Analysis of Bioactive Aroma Compounds in Essential Oils from Algerian Plants: Implications for Potential Antioxidant Applications.

In samples of Artemisia campestris (AC), Artemisia herba-alba (AHA) and Salvia jordanii (SJ) essential oils, up to 200 distinct volatile compounds were identified. Using headspace solid-phase microextraction combined with gas chromatography-olfactometry-mass spectrometry (HS-SPME-GC-O-MS), different panelists detected 52 of these compounds. This study offers the most detailed analysis of bioactive compound profiles conducted so far. The most abundant compounds identified were curcumene, making up 12.96% of AC, and camphor, constituting 21.67% of AHA and 19.15% of SJ. The compounds with the highest odor activity value (OAV) were (E,Z)-2,4-nonadienal (geranium, pungent), 3-nonenal (cucumber) and 2-undecenal (sweet) in AC, AHA and SJ, respectively. AHA essential oil showed significant antioxidant activity (IC50 = 41.73 ± 4.14 mg/g) and hydroxyl radical generation (hydroxylation percentage = 29.62 ± 3.14), as assessed by the diphenylpicrylhydrazyl (DPPH) method. In terms of oxygen radical absorbance capacity (ORAC), the strongest antioxidant activity was obtained for SJ essential oil (antioxidant activity of the essential oils, AOX = 337.49 ± 9.87).

Leuconostoc mesenteroides and Liquorilactobacillus mali strains, isolated from Algerian food products, are producers of the postbiotic compounds dextran, oligosaccharides and mannitol.

Six lactic acid bacteria (LAB) isolated from Algerian sheep's milk, traditional butter, date palm sap and barley, which produce dextran, mannitol, oligosaccharides and vitamin B2 have been characterized. They were identified as Leuconostoc mesenteroides (A4X, Z36P, B12 and O9) and Liquorilactobacillus mali (BR201 and FR123). Their exopolysaccharides synthesized from sucrose by dextransucrase (Dsr) were characterized as dextrans with (1,6)-D-glucopyranose units in the main backbone and branched at positions O-4, O-2 and/or O-3, with D-glucopyranose units in the side chain. A4X was the best dextran producer (4.5 g/L), while the other strains synthesized 2.1-2.7 g/L. Zymograms revealed that L. mali strains have a single Dsr with a molecular weight (Mw) of ~ 145 kDa, while the Lc. mesenteroides possess one or two enzymes with 170-211 kDa Mw. As far as we know, this is the first detection of L. mali Dsr. Analysis of metabolic fluxes from sucrose revealed that the six LAB produced mannitol (~ 12 g/L). The co-addition of maltose-sucrose resulted in the production of panose (up to 37.53 mM), an oligosaccharide known for its prebiotic effect. A4X, Z36P and B12 showed dextranase hydrolytic enzymatic activity and were able to produce another trisaccharide, maltotriose, which is the first instance of a dextranase activity encoded by Lc. mesenteroides strains. Furthermore, B12 and O9 grew in the absence of riboflavin (vitamin B2) and synthesized this vitamin, in a defined medium at the level of ~ 220 µg/L. Therefore, these LAB, especially Lc. mesenteroides B12, are good candidates for the development of new fermented food biofortified with functional compounds.

Optimization of amylase production by the biological control agent Bacillus halotolerans RFP74 using response surface methodology.

BACKGROUND: Over the years, excessive use of chemical pesticides to control plant pathogens has caused environmental problems. Therefore, biological solutions such as the use of microorganisms with antimicrobial capacity become indispensable. To inhibit the growth of plant pathogens, biological control agents use different mechanisms, including the production of hydrolytic enzymes. In this study, the production of amylase, an enzyme important for the prevention and control of plant diseases, by a biological control agent Bacillus halotolerans RFP74 was optimized using response surface methodology. RESULTS: Bacillus halotolerans RFP74 inhibited the growth of various phytopathogens including Alternaria and Bipolaris with an inhibition rate of more than 60%. In addition, it also demonstrated an essential production of amylase. Based on previous studies of amylase production in Bacillus, three parameters were considered significant: initial pH of the medium, incubation time, and temperature. Using the central composite design with Design Expert software, the optimized amylase production for B. halotolerans RFP74 is at a temperature of 37 °C, incubation time 51 h and pH 6. CONCLUSION: The biological control agent B. halotolerans RFP74 inhibited the growth of Alternaria and Bipolaris, demonstrating its broad spectrum of activity. Knowledge of the optimal condition required for the production of hydrolytic enzymes such as amylase provides information on the most effective application of this biological control agent.

