiotic properties of 14 antifungal Lactobacillus strains isolated from traditional fermenting Moroccan green olives. The molecular identification of strains indicated that they are composed of five Lactobacillus brevis, two Lactobacillus pentosus, and seven Lactobacillus plantarum. In combination with bile (0.3%), all the strains showed survival rates (SRs) of 83.19–56.51% at pH 3, while 10 strains showed SRs of 31.67–64.44% at pH 2.5. All the strains demonstrated high tolerance to phenol (0.6%) and produced exopolysaccharides. The autoaggregation, hydrophobicity, antioxidant activities, and surface tension value ranges of the strains were 10.29–41.34%, 15.07–34.67%, 43.11–52.99%, and 36.23–40.27 mN/m, respectively. Bacterial cultures exhibited high antifungal activity against Penicillium sp. The cell-free supernatant (CFS) of the cultures showed important inhibition zones against Candida pelliculosa (18.2–24.85 mm), as well as an antibacterial effect against some gram-positive and gram-negative bacteria (10.1–14.1 mm). The neutralized cell-free supernatant of the cultures displayed considerable inhibitory activity against C. pelliculosa (11.2–16.4 mm). None of the strains showed acquired or horizontally transferable antibiotic resistance or mucin degradation or DNase, hemolytic, or gelatinase activities. Lactobacillus brevis S82, Lactobacillus pentosus S75, and Lactobacillus plantarum S62 showed aminopeptidase, β-galactosidase, and β-glucosidase activities, while the other enzymes of API-ZYM were not detected. The results obtained revealed that the selected antifungal Lactobacillus strains are considered suitable candidates for use both as probiotic cultures for human consumption and for starters and as biopreservative cultures in agriculture, food, and pharmaceutical industries.

Two novel symmetrical macrocycles containing four pyrazolic units, with two different side arms were synthesized and characterized. Their antibacterial activity was investigated by determining the ...

Background This work aims to study the optimal conditions of the fermentation culture medium used for the production of extracellular enzymes (amylase, cellulase, lipase, and protease) from previously isolated Aspergillus niger strains in date by-products. Results The five most powerful isolates selected based on the zone of degradation formed on Petri plates by the substrate were subjected to the quantitative evaluation of their enzymatic production. All five strains showed almost similar API-ZYM profiles, with minor variations observed at the level of some specific enzyme expression. The production of cellulase and amylase was depending on pH and incubation temperatures. ASP2 strain demonstrated the high production rate of amylase (at pH 5 and 30 °C) and cellulase (at pH 6 and 30 °C) for 96 h of incubation. Conclusion The A. niger showed the ability to produce several extracellular enzymes and can be used in the valorization of different agroindustrial residues.

This study aimed to examine the influence of two prebiotics, fructo-oligosaccharides (FOS) and xylo-oligosaccharides (XOS), on probiotic properties (resistance to low pH and bile salt, hydrophobicity and auto-aggregation), metabolites production, and antimicrobial activity of probiotic Lactiplantibacillus (L. pentosus S42 and L. plantarum S61) and Levilactobacillus (L. brevis S27) strains isolated from fermented olive. The results demonstrated the ability of strains to ferment XOS more than FOS as a sole carbon source, resulting in pH reduction. The prebiotics (FOS and XOS) significantly increased (p

The aim of the present study was to evaluate some technological properties and potential probiotic of 14 Lactobacillus strains isolated from brines of natural fermenting Moroccan Picholine green olive. The brine samples, collected from industrial environments, were analyzed for their Physico-chemical and microbiological properties. The Lactobacillus strains were characterized for their technological and physiological properties. The results obtained showed that the olive brines have an average pH of 4.32, an acidity of 0.61% and chloride contents of 6.42%. LAB and yeasts are the most dominant microorganisms in olive brine samples. The selected Lactobacillus (14 strains) showed low resistance to pH 2 and high resistance to bile salts (up to 2%), with values ranges from 1.98%-4.70% and 63.12%-86.48%, respectively. All the Lactobacillus strains displayed high levels of acidification and can produce β-glucosidase, protease, and cellulase in large amounts. The diacetyl production is detected in five Lactobacillus strains.

Fermented green olives process, occurring in extreme environment characterized by low nutrients and high polyphenols and sodium chloride contents, is dominated by lactic acid bacteria (LAB) and yeasts. The probiotic LAB strains, mostly isolated from various fermented Mediterranean olive varieties and different countries, were Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus paracasei, Lactobacillus rhamnosus, and Lactobacillus coryniformis. Deep studies on probiotic and safety properties of yeasts need to be developed. Probiotic LAB isolated from fermented olives demonstrated, basing in vitro and in vivo tests, various health beneficial effects, mainly the antibacterial, antifungal, and antiadhesive effects against pathogens, the protective effect against virus infections, anticancer, and metals detoxification activities. Autochthonous or nonautochthonous LAB strains improved the fermentation process, the storage conditions, and the functional property of olives and other food products. The optimization of probiotics selection and application conditions may enhance their health-beneficial effects and technological properties.

International audience; The objective of this work is to study the oleuropein (OLP) biodegradation by a strain of Lactobacillus plantarum FSO175 under conditions (pH 4.5, NaCl 5% and glucose 1%), during 7 days of incubation at 30 °C, in modified MRS broth containing OLP as carbon source. The results obtained, by HPLC analyses, showed that the biodegradation of OLP by L. plantarum FSO175, is accompanied with increase of hydroxytyrosol (HT) content and acidity values. The yields of OLP degradation and HT accumulation are depending on carbon sources, stress conditions and time of incubation. So that, the drastic reduction in OLP biodegradation, obtained at pH 6.7 (trial B), decreased significantly (p

The synthesis of new bipyrazolic ligands functionalized by carboxyl groups, namely 3-Bis(3′-carboxyl-5′-methyl-l'-pyrazolyl) propan-2-ol (L1) and 1,3-Bis(3′-carboxyl-5′-methyl-l '-pyrazolyl),2-methyl propane (L2) is reported. Their corresponding [C13H15CuN4O5] (CuL1) and [C14H16CuN4O4] (CuL2) copper (II) complexes are also elaborated and characterized by elemental analysis, FTIR an UV–visible spectroscopy. The crystal structure of the CuL1 complex confirms that copper atom is 4-coordinated, in a distorted square planar geometry within the molecule, and achieves its coordination through weak intermolecular interactions leading to two dimensional slabs. This geometry is in agreement with UV–visible results which also evidence that structure of complexes are affected in DMSO in contrast to methanol. No antibacterial activity against all the tested bacterial strains has been found for the Cu (II) complexes. By contrast, CuL1 is characterized with good catalytic properties in the air-oxidation of catechol substrate to quinone.