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El-klila, Jben, Rayeb and Lben are artisanal dairy products typical of the North African region. These products are considered a good source of nutrients and a vector par excellence of indigenous lactic acid bacteria with significant technological and therapeutic potential. In this study, fifty-two Lactobacillus isolates from traditional dairy products (El-Klila, Jben and Rayeb) from the Ain Sefra region (southwestern of Algeria) were identified by phenotypic, genotypic and MALDI-TOF mass spectrometry methods. Phenotypic characterization allowed dividing the isolates into two groups: 7.69% of isolates mesophilic and strict heterofermentative and 92.31% isolates mesophilic and optional heterofermentative. The isolates identification by sequencing 16S rDNA was performed using the universal primers w02 and w18. Comparing the sequences of the isolates with the GenBank database (NCBI) revealed a high percentage with five species of Lactobacillus. Of the 52 isolates, thirteen were identified as Lactobacillus paracasei, four isolates were L. brevis, five isolates were L. rhamnosus and ten isolates were L. plantarum. The lasting twenty isolates were related, at the same time, to the plantarum species and the pentosus species. The use of MALDI-TOF mass spectrometry confirmed the identity of 36 strains of Lactobacillus. Of the 20 isolates related to the plantarum / pentosus group by 16S rDNA, 50% were identified as L. plantarum. Finally, the results of the two combined methods allowed us to correctly identify 80.76% of the Lactobacillus isolates at the genus and species level. The analysis by MALDI-TOF SM has proved to be a very reliable, fast (less than an hour) and inexpensive tool for identifying native Lactobacillus species from artisanal dairy products. This method can constitute a major tool for the study of the microbial biodiversity of artisanal food products.

Lactobacilli are of great importance to humans, as they are essential members of a healthy human microbiota at various niches and serve as biologically and functionally important components of a healthy human diet. For this reason, the isolation of lactobacilli strains from infant feces (less than 6 months old) was carried out in Bechar region, Algeria. In total, 62 strains were isolated, purified, and identified based on the physiological and biochemical methods. For final confirmation, API 50 CHL gallery was used. The iden ca on and phylogenetic analysis of isolated strains was performed by sequencing the 16S rRNA gene, which led us to identify four species with different percentages; Lactobacillus rhamnosus, L. fermentum, L.mucosa, L. plantarum. With regard to the characteristics of technological interest, most of the identified strains exhibited good lactic acid production. However, it was not until after 3 hours of incubation at 37 °C that isolated lactobacilli produced a maximum acidity, which reached Δ pH 0.54 in the reconstituted milk. The results were different with camel milk, in the first time, and this was observed in the acidity rate which was generally lower in this type of milk in which acidity reached Δ pH 0.47 .As regards the proteolytic power, the strains showed a high level of proteolysis. Regarding the lipolytic activity, it was observed that none of the lactobacilli tested expressed lipolytic activity in the presence of buffer and olive oil, whereas the results of the strains were different as regards the flavoring activity and the texturing activity.

The objective of this study is to isolate and characterize strains Helicobacetr pylori from gastric biopsies by upper gastrointestinal endoscopy. After a rapid urease test, two Helicobacter pylori strains isolated from four patients on blood agar. After extraction of DNA from these strains from homogenates of gastric biopsies, quantification by real-time PCR was performed to determine Helicobacter pylori on the one hand and sensitivity to clarithromycin species. Melting curve analyzes showed that these two strains are sensitive to the antibiotic.

The fitness of a particular strains of Bifidobacteria, Lactobacilli and Streptococci for commercial utilization depends on its rapid growth and acidification of milk as well as its acid and oxygen tolerence. From 20 samples of French commercial yoghurt, one species of bifidobacteria was identified as Bifidobacterium longum. Also, Lactobacillus acidophilus was isolated and identified from fermented milk. The rate of growth was 0.37 h-1 on TPY medium and 0.18 h-1 in milk with Bifidobactrium longum. The production of lactic acid was compared with pure and mixed cultures and the values were 90 and 64 mM at 37°C; 82 and 140 mM at 45°C. The maximum rate of lactic acid production was obtained with mixed culture at 45°C.Key words: Bifidobacterium longum, Lactobacillus acidophilus, fermented milk, growth, lactic acid.