Polyphasic Characterisation of Non-Starter Lactic Acid Bacteria from Algerian Raw Camel's Milk and Their Technological Aptitudes.

RESEARCH BACKGROUND: Consumption of spontaneously fermented camel´s milk is common in Algeria, making it a feasible source of diverse lactic acid bacteria (LAB) with the potential to be used as adjunct cultures to improve quality and safety of fermented dairy products. EXPERIMENTAL APPROACH: Twelve raw camel´s milk samples were used as a source of indigenous LAB, which were further characterised by examining39 phenotypic traits with technological relevance. RESULTS AND CONCLUSIONS: Thirty-five non-starter LAB (NSLAB) were isolated from 12 Algerian raw camel's milk samples and they were microbiologically, biochemically and genetically characterised. Some isolates showed proteolytic activity, acidifying capacity, the ability to use citrate, and to produce dextran and acetoin. Ethanol, acetaldehyde, methyl acetate, acetoin and acetic acid were the major volatile compounds detected. Cluster analysis performed using the unweighted group with arithmetic average (UPGMA) method, and based on the thirty-nine phenotypic characteristics investigated, reflected the microbial diversity that can be found in raw camel´s milk. NOVELTY AND SCIENTIFIC CONTRIBUTION: The isolated strains, from a non-typical source, showed interesting technological traits to be considered as potential adjunct cultures. Cluster analysis based on the examined phenotypic characteristics proved to be a useful tool for the typification of isolates when no genetic information is available. These findings may be of use towards an industrialised production of camel's milk dairy products.

Three New Reports of Trichoderma in Algeria: T. atrobrunneum, (South) T. longibrachiatum (South), and T. afroharzianum (Northwest).

The genus Trichoderma (Hypocreaceae, Ascomycota) consists of globally distributed fungi. In Algeria, few studies have explored the diversity of this genus, and in the majority of works identification is based on phenotypic characters. Here, nine Trichoderma strains were collected from Algeria in different locations, namely: seven in the south and two in the northwest. Also, we used 17 reference strains that were taken from the NCBI database for the phylogeny analysis. Our study is based on an integrated approach using micro and macro phenotypic characters and multiple DNA analysis (internal transcribed spacer (ITS): ITS1-4 region; translation elongation factor 1: tef1 gene). Our study reports, for the first time, three species of Trichoderma in Algeria, namely: T. atrobrunneum (south), T. longibrachiatum (south), and T. afroharzianum (northwest). It is noteworthy that T. atrobrunneum is a species previously described in European Mediterranean countries, and its presence in the soil of southern Algeria indicates that the diversity of the geographic environments and different climates of Algeria offers the possibility for the survival of diverse Trichoderma species. Knowledge on the diversity of these fungi may contribute to their future exploitation in biotechnological applications and to the biological control of plant diseases.

Characterization of Staphylococcus aureus Isolated from Food Products in Western Algeria.

The current study aimed to characterize Staphylococcus aureus isolates from foodstuffs collected from western Algeria. A total of 153 S. aureus isolates from various raw and processed foods were obtained and identified using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. Isolates were characterized by antimicrobial susceptibility testing and toxin gene detection. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were identified by detection of the mecA gene and characterized by staphylococcal cassette chromosome mec (SCCmec) typing. We found that 30.9% (153/495) of food samples were contaminated with S. aureus. Thirty-three (21.5%) S. aureus isolates were identified as MRSA, and 16.9% (26/153) carried the mecA gene. Three SCCmec types were identified of which type IV was the most common (69.2%) followed by type V (15.3%) and type II (7.6%). Two MRSA isolates were not typable with SCCmec typing. None of the examined isolates harbored mecC. Furthermore, 14.3% (22/153) of the isolates were toxigenic S. aureus. The cytotoxin gene pvl was detected in 11.1% of the S. aureus isolates. This gene was more commonly detected (76.4%) in MRSA isolates than in methicillin-suceptible Staphylococcus aureus (MSSA) isolates. The tsst-1 gene coding for toxic shock syndrome toxin was isolated rarely (3.2%) and only in MSSA isolates. According to disk diffusion test results, 70 isolates were resistant to only one antimicrobial drug, and 51 (33.3%) isolates were multidrug resistant. Other 32 isolates were susceptible to all antibiotics. Our study highlights, for the first time, a high prevalence of multidrug-resistant S. aureus isolates carrying pvl or tsst-1 found in food products in Algeria. The risk of MRSA transmission through the food chain cannot be disregarded, particularly in uncooked foods.

Rheology and bioactivity of high molecular weight dextrans synthesised by lactic acid bacteria.

Dextrans synthesised by three Leuconostoc mesenteroides strains, isolated from mammalian milks, were studied and compared with dextrans produced by Lc. mesenteroides and Lactobacillus sakei strains isolated from meat products. Size exclusion chromatography coupled with multiangle laser light scattering detection analysis demonstrated that the dextrans have molecular masses between 1.74×108Da and 4.41×108Da. Rheological analysis of aqueous solutions of the polymer revealed that all had a pseudoplastic behaviour under shear conditions and a random, and flexible, coil structure. The dextrans showed at shear zero a difference in viscosity, which increased as the concentration increased. Also, the purified dextrans were able to immunomodulate in vitro human macrophages, partially counteracting the inflammatory effect of Escherichia coli O111:B4 lipopolysaccharide. During prolonged incubation on a solid medium containing sucrose, dextran-producing bacteria showed two distinct phenotypes not related to the genus or species to which they belonged. Colonies of Lc. mesenteroides CM9 from milk and Lb. sakei MN1 from meat formed stable and compact mucoid colonies, whereas the colonies of the other three Leuconostoc strains became diffuse after 72h. This differential behaviour was also observed in the ability of the corresponding strains to bind to Caco-2 cells. Strains forming compact mucoid colonies showed a high level of adhesion when grown in the presence of glucose, which decreased in the presence of sucrose (the condition required for dextran synthesis). However no influence of the carbon source was detected for the adhesion ability of the other Lc. mesenteroides strains, which showed variable levels of binding to the enterocytes.

Genomic and proteomic characterization of bacteriocin-producing Leuconostoc mesenteroides strains isolated from raw camel milk in two southwest Algerian arid zones.

Information on the microbiology of camel milk is very limited. In this work, the genetic characterization and proteomic identification of 13 putative producing bacteriocin Leuconostoc strains exhibiting antilisterial activity and isolated from camel milk were performed. DNA sequencing of the 13 selected strains revealed high homology among the 16S rRNA genes for all strains. In addition, 99% homology with Leuconostoc mesenteroides was observed when these sequences were analysed by the BLAST tool against other sequences from reference strains deposited in the Genbank. Furthermore, the isolates were characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDITOF MS) which allowed for the identification of 2 mass peaks 6242 m/z and 5118 m/z that resulted to be specific to the species L. mesenteroides. Remarkably, the phyloproteomic tree provided more intraspecific information of L. mesenteroides than phylogenetic analysis. Accordingly, phyloproteomic analysis grouped L. mesenteroides strains into different subbranches, while all L. mesenteroides isolates were grouped in the same branch according to phylogenetic analysis. This study represents, to our knowledge, the first report on the use of MALDI-TOF MS on the identification of LAB isolated from camel milk.

Recent patents on bacteriocins: food and biomedical applications.

Most types of bacteria produce bacteriocins, which are proteinaceous extracellular compounds that can inhibit the growth of other undesirable microorganisms. Bacteriocins are receiving increasing attention, due to their many applications, ranging from their initial application in strategies for food preservation to more recent proposed uses in biomedical strategies aimed at fighting certain bacterial infections. Thus, while nisin has a long history of use as a safe additive in certain food products for the purpose of food preservation, certain bacteriocin-producing lactic acid bacteria, which are generally recognised as safe microorganisms, or their extracellular extracts are receiving increased attention as protective cultures or antimicrobial extracts in minimally processed food products. More recently, a number of these bacteriocinproducing cultures have been proposed for use in other applications, such as in probiotics, for the inhibition of biofilms in the food industry, or even as coadjuvants of combined therapeutical strategies along with other antimicrobial agents in biomedical applications. This review aims to provide a brief overview of the most relevant recent patents in this field.

Antimicrobial activity of lactic acid bacteria and the spectrum of their biopeptides against spoiling germs in foods

The objective of this study was to isolate LAB from dairy, meat products and agro-industrial wastes and to investigate their antagonist activity. A total of 141 isolates were screened for the inhibitory effect on ten indicator strains in the agar spot test. Results showed that strain LBbb0141 contained antimicrobial compound with wide spectrum that inhibited the growth of ten indicator Gram-positive and Gram-negative strains. The bacteriocin activity attained its maximum value using the MRS agar at initial pH 7.5 and 30°C incubation temperature.