The purpose of this research was to evaluate, the effect of incubation temperature and some substrates on exopolysaccharides (EPS) production. The S. thermophilus BN1 an EPS-producer strain isolated from cow milk was examined in this study. Skimmed milk, whole milk and cheese whey, were selected as culture media and two different temperatures were also tested. The EPS produced in the different studied conditions was purified and quantified. The strain BN1 was able to produce EPS in all established conditions. However, significant differences were observed in the amounts of produced EPS. The strain has been shown to produce high amounts of EPS at 37°C compared to 42°C (P

A recombinant strain of Lactococcus lactis displaying a cell-surface anchored fibronectin binding protein A (FnBPA) from Staphylococcus aureus (LL-FnBPA) had been shown to be more efficient in delivering plasmid than its wild-type counterpart both in vitro and in vivo, and have the ability to orientate the immune response toward a Th2 profile in a context of a DNA vaccination. The aim of this work was to test whether this LL-FnBPA strain could shape the immune response after mucosal administration in mice. For this, we used a mouse model of human papilloma virus (HPV)-induced cancer and a L. lactis strain displaying at its cell surface both HPV-16-E7 antigen (LL-E7) and FnBPA (LL-E7 + FnBPA). Our results revealed a more efficient systemic Th1 immune response with recombinant LL-E7 + FnBPA. Furthermore, mice vaccinated with LL-E7 + FnBPA were better protected when challenged with HPV-16-induced tumors. Altogether, the results suggest that FnBPA displays adjuvant properties when used in the context of mucosal delivery using L. lactis as a live vector. (C) 2016 Published by Elsevier Ltd.

The ability of Pseudomonas to grow and to produce siderophores is dependent on the iron content and the type of carbon sources in the medium. Under conditions of low-iron concentration the Pseudomonas isolates studied produced yellow-green fluorescent iron-binding peptide siderophores and the biosynthesis of this siderophores was affected by several different environmental parameters. Four basal media, supplemented with different concentration of iron, were employed to study the effect of iron and different organic carbon sources on siderophore production in Pseudomonas fluorescens. The highest siderophores concentration was obtained in succinate medium. Ferric iron increased the growth yield and completely repressed siderophores production above 200 μg/l, but had a positive effect below 160μg/l. Penicillin and lead elicited the production of siderophores in the presence of excess iron. Pre-treatment of the standard succinate medium with a,a-dipyridyl and 8-hydroxyquinoline to reduce the concentration of iron diminished both the growth yield and siderophore production, but a,a-dipyridyl increased significantly the amount of siderophores produced in the presence of 0.20 mg/l of the chelating ion.African Journal of Biotechnology Vol. 4 (7), pp. 697-702, 2005

Under CC BY 3.0 license. © The Author(s).-- Trabajo presentado en la International Conference on Applied Life Sciences (ICALS2012), celebrada en Turquía del 10 al 12 de septiembre de 2012. Turkey, September 10-12, 2012, This investigation describes three strains of Streptococcus thermophilus on the basis of production of acetaldehyde as aroma compounds. The strains under study (BN1, BN2 and BN3) were isolated from Algerian raw milk and were identified according to microbiological, biochemical, and genetic criteria. The growth of the strains and the determination of acetaldehyde were performed on M17 medium added to 0.5 and 3% (w/v) of lactose and sucrose. It was observed that the produced biomass (log cfu/ml), reached high values in the presence of 3% (w/v) of lactose and sucrose compared to that posted with 0.5% (w/v). The strains appeared to produce acetaldehyde. This production was more powerful in the case of concentration 3% (w/v) of lactose and sucrose. Strain BN1 produced approximately 205±75μmol and 218±90μmol of acetaldehyde respectively in the presence of 3% (w/v) of lactose and sucrose. This ratio was significantly higher (P

2nd International Conference on Biology, Environment and Chemistry (ICBEC). 28-30 december, 2011, Dubai, United Arab Emirates., This work investigates the influence of incubation temperature and culture media on exopolysaccharides (EPS) production. The S. thermophilus BN1 an EPS-producer strain isolated from cow milk was examined in this study. Skimmed milk, whole milk and cheese whey, were selected as culture media and two different temperatures were also tested. The EPS produced in the different studied conditions was purified and quantified. The strain BN1 was able to produce EPS in all established conditions. However, significant differences were observed in the amounts of produced EPS. The production of EPS reached the maximum values at 37°C in skimmed milk with amount of 548 PDM mg l-1, followed by the amounts of 375 PDM mg l-1 and 325 PDM mg l -1 respectively in whey and whole milk. In addition, a slight significant difference was noted on the biomass, pH and lactic acid values obtained from the three fermented substrates (p